CN100536182C - Nitride semiconductor device - Google Patents

Abstract

In order to improve the luminous output power and expand the application range of various application products of nitride semiconductor light-emitting elements by utilizing the characteristics of the active layer of the multi-quantum well structure, the n-side region with multiple nitride semiconductor layers and the In a nitride semiconductor light-emitting element in which an active layer is provided between the p-side regions of the multilayer nitride semiconductor layer, at least one of the n-side region and the p-side region is formed by laminating two kinds of nitride semiconductor films. multilayer film.

Description

Nitride semiconductor device

technical field

The present invention relates to nitride semiconductors (for example, In _{x Aly} Ga _{1- xy} N, 0≤x, 0≤y, x+y≤1) elements.

Background technique

Nitride semiconductors, as materials for high-brightness blue LEDs and pure green LEDs, have been practically used in various light sources such as full-color LED displays, traffic lights, and image scanner light sources. These LED elements basically have a structure in which the following layers are sequentially stacked on a sapphire substrate: a buffer layer made of GaN, an n-side contact layer made of GaN doped with Si, and a single quantum well structure (SQW: Single Quantum Well) with InGaN. -Quantum-Well) or an active layer with an InGaN multi-quantum well structure (MQW: Multi-Quantum-Well), a p-side cladding layer made of Mg-doped AlGaN, made of Mg-doped GaN The p-side contact layer; these components also show very excellent performance, that is, when the current is 20mA, the power is 5mW in the blue LED with the emission wavelength of 450nm, the external quantum efficiency is 9.1%, and the emission wavelength is 520nm The green LED has a medium power of 3mW and an external quantum efficiency of 6.3%.

In this way, a double heterostructure with an active layer is used in a nitride semiconductor light emitting device, and the active layer is an active layer with a single quantum well structure or a multiple quantum well structure with a well layer made of InGaN .

In addition, in nitride semiconductor light-emitting devices, since the multi-quantum well structure has a structure composed of a plurality of microstrips (mini band), the efficiency is high, and light can be realized even with a small current, so it can be expected that the single quantum well structure Improvement of device characteristics such as improvement of luminous output.

For example, as an LED element using an active layer of a multi-quantum well structure, a nitride semiconductor element is disclosed in Japanese Unexamined Patent Publication No. 10-135514. In order to improve its luminous efficiency and luminous intensity, the nitride semiconductor The element has at least the following layers: a barrier layer made of non-doped GaN, a light-emitting layer of a multi-quantum well structure composed of a well layer made of non-doped InGaN, and a barrier layer higher than the light-emitting layer. A cladding layer with a wide band gap.

However, when the active layer is made into a multi-quantum well structure, compared with the active layer of a single quantum well structure, the overall film thickness of the active layer is thicker, so there will be an increase in the vertical series resistance, for example , Vf (forward voltage) tends to increase in LED elements.

As a technique that may be used to lower Vf, for example, Japanese Patent Application Laid-Open No. 9-298341 describes a method in which the p-side optical waveguide layer and contact layer above the active layer are made of a superlattice layer containing an InAlGaN layer. laser components. This technology is to make the p-type nitride semiconductor layer into a superlattice structure of an In-containing nitride semiconductor layer. The nitride semiconductor layer contains In to increase the carrier concentration of the p-layer, thereby reducing the laser intensity. Component thresholding techniques. However, in reality, quaternary mixed crystal nitride semiconductors such as InAlGaN have poor crystallinity, and it is difficult to make In-containing nitride semiconductors p-type, so it is actually difficult to manufacture LED elements or LD elements.

Therefore, although the active layer of such a multiple quantum well structure can be expected to greatly increase the light emission output, it is difficult to fully realize the desired possibility.

In addition, with regard to the LD element, the applicant once published a nitride semiconductor laser element containing an active layer on a nitride semiconductor substrate, which achieved a continuous oscillation of more than 10,000 hours at room temperature for the first time in the world (ICNS '97 Collection of Manuscripts, October Issue 27-31, 1997, P444-446; and Jpn.J.Appl.Phys.Vol.36(1997)pp.L1568-1571 Part2, No.12A, December 1, 1997 ).

However, for example, in order to use LED elements for lighting sources, outdoor display devices exposed to direct sunlight, etc., elements with a further lower Vf and high luminous efficiency are required. In addition, in order to use an LD element in a light source such as an optical reader, further improvements such as lowering its threshold value and increasing its lifetime must be made.

In addition, recently, in a light-emitting device using this nitride semiconductor, research has been carried out. As disclosed in JP-A No. 8-97468, a p-side electrode, which has conventionally formed a p-side electrode with GaN, is formed using InGaN having a band gap energy smaller than that of GaN. type contact layer. That is, by using InGaN having a small bandgap energy, the potential barrier between the p-type contact layer and the p-side electrode is lowered to obtain good ohmic contact.

However, InGaN is difficult to grow as a film with few defects and good crystallinity, and it is difficult to obtain a desired ohmic contact with sufficiently low contact resistance. In addition, there is also a problem that contact resistance is unstable due to variations in the crystallinity of the formed InGaN layer. Therefore, it is difficult for a conventional nitride semiconductor device having a p-type contact layer made of InGaN to obtain a sufficiently low and stable operating voltage and a high output power at the same time. Therefore, for example, when constituting an LED element using a contact layer made of InGaN, there is a problem that the forward voltage (Vf) at 20 mA cannot be as low as 3.4V to 3.8V, and the variation is large.

In addition, elements made of nitride semiconductors may deteriorate even at a voltage of 100V, which is far lower than the static electricity generated by the human body, due to their structure, so care must be taken when handling them. Therefore, in order to further improve the reliability of the nitride semiconductor device, it is required to further improve its static voltage withstand performance.

Contents of the invention

The present invention is proposed in view of the above facts, and its purpose is mainly to increase the output power of nitride semiconductor elements such as LEDs and LDs, while reducing Vf and threshold value, so as to improve the luminous efficiency of the elements. Improving luminous efficiency is linked to improving the efficiency of other electronic devices using nitride semiconductors, such as photosensitive elements.

In addition, the object of the present invention is to use the active layer of multi-quantum well structure to give full play to its characteristics in order to further increase the luminous output power and expand the applicable range of various application products of nitride semiconductor light-emitting elements.

In addition, the object of the present invention is to provide a nitride semiconductor element, which can reduce the contact resistance between the p-side electrode and the p-type contact layer, and can obtain high output power at a stable low operating voltage .

Furthermore, the object of the present invention is to provide a nitride semiconductor light-emitting element capable of increasing the luminous output and having good static voltage resistance.

In the first nitride semiconductor device of the present invention, the Vf and the threshold value are lowered and the luminous efficiency is improved by the following configuration.

That is, the first nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer;

或以下。It is characterized in that at least one nitride semiconductor layer in the n-side region has a structure in which a first nitride semiconductor film containing In and a second nitride semiconductor film having a composition different from that of the first nitride semiconductor film are laminated. The n-side multilayer film layer, the film thickness of at least one of the above-mentioned first nitride semiconductor film or the above-mentioned second nitride semiconductor film is 100

or below.

或以下，最优选为50

或以下。由于通过这样地降低膜厚，多层膜层形成为超晶格结构，可以改善多层膜层的结晶性，因此能够提高它的输出功率。另外，有源层优选为至少含有In的氮化物半导体，优选为具有由InGaN构成的阱层的单量子阱结构或多量子阱结构。In the first nitride semiconductor element of the present invention, it is preferable that both the first nitride semiconductor film and the second nitride semiconductor film are 100 or below, more preferably 70

or below, most preferably 50

or below. By reducing the film thickness in this way, the multilayer film is formed into a superlattice structure, and the crystallinity of the multilayer film can be improved, so that its output can be improved. In addition, the active layer is preferably a nitride semiconductor containing at least In, and preferably has a single quantum well structure or a multiple quantum well structure having a well layer made of InGaN.

In addition, in the first nitride semiconductor device of the present invention, the first nitride semiconductor film is In _x Ga _1-x N (0<x<1), and the second nitride semiconductor film is In _y Ga _1-y N (0≤y<1, Y<X), most preferably GaN.

Furthermore, in the first nitride semiconductor device of the present invention, the film thickness of at least one of the first nitride semiconductor film or the second nitride semiconductor film may be such that the adjacent first nitride semiconductor film The films or the adjacent second nitride semiconductor films are different from each other. That is, in the case of forming a multilayer film layer in which the first nitride semiconductor film or the second nitride semiconductor film is laminated, the two layers of the second nitride semiconductor film (first nitride semiconductor film) are interposed. The film thickness of the first nitride semiconductor film (second nitride semiconductor film) may be different from each other.

Furthermore, in the first nitride semiconductor device of the present invention, the composition of the group III element in at least one of the first nitride semiconductor film or the second nitride semiconductor film may be such that, in the adjacent first nitride semiconductor film, Compositions of the same group III element are different from each other in the nitride semiconductor film or the adjacent second nitride semiconductor film. That is, in the case of forming a multilayer film layer in which the first nitride semiconductor film or the second nitride semiconductor film is laminated, the two layers of the second nitride semiconductor film (first nitride semiconductor film) are interposed. The ratio of the composition of the group III elements in the first nitride semiconductor film (second nitride semiconductor film) may be different from each other.

In addition, in the first nitride semiconductor device of the present invention, the n-side multilayer film layer may be formed separately from the active layer, but it is preferably formed in contact with the active layer in order to further increase output power.

In addition, in the first nitride semiconductor device of the present invention, the first nitride semiconductor film and the second nitride semiconductor film may be undoped. Here, the term "undoped" refers to a state in which impurities are intentionally not doped. For example, impurities mixed from adjacent nitride semiconductor layers due to diffusion are also referred to as undoped in the present invention. In addition, the concentration of impurities mixed by diffusion is distributed in a gradient in each layer in many cases.

In addition, in the first nitride semiconductor device of the present invention, either the first nitride semiconductor film or the second nitride semiconductor film may be doped with an n-type impurity. This kind of doping is called modulation doping, and the output power can be improved by modulation doping. In addition, as n-type impurities, group IV and group VI elements such as Si, Ge, Sn, and S can be selectively used, and Si and Sn are preferably used.

Furthermore, in the first nitride semiconductor device of the present invention, both the first nitride semiconductor film and the second nitride semiconductor film may be doped with n-type impurities. When doping n-type impurities, the concentration of the impurities is adjusted to be 5×10 ²¹ /cm ³ or less, preferably 1×10 ²⁰ /cm ³ or less. If it exceeds 5×10 ²¹ /cm ³ , the crystallinity of the nitride semiconductor layer deteriorates, and the output power tends to decrease on the contrary. The same applies to the case of modulation doping.

或以下。另外，在本发明中，进而优选第三氮化物半导体膜和第四氮化物半导体膜两者都在100或以下，进而优选在70

或以下，最优选为在50或以下。由于通过像这样地使膜厚减薄，多层膜层会成为超晶格结构，多层膜层的结晶性有所改善，因此可以提高输出功率。Furthermore, in the first nitride semiconductor device of the present invention, as the nitride semiconductor layer in the p-side region, there is a third nitride semiconductor film containing Al and a fourth nitride semiconductor film having a composition different from that of the third nitride semiconductor film. A p-side multilayer film layer formed by stacking compound semiconductor films, and preferably at least one of the third nitride semiconductor film or the fourth nitride semiconductor layer has a film thickness of 100

or below. In addition, in the present invention, it is further preferable that both the third nitride semiconductor film and the fourth nitride semiconductor film are at 100 or below, and preferably at 70

or below, most preferably at 50 or below. By reducing the film thickness in this way, the multilayer film becomes a superlattice structure, and the crystallinity of the multilayer film is improved, so that the output can be increased.

Furthermore, in the first nitride semiconductor device of the present invention, the third nitride semiconductor film is preferably Al _a Ga _1-a N (0<a≤1), and the fourth nitride semiconductor film is preferably In _b Ga _1-b N (0≤b<1, b<a), and it is more preferable that the fourth nitride semiconductor film is GaN.

In addition, in the first nitride semiconductor device of the present invention, the film thickness of at least one of the third nitride semiconductor film or the fourth nitride semiconductor film may be such that the adjacent third nitride semiconductor film The fourth nitride semiconductor films between or adjacent to each other are different from each other. That is, in the case of laminating the third nitride semiconductor film or the second nitride semiconductor film in multiple layers, the fourth nitride semiconductor film sandwiching the third nitride semiconductor film (fourth nitride semiconductor film) The film thickness of the film (third nitride semiconductor film) may also be different from each other.

Furthermore, in the first nitride semiconductor device of the present invention, the composition of the Group III element in at least one of the third nitride semiconductor film or the fourth nitride semiconductor film may be such that, in the adjacent third nitride semiconductor film, Compositions of the same group III element are different between the nitride semiconductor film and the adjacent fourth nitride semiconductor film. That is, in the case of forming a multilayer film layer in which a third nitride semiconductor film or a fourth nitride semiconductor film is laminated, the fourth nitride semiconductor film (fourth nitride semiconductor film) is sandwiched between the third nitride semiconductor film (fourth nitride semiconductor film). The composition ratios of group III elements in the nitride semiconductor film (third nitride semiconductor film) may also be different from each other.

Furthermore, in the first nitride semiconductor device of the present invention, the p-side multilayer film layer may be formed separately from the active layer, like the n-side multilayer film layer, but is preferably formed in contact with the active layer. By forming in contact with the active layer in this way, output power can be improved.

In addition, in the first nitride semiconductor device of the present invention, the third nitride semiconductor film and the fourth nitride semiconductor film may be undoped. When making the p-side multilayer film layer an undoped film layer, it is preferable to make its film thickness 0.1 μm or less. If it is thicker than 0.1 μm, it will be difficult to inject holes into the active layer, and the output power will tend to decrease easily. In addition, the definition of non-doping is the same as that of the n-side multilayer film.

In addition, in the first nitride semiconductor device of the present invention, either the third nitride semiconductor film or the fourth nitride semiconductor film may be doped with p-type impurities. By modulating the doping in this way, the output power tends to be improved easily. In addition, as p-type impurities, group II elements such as Mg, Zn, Cd, Be, and Ca can be selected, and Mg and Be are preferably used.

In addition, in the first nitride semiconductor device of the present invention, both the third nitride semiconductor film and the fourth nitride semiconductor film may be doped with p-type impurities. When doping p-type impurities, the concentration of the impurities should be adjusted to 1×10 ²² /cm ³ or below, preferably 5×10 ²⁰ /cm ³ or below. If it exceeds 1×10 ²² /cm ³ , the crystallinity of the nitride semiconductor layer deteriorates, which tends to lower the output. This is the same in the case of modulation doping.

In the second to fifth nitride semiconductor elements of the present invention, the luminous output of the nitride semiconductor element using the active layer of the multi-quantum well structure is improved by the following configuration, and the application of the nitride semiconductor element is expanded. range of nitride semiconductor devices.

That is, the second nitride semiconductor film of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, and is characterized in that in:

The at least one nitride semiconductor layer in the above-mentioned n-side region is the first n-side multilayer film layer formed by laminating at least two kinds of nitride semiconductor films, and the at least two kinds of nitride semiconductor films are doped with different concentrations of n Type impurities, and have different band gap energies;

At least one nitride semiconductor layer in the above-mentioned p-side region is a p-side multilayer film cladding layer formed by stacking third and fourth nitride semiconductor films, and the third and fourth nitride semiconductor films are respectively doped with Formed by p-type impurities, and the band gap energy is different from each other;

The above-mentioned active layer is a multi-quantum well structure composed of In _a Ga _1-a N (0≤a<1).

In addition, the third nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, and is characterized in that in:

The at least one nitride semiconductor layer in the above-mentioned n-side region is the first n-side multilayer film layer formed by laminating at least two kinds of nitride semiconductor films, and the at least two kinds of nitride semiconductor films are doped with different concentrations of n-type Impurities, having the same composition;

At least one nitride semiconductor layer in the above-mentioned p-side region is a p-side multilayer film cladding layer formed by stacking third and fourth nitride semiconductor films, and the third and fourth nitride semiconductor films are respectively doped with Formed by p-type impurities, and the band gap energy is different from each other;

The above-mentioned active layer is a multi-quantum well structure composed of In _a Ga _1-a N (0≤a<1).

In addition, in the second and third nitride semiconductor elements of the present invention, the concentration of the p-type impurity in the third nitride semiconductor film and the concentration of the p-type impurity in the fourth nitride semiconductor film may be different, or Can be the same.

In addition, the fourth nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, and is characterized in that in:

The at least one nitride semiconductor layer in the above-mentioned n-side region is a first n-side multilayer film layer formed by laminating at least two kinds of nitride semiconductor films, the at least two kinds of nitride semiconductor films having different concentrations of doped with The same composition of n-type impurities;

At least one nitride semiconductor layer in the p-side region is a p-side single-layer cladding layer composed of _{AlbGa1 -bN} (0≤b≤1) containing p-type impurities;

The above-mentioned active layer is a multi-quantum well structure composed of In _a Ga _1-a N (0≤a<1).

In addition, in the third or fourth nitride semiconductor element, it is preferable that the n-side first multilayer film layer is formed by stacking two kinds of nitride semiconductor films, and the two kinds of nitride semiconductor films are respectively composed of GaN, The n-type impurities are doped at mutually different concentrations.

Furthermore, the fifth nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, and is characterized in that in:

The at least one nitride semiconductor layer in the n-side region is a first n-side multilayer film formed by laminating at least two kinds of nitride semiconductor films, the at least two kinds of nitride semiconductor films are doped with different concentrations of n-type impurities, and the band gap energy is also different;

At least one nitride semiconductor layer in the p-side region is a p-side single-layer cladding layer composed of _{AlbGa1 -bN} (0≤b≤1) containing p-type impurities;

The above-mentioned active layer is a multi-quantum well structure composed of In _a Ga _1-a N (0≤a<1).

In addition, in the second to fifth nitride semiconductor elements, it is preferable to have an n-side second multilayer film layer between the above-mentioned n-side first multilayer film layer and the active layer, and the n-side second multilayer film layer The film layer is formed by laminating a first nitride semiconductor film containing In and a second nitride semiconductor film having a composition different from that of the first nitride semiconductor film.

Furthermore, in the second to fifth nitride semiconductor elements, in the n-side region, an n-side contact layer containing n-type impurities may be formed on the side closer to the substrate than the n-side first multilayer film layer. .

Further, in the second to fifth nitride semiconductor elements, it is preferable that the n-side contact layer is formed on the upper surface of the undoped GaN layer.

In addition, in the second to fifth nitride semiconductor elements, it is preferable that the above-mentioned undoped GaN layer is formed on a buffer layer composed of Ga _d Al _1-d N (0<d≤1) grown at a low temperature, and more preferably Further, a p-side GaN contact layer containing Mg as a p-type impurity may be formed on the p-side multi-layer coating layer or the p-side single-layer coating layer.

That is, in the second to fifth nitride semiconductor elements of the present invention, the n-side first multilayer film layer and the p-side multilayer film cladding layer or p-side A combination of single-layer film cladding layers is formed to improve luminous efficiency. Wherein, the n-side first multilayer film layer is composed of two or more nitride semiconductor layers with different n-type impurity concentrations on the n-side, and the p-side multilayer film cladding layer is formed on the p-side Composed of the third and fourth nitride semiconductor films, the p-side single-layer film cladding layer contains p-type impurities and is composed of Al _b Ga _1-b N (0≤b≤1).

By combining multiple nitride semiconductor layers having a specific composition, structure, etc. in this way, the performance of the active layer of the multi-quantum well structure can be efficiently exhibited. In addition, other nitride semiconductor layers preferable for combination with the active layer of the multi-quantum well structure are described below.

In the second to fifth nitride semiconductor elements of the present invention, if there is a first nitride semiconductor film containing In between the n-side first multilayer film layer and the active layer and a The n-side second multi-layer film formed by stacking the second nitride semiconductor film with different composition of the nitride semiconductor film can further improve the luminous efficiency, and meanwhile can reduce Vf to improve the luminous efficiency.

Furthermore, in the second to fifth nitride semiconductor elements of the present invention, if the n-side contact layer containing n-type impurities is formed on the side closer to the substrate than the above-mentioned n-side first multilayer film layer, the light emission can be improved. Output power, but also can reduce Vf.

Furthermore, in the second to fifth nitride semiconductor elements of the present invention, if the n-side contact layer is formed on the undoped GaN layer, the undoped GaN layer can be used as a crystallinity good Therefore, the crystallinity of the n-side contact layer as a layer forming the n-electrode can be improved, and the crystallinity of other nitride semiconductor layers such as the active layer formed on the n-side contact layer can be improved, so that further Increase luminous output power.

In addition, in the second to fifth nitride semiconductor devices of the present invention, if the above-mentioned undoped GaN layer is formed on a buffer composed of Ga _d Al _1-d N (0<d≤1) grown at low temperature layer, the crystallinity of the non-doped GaN layer can be further improved, and the crystallinity of the n-side contact layer can be further improved, so the luminous output power can be further improved; If a p-side GaN contact layer doped with Mg is formed on the cladding layer or a p-side single-layer film cladding layer, good p-type conductivity can be obtained. At the same time, the p-side GaN contact layer and the p-electrode formed thereon There is a good ohmic contact between them, which can further increase the output power of the light.

In addition, the sixth nitride semiconductor device of the present invention was completed after discovering that, by making the p-type contact layer containing In into a superlattice structure, it is possible to form a semiconductor device with few defects and good crystallinity. The p-type contact layer provides a nitride semiconductor element capable of obtaining stable high output power at a low operating voltage.

That is, in the sixth nitride semiconductor device of the present invention, an active layer is provided between a p-side region having a multilayer nitride semiconductor layer including a p-type contact layer and an n-side region including a multilayer nitride semiconductor layer. A nitride semiconductor element, characterized in that:

The p-type contact layer has a superlattice structure in which films including first and second nitride semiconductor films having different compositions are sequentially stacked, and among the two kinds of nitride semiconductor films, at least the first nitride semiconductor film Contains In.

Thus, the contact resistance between the p-side electrode and the p-type contact layer can be reduced, and high output power can be obtained at a stable low operating voltage.

In addition, in the sixth nitride semiconductor device of the present invention, it is preferable to form a composition graded layer whose composition continuously changes between the above-mentioned first nitride semiconductor film and the above-mentioned second nitride semiconductor film. By changing the composition of the first nitride semiconductor film to the composition of the above-mentioned second nitride semiconductor film, the crystallinity of the p-type contact layer can be further improved.

In addition, in the sixth nitride semiconductor device of the present invention, it is preferable to set the In content of the first nitride semiconductor film to be higher than the In content of the second nitride semiconductor film. In this way, the resistance of the p-type contact layer can be further reduced.

In addition, in the sixth nitride semiconductor device of the present invention, when one of the above-mentioned two types of nitride semiconductor layers is an In-containing layer, it is preferable that one of the above-mentioned first nitride semiconductor films is made of _{InxGa1 -xN} The other second nitride semiconductor film is a layer made of _{AlyGa1 -yN} .

Furthermore, in the sixth nitride semiconductor device of the present invention, either one of the first nitride semiconductor film and the second nitride semiconductor film may be doped with a p-type impurity, while the other may not be doped. p-type impurities.

In addition, in the sixth nitride semiconductor device of the present invention, when the first and second nitride semiconductor films are each doped with a p-type impurity, it is preferable that one nitride semiconductor layer is doped with 1×10 ¹⁹ /cm ³ to 5×10 ²¹ /cm ³ of p-type impurities, the other nitride semiconductor layer is doped in the range of 5×10 ¹⁸ /cm ³ to 5×10 ¹⁹ /cm ³ One nitride semiconductor layer is doped with a smaller amount of p-type impurities.

In addition, in the sixth nitride semiconductor device of the present invention, it is preferable that the first nitride semiconductor film is formed on the outermost surface, and the p-side electrode is formed in contact with the nitride semiconductor layer formed on the outermost surface. In addition, at this time, it is preferable to make the concentration of the p-type impurity in the first nitride semiconductor film larger than the concentration of the p-type impurity in the second nitride semiconductor film.

Furthermore, in the sixth nitride semiconductor device of the present invention, a p-type cladding layer made of a nitride semiconductor containing Al may be provided between the active layer and the p-type contact layer.

In the sixth nitride semiconductor device of the present invention, it is preferable that the P-type cladding layer has a layer composed of Al _x Ga _1-x N (0<x ≤ 1) and a layer composed of In _y Ga _1-y N (0 ≤y<1) is a superlattice structure formed by alternately stacking layers.

As described above, the sixth nitride semiconductor device of the present invention has a superlattice structure in which the first and second nitride semiconductor films having different compositions are alternately stacked, and in the above two nitride semiconductor layers, at least The first nitride semiconductor film has a p-type contact layer containing In. Thus, a p-type contact layer with few defects and good crystallinity can be formed. Since the resistance value of the p-type contact layer itself can be reduced, and the contact resistance between the p-side electrode and the p-type contact layer can be made very small, so It can obtain high output power under stable low working voltage.

In addition, the seventh and eighth nitride semiconductor elements of the present invention can improve the luminous output power of the nitride semiconductor element using the active layer of the multi-quantum well structure by the following structure, and make the static voltage resistance performance good, and expand the The scope of application of the nitride semiconductor device using the active layer of the multi-quantum well structure is shown.

That is, the seventh nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, and is characterized in that in:

The at least one nitride semiconductor layer in the above-mentioned n-side region is the first n-side multilayer film layer formed by stacking at least three layers in sequence, and the at least three layers are respectively: composed of a non-doped nitride semiconductor film a lower layer, an intermediate layer composed of a nitride semiconductor film doped with n-type impurities, and an upper layer composed of an undoped nitride semiconductor film;

At least one nitride semiconductor layer in the above p-side region is a p-side multi-layer film cladding layer formed by stacking third and fourth nitride semiconductor films, and the third and fourth nitride semiconductor films are respectively doped P-type impurities are removed, and the band gap energies are different from each other;

The above-mentioned active layer is a multi-quantum well structure composed of In _a Ga _1-a N (0≤a<1).

In addition, in the seventh nitride semiconductor device of the present invention, the p-type impurity concentration of the third nitride semiconductor film and the p-type impurity concentration of the fourth nitride semiconductor film may be different from each other or may be the same.

In addition, the eighth nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, It is characterized by:

The at least one nitride semiconductor layer in the above-mentioned n-side region is the first n-side multilayer film layer formed by stacking at least three layers in sequence, and the at least three layers are respectively: a lower layer composed of a non-doped nitride semiconductor , an intermediate layer composed of a nitride semiconductor doped with n-type impurities, and an upper layer composed of an undoped nitride semiconductor;

At least one nitride semiconductor layer in the p-side region is a p-side single-layer cladding layer composed of _{AlbGa1 -bN} (0≤b≤1) containing p-type impurities;

The above-mentioned active layer is a multiple quantum well structure containing In _a Ga _1-a N (0≤a<1).

的非掺杂的氮化物半导体构成的下层，由膜厚为50～1000

的掺杂了n型杂质的氮化物半导体构成的中间层，以及由膜厚为25～1000

的非掺杂的氮化物半导体构成的上层。Furthermore, in the seventh and eighth nitride semiconductor elements of the present invention, it is characterized in that the above-mentioned n-side first multilayer film layer includes: a film thickness of 100 to 10000

The lower layer composed of non-doped nitride semiconductor, with a film thickness of 50 to 1000

An intermediate layer made of nitride semiconductor doped with n-type impurities, and a film thickness of 25 to 1000

The upper layer composed of undoped nitride semiconductor.

In the seventh and eighth nitride semiconductor elements of the present invention, it is preferable to have a first nitride semiconductor film containing In between the above-mentioned n-side first multilayer film layer and the active layer, and a A second n-side multi-layer film formed by stacking second nitride semiconductor films with different compositions of the nitride semiconductor film.

Furthermore, in the seventh and eighth nitride semiconductor elements of the present invention, on the n-side nitride semiconductor layer, a layer closer to the substrate than the n-side first multilayer film layer (modulated doping) may be formed. One side has an n-side contact layer containing n-type impurities.

In the seventh and eighth nitride semiconductor elements of the present invention, it is preferable that the n-side contact layer is formed on the undoped GaN layer.

In addition, in the seventh and eighth nitride semiconductor elements of the present invention, in the above-mentioned nitride semiconductor element, the above-mentioned undoped GaN layer is formed on Ga _d Al _1-d N (0<d ≤ 1), a p-side GaN contact layer containing Mg as a p-type impurity may be formed on the above-mentioned p-side multilayer clad layer or p-side single-layer clad layer.

That is, in the seventh and eighth nitride semiconductor elements of the present invention, the n-side first multilayer film layer and the p-side multilayer film cladding layer or The p-side single-layer film cladding layer is formed in combination, so that the luminous efficiency can be improved, and a nitride semiconductor element with good luminous output power and good electrostatic withstand voltage can be obtained. Wherein, the n-side first multilayer film layer is composed of the specific layer structure of the non-doped lower layer, the middle layer doped with n-type impurities, and the non-doped upper layer in the n-side region. The p-side multilayer film cladding layer is composed of third and fourth nitride semiconductor films in the p-side region, and the p-side single-layer film cladding layer contains p-type impurities composed of _{AlbGa1 -bN} (0≤ b≤1) composition.

By combining multiple nitride semiconductor layers having a specific composition and stacked structure in this way, the performance of the active layer of the multi-quantum well structure can be efficiently exhibited, and the static voltage resistance performance can also be improved.

Furthermore, in the present invention, by combining the film thickness of each layer constituting the n-side first multilayer film layer within a specific range, it is possible to further improve the static voltage resistance performance while obtaining good luminous output power.

In addition, in the present invention, the so-called non-doped refers to a layer formed by not intentionally doping impurities, even if it is a layer in which impurities are diffused from adjacent layers or mixed with impurities due to contamination from raw materials or devices, as long as Even when impurities are not intentionally doped, it can be used as a non-doped layer. In addition, impurities mixed by diffusion may cause the impurity concentration to be distributed in a gradient within the layer.

In addition, in combination with the active layer of the multi-quantum well structure, other preferable nitride semiconductor layers are as follows.

In the present invention, if there is an n-side second multi-layer film layer between the above-mentioned n-side first multi-layer film layer and the active layer, the luminous efficiency can be further improved, and the voltage in the positive direction can also be reduced (hereinafter referred to as Called Vf), improve luminous efficiency. Wherein, the n-side second multilayer film layer is formed by laminating a first nitride semiconductor film containing In and a second nitride semiconductor film having a composition different from that of the first nitride semiconductor film.

Furthermore, in the present invention, if there is an n-side contact layer containing n-type impurities on the side closer to the substrate than the n-side first multilayer film layer, the luminous output can be increased and Vf can be reduced.

Furthermore, in the present invention, if the above-mentioned n-side contact layer is formed on the non-doped GaN layer, a non-doped GaN layer with good crystallinity can be obtained, thereby improving the n-side contact layer as a layer forming the n-electrode. The crystallinity of the side contact layer can also improve the crystallinity of other nitride semiconductor layers such as the active layer formed on the n-side contact layer, and can also improve the light emission output.

Furthermore, in the present invention, if the above-mentioned undoped GaN layer is formed on the buffer layer composed of Ga _d Al _1-d N (0<d≤1) grown at low temperature, the undoped GaN layer can be further improved. The crystallinity of the impurity GaN layer, the crystallinity of the n-side contact layer, etc. can be further improved, and the luminous output power can be further improved. Furthermore, since a p-side GaN contact layer doped with Mg is formed on the p-side multilayer film cladding layer or the p-side single-layer film cladding layer, good p-type characteristics can be easily obtained, It is also possible to obtain good ohmic contact between the p-side GaN contact layer and the p-electrode formed thereon, so that the light emission output can be further improved.

In addition, in the ninth to eleventh nitride semiconductor elements of the present invention, the n-side region and the p-side region respectively have multilayer film layers, and the multilayer film layer in the n-side region and the multilayer film layer in the p-side region The layers are asymmetrical in terms of composition or number of layers, which can improve luminous output power and static voltage resistance performance, and can reduce Vf, expanding the applicable range of various application products.

That is, the ninth nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, and is characterized in that in:

At least one nitride semiconductor layer in the above n-side region is an n-type multilayer film formed by stacking multiple nitride semiconductor films;

At least one nitride semiconductor layer in the p-side region is a p-type multilayer film layer formed by stacking multiple nitride semiconductor films; and

The composition constituting the n-type multilayer film layer is different from the composition constituting the p-type multilayer film layer.

In addition, the tenth nitride semiconductor element of the present invention is a nitride semiconductor element having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, and is characterized in that in:

At least one nitride semiconductor layer in the above n-side region is an n-type multilayer film formed by stacking multiple nitride semiconductor films;

At least one nitride semiconductor layer in the p-side region is a p-type multilayer film layer formed by stacking multiple nitride semiconductor films; and

The number of stacked nitride semiconductor films constituting the n-type multilayer film layer is different from the number of laminated layers of nitride semiconductor films constituting the p-type multilayer film layer.

Furthermore, the eleventh nitride semiconductor device of the present invention is a nitride semiconductor device having an active layer between an n-side region having a multilayer nitride semiconductor layer and a p-side region having a multilayer nitride semiconductor layer, It is characterized by:

At least one nitride semiconductor layer in the above n-side region is an n-type multilayer film formed by stacking multiple nitride semiconductor films;

At least one nitride semiconductor layer in the p-side region is a p-type multilayer film layer formed by stacking multiple nitride semiconductor films; and

The composition constituting the n-type multilayer film layer is different from the composition constituting the p-type multilayer film layer, and the number of laminated layers of the nitride semiconductor film constituting the above n-type multilayer film layer is different from that of the nitrogen compound film constituting the p-type multilayer film layer. The number of stacked layers of the compound semiconductor film varies.

In addition, in the ninth to eleventh nitride semiconductor elements of the present invention, preferably, the number of nitride semiconductor layers constituting the p-type multilayer film layer is greater than the number of nitride semiconductor layers constituting the n-type multilayer film layer. The number of layers is small.

In addition, in the ninth to eleventh nitride semiconductor elements of the present invention, it is preferable that the n-type multilayer film layer contains Al _z Ga _1-z N (0≤z<1) and In _p Ga _1-p N (0<P<1), the p-type multilayer film layer contains _{AlxGa1 -xN} (0<x<1= and _{InyGa1 -yN} (0≤y<1).

Furthermore, in the ninth to eleventh nitride semiconductor elements of the present invention, it is preferable that the p-type multilayer film layer and/or the n-type multilayer film layer are modulated and doped.

That is, in the ninth to eleventh nitride semiconductor devices of the present invention, as described above, n-type and p-type n-type multilayers having different compositions and/or numbers of layers are formed by sandwiching the active layer. film layer and p-type multilayer film layer, and the composition of the layer near the active layer of the device structure is specific, so it is possible to provide a nitride semiconductor device that can increase the luminous output power, reduce Vf, and have good static voltage resistance.

The active layer of the quantum well structure hides the possibility of increasing the luminous output power, so it is difficult to fully utilize the possibility of the quantum well structure in conventional devices.

On the other hand, the inventors of the present invention conducted various studies to fully utilize the performance of the active layer of the quantum well structure. The n-type multi-layer film and p-type multi-layer film layer of the present invention not only give full play to the performance of the active layer, but also realize the improvement of luminous output power, and also realize the reduction of Vf and the improvement of static voltage resistance.

Although the reason is not so certain, it is considered that it may be due to the increase in crystallinity due to the formation of a multilayer film, plus the improvement of the crystallinity of the active layer and the crystallinity of the layer forming the p-electrode, and further, due to the composition and/or layer The difference in the crystallization properties of the n-type multilayer film layer and the p-type multilayer film layer caused by the different numbers act synergistically, which has a good influence on the entire element, so the performance of the element (luminous output power, Vf, resistance electrostatic properties, etc.).

In the ninth to eleventh nitride semiconductor elements of the present invention, the so-called multilayer film layer is formed by stacking at least two or more single-layer nitride semiconductor layers with different compositions, so that Adjacent single-layer nitride semiconductor layers are formed in different ways, and multiple single-layer nitride semiconductor layers are laminated.

In addition, in the ninth to eleventh nitride semiconductor elements of the present invention, it means that the composition of the nitride semiconductor constituting the n-type multilayer film layer is different from the composition of the nitride semiconductor constituting the p-type multilayer film layer. The composition of the single-layer nitride semiconductors constituting the respective multilayer films may be the same, but the composition (all composition) of the entire film layers of the multilayer films formed by laminating multiple single-layer nitride semiconductor layers is inconsistent of. That is, the so-called n-type multilayer film layer and the p-type multilayer film layer may have partially identical compositions, but the compositions of the respective nitride semiconductor layers must be adjusted so that they are not completely identical.

For example, different compositions include elements constituting nitride semiconductors (for example, types of elements in binary mixed crystals and ternary mixed crystals), ratios of elements, or band gap energies. Also, in multilayer coatings, these values are overall averages.

In addition, in the present invention, the so-called difference in the number of stacked layers means that as long as the nitride semiconductor constituting the multilayer film layer is stacked by at least one or more layers in either p-type or n-type .

Furthermore, in the ninth to eleventh nitride semiconductor elements of the present invention, it is preferable that the number of nitride semiconductor layers constituting the p-type multilayer film layer is greater than the number of nitride semiconductor layers constituting the n-type multilayer film layer. A smaller number of layers is preferable because the luminous output, Vf, and static voltage resistance characteristics can all be improved.

Furthermore, in the ninth to eleventh nitride semiconductor devices of the present invention, the number of layers of the p-type multilayer film layer is at least one less than the number of layers of the n-type multilayer film layer. That's it.

Furthermore, in the ninth to eleventh nitride semiconductor devices of the present invention, the n-type multilayer film layer contains Al _z Ga _1-z N (0≤z<1) and In _p Ga _1-p N (0<p<1), making the p-type multilayer film layer contain Al _x Ga _1-x N (0<x<1) and In _y Ga _1-y N (0≤y<1), can obtain higher luminous output Power, Vf and static voltage withstand performance.

In addition, in the ninth to eleventh nitride semiconductor elements of the present invention, if the p-type multilayer film layer and/or the n-type multilayer film layer are modulated and doped, the luminous output power, Vf and endurance can be improved. Electrostatic properties.

In addition, in the ninth to eleventh nitride semiconductor elements of the present invention, modulation doping means that in a single-layer nitride semiconductor layer forming a multilayer film layer, each adjacent nitride semiconductor The impurity concentration in the layers is different, so that the adjacent nitride semiconductor layer of the multilayer film layer is not doped with impurities, while the other side is doped with impurities. In addition, the nitride semiconductor layers on both adjacent sides are doped with impurities. When impurity is added, the impurity concentration in adjacent nitride semiconductor layers may be different.

In addition, in the ninth to eleventh nitride semiconductor elements of the present invention, when the composition of the n-type multilayer film layer and the p-type multilayer film layer are different, the number and composition of the n-type multilayer film layer The number of layers of the p-type multilayer film layer can be the same or different, preferably the number of layers is different, and more preferably the number of layers of the p-type multilayer film layer is less than the number of layers of the n-type multilayer film layer. The aspects of light emission output, Vf, and static voltage resistance performance are preferable.

In addition, in the present invention, when the number of layers of the n-type multilayer film layer and the p-type multilayer film layer is different, the composition of the n-type multilayer film layer and the composition of the p-type multilayer film layer can be the same, or It may be different, but it is preferable to have a different composition, which is preferable in order to obtain the effects of the present invention as described above.

In addition, in the present invention, when the number of layers of the n-type multilayer film layer and the p-type multilayer film layer are different, the combination of the number of n-type and p-type layers is not particularly limited, as long as it is a p-type multilayer film layer The number of layers of the film layer and the n-type multilayer film layer is different, and any combination can be used. Preferably, as mentioned above, the number of layers of the p-type multilayer film layer is less than the number of layers of the n-type multilayer film layer. The aspect of the effect of the present invention described above is preferable.

Description of drawings

1 is a schematic cross-sectional view showing the structure of a nitride semiconductor device (LED device) according to Embodiment 1 of the present invention.

2 is a schematic cross-sectional view showing the structure of an LED element according to Example 2 of the present invention.

3 is a perspective view showing the structure of a nitride semiconductor light emitting element (LD element) according to Example 16 of the present invention.

4 is a schematic cross-sectional view showing the structure of a nitride semiconductor element (LED element) according to Embodiment 2 of the present invention.

5 is a schematic cross-sectional view showing the structure of a nitride semiconductor light-emitting element according to Embodiment 3 of the present invention.

6A is a schematic cross-sectional view showing the structure of a p-side contact layer of a nitride semiconductor light emitting device according to Embodiment 4 of the present invention.

FIG. 6B is a graph schematically showing the composition of In in FIG. 6A .

Fig. 7 is a graph showing the light absorptivity of the multilayer film (p-side contact layer) with respect to wavelength of the present invention.

8 is a schematic cross-sectional view showing the structure of a nitride semiconductor element (LED element) according to Embodiment 5 of the present invention.

9A is a graph showing the relative values of P0 and Vf with respect to the film thickness of the non-doped upper layer 305c in Embodiment 5. FIG.

FIG. 9B is a graph showing the relative value of the static voltage resistance performance with respect to the film thickness of the non-doped upper layer 305c in Embodiment 5. FIG.

FIG. 10A is a graph showing relative values of P0 and Vf with respect to the film thickness of the intermediate layer 305b in Embodiment 5. FIG.

FIG. 10B is a graph showing the relative value of the static voltage resistance performance with respect to the film thickness of the intermediate layer 305b in Embodiment 5. FIG.

11A is a graph showing relative values of P0 and Vf with respect to the film thickness of the non-doped lower layer 305a in Embodiment 5. FIG.

FIG. 11B is a graph showing the relative value of the static voltage resistance performance with respect to the film thickness of the non-doped upper layer 305a in Embodiment 5. FIG.

Detailed ways

Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings.

Implementation 1

1 is a schematic cross-sectional view showing the structure of a nitride semiconductor device (LED device) according to Embodiment 1 of the present invention. This LED element has a structure in which the following layers are sequentially stacked on a sapphire substrate 1: a first buffer layer 2 made of GaN; a second buffer layer 3 made of undoped GaN; The n-side contact layer 4 composed of; the third buffer layer 5 composed of non-doped GaN layer; the n-side multilayer film layer 6 composed of InGaN/GaN superlattice structure; the multiple quantum well composed of InGaN/GaN The active layer 7 of the structure; the p-side multilayer film layer 8 composed of AlGaN/GaN superlattice structure; the p-side contact layer 9 composed of Mg-doped GaN.

That is, the LED element of Embodiment 1 is formed on the sapphire substrate 1 by interposing the active layer 7 of the multi-quantum well structure between the n-side region 30 and the p-side region, the n-side region 30 consisting of the first The buffer layer 2, the second buffer layer 3, the n-side contact layer 4, the third buffer layer 5 and the n-side multilayer film layer 6, and the p-side region is composed of the p-side multilayer film layer 8 and the p-side contact layer 9 constituted.

或以下、优选为70

或以下、最优选为50

或以下，薄膜层的厚度处于弹性临界膜厚或以下，结晶性改善，且层叠于其上的第一或第二氮化物半导体膜的结晶性也能得到改善，所以可以改善多层膜层整体的结晶性，提高元件的输出功率。As shown in FIG. 1 , in the nitride semiconductor device according to Embodiment 1, in the n-side region 30 located below the active layer 7, there is a first nitride semiconductor film 6a containing In and a The n-side multilayer film layer 6 is formed by stacking the second nitride semiconductor film 6 b having a different composition from the first nitride semiconductor film 6 a. In the n-side multilayer film layer 6, it is preferable to form at least one or more first nitride semiconductor films 6a and second nitride semiconductor films 6b, respectively, for a total of three or more layers, and it is more preferable to stack at least two or more layers respectively. When the n-side multilayer film layer 6 is formed in contact with the active layer 7, a total of 4 or more layers are stacked, and the first layer (well layer or barrier layer) of the active layer is in contact with the multilayer layer. The film layer can be either the first nitride semiconductor film 6a or the second nitride semiconductor film 6b, and the stacking order of the n-side multilayer film layers does not need to be particularly limited. In addition, in FIG. 1, although the n-side multilayer film layer 6 is formed in contact with the active layer 7, in the present embodiment 1, it is also possible to form a layer between the multilayer film layer 6 and the active layer 7. There are layers made of other n-type nitride semiconductors between them. In addition, since at least one of the first nitride semiconductor film 6a or the second nitride semiconductor film 6b constituting the n-side multilayer film layer 6 has a thickness of 100

or below, preferably 70

or below, most preferably 50

or less, the thickness of the thin film layer is at or below the elastic critical film thickness, the crystallinity is improved, and the crystallinity of the first or second nitride semiconductor film stacked thereon can also be improved, so the overall multilayer film layer can be improved. The crystallinity improves the output power of the component.

The first nitride semiconductor film 6a is a nitride semiconductor containing In, preferably ternary mixed crystal _{InxGa1 -xN} (0<x<1), more preferably _InxGa having an x value of 0.5 or less. _1-x N, most preferably In _x Ga _1-x N having an x value of 0.1 or less. On the other hand, the second nitride semiconductor film 6b is not particularly limited as long as it is a nitride semiconductor film having a composition different from that of the first nitride semiconductor film 6a, but in order to grow a second nitride semiconductor film with good crystallinity 6b, to grow a nitride semiconductor having a binary mixed crystal or a ternary mixed crystal whose bandgap energy is larger than that of the first nitride semiconductor film 6a, if GaN is also used therein, a nitride semiconductor with good overall crystallinity can be grown. Multi-layer film. Therefore, the most preferable combination is a combination using _{InxGa1 -xN} having an x value of 0.5 or less as the first nitride semiconductor film 6a and using GaN as the second nitride semiconductor film 6b.

或以下，最优选为50

或以下。这样，通过将第一和第二氮化物半导体膜各自的膜厚设为100

或以下，从而第一和第二氮化物半导体膜的任意之一都处于弹性临界膜厚或以下，与以较厚的膜来生长的情况相比较，能够生长出结晶性良好的氮化物半导体。另外，如果通过将这两种膜都设为70

或以下，从而使多层膜层成为超晶格结构，在该结晶性良好的超晶格结构的多层膜层上生长有源层，则多层膜层就会起到缓冲层那样的作用，能够生长出结晶性良好的有源层。As a preferred embodiment, the thickness of both the first and second nitride semiconductor films is 100 or below, preferably 70

or below, most preferably 50

or below. In this way, by setting the respective film thicknesses of the first and second nitride semiconductor films to 100

or less, so that either of the first and second nitride semiconductor films has an elastic critical film thickness or less, and a nitride semiconductor with good crystallinity can be grown compared with the case of growing a thicker film. Also, if you set both membranes to 70

or below, so that the multilayer film layer becomes a superlattice structure, and the active layer is grown on the multilayer film layer of the superlattice structure with good crystallinity, then the multilayer film layer will play a role like a buffer layer , an active layer with good crystallinity can be grown.

In addition, in Embodiment 1, the film thickness of at least one of the first or second nitride semiconductor films may be set to be between adjacent first nitride semiconductor films or between adjacent second nitride semiconductor films. The compound semiconductor films are different from each other. For example, when the first nitride semiconductor film is InGaN and the second nitride semiconductor film is GaN, the film thickness of the InGaN layer located between the GaN layer and the GaN layer is increased by increasing the thickness of the InGaN layer between the GaN layer and the GaN layer. Gradually thickening or gradually thinning can change the refractive index inside the multilayer film layer, so it is possible to form a layer whose refractive index gradually changes. That is, substantially the same effect as that of forming a nitride semiconductor layer with a graded composition can be obtained. Therefore, in an element such as a laser element that must have an optical waveguide, the multilayer film layer can be used to form a waveguide to adjust the mode of the laser light.

In addition, the composition of the Group III element in at least one of the first or second nitride semiconductor films may be set to be between adjacent first nitride semiconductor films or between adjacent second nitride semiconductor films. are different from each other. For example, when the first nitride semiconductor film is InGaN and the second nitride semiconductor film is GaN, the In composition of the InGaN layer located between the GaN layer and the GaN layer is changed as it approaches the active layer. Gradually increase or decrease, similar to the case where the film thickness is sequentially changed, the refractive index can be changed inside the multilayer film layer, thereby substantially forming a nitride semiconductor layer with a gradually changing composition. In addition, as the composition of In gradually decreases, the refractive index tends to decrease gradually.

In addition, in Embodiment 1, both the first and second nitride semiconductor films may be undoped, both may be doped with n-type impurities, or either one may be doped with impurities. In order to improve the crystallinity, it is most preferable not to dope, next to modulation doping, and next to both doping. In addition, when both are doped with n-type impurities, the concentration of the n-type impurities in the first nitride semiconductor film may be different from the concentration of n-type impurities in the second nitride semiconductor film.

Furthermore, in Embodiment 1, as shown in FIG. 1 , a p-side multilayer film layer 8 is provided in the upper p-side region sandwiching the active layer 7. The p-side multilayer film layer 8 is composed of A third nitride semiconductor film 8a made of Al and a fourth nitride semiconductor film 8b having a composition different from that of the third nitride semiconductor film 8a are laminated. In the p-side multilayer film 8, like the n-side multilayer film 6, the third nitride semiconductor film 8a and the fourth nitride semiconductor film 8b are preferably formed in at least one layer or more, totaling three or more layers, More preferably, at least two or more layers are stacked respectively, and four or more layers are stacked in total. Furthermore, when a multilayer film is also provided in the p-side region, if the film thickness is thinner than that of the n-side multilayer film, the Vf and threshold of the device tend to decrease easily. As shown in Figure 1, when the p-side multilayer film layer 8 is formed in contact with the active layer 7, the p-side multilayer film layer in contact with the last layer (well layer or barrier layer) of the active layer Either the third nitride semiconductor film 8a or the fourth nitride semiconductor film 8b may be used. In addition, in FIG. 1, the p-side multilayer film layer 8 is formed in contact with the active layer 7, but it is also possible to have other nitride semiconductor layers between the multilayer film layer 8 and the active layer 7. formed layer.

In addition, in Embodiment 1, the film thicknesses of one or both of the third and fourth nitride semiconductor films may be set to be between adjacent third nitride semiconductor films or between adjacent third nitride semiconductor films. The fourth nitride semiconductor films are different from each other. For example, when the third nitride semiconductor film is made of AlGaN and the fourth nitride semiconductor film is made of GaN, the film thickness of the AlGaN layer located between the GaN layer and the GaN layer is increased by increasing the thickness of the AlGaN layer between the GaN layer and the GaN layer Gradual thickening or gradual thinning enables the refractive index to be changed inside the multilayer film layer, so that a layer whose refractive index gradually changes can be substantially formed. That is, substantially the same effect as that obtained by forming a composition-graded nitride semiconductor layer is obtained. Therefore, in an element such as a laser element that must have an optical waveguide and an optical confinement layer, the multilayer film can be used both as a waveguide and an optical confinement layer to adjust the mode of laser light.

In addition, the composition of one or both of the third and fourth nitride semiconductor films may be such that the composition of the Group III element is set to be between the adjacent third nitride semiconductor films or between the adjacent fourth nitride semiconductor films. The semiconductor films are different from each other. For example, when the first nitride semiconductor film is made of AlGaN and the second nitride semiconductor film is made of GaN, the amount of Al in the AlGaN layer located between the GaN layer and the GaN layer is increased as the active layer is approached. Gradually increasing or decreasing the composition, in the same manner as above, the refractive index can be changed inside the multilayer film layer, thereby substantially forming a nitride semiconductor layer with a graded composition. In addition, as the composition of Al gradually increases, the refractive index will gradually decrease. Therefore, it is possible to arrange these layers whose compositions are graded on the p-layer side according to different purposes.

The third nitride semiconductor film 8a is a nitride semiconductor containing Al, preferably ternary mixed crystal Al _a Ga _1-a N (0<x<1), and most preferably Al _a Ga with a value of 0.5 or less. _1-a N. If the value of a exceeds 0.5, the crystallinity tends to deteriorate and cracks tend to occur easily. On the other hand, the fourth nitride semiconductor film 8b is not particularly limited as long as it is a nitride semiconductor film having a composition different from that of the third nitride semiconductor film 8a, but in order to grow a fourth nitride semiconductor film with good crystallinity 8b, usually a binary mixed crystal or a ternary mixed crystal nitride semiconductor with a bandgap energy smaller than that of the third nitride semiconductor. If GaN is used, a multilayer film with good overall crystallinity can be grown . Therefore, as the most preferable combination, the third nitride semiconductor film 8a is Al _a Ga _1-a N having an a value of 0.5 or less, and the fourth nitride semiconductor film 8b is GaN.

或以下，优选为70

或以下，最优选为50

或以下。同样，第四氮化物半导体膜8b的膜厚也设为100

或以下，优选为70

或以下，最优选为50或以下。这样，通过将单一的第一或者第二氮化物半导体膜的膜厚设为100

或以下，从而该氮化物半导体的膜厚便位于弹性临界膜厚或以下，与以较厚的膜生长起来的情况相比，能够生长出结晶性良好的氮化物半导体，另外，由于氮化物半导体层的结晶性有所改善，因此在添加p型杂质的情况下，能够获得载流子浓度大而电阻率小的p层，能够降低元件的Vf、阈值等。Further, the film thickness of the third nitride semiconductor film 8a is set to 100

or below, preferably 70

or below, most preferably 50

or below. Similarly, the film thickness of the fourth nitride semiconductor film 8b is also set to 100

or below, preferably 70

or below, most preferably 50 or below. In this way, by setting the film thickness of a single first or second nitride semiconductor film to 100

or less, so that the film thickness of the nitride semiconductor is located at or below the elastic critical film thickness, compared with the case of growing a thicker film, a nitride semiconductor with good crystallinity can be grown. In addition, since the nitride semiconductor The crystallinity of the layer is improved, so when p-type impurities are added, a p-layer with a large carrier concentration and a low resistivity can be obtained, and the Vf and threshold value of the device can be reduced.

或以下，更优选为在500

或以下。这是因为如果超过0.1μm，非掺杂层的电阻值就会有增大的倾向。当在两者中都掺杂p型杂质时，第三氮化物半导体膜8a的p型杂质的浓度和第四氮化物半导体膜8b的p型杂质的浓度也可以不同。Both the third nitride semiconductor film 8 a and the fourth nitride semiconductor film 8 b may be undoped, or both may be doped with p-type impurities, or either one may be doped with p-type impurities. In order to obtain a p-layer with a high carrier concentration, modulation doping is most preferably performed. In addition, as mentioned above, in the case of non-doping, the film thickness should be 0.1 μm or less, preferably 700 μm or less.

or below, more preferably at 500

or below. This is because when the thickness exceeds 0.1 μm, the resistance value of the non-doped layer tends to increase. When both are doped with p-type impurities, the concentration of the p-type impurities in the third nitride semiconductor film 8a and the concentration of the p-type impurities in the fourth nitride semiconductor film 8b may also be different.

In the nitride semiconductor element of Embodiment 1 above, the p-side multilayer film layer 8 is formed in the p-side region 40, but the present invention is not limited thereto, and a single-layer film layer 8 may be formed as shown in FIG. 2 . The p-side cladding layer 18 is used to replace the p-side multilayer film layer 8 . In addition, in the nitride semiconductor device shown in FIG. 2 , the p-side region 41 is constituted by the p-side cladding layer 18 and the p-side contact layer 9 .

Variation

In the above Embodiment 1, the LED element was used as an example to describe, but the present invention is not limited thereto. Even if it is applied to a laser diode, the same effect as Embodiment 1 can be obtained, and further, the following out of shape.

That is, in the LD element, for example, a first nitride semiconductor film made of InGaN and a second nitride semiconductor film made of GaN are alternately laminated to form an n-side multilayer film layer, and the first nitride semiconductor film The film thickness of the semiconductor film is formed such that it increases sequentially toward the active layer. By constituting the n-side multilayer film layer in this way, in the n-side multilayer film layer, the closer to the active layer, the larger the ratio of InGaN with a large refractive index, so that the n-side multilayer film layer can become The layer whose refractive index is larger closer to the active layer has a graded refractive index.

In addition, in the LD element, a p-side multilayer film layer is formed by alternately stacking a third nitride semiconductor film made of AlGaN and a fourth nitride semiconductor film made of GaN, and the third nitride semiconductor film The thickness of the film is gradually reduced toward the direction of the active layer. By constituting the p-side multilayer film in this way, in the p-side multilayer film layer, the closer to the active layer, the smaller the proportion of AlGaN with a smaller refractive index, and the p-side multilayer film layer can be made The layer whose refractive index is larger closer to the active layer has a graded refractive index.

As in the first embodiment, since the LD element configured as described above can improve the crystallinity of each nitride semiconductor layer, the threshold voltage can be lowered, and the output power can be increased.

In addition, in the LD element, since any one of the n-side multilayer film layer and the p-side multilayer film layer sandwiching the active layer can be made to have a refractive index that increases as it approaches the active layer The graded layer, so it can form a good optical waveguide, which can easily and effectively adjust the laser mode.

Although in the LD element of the above example, the n-side and p-side multilayer film layers are made into layers with a graded refractive index by changing the film thickness of the first or third nitride semiconductor film, the present invention is not limited thereto. Alternatively, a layer having a graded refractive index may be formed by sequentially changing the film thicknesses of the second and fourth nitride semiconductor films.

In addition, in the present invention, by setting the composition of at least one group III element in the first or second nitride semiconductor film to be the same as that between adjacent first or second nitride semiconductor films, The composition of the group III elements changes gradually, giving them a graded refractive index. For example, when the first nitride semiconductor film is made of InGaN and the second nitride semiconductor film is made of GaN, the proportion of In in the first nitride semiconductor film is gradually increased as the first nitride semiconductor film approaches the active layer. It is possible to increase the refractive index as it approaches the active layer, and to form a nitride semiconductor layer having the same graded refractive index. In addition, in InGaN, as the composition of In increases, the refractive index also increases.

In addition, in the p-side multilayer film layer, by making the composition of the group III element in at least one of the third or fourth nitride semiconductor films such that the composition of the group III element between the adjacent third or fourth nitride semiconductor films can be Different between them, thus forming a layer with a graded refractive index. For example, when the third nitride semiconductor film is made of AlGaN and the fourth nitride semiconductor film is made of GaN, the Al composition of the AlGaN layer between the GaN layer and the GaN layer is gradually reduced as the active layer is approached. , it is possible to gradually change the refractive index inside the p-side multilayer film layer, and substantially form a nitride semiconductor layer with a graded composition. In addition, as the composition of Al increases, the refractive index decreases. Therefore, it is possible to arrange these layers whose compositions are graded on the p-layer side according to the purpose.

Embodiment 2

Next, referring to FIG. 4, a nitride semiconductor device according to Embodiment 2 of the present invention will be described.

The nitride semiconductor element of Embodiment 2 of the present invention is a light-emitting element having a double heterostructure on a substrate 1 having n-side regions 130 and The active layer 7 of the multi-quantum well structure sandwiched by the p-side region 140 .

In detail, in the nitride semiconductor device of Embodiment 2, as shown in FIG. 4, the n-side region 30 is composed of the following layers: a buffer layer 102, an undoped GaN layer 103, and an n-side region containing n-type impurities. The contact layer 4, the n-side first multilayer film layer 105 containing n-type impurities, and the n-side second multilayer film layer 6 composed of the first nitride semiconductor film 106a and the second nitride semiconductor film 106b; the p-side The region 30 is composed of the p-side cladding layer 108 formed of a multi-layer film or a single-layer film and the p-side GaN contact layer 9 doped with Mg. In addition, in the nitride semiconductor device according to the second embodiment, the n-electrode 12 is formed on the n-side contact layer 4 and the p-electrode 11 is formed on the p-side GaN contact layer 9 .

In addition, FIG. 4 shows an example in which a multilayer film in which a third nitride semiconductor film 108 a and a fourth nitride semiconductor film 108 b are laminated is used as the p-side cladding layer 108 .

In the present invention, as the substrate 1, sapphire whose C-plane, R-plane or A-plane is the main surface can be used, and other insulating substrates such as spinel (MgAl ₂ O ₄ ), and SiC (containing 6H, 4H, 3C), Si, ZnO, GaAs, GaN and other semiconductor substrates.

In the present invention, the material of the buffer layer 102 is a nitride semiconductor formed of Ga _d Al _1-d N (provided that d is in the range of 0<d≤1), and the smaller the ratio of Al, the better the crystallization. The more remarkable the performance improvement, the buffer layer 102 formed of GaN is more preferable.

The film thickness of the buffer layer 102 is adjusted in the range of 0.002 to 0.5 μm, preferably in the range of 0.005 to 0.2 μm, more preferably in the range of 0.01 to 0.02 μm. If the film thickness of the buffer layer 102 is within the above range, the crystal form of the nitride semiconductor can be improved, and the crystallinity of the nitride semiconductor grown on the buffer layer 102 can also be improved.

The growth temperature of the buffer layer 102 is adjusted to be in the range of 200 to 900°C, preferably in the range of 400 to 800°C. When the growth temperature is within the above temperature range, a good polycrystal can be obtained, and the crystallinity of the nitride semiconductor grown on the buffer layer 102 can be improved by using the polycrystal as a seed crystal, which is preferable.

In addition, the buffer layer 102 grown at such a low temperature may be omitted depending on the type of the substrate, the growth method, and the like.

Next, in the second embodiment, the undoped GaN layer 103 is grown without adding n-type impurities during growth. If this non-doped GaN layer 103 is grown on the buffer layer 102, the crystallinity of the non-doped GdN layer 103 can be improved, and the n-side contact layer 4 grown on the non-doped GaN layer 103 can also be improved. etc. crystallinity. The film thickness of the undoped GaN layer 103 is 0.01 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more. When the film thickness is within this range, each layer after the n-side contact layer 4 can be grown with good crystallinity, which is preferable. In addition, the upper limit of the film thickness of the undoped GaN layer 103 is not particularly limited, but it should be appropriately adjusted in consideration of manufacturing efficiency and the like.

Next, in the second embodiment, the n-type impurity-containing n-side contact layer 4 contains n-type impurities at a concentration of 3×10 ¹⁸ /cm ³ or more, preferably 5×10 ¹⁸ /cm ³ or more. When a large amount of n-type impurities is doped like this, and this layer is used as an n-side contact layer, Vf and threshold can be lowered. If the concentration of impurities exceeds the above range, it tends to be difficult to lower Vf. In addition, if the n-side contact layer 4 is formed on the non-doped GaN layer 103 with low n-type impurity concentration and good crystallinity, it does not matter even if there is a very high concentration of n-type impurities, and a good crystal can still be formed. sex. In the present invention, the upper limit of the n-type impurity concentration of the n-side contact layer 4 is not particularly limited, but it is preferably 5×10 ²¹ /cm ³ or less in order to ensure crystallinity for maintaining a good contact layer function.

The composition of the n-side contact layer 4 can be composed of In _e Al _f Ga _1-ef N (0≤e, 0≤f, e+f≤1). Alternatively, _{AlfGa1 -fN} having an f value of 0.2 or less is preferable since a nitride semiconductor layer with few crystal defects can be easily obtained. The film thickness of the n-side contact layer 4 is not particularly limited, but is 0.1 to 20 μm, preferably 0.5 to 10 μm, and most preferably 1 to 5 μm because it forms the n electrode. When the film thickness is within the above range, the resistance value can be lowered and the forward voltage of the light-emitting element can be lowered, which is preferable.

In addition, when the n-side first multilayer film layer 105 described later is formed as a relatively thick film and used as a contact layer, the n-side contact layer 4 can be omitted.

Next, in Embodiment 2, the n-side first multilayer film layer 105 is doped with different concentrations of n-type impurities and has different band gap energies, or the doping concentrations of n-type impurities are different but have the same composition. It is composed of a multilayer film formed by laminating at least two kinds of nitride semiconductor layers. The film thickness of the n-side first multilayer film layer 105 is 2 μm or less, preferably 1.5 μm or less, more preferably 0.9 μm or less. When the film thickness is within the above-mentioned range, the light emission output can be increased, which is preferable. In addition, the lower limit thereof is not particularly limited, and may be, for example, 0.05 μm or more.

The difference in impurity concentration among the nitride semiconductor layers constituting the multilayer film is called modulation doping. In this case, one layer is preferably in a state where no impurity is doped, that is, non-doped.

In the following, first, the case where the n-side first multilayer film layer 105 is a multilayer film in which at least two kinds of nitride semiconductor film layers having different bandgap energies are laminated will be described.

或以下，进而优选为70

或以下，最优选为10～40

的范围。当比100还要厚时，带隙能量大的氮化物半导体层和带隙能量小的氮化物半导体层的膜厚就达到了弹性变形的极限或以上，就会有膜层中很容易产生微小的裂纹或结晶缺陷等倾向。对带隙能量大的氮化物半导体层和带隙能量小的氮化物半导体层的膜厚的下限并没有特别的限制，只要厚度在一原子层或以上就可以，但如上所述，最优选为10或以上。The film thicknesses of the nitride semiconductor layer 105 a with a large band gap energy and the nitride semiconductor layer 105 b with a small band gap energy of the multilayer film layers constituting the n-side first multilayer film layer 105 are adjusted to 100 Å.

or below, more preferably 70

or less, most preferably 10 to 40

range. when compared to 100 When it is thicker, the film thickness of the nitride semiconductor layer with large band gap energy and the nitride semiconductor layer with small band gap energy reaches the limit of elastic deformation or more, and micro cracks or cracks are easily generated in the film layer. Tendencies such as crystal defects. The lower limit of the film thickness of the nitride semiconductor layer with large band gap energy and the nitride semiconductor layer with small band gap energy is not particularly limited, as long as the thickness is one atomic layer or more, but as mentioned above, it is most preferably 10 or above.

As mentioned above, if the n-side first multilayer film layer 105 has a thin multilayer film structure, the film thickness of each layer of the nitride semiconductor layer constituting the multilayer film layer can be made elastic. A nitride semiconductor with very few crystal defects can be grown at a critical film thickness or less. Furthermore, the crystallization defect from the substrate to the non-doped GaN layer 103 or the contact layer 4 on the n side can be prevented to a certain extent from occurring in the multilayer film layer, and growth on the multilayer film layer can be improved. The crystallinity of the n-side second multilayer film layer 106. Further, it also has an effect similar to HEMT.

The nitride semiconductor layer 105 a having a large band gap energy is preferably a nitride semiconductor containing at least Al, and more preferably grown Al _g Ga _1-g N (0<g≦1). On the other hand, the nitride semiconductor 105b having a small bandgap energy may be any nitride semiconductor as long as its bandgap energy is smaller than that of the nitride semiconductor 105a having a large bandgap energy. Nitride semiconductors of binary mixed crystals and ternary mixed crystals such as Al _h Ga _1-h N (0≤h<1, g>h), In _j Ga _1-j N (0≤j<1), because It is easy to grow, and good crystallinity is easy to obtain. Among them, it is particularly preferable that the nitride semiconductor 105a having a large band gap energy is Al _g Ga _1-g N (0<g<1) that does not substantially contain In, and that the nitride semiconductor 105b having a small band gap energy substantially does not contain In. Al's In _j Ga _1-j N (0≤j<1), among them, in order to obtain a multilayer film layer with excellent crystallinity, Al _g Ga with a mixed crystal ratio (g value) of Al of 0.3 or less is most preferred A combination of _1-g N (0<g≤0.3) and GaN.

In addition, when the n-side first multilayer film layer 105 is used as the light confinement layer and the carrier confinement layer to make it have the function of a cladding layer, it is necessary to grow a band gap energy ratio higher than that of the well layer of the active layer. Nitride semiconductors with higher energy. The nitride semiconductor layer having a large band gap energy is a nitride semiconductor having a high mixed crystal ratio of Al. Conventionally, if a nitride semiconductor having a high mixed crystal ratio of Al is grown as a thick film, cracks are likely to occur, and therefore crystal growth is very difficult. However, if the n-side first multilayer film layer 105 is made into a multilayer film layer as in the present invention, even if each nitride semiconductor layer (105a, 105b) constituting the multilayer film layer is made of Al mixture For a film with a relatively high crystal ratio, since the grown film thickness is at or below the elastic critical film thickness, cracks are not likely to occur. Therefore, since a film layer with a high Al mixed crystal ratio can be grown with good crystallinity, the effects of light confinement and carrier confinement can be improved, and the threshold voltage in the laser element and the Vf (positive polarity) in the LED element can be reduced. to the voltage).

Furthermore, it is preferable that the n-type impurity concentration of the n-side first multilayer film layer 105 is different between the nitride semiconductor layer 105 a with a large band gap energy and the nitride semiconductor layer 105 b with a small band gap energy. This is the so-called modulated doping, so if the concentration of n-type impurities in one layer is lowered, it is preferable to be in a state of no impurities (non-doped), and the other layer is doped to a high concentration, and the threshold value can be lowered Voltage, Vf, etc. This is because the mobility of such a layer increases by allowing a layer with a low impurity concentration to exist in the multilayer film, and by also presenting a layer with a high impurity concentration, a high carrier concentration can be maintained. Form a multi-layer film. That is, it may be due to the coexistence of a layer with low impurity concentration and high mobility and a layer with high impurity concentration and high carrier concentration, so that the film layer with high carrier concentration and high mobility becomes the cladding layer, Thereby lowering the threshold voltage and Vf.

In the case of doping a large amount of n-type impurities in the nitride semiconductor layer 105a having a large bandgap energy, the preferable doping amount in the nitride semiconductor layer 105a having a large bandgap energy is adjusted to 1×10 ¹⁷ /cm ³ - It is in the range of 1×10 ²⁰ /cm ³ , more preferably in the range of 1×10 ¹⁸ /cm ³ to 5×10 ¹⁹ /cm ³ . If it is less than 1×10 ¹⁷ /cm ³ , the difference from a nitride semiconductor layer with a small band gap energy will be small, and it will tend to be difficult to obtain a layer with a high carrier concentration. More than 1×10 ²⁰ /cm ³ tends to increase the leakage current of the element itself. On the other hand, the n-type impurity concentration of the nitride semiconductor layer having a small bandgap energy may be lower than that of the nitride semiconductor layer having a large bandgap energy, and is preferably 1/10 or more lower. It is most preferably non-doped, so that the film layer with the highest mobility can be obtained, but because the film thickness is too thin, there will be n-type impurities diffused from the side of the nitride semiconductor with a large band gap energy, and the amount is preferably 1× 10 ¹⁹ /cm ³ or less. As the n-type impurity, Si, Ge, Se, S, O and other group IVB and VIB elements in the periodic table are selected, and Si, Ge, and S are preferably used as the n-type impurity. The effect is also the same as that of doping a small amount of n-type impurities into a nitride semiconductor layer with a large band gap energy and doping a large amount of n-type impurities into a nitride semiconductor layer with a small band gap energy.

Although it has been described above that the doping of impurities in the facing multilayer film layer is preferably modulation doping, it is also possible to make the nitride semiconductor layer 105a with a large band gap energy and the nitride semiconductor layer 105b with a small band gap energy Concentrations of impurities are equal.

Furthermore, in the nitride semiconductor layers 105a, 105b of the multilayer film layers constituting the n-side first multilayer film layer 105, the layer doped with a high concentration of impurities is preferably close to the center of the semiconductor layer in the thickness direction. The part has a high impurity concentration, and the impurity concentration near both ends is low (preferably non-doped). Specifically, for example, in the case of forming a multilayer film with AlGaN doped with Si as an n-type impurity and an undoped GaN layer, since AlGaN is doped with Si, as a donor, it is necessary to transport electrons. to the conduction band, but the electrons will be trapped in the conduction band of GaN at low potential. Since GaN crystals are not doped with donor impurities, they are not subject to carrier scattering by impurities. Therefore, electrons can easily move in the GaN crystal, improving the mobility of electrons substantially. This is similar to the effect of a two-dimensional electron gas, where the actual mobility of electrons in the transverse direction increases and the resistivity decreases. Furthermore, if the central region of AlGaN with a large band gap energy is doped with a high concentration of n-type impurities, the effect will be further increased. That is, the ions of the n-type impurity contained in AlGaN (in this case, Si ions) are scattered to some extent by electrons migrating in GaN. However, if both ends in the thickness direction of the AlGaN layer are undoped, it is difficult to scatter Si, so the mobility of the undoped GaN layer is further improved.

Next, the case where the n-side first multilayer film layer 105 is formed by stacking nitride semiconductor layers of the same composition, and n-type impurities are doped between those nitride semiconductor layers at different concentrations will be described.

First, the nitride semiconductor constituting the n-side first multilayer film layer 105 is not particularly limited to a specific composition, as long as it has the same composition, and GaN is cited as a preferable material. When GaN is used to form the n-side first multilayer film layer 105, binary mixed crystal GaN can be grown with better crystallinity than ternary mixed crystal, and the crystallinity of the nitride semiconductor grown later can also be very good. .

In Embodiment 2 of the present invention, the n-type first multilayer film layer 105 can use a multilayer film, the multilayer film will be composed of the nitride semiconductor layer 105a composed of GaN containing n-type impurities and the nitride semiconductor layer 105a with the nitrogen The nitride semiconductor layer 105b made of GaN having different n-type impurity concentrations from the compound semiconductor layer 105a is laminated. In this case, either one of the nitride semiconductor films 105a and 105b is preferably an undoped film.

Even if the n-side first multilayer film layer composed of two kinds of nitride semiconductor layers formed by modulated doping with the same composition but with different doping amounts of n-type impurities is used, it is possible to obtain the same properties as those obtained by different bandgap energies, And the effect is the same in the case of modulating the n-side first multilayer film layer 105 composed of at least two kinds of film layers formed by doping.

优选为2000～3000

另外，构成多层膜的各层的膜厚为500

或以下，优选为200

或以下，更优选为100

或以下。另外，构成多层膜的各层的膜厚的下限也没有特别限定，只要是一原子层或以上即可，但优选为10或以上。当膜厚在上述范围内时，就可以结晶性良好地生长，并且能够提高发光输出功率。The concentration of n-type impurities is 1×10 ¹⁷ /cm ³ to 1×10 ²¹ /cm ³ , preferably 10 ¹⁸ /cm ³ to 1×10 ¹⁹ /cm ³ , more preferably 3×10 ¹⁸ /cm ³ to 7 ×10 ¹⁸ /cm ³ . In addition, in the present invention, although the total film thickness of the n-side first multilayer film layer 105 is not particularly limited, it is usually 1000 to 4000

Preferably 2000～3000

In addition, the film thickness of each layer constituting the multilayer film is 500

or below, preferably 200

or below, more preferably 100

or below. In addition, the lower limit of the film thickness of each layer constituting the multilayer film is not particularly limited, as long as it is one atomic layer or more, but it is preferably 10 or above. When the film thickness is within the above range, it can be grown with good crystallinity, and the luminous output can be improved.

In addition, the n-side first multilayer film layer 105 mentioned above can also be used as an n-side contact layer. or more than the film layer constituted. At this time, the film thickness of the n-side first multilayer film layer 105 is 0.5-4 μm, preferably 1-3 μm, more preferably 2-2.8 μm. At this time, the film thickness of the n-side first multilayer film layer 105 can be adjusted according to the number of laminated layers of the above-mentioned at least two or more nitride semiconductor layers and/or the film thickness of each layer. In addition, at this time, the thickness of each film layer constituting the n-side first multilayer film layer 105 may be the multilayer film layer of the thin film layer in the above-mentioned range. Within the above thickness range of the n-side first multilayer film layer 105, the thickness of each layer can also be adjusted according to two or more nitride semiconductors exceeding the above range.

In addition, as shown in FIG. 4, in Embodiment 2, there is an n-side second multilayer film layer 106 in the n-side region 130 located under the active layer 7, and the n-side second multilayer film layer 106 is formed by laminating a first nitride semiconductor film 106a containing In and a second nitride semiconductor film 106b having a composition different from that of the first nitride semiconductor film 106a. In the n-side second multilayer film layer 106, at least one or more layers of the first nitride semiconductor film 106a and the second nitride semiconductor film 106b are respectively formed, a total of two or more layers, preferably three or more layers, and most preferably three or more layers. Preferably, at least two layers or more are formed respectively, and a total of four layers or more are formed.

When the n-side second multilayer film layer 106 is formed in contact with the active layer 7, the layer that is in contact with the first layer (well layer or barrier layer) of the active layer 7 may be the first layer of the active layer 7. The first nitride semiconductor film 106a may also be the second nitride semiconductor film 106b, and the stacking sequence of the n-side second multilayer film layer 106 does not need to be particularly limited. In addition, in FIG. 4, although the n-side second multilayer film layer 106 is formed in contact with the active layer 7, it may also be formed between the n-side second multilayer film layer 106 and the active layer 7. It has layers made of other n-type nitride semiconductors.

或以下，进而优选为70

或以下，最优选为50

或以下。这样，由于膜的厚度变薄，n侧第二多层膜层106就成了超晶格结构，就可以改善n侧第二多层膜层106的结晶性，所以可以提高输出功率。In Embodiment 2, preferably, in the n-side second multilayer film layer 106, at least one of the first nitride semiconductor film 106a or the second nitride semiconductor film 106b has a film thickness of 100A. or below. In addition, it is more preferable to set the thicknesses of both the first nitride semiconductor film 106a and the second nitride semiconductor film 106b to 100.

or below, more preferably 70

or below, most preferably 50

or below. In this way, since the thickness of the film becomes thinner, the n-side second multilayer film layer 106 becomes a superlattice structure, and the crystallinity of the n-side second multilayer film layer 106 can be improved, so the output power can be increased.

In this way, if the above-mentioned n-side first multilayer film layer 105 and the above-mentioned n-side second multilayer film layer 106 are combined, the luminous output power can be further improved, and the voltage (Vf) in the forward direction can be further reduced, so it is preferable. Although the reason for this has not been determined, it is considered that the crystallinity of the active layer grown on the n-side second multilayer film layer 106 can be further improved.

The first nitride semiconductor film is a nitride semiconductor containing In, preferably ternary mixed crystal In _k Ga _1-k N (0<k<1), more preferably In _k Ga ₁ with a k value of 0.5 or less _-k N, most preferably In _k Ga _1-k N having a k value of 0.2 or less. On the other hand, the second nitride semiconductor film is not particularly limited as long as it is a nitride semiconductor having a composition different from that of the first nitride semiconductor film, but in order to grow a second nitride semiconductor film with good crystallinity, a Binary mixed crystal or ternary mixed crystal nitride semiconductor with bandgap energy larger than that of the first nitride semiconductor is grown in the n-side second multilayer film layer 106, and the second nitride semiconductor film 106b is preferably In _m Ga _1-m N (0≤m<1, m<k) is most preferably GaN in order to grow a multilayer film with good overall crystallinity. Therefore, the most preferable combination is a combination using In _k Ga _1-k N having a k value of 0.5 or less as the first nitride semiconductor film and GaN as the second nitride semiconductor film.

Furthermore, the film thickness of at least one of the first nitride semiconductor film 106a or the second nitride semiconductor film 106b may be greater than that between adjacent first nitride semiconductor films 106a or between adjacent second nitride semiconductor films 106a. The compound semiconductor films 106b may be different from each other or may be the same. In addition, the term that the film thicknesses are different between adjacent layers means that, for example, when forming a multilayer film layer in which the first nitride semiconductor film 106a or the second nitride semiconductor film 106b is stacked in multiple layers, The film thicknesses of the first nitride semiconductor film 106a (second nitride semiconductor film 106b ) sandwiching the second nitride semiconductor film 106b (first nitride semiconductor film 106a ) are different from each other.

For example, when the first nitride semiconductor film 106a is made of InGaN and the second nitride semiconductor film 106b is made of GaN, since the thickness of the InGaN layer between the GaN layer and the GaN layer is increased as the thickness of the GaN layer approaches the active layer, Gradually thickening or thinning will change the refractive index inside the multilayer film layer, so a layer whose refractive index gradually changes can be substantially formed. That is, substantially the same effect as that obtained by forming a composition-graded nitride semiconductor layer can be obtained. Therefore, in an element such as a laser element that must have an optical waveguide, the waveguide can be formed with a multilayer film layer to adjust the mode of the laser light.

Furthermore, the composition of the Group III element in at least one of the first nitride semiconductor film 106a or the second nitride semiconductor film 106b may be between adjacent first nitride semiconductor films 106a or between adjacent first nitride semiconductor films 106a. Compositions of the same group III elements are different among the second nitride semiconductor films 106b. This means that, in the case of forming a multilayered film layer in which the first nitride semiconductor film 106a or the second nitride semiconductor film 106b is stacked, the second nitride semiconductor film 106b (the first nitride semiconductor film 106b The composition ratios of group III elements in the first nitride semiconductor film 106a (second nitride semiconductor film 106b ) of the semiconductor film 106a) are different from each other.

For example, if the compositions of the same group III elements are made different from each other, when the first nitride semiconductor film 106a is made of InGaN and the second nitride semiconductor film 106b is made of GaN, by making the GaN layer and the GaN layer The In composition of the InGaN layer between them gradually increases or decreases as it approaches the active layer, which can be the same as the above embodiment, so that the refractive index inside the multilayer film layer changes, and a nitride semiconductor with a gradually changing composition is formed. layer. In addition, as the In composition decreases, the refractive index also tends to decrease.

Although the n-side second multilayer film layer 106 can also be formed away from the active layer, it is most preferably formed in contact with the active layer. When it is formed in contact with the active layer, it tends to be easier to increase the output power.

In addition, in the n-side second multilayer film layer 106, both the first nitride semiconductor film 106a and the second nitride semiconductor film 106b may be undoped, or both may be doped with n-type impurities. , In addition, impurities can also be doped in either one. In order to improve the crystallinity and increase the output power, it is most preferable not to dope, followed by modulated doping of n-type impurities in either the first nitride semiconductor film 106a or the second nitride semiconductor film 106b, and then both. are doped with impurities.

In addition, when both are doped with n-type impurities, the concentration of n-type impurities in the first nitride semiconductor film 106a may be different from the concentration of n-type impurities in the second nitride semiconductor film 106b.

In addition, as n-type impurities, it is preferable to select group IV and group VI elements such as Si, Ge, Sn, and S, and it is more preferable to use Si and Sn.

Here, the so-called non-doping refers to a state in which impurities are not intentionally doped subjectively, for example, impurities are mixed from adjacent nitride semiconductor layers due to diffusion, and it is still referred to as non-doping in the present invention. In addition, the concentration of impurities mixed in due to diffusion is mostly distributed in a gradient within the film layer.

In addition, when n-type impurities are doped into the first nitride semiconductor film 106a and/or the second nitride semiconductor film 106b, the concentration of the impurities is adjusted to be 5×10 ²¹ /cm ³ or less, preferably 1×10 21 /cm 3 or less. 10 ²⁰ /cm ³ or less. If the concentration exceeds 5×10 ²¹ /cm ³ , the crystallinity of the nitride semiconductor layer deteriorates, and the output power tends to decrease on the contrary. This is also true when modulating doping.

或以下，优选为70

或以下，更优选为50

或以下。通过使单一氮化物半导体层的膜厚为100或以下，可以使氮化物半导体单一层的膜厚成为弹性临界膜厚或其以下，与以厚膜生长起来情况相比，可以生长出结晶性良好的氮化物半导体。另外，由于两种膜厚都在70或以下，所以n侧的第二多层膜层6的结构成为超晶格(多层膜)结构，如果在该结晶性良好的多层膜结构上生长有源层，则n侧第二多层膜层6就起到缓冲层的作用，就可以结晶性良好地生长有源层。Furthermore, in the n-side second multilayer film layer 106, the film thickness of the first and second nitride semiconductor films is 100

or below, preferably 70

or below, more preferably 50

or below. By making the film thickness of a single nitride semiconductor layer 100 When the film thickness of the single nitride semiconductor layer is equal to or less than the elastic critical film thickness, it is possible to grow a nitride semiconductor having better crystallinity than when a thick film is grown. In addition, since both film thicknesses are at 70 or below, so the structure of the second multilayer film layer 6 on the n side becomes a superlattice (multilayer film) structure. The layer 6 acts as a buffer layer, and the active layer can be grown with good crystallinity.

In Embodiment 2, the active layer 7 of the multi-quantum well structure is formed of a nitride semiconductor containing In and Ga, preferably In _a Ga _1-a N (0≤a<1), and is n-type or p-type. Both types are acceptable, but strong interband luminescence can be obtained by non-doping (without adding impurities), and the half-width of the luminescence wavelength is narrowed, so it is preferred. Active layer 7 may also be doped with n-type impurities and/or p-type impurities. If n-type impurities are doped in the active layer 7, compared with non-doped ones, the inter-band luminous intensity can be further enhanced. When the active layer 7 is doped with p-type impurities, the peak wavelength can be shifted to a side 0.5 eV lower than the energy of the peak wavelength of interband luminescence, and the half width can be widened. If the active layer is doped with both p-type and n-type impurities, the luminous intensity of the above-mentioned active layer doped with only p-type impurities can be further increased. Especially when forming an active layer doped with a p-type dopant, it is preferable that the conductivity type of the active layer is also doped with an n-type dopant such as Si so that the whole becomes n-type. In order to grow an active layer with good crystallinity, it is most preferably non-doped.

或以下，优选为70

或以下，进而优选为50

或以下。在本发明中，阱层的膜厚的下限没有特别的限制，但一般为一原子层或以上，优选为10

或以上。如果阱层的厚度比100

还要厚，就会有难以提高输出功率的倾向。The stacking order of the barrier layer and the well layer of the active layer 7 is not particularly limited, and the stacking may start from the well layer and end with the well layer; or start stacking from the well layer and end with the barrier layer. In addition, stacking may start from a barrier layer and end with a barrier layer; or stacking may start from a barrier layer and end with a well layer. As the film thickness of the well layer, adjust to 100

or below, preferably 70

or below, more preferably 50

or below. In the present invention, the lower limit of the film thickness of the well layer is not particularly limited, but it is generally one atomic layer or more, preferably 10

or above. If the thickness of the well layer is greater than 100

If it is thicker, it tends to be difficult to increase the output power.

或以下，优选为500

或以下，更优选为300

或以下。本发明对势垒层的膜厚的下限没有特别限制，一般为一原子层或以上，优选为10

或以上。当势垒层在上述范围内时，提高输出功率就很容易，因而优选。更进一步，本发明对于有源层7的整体膜厚没有特别限制，考虑到LED元件等的期望的波长等，调整势垒层和阱层的各自的层叠数、层叠顺序，来调整有源层7的总膜厚。On the other hand, the thickness of the barrier layer is adjusted to 2000

or below, preferably 500

or below, more preferably 300

or below. The lower limit of the film thickness of the barrier layer in the present invention is not particularly limited, generally one atomic layer or more, preferably 10

or above. When the barrier layer is within the above range, it is easy to increase the output power, which is preferable. Further, the present invention has no particular limitation on the overall film thickness of the active layer 7, and the active layer is adjusted by adjusting the respective stacking numbers and stacking order of the barrier layer and the well layer in consideration of the desired wavelength of the LED element and the like. 7 total film thickness.

In Embodiment 2, the p-side cladding layer is made of the third nitride semiconductor film 108a having a larger bandgap energy and the fourth nitride semiconductor film 108a having a smaller bandgap energy than the third nitride semiconductor film 108a. The film 108b is laminated, and the p-side multilayer film cladding layer 108 has a different or the same p-type impurity concentration. However, in the present invention, a single layer composed of _{AlbGa1 -bN} (0≤b≤1) containing p-type impurities may also be used.

Next, first, the case where the p-side cladding layer has a multilayer film structure (superlattice structure) of the p-side multilayer film cladding layer 108 will be described.

或以下、进而优选为70

或以下、最优选为10～40

的膜厚。第三氮化物半导体膜108a和第四氮化物半导体膜108b的膜厚既可以相同，也可以不同。当多层膜结构的各层的膜厚在上述范围内时，则各氮化物半导体的膜厚都在弹性临界膜厚或以下，与在厚膜上生长起来的情况相比，能够生长出结晶性良好的氮化物半导体，另外，由于氮化物半导体层的结晶性变为良好，所以在添加了p型杂质的情况下，可以获得载流子浓度大、电阻率小的p层，且具有易于降低元件的Vf和阈值的倾向。将这种膜厚的两种膜层形成一对，进行多次层叠，从而形成了多层膜层。另外，p侧多层膜包覆层108的总膜厚的调整是通过调整第三和第四氮化物半导体膜的各层的膜厚、调整层叠的次数来进行的。p侧多层膜包覆层108的总膜厚没有特别的限制，但一般为2000

或以下，优选为1000

或以下，更优选为500

或以下，当总膜厚在该范围内时，可以提高发光输出功率，降低正向电压(Vf)，因而优选。The film thicknesses of the third nitride semiconductor film 108a and the fourth nitride semiconductor film 108b constituting the multilayer film layer of the p-side multilayer film cladding layer 108 are adjusted to 100

or below, more preferably 70

or below, most preferably 10 to 40

film thickness. The film thicknesses of the third nitride semiconductor film 108a and the fourth nitride semiconductor film 108b may be the same or different. When the film thickness of each layer of the multilayer film structure is within the above-mentioned range, the film thickness of each nitride semiconductor is at or below the elastic critical film thickness, and compared with the case of growing on a thick film, crystal growth can be achieved. In addition, since the crystallinity of the nitride semiconductor layer becomes good, when a p-type impurity is added, a p-layer with a large carrier concentration and a low resistivity can be obtained, and has the characteristics of easy Tendency to lower the Vf and threshold of the device. Two kinds of film layers having such a film thickness are formed into a pair and laminated a plurality of times to form a multilayer film layer. In addition, the adjustment of the total film thickness of the p-side multilayer cladding layer 108 is performed by adjusting the film thicknesses of the respective layers of the third and fourth nitride semiconductor films and adjusting the number of laminations. The total film thickness of the p-side multilayer film cladding layer 108 is not particularly limited, but is generally 2000

or below, preferably 1000

or below, more preferably 500

or less. When the total film thickness is within this range, the luminous output can be increased and the forward voltage (Vf) can be reduced, which is preferable.

The third nitride semiconductor film 108a is preferably a nitride semiconductor containing at least Al, and more preferably Al _n Ga _1-n N (0<n≤1) is grown; the fourth nitride semiconductor film 108b is preferably grown Al _p Ga ₁ Nitride semiconductors of binary mixed crystals and ternary mixed crystals such as pN (0≤p<1, n _> p) and _{InrGa1 -rN} (0≤r≤1).

If the p-side cladding layer is made into the p-side multilayer film cladding layer 108 of superlattice structure, crystallinity can be improved, resistivity can be lowered, and Vf can be lowered.

The p-type impurity concentrations of the third nitride semiconductor film 108a and the fourth nitride semiconductor film 108b of the p-side multilayer film cladding layer 108 are different, so that the impurity concentration in one layer is high and the impurity concentration in the other layer is high. Small. Like the n-side first multilayer film 5, if the concentration of the p-type impurity in the third nitride semiconductor film 108a having a large bandgap energy is increased and the concentration of the fourth nitride semiconductor film 108b having a small bandgap energy is decreased, The concentration of p-type impurities, or no doping, can reduce the threshold voltage, Vf, etc. In addition, the opposite is also possible. That is, the concentration of p-type impurities in the third nitride semiconductor film 108a having a large bandgap energy may be reduced, and the concentration of p-type impurities in the fourth nitride semiconductor film 108b having a small bandgap energy may be increased.

The preferable doping amount of the third nitride semiconductor film 108a is adjusted to be in the range of 1×10 ¹⁸ /cm ³ to 1×10 ²¹ /cm ³ , more preferably 1×10 ¹⁹ /cm ³ to 5×10 ²⁰ /cm 3 ^cm3 range. If it is less than 1×10 ¹⁸ /cm ³ , similarly, the difference with the fourth nitride semiconductor film 108b becomes small, and similarly, it tends to be difficult to obtain a film layer with a high carrier concentration; 10 ²¹ /cm ³ , the crystallinity tends to deteriorate. On the other hand, the p-type impurity concentration of the fourth nitride semiconductor film 108b only needs to be lower than that of the third nitride semiconductor film 108a, and is preferably 1/10 or more lower. Most preferably, it is not doped, so that the layer with the highest mobility can be obtained, but because the film thickness is very thin, there will be p-type impurities diffused from the third nitride semiconductor, and the amount is preferably 1×10 ²⁰ /cm ³ or less. The same applies to the case where a small amount of p-type impurities is doped into the third nitride semiconductor film 108a having a large bandgap energy and a large amount of p-type impurities is doped into the fourth nitride semiconductor film 108b having a small bandgap energy. .

As p-type impurities, elements of group IIA and group IIB in the periodic table such as Mg, Zn, Ca, and Be can be selected, and Mg, Ca, etc. are preferably used as p-type impurities.

Furthermore, in the nitride semiconductor layer constituting the multilayer film, the film layer doped with impurities at a high concentration increases the impurity concentration near the center of the semiconductor layer and decreases the impurity concentration near the two sides in the thickness direction. (preferably non-doped), which can reduce the resistivity, so it is preferred.

或以下，优选为1000

或以下，更优选为500～100

当膜厚在上述范围内时，则可提高发光输出功率，降低Vf，因而优选。p侧单层膜包覆层的组成是Al_bGa_1-bN(0≤b≤1)。Next, when the p-side cladding layer is formed of a single-layer film of _{AlbGa1 -bN} (0≤b≤1) containing p-type impurities, the p-side single-layer film cladding layer film Thickness is 2000

or below, preferably 1000

or below, more preferably 500 to 100

When the film thickness is within the above range, the luminous output can be increased and Vf can be lowered, which is preferable. The composition of the cladding layer of the p-side monolayer film is Al _b Ga _1-b N (0≤b≤1).

In addition, although the cladding layer of the single-layer film has slightly poorer crystallinity than the p-side cladding layer of the above-mentioned multi-film structure, it can be crystallized by combining with the above-mentioned n-side first multilayer film layer 105. Grow well, and can lower the threshold and Vf. Furthermore, although it is a single-layer film, it can reduce the degradation of device performance by combining it with other film layers in this way, and because it is a single-layer film layer, the manufacturing process can be simplified, which is preferable in mass production.

The p-type impurity concentration of the p-side monolayer cladding layer is 1×10 ¹⁸ /cm ³ to 1×10 ²¹ /cm ³ , preferably 5×10 ¹⁸ /cm ³ to 5×10 ²⁰ /cm ³ , more preferably 5×10 ¹⁹ /cm ³ to 1×10 ²⁰ /cm ³ . If the impurity concentration is within the above range, a good p-type film layer can be obtained, which is preferable.

Next, in the present embodiment, when the Mg-doped p-side GaN contact layer 9 is made into a single layer, its composition is made into a binary mixed crystal nitride semiconductor not containing In and Al. In the case of a single layer, if In and Al are contained, good ohmic contact with the p-electrode 11 cannot be obtained, and the luminous efficiency will decrease. The film thickness of the p-side contact layer 9 is 0.001 to 0.5 μm, preferably 0.01 to 0.3 μm, more preferably 0.05 to 0.2 μm. If the film thickness is less than 0.001 μm, it is easy to have an electrical short circuit with the p-type GaAlN cladding layer, and it is difficult to function as a contact layer. In addition, if the GaN contact layer of a binary mixed crystal having a different composition is stacked on the GaAlN cladding layer of a ternary mixed crystal, and the film thickness thereof is made larger than 0.5 μm, it is easy to make the p-side GaN contact layer In 9, lattice defects due to mismatch between crystals are generated, and the crystallinity tends to decrease. In addition, the thinner the film thickness of the contact layer, the more Vf can be lowered, and the luminous efficiency can be improved more. In addition, if the p-type impurity of the p-type GaN contact layer 9 is Mg, p-type characteristics can be easily obtained, and an ohmic contact can also be easily obtained. The concentration of Mg is 1×10 ¹⁸ /cm ³ to 1×10 ²¹ /cm ³ , preferably 5×10 ¹⁹ /cm ³ to 3×10 ²⁰ /cm ³ , most preferably about 1×10 ²⁰ /cm ³ . When the concentration of Mg is within this range, a good p-type film can be easily obtained and Vf can be lowered, which is preferable.

In addition, n-electrode 12 and p-electrode 11 are respectively formed on n-side contact layer 4 and on Mg-doped p-side GaN contact layer 9 . Materials for the n-electrode 12 and the p-electrode 11 are not particularly limited. For example, W/Al can be used for the n-electrode 12, and Ni/Au can be used for the p-electrode 11.

Embodiment 3

Next, Embodiment 3 of the present invention will be described with reference to FIG. 5 .

As shown in FIG. 5 , the nitride semiconductor light-emitting device according to Embodiment 3 of the present invention is structured as follows: On a substrate 1 made of, for example, sapphire, a first n-side nitride semiconductor layer 203 is sequentially formed via a buffer layer 202 , The second n-side nitride semiconductor layer 204 , the third n-side nitride semiconductor layer 205 , the active layer 7 , the p-side cladding layer 108 and the p-side contact layer 208 . Further, in the third embodiment, the light-transmitting p-electrode 10 is formed on substantially the entire upper surface of the p-side contact layer 208, and the p-pad electrode 11 for bonding is formed on a part of the p-electrode. In addition, the surface of the second n-side nitride semiconductor layer 204 is exposed on one side of the light-emitting element, and the n-electrode 12 is formed on the exposed portion.

Here, as shown in FIG. 5, in the nitride semiconductor light-emitting element of Embodiment 3, the buffer layer 202, the first n-side nitride semiconductor layer 203, the second n-side nitride semiconductor layer 204, and the third n-side The nitride semiconductor layer 205 constitutes the n-side region 230 , and the p-side cladding layer 108 and the p-side contact layer 208 constitute the n-side region 240 .

Here, especially in the third embodiment, the p-side contact layer 208 has a superstructure formed by alternately laminating first nitride semiconductor films 208a and second nitride semiconductor films 208b having different compositions. In the crystal lattice structure, at least the first nitride semiconductor film 208a contains In among the above two kinds of nitride semiconductor layers. In this way, among the above-mentioned two types of nitride semiconductor layers constituting the p-side contact layer 208, at least one of the first nitride semiconductor films 208a contains In, and the first and second nitride semiconductor films 208a, 208b are alternately stacked. With a superlattice structure, the p-side contact layer 208 with very few defects and good crystallinity can be formed. Therefore, it is possible to form the p-side contact layer 208 which has a lower resistance value and makes good ohmic contact with the p-electrode 10 than the conventional example made of a single layer of InGaN having a non-superlattice structure.

In further detail, in Embodiment 3, the p-side contact layer 208 can be constituted by combining, for example, the first nitride semiconductor film 208a and the second nitride semiconductor film 208b shown in Table 1 below.

Table 1

The first nitride semiconductor film 208a The second nitride semiconductor film 208b 1 In_xGa_1-xN GaN 2 In_xGa_1-xN In_yGa_1-yN(x>y) 3 In_xGa_1-xN Al_yGa_1-yN(0<z<1)

Here, in the third embodiment, in order to form the first nitride semiconductor film 8a with few crystal defects, _{InxGa1 -xN} in Table 1 is preferably set to x<0.5, more preferably x<0.4, Furthermore, it is preferable to set x<0.3.

或以下，进而优选为200

或以下。另外，构成p型接触层的第一和第二氮化物半导体膜的膜厚分别优选设定为100

或以下，更优选为70

或以下，进而优选为50

或以下。另外，最优选为设定在10～40

的范围内。In addition, in the present invention, since the thicker the film thickness of the p-type contact layer is, the higher the resistance value in the thickness direction is, the thickness is preferably set to 0.1 μm or less, more preferably 500 μm or less.

or below, more preferably 200

or below. In addition, the film thicknesses of the first and second nitride semiconductor films constituting the p-type contact layer are preferably set to 100

or below, more preferably 70

or below, more preferably 50

or below. In addition, it is most preferable to set it at 10 to 40

In the range.

以下，是因为如果第一和第二氮化物半导体膜208a、208b的膜厚大于100

的话，各氮化物半导体层就成为弹性变形限度以上的膜厚，很容易在膜层中产生微小的裂纹或结晶缺陷，不能有效地发挥作为超晶格结构的效果。另外，在本发明中，第一和第二氮化物半导体膜208a、208b只要为至少一原子层或以上即可，优选为如上述那样设定为10

或以上。The film thickness of the first and second nitride semiconductor films 208a, 208b constituting the p-side contact layer 208 is set at 100

Below, because if the film thickness of the first and second nitride semiconductor films 208a, 208b is greater than 100

If this is not the case, each nitride semiconductor layer becomes thicker than the limit of elastic deformation, microcracks or crystal defects are likely to occur in the film layer, and the effect as a superlattice structure cannot be effectively exerted. In addition, in the present invention, the first and second nitride semiconductor films 208a and 208b need only be at least one atomic layer or more, and it is preferable to set 10 layers as described above.

or above.

In addition, in the present invention, it is only necessary to add p-type impurities such as Mg to at least one of the first nitride semiconductor film 208a and the second nitride semiconductor film 208b so that the p-side contact layer 208 exhibits p-type conductivity as a whole. That's it. In addition, when both the first nitride semiconductor film 208a and the second nitride semiconductor film 208b are doped with p-type impurities, it is preferable to make the p-type impurity concentration of one nitride semiconductor layer higher than that of the other nitride semiconductor layer. The concentration is high (hereinafter referred to as modulation doping).

In this way, by setting the impurity concentration of one of the first nitride semiconductor film 208a and the second nitride semiconductor film 208b higher than that of the other, it is possible to generate a higher concentration in the nitride semiconductor layer of the higher impurity concentration. A large number of carriers can make the mobility in the other nitride semiconductor layer with a low impurity concentration higher than that in the one nitride semiconductor layer. Accordingly, since the carrier concentration and mobility of the entire superlattice structure layer formed by stacking the first and second nitride semiconductor films 208a and 208b can be increased simultaneously, the resistance of the p-side contact layer 208 can be reduced. value. Therefore, by further performing modulation doping as described above in the p-side contact layer 208 , the nitride semiconductor device according to Embodiment 3 can reduce the voltage in the forward direction at a predetermined current value.

In addition, when modulation doping is performed as described above, it is preferable to dope one nitride semiconductor layer with a p-type impurity in the range of 1×10 ¹⁹ /cm ³ to 5×10 ²¹ /cm ³ , and to dope the other nitride semiconductor layer with p-type impurities. The nitride semiconductor layer is doped in the range of 5×10 ¹⁸ /cm ³ to 5×10 ¹⁹ /cm ³ , and has a smaller amount of p-type impurities than the above-mentioned one nitride semiconductor layer. If more than 5×10 ²¹ /cm ³ of p-type impurities are added to the nitride semiconductor layer, the crystallinity will deteriorate, the resistance value will increase, and it will be difficult to obtain a good ohmic contact; if less than 5 ×10 ¹⁸ /cm ³ , sufficient carrier concentration cannot be obtained, and the output power will decrease.

In addition, in the present invention, in the p-side contact layer 208, any one of the first nitride semiconductor film 208a or the second nitride semiconductor film 208b may be set as the uppermost layer, or any one of them may be used together with The p-side cladding layer 108 is in contact with each other. However, in the present invention, it is preferable to form the first nitride semiconductor film 208a containing In as the uppermost layer, and form the p-electrode on the upper surface of the first nitride semiconductor film 8a. In this way, the ohmic contact resistance between the p-side contact layer 208 and the p-electrode can be reduced.

That is, since the first nitride semiconductor film 208a contains In or contains a large amount of In, the bandgap can be reduced compared with the second nitride semiconductor film 208b, and the energy level at the lower end of the conduction band of the metal constituting the p-electrode can be made comparable to that of the second nitride semiconductor film 208b. A difference between the energy levels at the upper end of the valence band of the nitride semiconductor film 208a is reduced, so the ohmic contact resistance can be reduced.

或以下，最优选设定在10～40的范围内。这样通过将p型包覆层制成超晶格结构，就能够降低p型包覆层的电阻值。另外，p侧包覆层108的整体膜厚优选设定为100

～2μm，进而优选为500

～1μm。通过设定成这样的膜厚，就能作为良好的载流子封闭层进行工作，而且p侧包覆层整体的电阻值也比较低。In addition, in the nitride semiconductor light-emitting device according to Embodiment 3, the p-type cladding layer preferably has a layer composed of _{AlxGa1 -xN} (0<x≤1) and a layer composed of _{InyGa1 -} yN. (0≤y<1) is a superlattice structure formed by alternate lamination of film layers. The film thickness of each layer constituting the p-type cladding layer is preferably set to the elastic deformation limit or less, that is, 100 or below, more preferably 70 or below, more preferably 50

or below, most preferably set at 10-40 In the range. In this way, by forming the p-type cladding layer into a superlattice structure, the resistance value of the p-type cladding layer can be reduced. In addition, the overall film thickness of the p-side cladding layer 108 is preferably set to 100

~2μm, more preferably 500

~1 μm. By setting such a film thickness, it is possible to function as a good carrier confinement layer, and the overall resistance value of the p-side cladding layer is also relatively low.

Embodiment 4

As shown in FIG. 6A , the nitride semiconductor device according to Embodiment 4 of the present invention differs from Embodiment 3 in that, in the p-side contact layer 208 , further between the first nitride semiconductor film 208 a and the second nitride semiconductor film A graded composition layer 208c is formed between 208b, and the others are the same as those in Embodiment 3. Here, the composition graded layer 208c refers to a layer whose composition changes continuously in the thickness direction so as to gradually change from the composition of the first nitride semiconductor film 208a to the composition of the second nitride semiconductor film 208b. For example, in the case where the first nitride semiconductor film 208a is In _x Ga _1-x N and the second nitride semiconductor film 208b is GaN, the composition graded layer 208c is a film layer that, as shown in FIG. The composition ratio (x) of In gradually decreases along the thickness direction of the surface in contact with the first nitride semiconductor film 208 a and the surface in contact with the second nitride semiconductor film 208 b. In addition, in the second embodiment, as long as the composition ratio of the composition gradient layer 208c decreases gradually, it is not necessarily necessary that the composition changes linearly in the thickness direction as shown in FIG. 6B.

In the nitride semiconductor device according to the second embodiment constituted as above, since the composition does not change abruptly in the boundary region between the first nitride semiconductor film 208a and the second nitride semiconductor film 208b, the film growth , in the boundary region between the first nitride semiconductor film 208a and the second nitride semiconductor film 208b, segregation of a specific element can be prevented. As a result of preventing segregation of specific elements in this way, the first nitride semiconductor film 208 a and the second nitride semiconductor film 208 b with fewer crystal defects can be grown.

In the above-mentioned example where the first nitride semiconductor film 208a is In _x Ga _1-x N and the second nitride semiconductor film 208b is GaN, it is possible to prevent the gap between the first nitride semiconductor film 208a and the second nitride semiconductor film 208b. The segregation of In can improve the crystallinity.

Embodiment 5

Next, the nitride semiconductor device according to Embodiment 5 of the present invention will be described using FIG. 8 , which is a schematic cross-sectional view thereof.

As shown in FIG. 8 , the nitride semiconductor element of Embodiment 5 has the following structure, that is, the following film layers are sequentially stacked on the substrate 1: a buffer layer 102, an undoped GaN layer 103, and an n-type impurity-containing GaN layer. The n-side contact layer 4 is the n-side first multi-layer film layer 305 composed of the non-doped lower layer 305a, the middle layer 305b doped with n-type impurities, and the non-doped upper layer 305c. The n-side second multilayer film layer 306 composed of the nitride semiconductor film 306a and the second nitride semiconductor film 306b, the active layer 7 of the multi-quantum well structure, and the p-side multi-quantum well structure composed of the third and fourth nitride semiconductor films A film cladding layer 8 or a p-side single-layer film cladding layer 8, and a p-side GaN contact layer 9 doped with Mg. Furthermore, an n-electrode 12 is formed on the n-side contact layer 4 , and a p-electrode 11 is formed on the p-side GaN contact layer 9 .

Here, in the nitride semiconductor device of the embodiment, the buffer layer 102, the undoped GaN layer 103, the n-side contact layer 4, the n-side first multilayer film layer 305, and the n-side second multilayer film layer 306 constitutes the n-side region 330 , and the p-side region is constituted by the p-side cladding layer 108 and the p-side GaN contact layer 9 .

In Embodiment 5, as the substrate 1, sapphire whose main surface is the C-plane, R-plane, or A-plane can be used, and an insulating substrate such as spinel (MgAl ₂ O ₄ ), and SiC (including 6H, 4H, 3C), Si, ZnO, GaAs, GaN and other semiconductor substrates.

In Embodiment 5, as the buffer layer 102, a nitride semiconductor made of _{GadAl1 -dN} (provided that d is in the range of 0<d≤1) can be cited, and the smaller the proportion of Al is, the better. , the more significant the improvement in crystallinity is, the buffer layer 102 made of GaN is more preferable.

The film thickness of the buffer layer 102 is adjusted to be within a range of 0.002 to 0.5 μm, preferably 0.005 to 0.2 μm, more preferably 0.01 to 0.02 μm. When the film thickness of the buffer layer 102 is within the above-mentioned range, the crystal form of the nitride semiconductor is favorable, and the crystallinity of the nitride semiconductor grown on the buffer layer 102 is also improved.

The growth temperature of the buffer layer 102 is adjusted to be within a range of 200°C to 900°C, preferably within a range of 400°C to 800°C. When the growth temperature is within the above range, good polycrystals are crystallized, and the crystallinity of the nitride semiconductor grown on the buffer layer 102 can be improved by using such polycrystals as seed crystals, which is preferable.

In addition, the buffer layer 102 grown at a low temperature may also be omitted depending on the type of the substrate, the growth method, and the like.

Next, in the fifth embodiment, the undoped GaN layer 103 means a layer grown without adding n-type impurities during the growth process. When the non-doped GaN layer 103 is grown on the buffer layer 102, the crystallinity of the non-doped GaN layer 103 is good, and the crystallinity of the n-side contact layer 4 etc. grown on the non-doped GaN layer 103 is also changed. well done. The film thickness of the undoped GaN layer 103 is 0.01 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more. When the film thickness is within this range, each layer after the n-side contact layer 4 can be grown with good crystallinity, which is preferable. In addition, the upper limit of the film thickness of the undoped GaN layer 103 is not particularly limited, but may be appropriately adjusted according to factors such as production efficiency.

Next, in the present Embodiment 5, the n-type impurity-containing n-side contact layer 4 contains n-type impurities at a concentration of 3×10 ¹⁸ /cm ³ or more, preferably 5×10 ¹⁸ /cm ³ or more. If more n-type impurities are doped like this, and then the film layer is used as the n-side contact layer, Vf and threshold can be lowered. If the concentration of impurities exceeds the above-mentioned range, it tends to be difficult to lower Vf. In addition, when the n-side contact layer 4 is formed on the non-doped GaN layer 103 with a low concentration of n-type impurities and good crystallinity, good crystallinity can be formed even with a high concentration of n-type impurities. The upper limit of the n-type impurity concentration of n-side contact layer 4 is not particularly limited, but is preferably 5×10 ²¹ /cm ³ or less in order to maintain the function of the contact layer.

The composition of the n-side contact layer 4 can be composed of In _e Al _f Ga _1-ef N (0 ≤ e, 0 ≤ f, e + f ≤ 1). Although the composition is not particularly limited, it is preferably GaN, and the value of f is Al _f Ga _1-f N of 0.2 or less, so that a nitride semiconductor layer with few crystal defects can be easily obtained. The film thickness of the n-side contact layer 4 is not particularly limited, but is 0.1 to 20 μm, preferably 0.5 to 10 μm, more preferably 1 to 5 μm, since it forms the n electrode. When the film thickness is within the above-mentioned range, the resistance value can be lowered, and the Vf value of the light-emitting element can be lowered, which is preferable.

In addition, when the n-side first multilayer film layer 305 described later is formed into a thick film, the n-side contact layer 4 can be omitted.

Next, in Embodiment 5, the n-side first multilayer film layer 305 is composed of at least three film layers. Starting from the substrate side, the three film layers are respectively the non-doped lower layer 305a, the doped lower layer 305a, and the doped layer. The middle layer 305b doped with n-type impurities, and the non-doped upper layer 305c.

Although each layer constituting the n-side first multilayer film layer 305 may have no direct influence on device characteristics such as static voltage resistance when each is a single layer, when the layers are combined to form the n-side first multilayer film layer When 305, as a whole, there is a unique function that can significantly improve the characteristics of the component, especially the luminous output power and static voltage resistance performance. In fact, this effect is an unexpected effect obtained when initially manufacturing a device in which layers are stacked. In other words, the present invention was accomplished by discovering such an effect.

Here, layers other than the above-mentioned lower layer 305a to upper layer 305c may be provided on the n-side first multilayer film layer 305 . In addition, the n-side first multilayer film layer 305 may be in contact with the active layer, or there may be other layers between it and the active layer.

As the nitride semiconductor constituting these lower layer 305a to _upper layer 305c, nitride semiconductors of various compositions represented by _{IngAlhGa1 -ghN} (0≤g<1, 0≤h<I) can be used, preferably A nitride semiconductor having a composition composed of GaN can be cited. In addition, the composition of each layer of the first multilayer film layer 305 may be the same or different.

优选为1000～10000更优选为2000～6000

如果第一多层膜层5的膜厚在上述范围内，从Vf的最适合化和耐静电压性能的提高的方面优选。Although the film thickness of the n-side first multilayer film layer 305 is not particularly limited, it is usually 175-12000

Preferably 1000～10000 More preferably 2000-6000

When the film thickness of the first multilayer film layer 5 is within the above-mentioned range, it is preferable from the viewpoint of optimizing Vf and improving static voltage resistance performance.

The adjustment of the film thickness of the first multilayer film layer 5 with the film thickness of the above-mentioned range is preferably to properly adjust the film thickness of each layer of the lower layer 305a, the middle layer 305b and the upper layer 305c, so that the thickness of the first multilayer film layer 5 The total film thickness is within the above range.

In addition, in Embodiment 5, although the film thicknesses of the lower layer 305a, intermediate layer 305b, and upper layer 305c constituting the n-side first multilayer film layer 305 are not particularly limited, in the present invention, in order to find The preferred range of the film thickness of each layer was studied experimentally as follows.

(1) Test 1

中间层5b的膜厚为350而上层5c的膜厚逐渐变化的LED元件，对各元件(各种膜厚)的正向电压、发光输出功率和耐静电压特性进行了测定。The film thickness of making lower layer 5a is 3000

The film thickness of the intermediate layer 5b is 350 On the other hand, the LED elements in which the film thickness of the upper layer 5c gradually changed were measured for each element (various film thicknesses) in terms of forward voltage, luminous output, and static voltage withstand characteristics.

The results are shown in Figures 9A and 9B.

(2) Test 2

上层5c的膜厚为50

而中间层5b的膜厚逐渐变化的LED元件，对各元件(各种膜厚)的正向电压、发光输出功率和耐静电压特性进行了测定。The film thickness of making lower layer 5a is 3000

The film thickness of the upper layer 5c is 50

As for the LED elements in which the film thickness of the intermediate layer 5b was gradually changed, the forward voltage, luminous output, and static voltage withstand characteristics of each element (various film thicknesses) were measured.

The results are shown in Fig. 10A and Fig. 10B.

(3) Test 3

上层5c的膜厚为50

而下层5a的膜厚逐渐变化的LED元件，对各元件(各种膜厚)的正向电压、发光输出功率和耐静电压特性进行了测定。The film thickness of making middle layer 5b is 350

The film thickness of the upper layer 5c is 50

As for the LED elements in which the film thickness of the lower layer 5a gradually changed, the forward voltage, luminous output, and static voltage withstand characteristics of each element (various film thicknesses) were measured.

The results are shown in Fig. 11A and Fig. 11B.

In addition, for the various LED elements produced in this test, except for the film thickness of each layer of the n-side first multilayer film layer, other production conditions are the same as those in Example 34 below. In addition, the characteristics shown in FIGS. 9A to 11B are all characteristics of an LED element of a conventional example used in comparison with Example 34. FIG. In addition, in FIGS. 9A to 11B , Po represents light emission output power, and Vf represents forward voltage.

优选为500～8000

更优选为1000～5000

如图11A与图11B所示，如果非掺杂的下层305a的膜厚逐渐增厚，耐静电压特性就会上升，但在10000附近，Vf急剧上升；另一方面，如果膜厚减薄，Vf也下降，耐静电压特性的下降增大，这是由于在厚度小于100

时，随着耐静电压特性的下降，材料利用率也大幅度下降。From the above test results, the film thickness of the non-doped lower layer 305a is 100-10000

Preferably 500-8000

More preferably 1000-5000

As shown in FIG. 11A and FIG. 11B, if the film thickness of the non-doped lower layer 305a is gradually increased, the ESD characteristics will increase, but at 10000 Nearby, Vf rises sharply; on the other hand, if the film thickness is reduced, Vf also decreases, and the drop in static voltage characteristics increases. This is due to the fact that when the thickness is less than 100

, with the decline of static voltage resistance, the utilization rate of materials also drops significantly.

In addition, in consideration of improving the effect of reducing the crystallinity of the n-side contact layer 4 containing n-type impurities, it is preferable to grow the upper layer 305a with a film thickness such that the crystallinity can be improved.

优选为100～500

更优选为150～400

这种掺杂了杂质的中间层305b是使载流子浓度充分、对发光输出功率有比较大的作用的层，如果没有形成该层，就会有发光输出功率显著降低的倾向。另外，在图10A中显示了，直至中间层305b的膜厚减小到25

左右时，发光输出功率也只是稍有下降，这是因为考虑到即使中间层305b的膜厚为50

发光输出功率也不会下降，从而对其他层的膜厚进行调整的缘故。另外，如图10A所示，当膜厚超过1000时，发光输出功率会有大幅度地下降的倾向。另一方面，如图10B所示，单看耐静电压特性，当中间层305b的膜厚很厚时，耐静电压特性良好，而当膜厚小于50

时，就会有耐静电压特性大幅度下降的倾向。The film thickness of the intermediate layer 305b doped with n-type impurities is 50-1000

Preferably 100-500

More preferably 150-400

The intermediate layer 305b doped with impurities is a layer that has a sufficient carrier concentration and has a relatively large effect on the luminous output. If this layer is not formed, the luminous output tends to decrease significantly. In addition, in FIG. 10A, until the film thickness of the intermediate layer 305b is reduced to 25

When left and right, the luminous output power is only slightly reduced. This is because considering that even if the film thickness of the intermediate layer 305b is 50

This is because the film thickness of other layers is adjusted without decreasing the luminous output. In addition, as shown in Figure 10A, when the film thickness exceeds 1000 , the luminous output power tends to drop significantly. On the other hand, as shown in FIG. 10B, looking at the static voltage resistance characteristics alone, when the film thickness of the intermediate layer 305b is very thick, the static voltage resistance characteristics are good, and when the film thickness is less than 50

, there is a tendency for the static voltage resistance characteristics to drop significantly.

优选为25～500

更优选为25～150

该非掺杂的上层305c与有源层相接或与它最接近而形成在第一多层膜中，对泄漏电流的防止有很大的关系，当上层305c的膜厚不到25时，会有泄漏电流增加的倾向。另外，如图9A和9B所示，当上层305c的膜厚超过1000时，Vf将上升，而耐静电压特性将下降。The film thickness of the non-doped upper layer 305c is 25-1000

Preferably 25-500

More preferably 25-150

The non-doped upper layer 305c is formed in the first multilayer film in contact with the active layer or is closest to it, which has a great relationship with the prevention of leakage current. When the film thickness of the upper layer 305c is less than 25 , there is a tendency for the leakage current to increase. In addition, as shown in FIGS. 9A and 9B, when the film thickness of the upper layer 305c exceeds 1000 When, Vf will rise, and the static voltage resistance characteristic will drop.

As mentioned above, the film thickness of each layer from the lower layer 305a to the upper layer 305c is very important for the characteristics of the element which is easily affected by the variation of the film thickness of each layer. All of these characteristics are substantially uniform to a good degree, especially the luminous output power and static voltage resistance characteristics become good, and by setting the film thickness of each layer within the above range, it is possible to meet higher standards and achieve Obtain higher luminous output power, or further improve the reliability of products.

In addition, the combination of the film thickness of each layer of the first multilayer film 305 can be appropriately adjusted according to various conditions such as changes in the composition of the active layer that change with the type of emission wavelength or the shape of the electrodes and LED elements, in order to obtain best results. By appropriately combining the film thicknesses of each layer within the above-mentioned ranges, various performances related to the combination of film thicknesses of each layer can be improved compared with conventional devices, and good luminous output power and static voltage resistance characteristics can be obtained.

The composition of each layer constituting the above-mentioned first multilayer film layer can be as long as it is the composition represented by the following formula In _g Al _h Ga _1-gh N (0≤g<1, 0≤h<1), and the composition of each layer can be The same or different, preferably a composition with a small ratio of In and Al, more preferably a film layer made of GaN.

The doping amount of n-type impurities in the intermediate layer 305b doped with n-type impurities in the above-mentioned first multilayer film layer 305 is not particularly specified, but generally the concentration should be 3×10 ¹⁸ /cm ³ or above, preferably 5×10 ¹⁸ /cm ³ or more. The upper limit of the n-type impurity is not particularly specified, but it should be limited to not deteriorating the crystallinity too much, and generally preferably 5×10 ²¹ /cm ³ or less. When the impurity concentration of the intermediate layer of the first multilayer film layer is within the above range, it is preferable from the viewpoints of increasing the luminous output and reducing Vf.

As the n-type impurity, Si, Ge, Se, S, O and other group IVB or VIB elements in the periodic table can be selected, and Si, Ge, S is preferably used as the n-type impurity.

In addition, at the interface of the above-mentioned first multilayer film layer 305, each layer can also be used as two kinds of layers within the range that does not interfere with the functions of each layer and element.

或以下，更优选为70

或以下，进而优选为50

或以下。由于通过这样减薄膜厚，多层膜层便成为超晶格结构，多层膜层的结晶性变好了，所以具有提高输出功率的倾向。Next, in the present Embodiment 5, the n-side second multilayer film layer 306 is composed of a multilayer film composed of the first nitride semiconductor film 306a containing In and having the same The second nitride semiconductor film 306b having a different composition from the first nitride semiconductor film 306a is laminated. The film thickness of at least one of the first nitride semiconductor film 306a or the second nitride semiconductor film 306b, preferably both are 100A.

or below, more preferably 70

or below, more preferably 50

or below. By reducing the film thickness in this way, the multilayer film becomes a superlattice structure, and the crystallinity of the multilayer film becomes better, so the output power tends to be improved.

If the film thickness of at least one of the first nitride semiconductor film 306a or the second nitride semiconductor film 306b is 100 or less, the thickness of the thin film layer is below the elastic critical film thickness, and the crystallization will become better, and the crystallinity of the first nitride semiconductor film 306a or the second nitride semiconductor film 306b stacked on it will also be improved. The overall crystallinity of the film layer will also be improved, so the output power of the device will be improved.

或以下，氮化物半导体单独一层就处于弹性临界膜厚或以下，与以厚膜生长的情况以及第一氮化物半导体膜306a或第二氮化物半导体膜306b中的一方为100

或以下的情况相比，能够生长出结晶性良好的氮化物半导体。另外，当双方的膜都为70

或以下时，则n侧第二多层膜层306便成为超晶格结构，当在该结晶性良好的多层膜结构上生长有源层时，n侧第二多层膜层306能起缓冲层那样的作用，有源层能以更好的结晶性生长起来。In addition, if both the film thicknesses of the first nitride semiconductor film 306a and the second nitride semiconductor film 306b are 100

or below, a single nitride semiconductor layer is at or below the elastic critical film thickness, which is 100 Å in the case of growing with a thick film and one of the first nitride semiconductor film 306a or the second nitride semiconductor film 306b.

Compared with the following cases, a nitride semiconductor with good crystallinity can be grown. In addition, when the membranes of both sides are 70

or below, the n-side second multilayer film layer 306 becomes a superlattice structure, and when an active layer is grown on the multilayer film structure with good crystallinity, the n-side second multilayer film layer 306 can act as a superlattice structure. With the function of the buffer layer, the active layer can grow with better crystallinity.

In Embodiment 5, if the n-side first multilayer film layer 305 and the above n-side second multilayer film layer 306 are combined in the n-side region 330, the luminous output power will be increased and Vf will be reduced, so it is preferable . The reason for this is not definite, but it is considered that the crystallinity of the active layer grown on the n-side second multilayer film layer 306 becomes better.

In addition, the film thickness of at least one of the first nitride semiconductor film 306a or the second nitride semiconductor film 306b of the n-side second multilayer film layer 306 may be greater than that of the adjacent first nitride semiconductor film 306a. Sometimes or the second nitride semiconductor films 306b are different from each other, or may be the same. Preferably, the film thickness of at least one of the first nitride semiconductor film 306a or the second nitride semiconductor film 306b of the n-side second multilayer film layer 306 is between adjacent first nitride semiconductor films 306a or The second nitride semiconductor films 306b are different from each other.

The so-called film thickness is different between adjacent layers means that when forming a multi-layered film layer formed by laminating the first nitride semiconductor film 306a and the second nitride semiconductor film 306b, the second nitride semiconductor film 306b The film thickness of the compound semiconductor film 306b (first nitride semiconductor film 306a ) is different from the film thickness of the first nitride semiconductor film 306a (second nitride semiconductor film 306b ) sandwiching it.

For example, when the first nitride semiconductor film 306a is InGaN and the second nitride semiconductor film 306b is GaN, the thickness of the InGaN layer between the GaN layer and the GaN layer gradually increases as it approaches the active layer, or gradually Thinning, so that the refractive index changes inside the multilayer film layer, so it is possible to substantially form a film layer with a gradually changing refractive index. That is, substantially the same effect as that of forming a nitride semiconductor with a graded composition can be obtained. Therefore, in an element such as a laser element that must have an optical waveguide channel, the mode of the laser light can be adjusted by forming the optical waveguide channel in the multilayer film layer.

In addition, the composition of group III elements in at least one of the first or second nitride semiconductor films may be different from each other between adjacent first nitride semiconductor films 306a or between adjacent second nitride semiconductor films 306b. Not the same, or can be the same. Preferably, the composition of the Group III element in at least one of the first nitride semiconductor film or the second nitride semiconductor film is between adjacent first nitride semiconductor films or between adjacent second nitride semiconductor films. are different from each other. The so-called mutual difference means that in the case of forming a multilayer film layer in which the first nitride semiconductor film or the second nitride semiconductor film is laminated, the second nitride semiconductor film (first nitride semiconductor film) The composition ratio of the group III element in the film is different from the composition ratio of the group III element in the first nitride semiconductor film (second nitride semiconductor film) sandwiching it.

For example, if the compositions of the same group III elements are made different from each other, when the first nitride semiconductor film is InGaN and the second nitride semiconductor film is GaN, by making the composition of In in the InGaN layer between the GaN layer and the GaN layer Gradually increasing or decreasing as it gets closer to the active layer, the refractive index can be changed inside the multilayer film layer, and a nitride semiconductor layer with a composition grade can be formed substantially. In addition, as the In composition decreases, the refractive index also tends to decrease.

The above-mentioned n-side second multilayer film layer 306, for example, as shown in FIG. 8, has a first nitride semiconductor film containing In and An n-side second multilayer film layer 306 in which a second nitride semiconductor film having a composition different from that of the first nitride semiconductor film is stacked. In the n-side second multilayer film layer 306, the first nitride semiconductor film and the second nitride semiconductor film are preferably formed in at least one layer or more, a total of two layers or more, preferably three layers or more, and more preferably At least two or more layers are stacked each, for a total of four or more layers.

The n-side second multilayer film layer 306 can be formed away from the active layer, but is most preferably formed in contact with the active layer. When it is formed in contact with the active layer, it tends to be easier to increase the output power.

When the n-side second multilayer film layer 306 is formed in contact with the active layer, the multilayer film layer in contact with the initial film layer (well layer or barrier layer) of the active layer can be the first nitrogen The compound semiconductor film may also be a second nitride semiconductor film, and the stacking order of the n-side second multilayer film layer 306 is not particularly limited. In addition, although the n-side second multilayer film layer 306 is formed in contact with the active layer 7 in FIG. Film layers composed of other n-type nitride semiconductors.

The first nitride semiconductor film is a nitride semiconductor containing In, preferably ternary mixed crystal In _k Ga _1-k N (0<k<1), more preferably In _k Ga ₁ having a k value of 0.5 or less _-k N, most preferably In _k Ga _1-k N having a k value of 0.2 or less. On the other hand, the second nitride semiconductor film is not particularly limited as long as it is a nitride semiconductor having a composition different from that of the first nitride semiconductor film, but in order to grow a second nitride semiconductor film with good crystallinity , so that it grows into In _m Ga _1-m N (0≤m<1, m<k) of binary mixed crystal or ternary mixed crystal (0≤m<1, m<k) whose bandgap energy is larger than that of the first nitride semiconductor film, preferably GaN. When the second nitride semiconductor is GaN, a multilayer film with good crystallinity as a whole can be grown. As a preferred combination, the first nitride semiconductor is In _k Ga _1-k N (0<k<1), and the second nitride semiconductor is In _m Ga _1-m N (0≤m<1, m<1). k), preferably a combination of GaN. As a further preferable combination, the first nitride semiconductor film is In _k Ga _1-k N having a k value of 0.5 or less, and the second nitride semiconductor film is GaN.

Both of the first and second nitride semiconductor films may be undoped, both may be doped with an n-type impurity, or either one may be doped with an impurity (modulated doping). In order to improve the crystallinity, it is preferred that both are not doped, followed by modulation doping, and thirdly both are doped. In addition, when both are doped, the concentration of the n-type impurity in the first nitride semiconductor film may be different from the concentration of the n-type impurity in the second nitride semiconductor film.

In addition, doping either one of the first nitride semiconductor film and the second nitride semiconductor film with an n-type impurity is called modulation doping, and the output power tends to be easily improved by such modulation doping.

In addition, as n-type impurities, it is preferable to select group IV and group VI elements such as Si, Ge, Sn, and S, and it is more preferable to use Si and Sn.

When doping n-type impurities, the concentration of the impurities is adjusted to be 5×10 ²¹ /cm ³ or less, preferably 1×10 ²⁰ /cm ³ or less. If it is more than 5×10 ²¹ /cm ³ , the crystallinity of the nitride semiconductor layer will deteriorate, and vice versa, the output tends to decrease. The same is true in the case of modulation doping.

In Embodiment 5, the active layer 7 of the multi-quantum well structure is formed of a nitride semiconductor containing In and Ga, preferably In _a Ga _1-a N (0≤a<1), regardless of n Both p-type and p-type are acceptable, but if it is non-doped (no impurities are added), strong interband emission can be obtained, and the half-width of the emission wavelength is narrowed, so it is preferable. Active layer 7 may also be doped with n-type and/or p-type impurities. When n-type impurities are doped in the active layer 7, the inter-band luminous intensity can be further enhanced compared with non-doping. When the active layer 7 is doped with a p-type impurity, the peak wavelength can be shifted to an energy side about 0.5 eV lower than the peak wavelength of interband luminescence, but the half width is widened. When the active layer is doped with both p-type and n-type impurities, the luminous intensity of the active layer doped with only p-type impurities can be further enhanced. In particular, when forming an active layer doped with a p-type dopant, it is preferable to dope an n-type dopant such as Si because the conductivity type of the active layer becomes n-type as a whole. In order to grow an active layer with good crystallinity, non-doping is most preferable.

或以下，优选为70

或以下，进而优选为50

或以下。阱层膜厚的上限没有特别的限制，但一般为一原子层或以上，优选为10或以上。当阱层的膜厚超过100

时，会有输出功率难以提高的倾向。The stacking order of the barrier layer and the well layer of the active layer 7 need not be particularly limited, from the well layer to the end of the well layer, from the well layer to the end of the barrier layer, from the barrier layer to the barrier layer end, or start stacking from the barrier layer to the end of the well layer, all can be. As the film thickness of the well layer, it is generally adjusted to 100

or below, preferably 70

or below, more preferably 50

or below. The upper limit of the thickness of the well layer is not particularly limited, but is generally one atomic layer or more, preferably 10 or above. When the film thickness of the well layer exceeds 100

, it tends to be difficult to increase the output power.

或以下，更优选为300

或以下。势垒层膜厚的上限并没有特别的限制，但一般为一原子层或以上，优选为10或以上。当势垒层在上述范围内时，就能很容易地提高输出功率，因而优选。另外，对有源层7的整体膜厚也没有特别的限制，可以在考虑LED元件等的所希望的波长等之后，调节势垒层和阱层的各自的层叠层数、层叠顺序，调整有源层7的总膜厚。On the other hand, the thickness of the barrier layer is generally adjusted to 2000 or below, preferably 500

or below, more preferably 300

or below. The upper limit of the film thickness of the barrier layer is not particularly limited, but it is generally one atomic layer or more, preferably 10 or above. When the barrier layer is within the above range, the output power can be easily increased, which is preferable. In addition, there is no particular limitation on the overall film thickness of the active layer 7, and the number of stacked layers and the stacking order of the barrier layer and the well layer can be adjusted in consideration of the desired wavelength of the LED element, etc. The total film thickness of the source layer 7.

In Embodiment 5, the p-side cladding layer 8 is formed by laminating a third nitride semiconductor film having a larger bandgap energy and a fourth nitride semiconductor film having a lower bandgap energy than the third nitride semiconductor film. Multi-layer films with different or identical p-type impurity concentrations, or a single layer composed of Al _b Ga _1-b N (0≤b≤1) containing p-type impurities.

Next, first, the case where the p-side cladding layer 8 is a p-side multilayer cladding layer having a multilayer film structure (superlattice structure) will be described.

或以下，最优选为10～40

第三氮化物半导体膜和第四氮化物半导体膜的膜厚既可以相同，也可以不同。当多层膜结构中的各层的膜厚在上述范围内时，氮化物半导体的各层膜厚都在弹性临界膜厚或以下，与以厚膜生长的情况相比，能够生长出结晶性良好的氮化物半导体，另外，氮化物半导体层的结晶性得以改善，所以在添加了p型杂质的情况下，可以获得载流子浓度大、电阻率小的p层，易于降低元件的Vf和阈值。将这样膜厚的两种层作为一对并多次层叠起来，就形成了多层膜层。接下来，p侧多层膜包覆层8总膜厚的调整通过调整第三和第四氮化物半导体层各层的膜厚、调整层叠的次数来调整。p侧多层膜包覆层8的总膜厚没有特别的规定，但一般为2000

或以下，优选为1000

或以下，更优选为500或以下，当总膜厚在上述范围内时，发光输出功率高，正向电压(Vf)较低，因而优选。The film thicknesses of the third and fourth nitride semiconductor films constituting the multilayer film cladding layer 17 of the p-side multilayer film were adjusted to be 100 or below, more preferably 70

or less, most preferably 10 to 40

The film thicknesses of the third nitride semiconductor film and the fourth nitride semiconductor film may be the same or different. When the film thickness of each layer in the multilayer film structure is within the above range, the film thickness of each layer of the nitride semiconductor is at or below the elastic critical film thickness, and compared with the case of growing with a thick film, crystallinity can be grown. Good nitride semiconductor, in addition, the crystallinity of the nitride semiconductor layer is improved, so when p-type impurities are added, a p-layer with high carrier concentration and low resistivity can be obtained, and it is easy to reduce the Vf and threshold. Two types of layers with such a film thickness are used as a pair and laminated multiple times to form a multilayer film layer. Next, the adjustment of the total film thickness of the p-side multilayer cladding layer 8 is adjusted by adjusting the film thicknesses of the third and fourth nitride semiconductor layers and adjusting the number of laminations. The total film thickness of the p-side multilayer film cladding layer 8 is not particularly regulated, but is generally 2000

or below, preferably 1000

or below, more preferably 500 When the total film thickness is within the above range, the luminous output is high and the forward voltage (Vf) is low, which is preferable.

The third nitride semiconductor film preferably grows a nitride semiconductor containing at least Al, preferably Al _n Ga _1-n N (0<n≤1); the fourth nitride semiconductor film preferably grows Al _p Ga _1-p N ( 0≤p<1, n>p), _{InrGa1 -rN} (0≤r≤1) such as binary mixed crystal, ternary mixed crystal nitride semiconductor growth. If the p-side cladding layer 8 is made into a superlattice structure, the crystallinity will be improved, the resistivity will be lowered, and Vf will tend to be lowered.

The p-type impurity concentrations of the third nitride semiconductor film and the fourth nitride semiconductor film of the p-side multilayer cladding layer 8 are different, such that one layer has a high impurity concentration and the other layer has a low impurity concentration. Like the n-side cladding layer 12, the concentration of the p-type impurity in the third nitride semiconductor film having a large bandgap energy is increased, and the concentration of the p-type impurity in the fourth nitride semiconductor film having a small bandgap energy is increased. Reduced, preferably not doped, so that the threshold voltage, Vf, etc. can be reduced. Alternatively, on the contrary, the concentration of the p-type impurity in the third nitride semiconductor film having a large bandgap energy may be reduced, while the concentration of the p-type impurity in the fourth nitride semiconductor film having a small bandgap energy may be reduced. increase.

The preferred doping amount of the third nitride semiconductor film is adjusted within the range of 1×10 ¹⁸ /cm ³ to 1×10 ²¹ /cm ³ , preferably 1×10 ¹⁹ /cm ³ to 5×10 ²⁰ /cm ³ . If it is less than 1×10 ¹⁸ /cm ³ , the difference with the fourth nitride semiconductor film will also decrease, and it will also tend to be difficult to obtain a film with a high carrier concentration; in addition, if it is greater than 1×10 ²¹ /cm cm ³ , the crystallinity tends to deteriorate. On the other hand, the p-type impurity concentration of the fourth nitride semiconductor film only needs to be less than that of the third nitride semiconductor film, and is preferably less than 1/10 or more. The most preferred is no doping, so that the film layer with the highest mobility can be obtained, but because of the thin film thickness, there will be p-type impurities diffused from the third nitride semiconductor side, and the amount is preferably 1×10 ²⁰ /cm ³ or less. The same applies to the case where the third nitride semiconductor film with a large bandgap energy is doped with a small amount of p-type impurities and the fourth nitride semiconductor film with a small bandgap energy is doped with a large amount of p-type impurities.

As the p-type impurity, Mg, Zn, Ca, Be, and other group IIA and IIB elements in the periodic table are selected, and Mg, Ca, and the like are preferably used as the p-type impurity.

Furthermore, in order to reduce the resistivity, it is preferable that in the nitride semiconductor layer constituting the multilayer film, in the thickness direction, the impurity concentration of the layer doped with a high concentration of impurities is high near the center portion of the semiconductor layer, and the impurity concentration near both sides is preferably high. The impurity concentration is low (preferably non-doped).

或以下，优选为1000

或以下，更优选为500～100或以下。当膜厚在上述范围内时，就能提高发光输出功率，降低Vf，因而优选。p侧单层膜包覆层8的组成是Al_bGa_1-bN(0≤b≤1)。Next, when the p-side cladding layer 8 is composed of a single layer formed of _{AlbGa1 -bN} (0≤b≤1) containing p-type impurities as described below, then The film thickness of the p-side single-layer film cladding layer 8 is generally 2000

or below, preferably 1000

or below, more preferably 500 to 100 or below. When the film thickness is within the above range, the luminous output can be increased and Vf can be lowered, which is preferable. The composition of the p-side monolayer film cladding layer 8 is _{AlbGa1 -bN} (0≤b≤1).

In addition, although the cladding layer of the single-layer film has slightly poorer crystallinity than the p-side cladding layer of the above-mentioned multi-film layer structure, it can be crystallized well by combining with the above-mentioned first multilayer film layer 4. Growing up, can also lower the threshold and Vf. Furthermore, in this way, even if it is a single-layer film layer, the reduction in device performance can be reduced by combining it with other layer structures, and because it is a single-layer film layer, the manufacturing process can be simplified. Time is preferred.

The p-type impurity concentration of the p-side monolayer cladding layer 8 is in the range of 1×10 ¹⁸ /cm ³ to 1×10 ²¹ /cm ³ , preferably 5×10 ¹⁸ /cm ³ to 5×10 ²⁰ /cm 3 cm ³ , more preferably 5×10 ¹⁹ /cm ³ to 1×10 ²⁰ /cm ³ . If the impurity concentration is within the above range, a good p-type film layer can be obtained, which is preferable.

Next, in Embodiment 5, the composition of the Mg-doped p-side GaN contact layer 9 is a binary mixed crystal nitride semiconductor containing no In or Al. If In and Al are contained, ohmic contact with the p-electrode 11 cannot be obtained, and the luminous efficiency is lowered. The film thickness of the p-side contact layer 9 is 0.001 to 0.5 μm, preferably 0.01 to 0.3 μm, more preferably 0.05 to 0.2 μm. If the film thickness is less than 0.001 μm, an electrical short circuit easily occurs with the p-type GaAlN cladding layer, making it difficult to function as a contact layer. In addition, since a GaN contact layer with a different binary mixed crystal composition is stacked on the GaAlN cladding layer of a ternary mixed crystal, if its film thickness is made to be greater than 0.5 μm, it is easy to make the p-side GaN contact layer In 9, lattice defects due to mismatch between crystals occurred, and the crystallinity tended to decrease. In addition, the thinner the film thickness of the contact layer, the lower the Vf, and the more the luminous efficiency can be improved. In addition, if the p-type impurity of the p-type GaN contact layer 9 is Mg, p-type characteristics can be easily obtained, and an ohmic contact can also be easily obtained. The concentration of Mg is 1×10 ¹⁸ /cm ³ to 1×10 ²¹ /cm ³ , preferably 5×10 ¹⁹ /cm ³ to 3×10 ²⁰ /cm ³ , more preferably about 1×10 ²⁰ /cm ³ . When the concentration of Mg is within this range, a good p-type film can be easily obtained and Vf can be lowered, so it is preferable.

In addition, n-electrode 12 and p-electrode 11 are respectively formed on n-side contact layer 4 and on Mg-doped p-side GaN contact layer 9 . Materials for the n-electrode and the p-electrode are not particularly limited. For example, W/Al can be used as the n-electrode, and Ni/Au can be used as the p-electrode.

Embodiment 6

Next, a nitride semiconductor device according to Embodiment 6 of the present invention will be described.

The nitride semiconductor element of Embodiment 6 is a nitride semiconductor having an n-type multilayer film layer and a p-type multilayer film layer, and its basic configuration is the same as that of Embodiment 1, so it will be described with reference to FIG. 1 as appropriate.

The nitride semiconductor element of Embodiment 6 is obtained by sequentially laminating the following layers on a sapphire substrate 1: a buffer layer 2 made of GaN, an undoped GaN layer 3, and a n layer made of GaN doped with Si. Side contact layer 4, undoped GaN layer 5, n-type multi-layer film layer 6, active layer 7 of multi-quantum well structure composed of InGaN/GaN, p-type multi-layer film layer 8, doped with Mg p-type contact layer 9 made of GaN. The composition and/or number of layers of each nitride semiconductor constituting the n-type multilayer film layer 6 and the p-type multilayer film layer 8 are different from the first embodiment in that the n side and the p side are different. In addition, in the nitride semiconductor device according to Embodiment 6, various multilayer layers described in Embodiments 1 to 5 can be used as n-type multilayer layer 6 and p-type multilayer layer 8 .

Here, in FIG. 1, an n-type multilayer film layer is provided as an n-type nitride semiconductor, and a p-type multilayer film layer is provided as a p-type nitride semiconductor layer. Two or more layers of film layers are respectively arranged in the regions. For example, if the above-mentioned undoped GaN layer 5 is made into a multilayer film layer as described below, the multilayer film layer is a lower layer made of an undoped nitride semiconductor starting from the substrate side, and a doped An intermediate layer composed of a nitride semiconductor containing n-type impurities and an upper layer composed of a non-doped nitride semiconductor are sequentially stacked to further improve the luminous output power, Vf and static voltage resistance characteristics, so it is preferable. In this way, when there are two kinds of n-type multilayer film layers in the n-side region, it is only necessary that any one of the two kinds of n-type multilayer film layers has more layers than the p-type multilayer film layer.

First, the multilayer film layer will be described.

In Embodiment 6, the n-type multilayer film layer 6 only needs to be composed of at least two or more nitride semiconductors with different compositions. As a preferable composition, _{AlzGa1 -zN} (0≤z <1) Two compositions of [first nitride semiconductor film] and In _p Ga _1-p N (0<p<1) [second nitride semiconductor film].

As a preferable composition of the first nitride semiconductor film, the crystallinity is better as the z value in the chemical formula of the above first nitride semiconductor film is smaller, and the z value is more preferably 0, that is, GaN.

In addition, as a preferable composition of the second nitride semiconductor film, there is In _p Ga _1-p N in which the p value in the chemical formula representing the above-mentioned second nitride semiconductor film is 0.5 or less, more preferably the p value is 0.1 or less In _p Ga _1-p N.

In the present invention, as a preferable combination of the first nitride semiconductor film and the second nitride semiconductor film, the first nitride semiconductor film is GaN, and the second nitride semiconductor film is In _x having an x value of 0.5 or less. Combination of Ga _1-x N.

In addition, the n-type multilayer film layer 6 composed of the above-mentioned composition forms at least one or more first nitride semiconductor film and second nitride semiconductor film respectively, a total of two or more layers or three or more layers, preferably At least two or more layers are stacked, and a total of four or more layers are stacked; preferably, at least seven or more layers are stacked, and a total of 14 or more layers are stacked.

The upper limit of the number of stacked layers of the first nitride semiconductor film and the second nitride semiconductor film is not particularly limited, but is, for example, 500 layers or less. If it exceeds 500 layers, the stacking time will be too long, the operation will be complicated, and the characteristics of the device will tend to decline slightly.

或以下，更优选为50

或以下。The film thickness of the single-layer nitride semiconductor layer constituting the n-type multilayer film layer 6 is not particularly limited, but the film thickness of at least one single-layer nitride semiconductor layer among the two or more nitride semiconductor layers is 100 Å. or below, preferably 70

or below, more preferably 50

or below.

In this way, by making the film thickness of the single-layer nitride semiconductor layer constituting the n-type multilayer film layer 6 very thin, the multilayer film layer forms a superlattice structure, and the crystallinity of the multilayer film layer becomes better, so There is a tendency to increase the output power.

或以下，优选为70

或以下，最优选为50

或以下。When the n-type multilayer film layer 6 is composed of a first nitride semiconductor film and a second nitride semiconductor film, at least one of them has a film thickness of 100

or below, preferably 70

or below, most preferably 50

or below.

或以下的薄膜层时，单层的氮化物半导体层的厚度分别处于弹性临界膜厚或以下，结晶性良好。当在该改善了结晶性的氮化物半导体层上进而再生长起膜厚为弹性临界膜厚或以下的氮化物半导体时，它的结晶性也将良好。由此，第一和第二氮化物半导体膜的结晶性随着层叠而得到改善，作为其结果，改善了n型多层膜层6整体的结晶性。这样，由于n型多层膜层6整体的结晶性变良好，元件的发光输出功率就提高了。When the film thickness of at least one of the first nitride semiconductor film and the second nitride semiconductor film is 100

In the case of a thin film layer of 1000 or less, the thickness of the single-layer nitride semiconductor layer is respectively less than or equal to the elastic critical film thickness, and the crystallinity is good. When a nitride semiconductor having a film thickness equal to or less than the elastic critical film thickness is further grown on the nitride semiconductor layer having improved crystallinity, the crystallinity thereof will also be good. As a result, the crystallinity of the first and second nitride semiconductor films is improved along with lamination, and as a result, the crystallinity of the entire n-type multilayer film layer 6 is improved. In this way, since the overall crystallinity of the n-type multilayer film layer 6 becomes better, the luminous output of the device is improved.

或以下，最优选为50

或以下。The preferred film thicknesses of the first nitride semiconductor film and the second nitride semiconductor film are both 100 or below, preferably 70

or below, most preferably 50

or below.

When both the film thicknesses of the first and second nitride semiconductor films constituting the n-type multilayer film layer 6 are 100 When the thickness of the single-layer nitride semiconductor layer is equal to or less than the elastic critical thickness, it is possible to grow a nitride semiconductor having better crystallinity than when a thick film is grown.

或以下时，多层膜层便成了超晶格结构，结晶性变得良好，如果在这种结晶性良好的超晶格结构上生长有源层，则n型多层膜层6就会起到缓冲层的作用，就能结晶性良好地生长有源层。In addition, when the film thicknesses of the first and second nitride semiconductor films of the n-type multilayer film layer 6 are both set to 70

or below, the multilayer film layer has just become superlattice structure, and crystallinity becomes good, if grow active layer on the superlattice structure with good crystallinity, then n-type multilayer film layer 6 will be By functioning as a buffer layer, the active layer can be grown with good crystallinity.

优选为25～5000

更优选为25～1000

当膜厚在这一范围内时，结晶性良好，元件的输出功率提高。The total film thickness of the n-type multilayer film layer 6 is not particularly limited, but it is generally 25 to 10,000

Preferably 25-5000

More preferably 25-1000

When the film thickness is within this range, the crystallinity is good, and the output of the device is improved.

The formation position of the n-type multilayer film layer 6 is not particularly limited, it can be formed in contact with the active layer 7, or can be formed away from the active layer 7, preferably the n-type multilayer film layer 6 and the active layer 7 connected to form.

When the n-type multilayer film layer 6 is formed in contact with the active layer 7, the n-type multilayer film layer 6 constituting the first film layer of the active layer 7, that is, the well layer or the barrier layer is in contact with the active layer 7. The nitride semiconductor layer may be either the first nitride semiconductor film or the second nitride semiconductor film. The stacking order of the first nitride semiconductor film and the second nitride semiconductor film constituting the n-type multilayer film layer 6 in this way is not particularly limited. That is, stacking may start from the first nitride semiconductor and end with the first nitride semiconductor; or start stacking from the first nitride semiconductor and end with the second nitride semiconductor; or start stacking from the second nitride semiconductor and end with the second nitride semiconductor. end with a nitride semiconductor; alternatively, lamination may start from the second nitride semiconductor film and end with the second nitride semiconductor.

In FIG. 1, the n-type multilayer film layer 6 is formed in contact with the active layer 7, but as described above, when the n-type multilayer film layer 6 is formed away from the active layer 7, the n-type multilayer film layer A layer made of other n-type nitride semiconductors may also be formed between the multilayer film layer 6 and the active layer 7 .

In Embodiment 6, the single-layer nitride semiconductor layer constituting the n-type multilayer film layer 6, such as the first and second nitride semiconductor films, may be undoped or doped with n-type. Impurities.

In Embodiment 6, the so-called non-doping refers to a state in which impurities are not intentionally doped subjectively. It is non-doped. In addition, the impurity concentration of the impurity mixed by diffusion is mostly distributed in a gradient within the film layer.

In the case where the single-layer nitride semiconductor layer constituting the n-type multilayer film layer 6 is composed of a first nitride semiconductor film and a second nitride semiconductor film, the first and second nitride semiconductor films may be both It is non-doped, and both of them may be doped with n-type impurities, or either of them may be doped with impurities.

doping either one of the first nitride semiconductor film and the second nitride semiconductor film with an n-type impurity, or doping both with an n-type impurity with different concentrations in adjacent nitride semiconductor layers, is called This is modulation doping, and the output power tends to be easily increased by modulation doping.

In addition, when both the first nitride semiconductor film and the second nitride semiconductor film are doped with n-type impurities, the concentrations of impurities in adjacent single-layer nitride semiconductor layers may be different or the same, preferably different.

In order to improve the crystallinity, non-doping is most preferable, next is modulation doping in which the adjacent side is non-doped, and next is modulation doping in which both adjacent sides are doped.

In addition, when both the first nitride semiconductor film and the second nitride semiconductor film are doped with n-type impurities, any one of the film layers may have a higher impurity concentration.

There is no particular limitation on the impurity concentration when doping n-type impurities, but it is generally adjusted to 5×10 ²¹ /cm ³ or less, preferably 1×10 ²⁰ /cm ³ or less, and the lower limit is 5×10 ¹⁶ /cm ³ . If it exceeds 5×10 ²¹ /cm ³ , the crystallinity of the nitride semiconductor layer will deteriorate, and on the contrary, the output tends to decrease. This is also true in the case of modulation doping.

In the present invention, group IV and group VI elements such as Si, Ge, Sn, and S are preferably selected as n-type impurities, and Si and Sn are more preferably used.

Next, the p-type multilayer film layer 8 will be described.

In Embodiment 6, the p-type multilayer film layer 8 only needs to be composed of at least two or more nitride semiconductors with different compositions. As a preferable composition, _{AlxGa1 -xN} (0<x <1) Two compositions of [third nitride semiconductor film] and In _y Ga _1-y N (0≤y<1) [fourth nitride semiconductor film].

A preferable composition of the third nitride semiconductor film is _{AlxGa1 -xN} in which the x value of the chemical formula of the above-mentioned third nitride semiconductor film is 0.5 or less. When x exceeds 0.5, crystallinity tends to deteriorate and cracks tend to be easily generated.

In addition, a preferable composition of the fourth nitride semiconductor film is GaN having a y value of 0 in the above-mentioned chemical formula representing the fourth nitride semiconductor film. When the value of y is 0, it tends to be possible to easily grow a multilayer film with good overall crystallinity.

In Embodiment 6, as a preferable combination of nitride semiconductors constituting the n-type multilayer film layer 8, the third nitride semiconductor film is AlxGa1-xN whose x value is 0.5 or less, and the fourth nitride semiconductor film is _{AlxGa1 -xN} . The nitride semiconductor film is a combination of GaN.

In addition, the p-type multilayer film layer 8 composed of the above-mentioned composition forms at least one or more third nitride semiconductor film and fourth nitride semiconductor film respectively, a total of two or more layers or three or more layers, preferably At least two or more layers are stacked each, and a total of four or more layers are stacked.

The upper limit of the number of stacked layers of the third nitride semiconductor film and the fourth nitride semiconductor film is not particularly limited, but it is, for example, 100 layers or less in consideration of manufacturing steps such as stacking time and device characteristics.

优选为25～5000

更优选为25～1000当膜厚在这一范围内时，结晶性良好，元件的输出功率提高。The total film thickness of the p-type multilayer film layer 8 is not particularly limited, but it is generally 25 to 10,000

Preferably 25-5000

More preferably 25-1000 When the film thickness is within this range, the crystallinity is good, and the output of the device is improved.

In addition, in the present invention, if the p-type multilayer film layer 8 is formed with a relatively thin film thickness within the above-mentioned range, Vf and threshold value of the element tend to be lowered easily.

或以下，优选为70或以下，更优选为50

或以下。The film thickness of the single-layer nitride semiconductor layer constituting the p-type multilayer film layer 8 is not particularly limited, but the film thickness of the single-layer nitride semiconductor layer of at least one nitride semiconductor layer of two or more nitride semiconductor layers The thickness is generally 100

or below, preferably 70 or below, more preferably 50

or below.

In this way, by making the film thickness of the single-layer nitride semiconductor layer constituting the p-type multilayer film layer 8 very thin, the multilayer film layer becomes a superlattice structure, and the crystallinity of the multilayer film layer is improved, so When p-type impurities are added, a p-layer with a high carrier concentration and a low resistivity can be obtained, and the Vf and threshold of the device tend to decrease easily. In this way, high luminous output power can be obtained with little power consumption.

或以下，优选为70或以下，最优选为50

或以下。当第三氮化物半导体膜和第四氮化物半导体膜中的至少一方的膜厚是100

或以下的薄膜层时，单层的氮化物半导体层的厚度都为弹性临界膜厚或以下，结晶性变得良好。当在该改善了结晶性的氮化物半导体层上进而再生长膜厚为弹性临界膜厚或以下的氮化物半导体时，其结晶性就变得更好了。由此，第三和第四氮化物半导体膜的结晶性是随着层叠而改善的，作为结果，p型多层膜层8的整体结晶性改善了。这样，由于p型多层膜层8的整体结晶性变好，在添加了p型杂质的情况下，可以获得载流子浓度大、电阻率小的p型层，元件的Vf、阀值具有容易降低的倾向。于是，就能以很低的电力消耗获得很高的发光输出功率。When the p-type multilayer film layer 8 is formed by the third nitride semiconductor film and the fourth nitride semiconductor film, at least one of them has a film thickness of 100

or below, preferably 70 or below, most preferably 50

or below. When the film thickness of at least one of the third nitride semiconductor film and the fourth nitride semiconductor film is 100

In the case of a thin film layer having a thickness of 0.5 or less, the thickness of the single-layer nitride semiconductor layer is equal to or less than the elastic critical film thickness, and the crystallinity becomes good. When a nitride semiconductor having a film thickness equal to or less than the elastic critical film thickness is further grown on the nitride semiconductor layer having improved crystallinity, the crystallinity becomes even better. Thus, the crystallinity of the third and fourth nitride semiconductor films is improved as they are laminated, and as a result, the overall crystallinity of the p-type multilayer film layer 8 is improved. In this way, since the overall crystallinity of the p-type multilayer film layer 8 becomes better, in the case of adding a p-type impurity, a p-type layer with a large carrier concentration and a small resistivity can be obtained, and the Vf and threshold of the element have Tendency to drop easily. Therefore, high luminous output power can be obtained with very low power consumption.

或以下，优选为70

或以下，最优选为50

或以下。The preferred film thicknesses of the third nitride semiconductor film and the fourth nitride semiconductor film are generally 100 for both.

or below, preferably 70

or below, most preferably 50

or below.

或以下时，单层的氮化物半导体层的膜厚就变为弹性临界膜厚或以下，与以厚膜生长的情况相比，能够生长出结晶性良好的氮化物半导体。When both the film thicknesses of the third and fourth nitride semiconductor films constituting the p-type multilayer film layer 8 are 100

When the thickness of the single-layer nitride semiconductor layer is equal to or less than the elastic critical thickness, a nitride semiconductor with better crystallinity can be grown compared to the case of growing a thick film.

或以下时，多层膜层便成为超晶格结构，结晶性变得良好，元件的Vf、阈值等很容易降低，在提高发光输出功率方面是优选的。In addition, when both the film thicknesses of the third and fourth nitride semiconductor films of the p-type multilayer film layer 8 are 70

At or below, the multilayer film layer becomes a superlattice structure, the crystallinity becomes good, and the Vf and threshold value of the device are easily reduced, which is preferable in terms of increasing the luminous output power.

The formation position of the p-type multilayer film layer 8 is not particularly limited, it can be formed in contact with the active layer 7, and can also be formed away from the active layer 7, preferably the p-type multilayer film layer 8 and the active layer 7 connected to form. When the p-type multilayer film layer 8 is formed in contact with the active layer 7, it is easy to increase the luminous output, which is preferable.

When the p-type multilayer film layer 8 is formed in contact with the active layer 7, as the p-type multilayer film layer 8 that is in contact with the first film layer of the active layer 7, that is, the well layer or the barrier layer, The nitride semiconductor layer may be the third nitride semiconductor film or the fourth nitride semiconductor film. The stacking order of the third nitride semiconductor layer and the fourth nitride semiconductor film constituting the p-type multilayer film layer 8 in this way is not particularly limited. That is, it may be stacked starting from the third nitride semiconductor film and ending with the third nitride semiconductor film; or starting from the third nitride semiconductor film and ending with the fourth nitride semiconductor film; or starting from the fourth nitride semiconductor film The stacking starts and ends with the third nitride semiconductor film; alternatively, the stacking may start with the fourth nitride semiconductor film and end with the fourth nitride semiconductor film.

In FIG. 1, the p-type multilayer film layer 8 is formed in contact with the active layer 7, but as described above, when the p-type multilayer film layer 8 is formed apart from the active layer 7, the p-type multilayer film layer A film layer composed of other p-type nitride semiconductors may also be formed between the multilayer film layer 8 and the active layer 7 .

In addition, in Embodiment 6, both the third nitride semiconductor film and the fourth nitride semiconductor film may be undoped, either one may be doped with a p-type impurity, or both may be doped. doped with p-type impurities.

或以下，进而优选为500

或以下。当膜厚超过0.1μm时，就难以向有源层中注入空穴，会有容易降低发光输出功率的倾向。另外，当膜厚超过0.1μm时，还有使非掺杂膜层的电阻值升高的倾向。In the case where both the third and fourth nitride semiconductor films constituting the p-type multilayer film layer 8 are non-doped, the film thickness of the p-type multilayer film layer 8 is generally 0.1 μm or less, preferably 700 μm.

or below, more preferably 500

or below. When the film thickness exceeds 0.1 μm, it becomes difficult to inject holes into the active layer, and the light emission output tends to tend to decrease. In addition, when the film thickness exceeds 0.1 μm, the resistance value of the non-doped film layer tends to increase.

In addition, when modulation doping is performed in which impurities are doped in either of the third and fourth nitride semiconductor films, it tends to be easier to increase the light emission output. In addition, modulation doping is preferable because it is easy to obtain a p-layer with a high carrier concentration.

In addition, when both the third and fourth nitride semiconductor films are doped with p-type impurities, the carrier concentration can be further increased compared to the case where only one is doped with p-type impurities, so Vf Low and therefore preferred. In the case where both the third and fourth nitride semiconductor films are doped with p-type impurities, the impurity concentrations between adjacent nitride semiconductor layers may be the same, but are preferably different (modulated doping).

In Embodiment 6, when p-type impurities are doped in the p-type multilayer film layer 8, as the p-type impurities, group II elements such as Mg, Zn, Cd, Be, and Ca are preferably selected, and Mg, Be, and the like are preferably used. .

In the case of doping with p-type impurities, the concentration of the impurities is adjusted to be 1×10 ²² /cm ³ or less, preferably 5×10 ²⁰ /cm ³ or less. If it exceeds 1×10 ²² /cm ³ , the crystallinity of the nitride semiconductor layer deteriorates, and the light emission output tends to decrease. The lower limit of the doping amount of p-type impurities is not particularly limited, but is generally 5×10 ¹⁶ /cm ³ or more.

Next, the layers forming the structure of elements other than the n-type multilayer film layer 6 and the p-type multilayer film layer 8 shown in FIG. 1 will be described, but the present invention is not limited thereto.

As the substrate 1, sapphire with C plane, R plane, or A plane as the main surface can be used. In addition, there are also insulating substrates such as spinel (MgAl ₂ O ₄ ), and SiC (containing 6H, 4H, 3C), Si, ZnO, GaAs, GaN and other semiconductor substrates.

As the buffer layer 2, a nitride semiconductor composed of Ga _d Al _1-d N (provided that d is in the range of 0<d≤1) can be mentioned, and it is preferable that the smaller the composition ratio of Al, the more remarkable the improvement of crystallinity , more preferably the buffer layer 2 made of GaN.

The film thickness of the buffer layer 2 is adjusted to be in the range of 0.002 to 0.5 μm, preferably 0.005 to 0.2 μm, more preferably 0.01 to 0.02 μm. When the film thickness of the buffer layer 2 is within the above range, the crystal form of the nitride semiconductor is good, and the crystallinity of the nitride semiconductor grown on the buffer layer 2 can be improved.

The growth temperature of the buffer layer 2 is adjusted to be in the range of 200 to 900°C, preferably 400 to 800°C. When the growth temperature is within the above range, polycrystals with good crystallization are grown, and using the polycrystals as seeds can improve the crystallinity of the nitride semiconductor grown on the buffer layer 2, which is preferable. In addition, the buffer layer 2 grown at such a low temperature may be omitted depending on the type of substrate, the method of growth, and the like.

As the undoped GaN layer 3, it is grown at a higher temperature than the buffer layer 2, for example, 900°C to 1100°C, and is formed from In _f Al _g Ga _1-fg N (0≤f, 0 ≤g, f+g≤1), the composition is not particularly limited, but it is preferably GaN, Al _g Ga _1-g N with a g value of 0.2 or less, so that it is easy to obtain nitrides with few crystal defects semiconductor layer. In addition, the film thickness does not need to be particularly limited, and the film is grown thicker than the buffer layer, generally with a film thickness of 0.1 μm or more.

As the n-type contact layer 4 made of Si-doped GaN, like the undoped GaN layer 3, it can be made of In _f Al _g Ga _1-fg N (0≤f, 0≤g, f+g≤ 1) The composition, although not particularly limited, is preferably GaN and _{AlgGa1 -gN} with a g value of 0.2 or less, so that a nitride semiconductor layer with few crystal defects can be easily obtained. The film thickness is not particularly limited, but it is preferably grown with a film thickness of 0.1 μm or more because it is a film layer forming an n-electrode. Furthermore, the n-type impurity is preferably doped at such a high concentration that it does not degrade the crystallinity of the nitride semiconductor, that is, it is preferably within the range of 1×10 ¹⁸ /cm ³ to 5×10 ²¹ /cm ³ Doped.

As the undoped GaN layer 5, it may be composed of In _f Al _g Ga _1-fg N (0≤f, 0≤g, f+g≤1) as above, although its composition need not be particularly limited, However, GaN, _{AlgGa1 -gN} having a g value of 0.2 or less, or _{InfGa1 -fN} having an f value of 0.1 or less is preferable, since it is easy to obtain a nitride semiconductor layer with few crystal defects. By growing this non-doped GaN layer, unlike the case where the next layer is grown directly on the n-type contact layer 4 doped with a high concentration of impurities, the crystallinity of the bottom layer is also good, so the next grown n-type layer is mostly The layer 6 is easy to grow, and when the active layer 7 is grown on the n-type multilayer layer, the growth is easier and the crystallinity becomes good, so it is preferable. In this way, if the n-type contact layer 4 composed of a nitride semiconductor doped with a high concentration of impurities is laminated on the non-doped GaN layer 3 composed of a non-doped nitride semiconductor layer and then the laminate is composed of a non-doped If the non-doped GaN layer 5 made of a nitride semiconductor is further formed into a structure in which the above-mentioned n-type multilayer film layer 6 is laminated, when it is made into an LED element, Vf tends to decrease easily. In addition, when the n-type multilayer film layer 6 is non-doped, the non-doped GaN layer 5 may be omitted.

In addition, in Embodiment 6, as in Embodiment 5, instead of the above-mentioned non-doped GaN layer 5, it is also possible to make the non-doped lower layer 305a, the intermediate layer 305b doped with n-type impurities, and the non-doped GaN layer 305b. The upper layer 305c constitutes a multi-layer film layer.

The multi-layer film layer consists of at least three layers, starting from the substrate side, they are the non-doped lower layer 305a, the middle layer 305b doped with n-type impurities, and the non-doped upper layer 305c. There may also be other film layers on the multi-layer film layer besides the above-mentioned lower layer 305a to upper layer 305c. In addition, the multilayer film layer may be in contact with the active layer, or may have other layers between it and the active layer.

As the nitride semiconductor constituting the lower layer 305a to the _upper layer 305c, nitride semiconductors having various compositions represented by _{IngAlhGa1 -ghN} (0≤g<1, 0≤h<1) can be used. Preferably, a nitride semiconductor having a composition composed of GaN is used, and the composition of each layer of the multilayer film layer may be the same or different.

优选为1000～10000

更优选为2000～6000

当多层膜层的膜厚在上述范围内时，能实现Vf的最适化和耐静电压特性的提高，因而优选。The film thickness of the multi-layer film is not particularly limited, generally 175-12000

Preferably 1000～10000

More preferably 2000-6000

When the film thickness of the multilayer film layer is within the above-mentioned range, optimization of Vf and improvement of static voltage resistance characteristics can be realized, which is preferable.

Adjustment of the film thickness of the multilayer film layer having the film thickness in the above-mentioned range is preferably appropriately adjusted the film thicknesses of the lower layer 305a, the middle layer 305b and the upper layer 305c so that the total thickness of the multilayer film layer is within the above-mentioned range.

The film thickness of each layer of the lower layer 305a, the middle layer 305b and the upper layer 305c constituting the multilayer film layer is not particularly limited, but because their stacked positions in the multilayer film layer have different influences on the various characteristics of the element, so special Pay attention to the characteristics of each layer that have a great relationship with the performance of the component, fix the film thickness of any two layers, and then change the film thickness of the remaining layer in stages, measure the film thickness within the range of good characteristics, and then adjust The film thickness of each layer is used to determine the range of film thickness.

Although the individual layers of the multilayer film have no direct influence on the static voltage resistance characteristics, by combining the layers into a multilayer film as a whole, the characteristics of various elements are improved, and at the same time, especially the luminous output The power and ESD characteristics are significantly improved.

优选为500～8000

更优选为1000～5000

当非掺杂的下层305a的膜厚逐渐增厚时，耐静电压特性也逐渐上升，但在10000

附近Vf急剧上升；另一方面，当膜厚减薄时，Vf也随着降低，但耐静电压特性降低得多，在不到100

时，随着耐静电压的下降，材料利用率有大幅度下降的倾向。另外，由于考虑到上层305a改善了含有n型杂质的n侧接触层4的结晶性的下降的影响，所以优选以结晶性的改善为良好的程度的膜厚来生长。The film thickness of the non-doped lower layer 305a is generally 100-10000

Preferably 500-8000

More preferably 1000-5000

When the film thickness of the non-doped lower layer 305a is gradually thickened, the ESD characteristics are also gradually increased, but at 10000

Nearby Vf rises sharply; on the other hand, when the film thickness decreases, Vf also decreases, but the static voltage resistance characteristics are much lower, at less than 100

, with the decline of static voltage, the material utilization tends to drop significantly. In addition, since the upper layer 305a is considered to improve the influence of the decrease in crystallinity of the n-side contact layer 4 containing n-type impurities, it is preferably grown with a film thickness such that improvement in crystallinity is good.

优选为100～500

更优选为150～400

该掺杂了杂质的中间层305b是使载流子的浓度充分、对发光输出功率有比较大的作用的层，如果没有形成该膜层，则会有发光输出功率显著下降的倾向。如果膜厚超过1000

就会有发光输出功率大幅度下降到难以成为商品的程度的倾向。另一方面，当中间层305b的膜厚加厚时，耐静电压特性良好，但如果膜厚不到50就会有耐静电压特性大幅度下降的倾向。The film thickness of the intermediate layer 305b doped with n-type impurities is generally 50-1000

Preferably 100-500

More preferably 150-400

The impurity-doped intermediate layer 305b is a layer that has a sufficient carrier concentration and has a relatively large effect on the luminous output. If this layer is not formed, the luminous output tends to decrease significantly. If the film thickness exceeds 1000

There is a tendency that the luminous output power is greatly reduced to such an extent that it is difficult to become a commercial product. On the other hand, when the film thickness of the intermediate layer 305b is increased, the static voltage resistance characteristic is good, but if the film thickness is less than 50 There is a tendency that the static voltage resistance characteristics will be greatly reduced.

优选为25～500

更优选为25～150

该非掺杂的上层305c在第一多层膜层中是与有源层相接或最接近而形成的，与泄漏电流的防止有很大关系，但如果上层305c的膜厚不到25

泄漏电流就有增大的倾向。另外，当上层305c的膜厚超过1000

时，就有Vf上升而耐静电压特性下降的倾向。The film thickness of the non-doped upper layer 305c is generally 25-1000

Preferably 25-500

More preferably 25-150

The non-doped upper layer 305c is formed in contact with or closest to the active layer in the first multilayer film layer, which has a great relationship with the prevention of leakage current, but if the film thickness of the upper layer 305c is less than 25

The leakage current tends to increase. In addition, when the film thickness of the upper layer 305c exceeds 1000

, there is a tendency for the Vf to rise and the static voltage resistance characteristics to decline.

As mentioned above, regarding the film thickness of each layer from the lower layer 305a to the upper layer 305c, attention should be paid to the device characteristics that are more affected by the film thickness fluctuation of each layer. The various properties of the component are excellent, especially the luminous output power and static voltage resistance characteristics are improved. By specifying the film thickness of each layer, good luminous output power and good static voltage resistance characteristics can be obtained, which can reach the product's Further improvement in reliability.

In addition, the combination of the film thickness of each layer of the multilayer film layer can be appropriately adjusted according to various conditions such as the composition change of the active layer, the shape of the electrode, and the LED element that change according to the type of light emission wavelength, so as to obtain the best result. Effect. By appropriately combining the film thicknesses in the above-mentioned ranges, the performance related to the combination of the film thicknesses of each layer can be achieved to achieve better luminous output power and better static voltage resistance characteristics than conventional ones.

The composition of each layer 305a, 305b, 305c constituting the multilayer film layer can be as long as it is a composition represented by In _m Al _n Ga _1-mn N (0≤m<1, 0≤n<1), and the composition of each layer They may be the same or different, but a composition with a small ratio of In and Al is preferable, and a film layer made of GaN is more preferable.

The doping amount of the n-type impurity in the n-type impurity-doped intermediate layer 5b is not particularly limited, and generally the concentration is 3×10 ¹⁸ /cm ³ or above, preferably 5×10 ¹⁸ /cm ³ or above. The upper limit of the n-type impurity is not particularly limited, but it is preferably 5×10 ²¹ /cm ³ or less as the limit to the extent that the crystallinity does not deteriorate too much. When the impurity concentration of the intermediate layer of the first multilayer film layer is within the above-mentioned range, it is preferable from the viewpoints of improvement of luminous output power and reduction of Vf.

As n-type impurities, elements of Group IVB and Group VIB of the periodic table such as Si, Ge, Se, S, and O are selected, and Si, Ge, and S are preferably used as n-type impurities.

In addition, at the interface of the multi-layer film layer, each layer can also be used as two film layers within the scope of not hindering the functions of each layer and element.

Next, as the active layer 7, a nitride semiconductor containing at least In can be cited, preferably a single quantum well structure or a multiple quantum well structure having a well layer containing In _j Ga _1-j N (0≤j<1) nitride semiconductors.

或以下，优选为70

或以下，进而优选为50

或以下。当比100

更厚时，就会有难以提高输出功率的倾向。另一方面，势垒层的厚度一般调整为300

或以下，优选为250

或以下，最优选为200或以下。The stacking order of the active layer 7 can start with the well layer and end with the well layer, can start with the well layer and end with the barrier layer, or start with the barrier layer and end with the well layer. The order is not particularly limited. As the film thickness of the well layer, it is generally adjusted to 100

or below, preferably 70

or below, more preferably 50

or below. when compared to 100

When it is thicker, it tends to be difficult to increase the output power. On the other hand, the thickness of the barrier layer is generally adjusted to 300

or below, preferably 250

or below, most preferably 200 or below.

Next, as the p-type contact layer 9 made of Mg-doped GaN, it may be made of In _f Al _g Ga _1-fg N (0≤f, 0≤g, f+g≤1) as described above, Its composition is not particularly limited, but it is preferably GaN, so that a nitride semiconductor layer with few crystal defects can be easily obtained, and a good ohmic contact with the p-electrode material can be easily obtained.

In addition, the p-electrode and n-electrode used in the present invention are not particularly limited, conventionally known electrodes and the like can be used, for example, the electrodes described in the examples can be mentioned.

Example

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

Example 1

Example 1 is an example related to Embodiment 1 of the present invention, as shown in FIG. 1 .

In this embodiment 1, the substrate 1 made of sapphire (C surface) is placed in the reaction vessel of MOVPE, and the temperature of the substrate is raised to 1050°C while passing hydrogen gas to clean the substrate, and then the following layers. In addition, the substrate 1 can also use sapphire whose main surface is the R surface or the A surface other than the C surface, and can also use an insulating substrate such as spinel (MgAl ₂ O ₄ ), and SiC (containing 6H, 4H, 3C ), Si, ZnO, GaAs, GaN and other semiconductor substrates.

(first buffer layer 2)

Next, lower the temperature to 510°C, use hydrogen as a carrier gas, and use ammonia and TMG (trimethylgallium) as a raw material gas, on the substrate 1 at about 200 The buffer layer 202 made of GaN is grown to a film thickness of . In addition, the first buffer layer 2 grown at a low temperature may be omitted depending on the type of the substrate, the growth method, and the like.

(second buffer layer 3)

After the first buffer layer 2 was grown, only the supply of TMG was stopped, and the temperature was raised to 1050°C. After reaching 1050° C., the second buffer layer 3 made of undoped GaN is grown with a film thickness of 1 μm using TMG and ammonia gas as raw material gases. The second buffer layer 3 is grown at a higher temperature than the previously grown first buffer layer 2, such as 900°C to 1100°C, and it can be formed from In _{x AlyGa 1-xy} N (0≤x, 0≤ y, x+y≤1), the composition is not particularly limited, but is preferably GaN, and _{AlxGa1 -xN} whose x value is 0.2 or less, so that it is easy to obtain a nitride semiconductor with few crystal defects layer. In addition, the film thickness is not particularly limited, and it is grown with a film thickness thicker than the buffer layer, usually with a film thickness of 0.1 μm or more.

(n-side contact layer 4)

Next, at 1050°C, the n-side GaN doped with Si at a concentration of 3×10 ¹⁹ /cm ³ was grown with a film thickness of 3 μm using TMG and ammonia gas as the source gas and silane gas as the impurity gas. contact layer. The n-side contact layer 4, like the second buffer layer 3, can be composed of _{InxAlyGa1 -} xyN (0≤x, 0≤y, x+y≤1), although its _composition is not particularly limited, However, GaN and _{AlxGa1 -xN} having an x value of 0.2 or less are preferable, since it is easy to obtain a nitride semiconductor layer with few crystal defects. The film thickness is not particularly limited, but it is preferably grown with a film thickness of 0.1 μm or more because it is a layer forming an n-electrode. Furthermore, it is preferable to dope the n-type impurity at such a high concentration as not to deteriorate the crystallization properties of the nitride semiconductor, preferably in the range of 1×10 ¹⁸ /cm ³ to 5×10 ²¹ /cm ³ .

(third buffer layer 5)

的膜厚生长出由非掺杂的GaN构成的第三缓冲层5。该第三缓冲层5也可以由In_xAl_yGa_1-x-yN(0≤x、0≤y、x+y≤1)构成，其组成虽不必作特别限定，但优选为GaN、x值为0.2或以下的Al_xGa_1-xN、或者是y值为0.1或以下的In_yGa_1-yN，这样就很容易获得结晶缺陷少的氮化物半导体层。通过生长成该非掺杂的GaN层，与在掺杂了高浓度杂质的n侧接触层4上直接生长有源层不同，衬底部分的结晶性良好，所以很容易生长接着要生长的氮化物半导体。这样，如果制成三层结构，所述三层结构是在由非掺杂的氮化物半导体层构成的第二缓冲层3上，层叠上由掺杂了高浓度n型杂质的氮化物半导体构成的n侧接触层4，接着再层叠上由非掺杂的氮化物半导体(也包含n侧多层膜层)构成的第三缓冲层5而成的，在做成LED元件时，就会有很容易使Vf下降的倾向。另外，在n侧多层膜层6为非掺杂的情况下，可以省略第三缓冲层5。Then, only the supply of silane gas is stopped, and at 1050°C, the same 100

The third buffer layer 5 made of undoped GaN was grown to a film thickness of . The third buffer layer 5 may also be composed of _{InxAlyGa1 -} xyN (0≤x, 0≤y, x+y≤1). Although its _composition is not particularly limited, it is preferably GaN, x value _{AlxGa1 -xN} having a y value of 0.2 or less, or _{InyGa1 -yN} having a y value of 0.1 or less can easily obtain a nitride semiconductor layer with few crystal defects. By growing this non-doped GaN layer, unlike growing the active layer directly on the n-side contact layer 4 doped with a high concentration of impurities, the crystallinity of the substrate part is good, so it is easy to grow the nitrogen to be grown next. compound semiconductors. In this way, if a three-layer structure is made, the three-layer structure is formed on the second buffer layer 3 composed of an undoped nitride semiconductor layer, and the stack is composed of a nitride semiconductor doped with a high concentration of n-type impurities. n-side contact layer 4, and then laminated with a third buffer layer 5 made of non-doped nitride semiconductor (also including n-side multilayer film layer), when it is made into an LED element, there will be Vf tends to drop easily. In addition, when the n-side multilayer film layer 6 is non-doped, the third buffer layer 5 may be omitted.

(n-side multilayer film layer 6)

的第一氮化物半导体膜，接着升高温度，在其上生长厚度为25

的、由GaN构成的第二氮化物半导体膜。然后，反复重复以上的操作，以膜厚为500

生长出由以第一+第二的顺序交互各自层叠10层的，超晶格结构构成的n侧多层膜层。Next, lower the temperature to 800°C, and use TMG, TMI, and ammonia to grow a non-doped In _0.03 Ga _0.97 N layer with a thickness of 25

The first nitride semiconductor film, then raise the temperature, grow on it with a thickness of 25

The second nitride semiconductor film made of GaN. Then, repeat the above operations repeatedly, with a film thickness of 500

An n-side multilayer film composed of a superlattice structure with 10 layers stacked alternately in the order of first + second is grown.

(active layer 7)

的膜厚生长出由非掺杂的In_0.4Ga_0.6N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层的顺序将5层势垒层和4层阱层交替地层叠起来，就生长成由总厚度为1120

的多量子阱结构构成的有源层7。虽然有源层7是以势垒层开始层叠的，但是也可以以阱层开始层叠以阱层结束，另外，在以阱层开始以势垒层结束时，也可以以势垒层开始层叠以阱层结束，层叠的顺序不必作特别的限定。作为阱层的膜厚，一般调整为100

或以下，优选为70

或以下，进而优选为50

或以下。如果超过100

就会有难以提高输出功率的倾向。另一方面，势垒层的厚度一般调整为300

或以下，优选为250

或以下，最优选为200或以下。Next, with 200 grow a barrier layer made of non-doped GaN, then keep the temperature at 800°C, use TMG, TMI, and ammonia to 30

A well layer made of non-doped In _0.4 Ga _0.6 N was grown with a film thickness of . Then, in the order of barrier layer + well layer + barrier layer + well layer... + barrier layer, 5 barrier layers and 4 well layers are alternately stacked, and the total thickness is grown into for 1120

The active layer 7 is composed of multiple quantum well structures. Although the active layer 7 is stacked starting with the barrier layer, it may also be stacked starting with the well layer and ending with the well layer. In addition, when starting with the well layer and ending with the barrier layer, it may also be stacked starting with the barrier layer and ending with the well layer. The well layer ends, and the stacking sequence does not need to be particularly limited. As the film thickness of the well layer, it is generally adjusted to 100

or below, preferably 70

or below, more preferably 50

or below. if more than 100

It tends to be difficult to increase the output power. On the other hand, the thickness of the barrier layer is generally adjusted to 300

or below, preferably 250

or below, most preferably 200 or below.

(p-side multilayer film layer 8)

的膜厚生长出由掺杂5×10¹⁹/cm³的Mg的p型Al_0.05Ga_0.95N构成的第三氮化物半导体膜，接着，停止Cp2Mg、TMA，以25

的膜厚生长出由非掺杂的GaN构成的第四氮化物半导体膜。然后，反复重复以上的操作，以200

的膜厚生长出由以第三+第四的顺序交替地分别层叠4层的超晶格构成的p侧多层膜层8。Next, using TMG, TMA, ammonia, Cp2Mg (magnesocene), at 25

A third nitride semiconductor film composed of p-type Al _0.05 Ga _0.95 N doped with Mg of 5×10 ¹⁹ /cm ³ was grown with a film thickness of

A fourth nitride semiconductor film made of undoped GaN is grown with a film thickness of . Then, repeat the above operation repeatedly, with 200

A p-side multilayer film layer 8 consisting of four superlattice layers stacked alternately in the order of third + fourth is grown.

(p-side contact layer 9)

的膜厚生长出由掺杂了1×10²⁰/cm³的Mg的p型GaN构成的p侧接触层208。p侧接触层208也可以由In_xAl_yGa_1-x-yN(0≤x、0≤y、x+y≤1)构成，其组成虽不必作特别限定，但优选采用GaN，这样容易获得结晶缺陷少的氮化物半导体层，而且容易得到与p电极材料良好的欧姆接触。Next, at 1050°C, using TMG, ammonia, Cp2Mg, at 700

A p-side contact layer 208 made of p-type GaN doped with Mg of 1×10 ²⁰ /cm ³ was grown with a film thickness of . The p-side contact layer 208 can also be made of _{InxAlyGa1 -xyN} (0≤x, 0≤y, x+y≤1). Although its _composition is not particularly limited, it is preferably GaN, which is easy to obtain The nitride semiconductor layer has few crystal defects, and it is easy to obtain good ohmic contact with the p-electrode material.

After the reaction, the temperature was lowered to room temperature, and then the wafer was placed in the reaction container, and annealed at 700° C. in a nitrogen atmosphere to further reduce the resistance of the p-type layer.

After the annealing, the wafer is taken out from the reaction vessel, and a mask of a predetermined shape is formed on the surface of the p-side contact layer 9 of the uppermost layer, and etched from the p-side contact layer with an RIE (reactive ion etching) device, As shown in FIG. 1, the surface of the n-side contact layer 4 is exposed.

的含有Ni和Au的透光性p电极10，再在该p电极10上形成膜厚为0.5μm的由键合用的Au构成的p焊盘电极11。另一方面，在由于蚀刻而暴露出来的n侧接触层4的表面上形成含W和Al的n电极12，就成为LED元件了。After etching, a film thickness of 200 is formed on almost the entire surface of the uppermost p-side contact layer

A light-transmitting p-electrode 10 containing Ni and Au was formed, and a p-pad electrode 11 made of Au for bonding was formed on the p-electrode 10 with a film thickness of 0.5 μm. On the other hand, an n-electrode 12 containing W and Al is formed on the surface of the n-side contact layer 4 exposed by etching to obtain an LED element.

Under the forward voltage of 20mA, the LED element can display 520nm pure green light, and the Vf is only 3.2V. Compared with the previous multi-quantum well structure LED element, the Vf is reduced by nearly 0.8V, and the output power is increased by more than two times. . Therefore, it is possible to obtain an LED having substantially the same characteristics as a conventional LED element at 10 mA.

In this embodiment, the second nitride semiconductor film constituting the n-side multilayer film layer is made of GaN, but it may also be made of other In _{x Aly} Ga _1-xy N (0≤x, 0≤y, x+y≦1), preferably an InGaN composition having a smaller In composition than the first nitride semiconductor. In addition, the fourth nitride semiconductor film constituting the p-side multilayer film layer is made of GaN, but it may also be made of other In _{x Aly} Ga _1-xy N (0≤x, 0≤y, x+y≤ 1) It is preferably composed of AlGaN having a smaller Al composition than the third nitride semiconductor.

In addition, the composition of the conventional LED element is formed by sequentially laminating the following film layers on the first buffer layer made of GaN: the second buffer layer made of undoped GaN, the second buffer layer made of Si-doped GaN n-side contact layer, active layer formed by the same multi-quantum well structure as in Example 1, single-layer Mg-doped Al _0.1 Ga _0.9 N layer, p-side contact layer formed by Mg-doped GaN .

Example 2

Example 2 is an LED element as shown in FIG. 2 . In this embodiment, except that the third buffer layer 5 is not grown, and the p-side multilayer film layer 8 is not made into a superlattice structure, the 200 Except for the p-side cladding layer 108 composed of a p-type Al _0.1 Ga _0.9 N layer doped with Mg of 5×10 ¹⁹ /cm ³ to grow a film thickness of , the other is the same as that of Example 1 to produce an LED components, then also at 20mA, Vf is 3.3V, showing very good values, and the output power is also increased by more than 1.8 times.

Example 3

的膜厚生长出由掺杂了5×10¹⁹/cm³的Mg的p型Al_0.1Ga_0.9N层所构成的p侧包覆层108之外，其他都与实施例1相同而制成LED元件，这时能够获得具有与实施例2几乎同等的特性的LED元件。In this embodiment, except that when growing the n-side multilayer film 6, the second nitride semiconductor film is made of GaN doped with Si at a concentration of 1×10 ¹⁸ /cm ³ , and the p-side The multi-layer film layer is made into a superlattice structure, with 200

Except for the p-side cladding layer 108 composed of a p-type Al _0.1 Ga _0.9 N layer doped with Mg of 5×10 ¹⁹ /cm ³ to grow a film thickness of , the other is the same as that of Example 1 to produce an LED In this case, an LED element having almost the same characteristics as in Example 2 can be obtained.

Example 4

In this embodiment, except that when growing the n-side multilayer film layer 6, the first nitride semiconductor film is made into a film layer of In _0.03 Ga _0.97 doped with 1×10 ¹⁸ /cm ³ Si, and the second The dinitride semiconductor film is made of GaN doped with 5×10 ¹⁸ /cm ³ Si. In addition, instead of making the p-side multilayer film into a superlattice structure, it is made of GaN doped with 5×10 ¹⁹ /cm ³ except for the p-side cladding layer 108 composed of p-type Al _0.1 Ga _0.9 N layer of Mg, the others are the same as in Example 1 to make an LED element. At this time, Vf is 3.4V under 20mA, and the output power Compared with the conventional one, it shows more than 1.5 times superior characteristics.

Example 5

In this embodiment, except that the third buffer layer 5 is not grown, and when the p-side multilayer film 8 is grown, a fourth nitride semiconductor film doped with 1×10 ¹⁹ /cm ³ of Mg is grown. Except for the p-type GaN layer, an LED element was manufactured in the same manner as in Example 1. In this case, an LED element having almost the same characteristics as in Example 1 could be obtained.

Example 6

的第三氮化物半导体膜和由非掺杂的GaN构成的膜厚为25

的第四氮化物半导体膜，总膜厚为100之外，其他都与实施例1相同而制成LED元件时，能获得大致与实施例4同样特性的LED元件。In this embodiment, except that the third buffer layer 5 is not grown, and when the p-side multilayer film layer 8 is grown, two layers each made of non-doped Al _0.1 Ga _0.9 N with a film thickness of 25

The third nitride semiconductor film and the film thickness made of undoped GaN are 25

The fourth nitride semiconductor film, the total film thickness is 100 Other than that, when an LED element was produced in the same manner as in Example 1, an LED element having substantially the same characteristics as in Example 4 was obtained.

Example 7

的由非掺杂的In_0.03Ga_0.97N形成的第一氮化物半导体膜，接着生长出25

的由非掺杂的GaN形成的第二氮化物半导体膜。然后，生长出45

的非掺杂的In_0.03Ga_0.97N形成的膜层，再生长出25的非掺杂的GaN层，然后，生长出40的非掺杂的In_0.03Ga_0.97N层。这样，每次都仅使第一氮化物半导体膜的生长减少5

一直到只生长5

为止。将第一膜层与第二膜层如此交替层叠，每一种膜层各层叠10层，生长出由超晶格结构形成的n侧多层膜，合计膜厚为525

Compared with Embodiment 1, the present embodiment has the changes described below. That is, when growing the n-side multilayer film layer 6, the 50

The first nitride semiconductor film formed by non-doped In _0.03 Ga _0.97 N, followed by growth of 25

The second nitride semiconductor film formed of undoped GaN. Then, grow 45

The film layer formed by non-doped In _0.03 Ga _0.97 N grows 25 An undoped GaN layer is then grown out of 40 undoped In _0.03 Ga _0.97 N layer. In this way, only the growth of the first nitride semiconductor film is reduced by 5 each time.

Until only grow 5

until. The first film layer and the second film layer are stacked alternately in this way, each film layer is stacked 10 layers, and an n-side multilayer film formed by a superlattice structure is grown, with a total film thickness of 525

的膜厚生长出由掺杂了5×10¹⁹/cm³的Mg的p型Al_0.05Ga_0.95N形成的第三氮化物半导体膜，接着以25

的膜厚生长出由非掺杂的GaN形成的第四氮化物半导体膜，接着再使掺杂了同样浓度的Mg的p型In_0.05Ga_0.95N层生长到35

再使非掺杂的GaN层生长到25

这样，每次都仅使第三氮化物半导体膜的生长减少5

一直到只生长20

为止。将第三膜层与第四膜层如此交替层叠，每一种膜层各层叠5层，生长出由超晶格结构形成的p侧多层膜，合计膜厚为275

On the other hand, when growing the p-side multilayer film layer 8, with 40

A third nitride semiconductor film formed of p-type Al _0.05 Ga _0.95 N doped with 5×10 ¹⁹ /cm ³ Mg was grown with a film thickness of 25

A _fourth nitride semiconductor film _made of non-doped GaN is grown with a film thickness of

Then grow the undoped GaN layer to 25

In this way, only the growth of the third nitride semiconductor film is reduced by 5 each time.

Until only grow 20

until. The third film layer and the fourth film layer are stacked alternately in this way, each film layer is stacked 5 layers, and a p-side multilayer film formed by a superlattice structure is grown, with a total film thickness of 275

In this example, an LED element was obtained in the same manner as in Example 1 except for the above-mentioned parts, so that an element having substantially the same characteristics as the LED element in Example 1 could be obtained. In addition, in this embodiment, only the film thickness of the first nitride semiconductor film constituting the n-side multilayer film layer 6 is changed, but the same effect can be obtained by changing the film thickness of the second nitride semiconductor film. In addition, although only the film thickness of the third nitride semiconductor film constituting the p-side multilayer film layer 8 is changed, the same effect can be obtained by changing the film thickness of the fourth nitride semiconductor film.

Example 8

接着使由非掺杂的GaN形成的第二氮化物半导体膜生长到25

然后，使In的摩尔比稍大的InGaN层生长到25

再使非掺杂的GaN层生长到25

这样，使第一氮化物半导体膜的In的组成逐渐增加而生长，使第一膜层与第二膜层交替层叠，每一种膜层各层叠10层，最后，使第一层为In_0.3Ga_0.7N，从而生长出总膜厚为500

的n侧多层膜层。Compared with Embodiment 1, the present embodiment has the changes described below. That is, when growing the n-side multilayer film layer 6, the first nitride semiconductor film formed of undoped In _0.03 Ga _0.97 N is grown to 25

Next, a second nitride semiconductor film formed of undoped GaN is grown to 25

Then, grow an InGaN layer with a slightly larger molar ratio of In to 25

Then grow the undoped GaN layer to 25

In this way, the composition of In of the first nitride semiconductor film is gradually increased to grow, the first film layer and the second film layer are alternately stacked, and each film layer is stacked with 10 layers. Finally, the first layer is made of In _0.3 Ga _0.7 N, thus growing a total film thickness of 500

The n-side multilayer film layer.

的膜厚生长出由掺杂了5×10¹⁹/cm³的Mg的p型Al_0.05Ga_0.95N形成的第三氮化物半导体膜，接着以25的膜厚生长出由非掺杂的GaN形成的第四氮化物半导体膜，接着再使掺杂同样量的Mg但Al的组成稍多的p型AlGaN层生长到25

再使非掺杂的GaN层生长到25

这样，使第三氮化物半导体膜的Al的组成逐渐增加而生长，使第三膜层与第四膜层交替层叠，每一种膜层各层叠4层，最后，使第三层为Al_0.2Ga_0.8N，从而生长出总膜厚为200

的p侧多层膜。On the other hand, when growing the p-side multilayer film layer 8, with 25

A third nitride semiconductor film formed of p-type Al _0.05 Ga _0.95 N doped with 5×10 ¹⁹ /cm ³ Mg was grown with a film thickness of 25 A fourth nitride semiconductor film made of non-doped GaN is grown, and then a p-type AlGaN layer doped with the same amount of Mg but slightly more Al is grown to 25

Then grow the undoped GaN layer to 25

In this way, the Al composition of the third nitride semiconductor film is gradually increased to grow, the third film layer and the fourth film layer are alternately stacked, and each film layer is stacked in four layers. Finally, the third layer is made of Al _0.2 Ga _0.8 N, thus growing a total film thickness of 200

p-side multilayer film.

In this example, an LED element was obtained in the same manner as in Example 1 except for the above-mentioned parts, so that an element having substantially the same characteristics as the LED element in Example 1 could be obtained. In addition, in this embodiment, although only the composition of group III elements of the first nitride semiconductor film constituting the n-side multilayer film 6 is changed, when the second nitride semiconductor film is made of a ternary mixed crystal or The same effect can also be obtained by changing the composition of group III elements of the nitride semiconductor of the primary mixed crystal. In addition, although only the composition of group III elements of the third nitride semiconductor film constituting the p-side multilayer film layer 8 is changed above, when the fourth nitride semiconductor film is made of a ternary mixed crystal or a quaternary mixed crystal, For nitride semiconductors, the same effect can be obtained by changing the composition of group III elements.

Example 9

的膜厚生长由掺杂了5×10¹⁹/cm³的Mg的p型Al_0.1Ga_0.9N层构成的p侧包覆层108以外，其他都与实施例7相同而制成LED元件，这样，可以获得具有与实施例2大致同等的特性的LED元件。In this embodiment, except that the p-side multilayer film layer 8 is not made into a multilayer film layer, but with 200

Except for growing the p-side cladding layer 108 composed of a p-type Al _0.1 Ga _0.9 N layer doped with Mg of 5×10 ¹⁹ /cm ³ to a film thickness of , everything else was the same as that of Example 7 to produce an LED element. , an LED element having almost the same characteristics as in Example 2 can be obtained.

Example 10

的膜厚生长由掺杂了5×10¹⁹/cm³的Mg的p型Al_0.1Ga_0.9N层构成的p侧包覆层108以外，其他都与实施例8相同而制成LED元件，这样，可以获得具有与实施例2大致同等的特性的LED元件。In this embodiment, except that the p-side multilayer film layer 8 is not made into a multilayer film layer, but with 200

Except for growing the p-side cladding layer 108 composed of a p-type Al _0.1 Ga _0.9 N layer doped with Mg of 5×10 ¹⁹ /cm ³ to a film thickness of , everything else was the same as in Example 8 to produce an LED element. , an LED element having almost the same characteristics as in Example 2 can be obtained.

Example 11

In this example, in addition to changing the composition of In of the first nitride semiconductor constituting the n-side multilayer film opposite to that of Embodiment 8, the composition of Al of the third nitride semiconductor constituting the p-side multilayer film is changed to In addition to the opposite change, that is, in addition to making the composition of In in the first nitride semiconductor film less as it approaches the active layer, and making the composition of Al in the third nitride semiconductor film less as it moves away from the active layer, Other things were the same as that of Example 8, and an LED element was produced, so that an LED element having substantially the same characteristics as that of Example 8 could be obtained.

Example 12

接着使由非掺杂的In_0.05Ga_0.95N形成的第二氮化物半导体膜生长到25之外，其他都与实施例1相同而制成LED元件，这样，就能够获得具有与实施例1的LED元件大致同等的特性的LED元件。In this embodiment, except when growing the n-side multilayer film layer 6, the first nitride semiconductor film formed of non-doped In _0.2 Ga _0.8 N is grown to 25

Next, a second nitride semiconductor film formed of undoped In _0.05 Ga _0.95 N is grown to 25 Other than that, an LED element was produced in the same manner as in Example 1, and thus, an LED element having characteristics substantially equivalent to those of the LED element in Example 1 could be obtained.

Example 13

接着使由非掺杂的In_0.1Ga_0.9N形成的第二氮化物半导体膜生长到25

之外，其他都与实施例1相同而在制成LED元件，这样，就能够获得具有与实施例1的LED元件大致同等的特性的LED元件。In this embodiment, except when growing the p-side multilayer film layer 8, the first nitride semiconductor film formed of Mg-doped Al _0.05 Ga _0.95 N is grown to 25

Next, a second nitride semiconductor film formed of non-doped In _0.1 Ga _0.9 N is grown to 25

Other than that, an LED element was produced in the same manner as in Example 1, and thus, an LED element having characteristics substantially equivalent to those of the LED element in Example 1 could be obtained.

Example 14

接着使由非掺杂的GaN形成的第二氮化物半导体膜生长到25

即除了使第一氮化物半导体膜的膜厚生长到200

之外，其他都与实施例1相同而制成LED元件，这样，就能够获得具有与实施例1的LED元件大致同等的特性的LED元件。In this embodiment, except when growing the n-side multilayer film layer 6, the first nitride semiconductor film formed of non-doped In _0.03 Ga _0.97 N is grown to 200

Next, a second nitride semiconductor film formed of undoped GaN is grown to 25

That is, in addition to growing the film thickness of the first nitride semiconductor film to 200

Other than that, an LED element was produced in the same manner as in Example 1, and thus, an LED element having characteristics substantially equivalent to those of the LED element in Example 1 could be obtained.

Example 15

之外，其他都与实施例1相同而制成LED元件，这样，就能够获得具有与实施例1的LED元件大致同等的特性的元件。In this embodiment, except when growing the p-side multilayer film layer 8, the film thickness of the first nitride semiconductor film formed of Mg-doped Al _0.05 Ga _0.95 N is grown to 200

Other than that, an LED element was produced in the same manner as in Example 1, and thus, an element having characteristics substantially equivalent to those of the LED element in Example 1 could be obtained.

Example 16

The nitride semiconductor device according to Example 16 of the present invention is a laser diode having an active layer 56 between a p-side region 80 and an n-side region 70 as shown in FIG. 3 .

The laser diode of the present Example 16 is fabricated by growing the following layers on an 80 μm thick GaN substrate 50:

(1) n-type GaN layer 52 formed of 3 μm thick Si-doped GaN;

(2) In _0.1 Ga _0.9 N layer 53 with a thickness of 0.1 μm;

(3) n-side cladding layer 54 of superlattice structure formed by _{InxGa1 -xN} /n-type GaN;

(4) 0.1 μm thick n-type GaN optical guiding layer 55 doped with Si;

(5) Active layer 56 of In _0.4 Ga _0.6 N/In _0.02 Ga _0.98 N multiple quantum well structure;

(6) The thickness doped with Mg is 200 Al _0.2 Ga _0.8 N layer 57;

(7) a p-type GaN optical guiding layer 58 doped with Mg with a thickness of 0.1 μm;

(8) a p-side cladding layer 59 of a superlattice structure formed by _{AlyGa1 -yN} /p-type GaN;

(9) Mg-doped p-type GaN contact layer 60 with a thickness of 0.05 μm.

的掺杂了Si的GaN层和厚度为25

的非掺杂的In_xGa_1-xN层、各240层交替层叠起来而形成的，在整体上显示n型导电性。在这里，在n侧包覆层54中，非掺杂的In_xGa_1-xN膜随着接近有源层，In的量增加，通过使x的值在0.01～0.3的范围内依次变化，就使n侧包覆层54的组成渐变。In addition, the n-side cladding layer 54 is made of a thickness of 25

A Si-doped GaN layer and a thickness of 25

The non-doped In _x Ga _1-x N layers, each 240 layers are stacked alternately, and show n-type conductivity as a whole. Here, in the n-side cladding layer 54, the amount of In increases as the undoped In _x Ga _1-x N film approaches the active layer, and the value of x is sequentially changed in the range of 0.01 to 0.3 , the composition of the n-side cladding layer 54 is gradually changed.

掺杂了Si的4层In_0.15Ga_0.85N阱层和厚度为50

掺杂了Si的In_0.02Ga_0.98N势垒层而成的。In addition, the active layers 56 are alternately provided with a thickness of 20

4 layers of In _0.15 Ga _0.85 N well layer doped with Si and a thickness of 50

It is made of In _0.02 Ga _0.98 N barrier layer doped with Si.

的掺杂了Mg的GaN层和厚度为25

的非掺杂的Al_yGa_1-yN层、各120层交替层叠起来而形成的，在整体上显示p型导电性。在这里，在p侧包覆层59中，非掺杂的Al_yGa_1-yN膜随着接近有源层，Al的量减少，通过使y的值在0.01～0.2的范围内依次变化，就使p侧包覆层59的组成渐变。Furthermore, the p-side cladding layer 59 has a thickness of 25

Mg-doped GaN layer and a thickness of 25

120 layers of non-doped _{AlyGa 1-y} N layers are stacked alternately, showing p-type conductivity as a whole. Here, in the p-side cladding layer 59, the amount of Al decreases as the undoped _{AlyGa1 -yN} film approaches the active layer, and the value of y is sequentially changed in the range of 0.01 to 0.2 , the composition of the p-side cladding layer 59 is graded.

In Example 16, after forming the above-mentioned layers (1) to (9), a ridge-shaped 3 μm-wide and 450 μm-long ridge made of Ni/Au is formed on the p-type contact layer 60 by etching. p-side electrode 61 . An n-side electrode made of Ti/Al was formed on the n-type GaN layer located on one side of the ridge.

In addition, in the laser diode of Example 16, by forming two pairs of TiO ₂ /SiO ₂ on both end faces of the ridge, the reflectance of both end faces becomes 50%.

In the semiconductor laser diode of Example 16 manufactured as described above, continuous oscillation at room temperature with a small threshold current can be obtained.

As described above, even if the multilayer film layer (superlattice layer) is formed apart from the active layer, good results as shown in Example 16 can be obtained.

Example 17

Example 17 is an example related to Embodiment 2 shown in FIG. 4 .

In this embodiment, the substrate 1 made of sapphire (C surface) is placed in the MOVPE reaction vessel, and the temperature of the substrate is raised to 1050° C. to clean the substrate while flowing hydrogen gas.

(buffer layer 102)

的由GaN形成的缓冲层102。Next, lower the temperature to 510°C, use hydrogen as the carrier gas, and use ammonia and TMG (trimethylgallium) as the raw material gases to grow a film with a thickness of about 150 on the substrate 1.

The buffer layer 102 formed of GaN.

(undoped GaN layer 103)

After the growth of the buffer layer 102, only the supply of TMG was stopped, and the temperature was raised to 1050°C. After reaching 1050° C., a non-doped GaN layer 103 with a film thickness of 1.5 μm is grown by using TMG and ammonia gas as raw material gases.

(n-side contact layer 4)

Next, at 1050°C, ammonia gas and TMG (trimethylgallium) were also used as raw material gases, and silane gas was used as impurity gas to grow a film doped with 4.5×10 ¹⁸ /cm ³ with a film thickness of 2.25 μm. The n-side contact layer 4 is formed of Si and GaN.

(n-side first multilayer film layer 105)

的非掺杂的GaN层；然后，在同样的温度下，再添加硅烷气体，生长出膜厚为25

的、掺杂了4.5×10¹⁸/cm³的Si的GaN层。这样，就生长出由膜厚为75

的、由非掺杂GaN构成的A层，和具有掺杂了Si的GaN的、膜厚为25

的B层构成的一对膜层。然后，将成对的膜层层叠25层，使其厚度达到2500

从而生长出由超晶格结构的多层膜层构成的n侧第一多层膜层105。Next, only the supply of silane gas was stopped, and at 1050°C, using ammonia and TMG, a film thickness of 75

undoped GaN layer; then, at the same temperature, add silane gas to grow a film with a thickness of 25

GaN layer doped with 4.5×10 ¹⁸ /cm ³ Si. In this way, a film with a thickness of 75

A layer composed of non-doped GaN, and a layer A with Si-doped GaN with a film thickness of 25

A pair of film layers composed of the B layer. Then, the paired film layers were laminated 25 times to a thickness of 2500

Thus, the n-side first multilayer film layer 105 composed of multilayer film layers of superlattice structure is grown.

(n-side second multilayer film layer 106)

然后，将温度降到800℃，使用TMG、TMI、氨，生长出由非掺杂的In_0.13Ga_0.87N构成的、厚度为20

的第一氮化物半导体膜106a。然后，反复重复以上的操作，以第二+第一的顺序各交替地层叠10层，最后生长出40

的由GaN构成的第二氮化物半导体膜106b，从而成长为超晶格结构的多层膜构成的、膜厚为640

的n侧第二多层膜层106。Next, at the same temperature, the second nitride semiconductor film 106b made of undoped GaN is grown to 40

Then, lower the temperature to 800°C, and use TMG, TMI, and ammonia to grow a non-doped In _0.13 Ga _0.87 N layer with a thickness of 20

first nitride semiconductor film 106a. Then, repeat the above operations repeatedly, and alternately stack 10 layers in the order of the second + first, and finally grow 40 layers.

The second nitride semiconductor film 106b made of GaN is grown into a multilayer film with a superlattice structure, and the film thickness is 640

n-side second multilayer film layer 106 .

(active layer 7)

的由非掺杂的GaN构成的势垒层，然后，使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30

的由非掺杂的In_0.4Ga_0.6N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层这样的顺序，将5层势垒层和4层阱层交替地层叠起来，从而生长成总厚度为1120

的、多量子阱结构构成的有源层7。Next, a film thickness of 200

The barrier layer made of non-doped GaN, then, keep the temperature at 800 ° C, use TMG, TMI, ammonia, grow a film thickness of 30

A well layer composed of non-doped In _0.4 Ga _0.6 N. Then, in the order of barrier layer+well layer+barrier layer+well layer...+barrier layer, 5 barrier layers and 4 well layers are stacked alternately to grow the total Thickness is 1120

The active layer 7 is composed of multi-quantum well structure.

(p-side multilayer film cladding layer 108)

的、由掺杂了1×10²⁰/cm³的Mg的p型Al_0.2Ga_0.8N构成的第三氮化物半导体膜108a；接着，使温度下降到800℃，使用TMG、TMI、氨、Cp2Mg，生长出膜厚为25

的、由掺杂了1×10²⁰/cm³的Mg的In_0.03Ga_0.97N构成的第四氮化物半导体膜108b。然后，反复重复以上的操作，以第三+第四的顺序各交替地层叠5层，最后生长出膜厚40

的第三氮化物半导体膜108a，从而成长为超晶格结构的多层膜所组成的、膜厚为365

的p侧多层膜层包覆层108。Then, at 1050°C, using TMG, TMA, ammonia, Cp2Mg (dimagnesium), a film thickness of 40

A third nitride semiconductor film 108a made of p-type Al _0.2 Ga _0.8 N doped with 1×10 ²⁰ /cm ³ Mg; then, the temperature was lowered to 800°C, and TMG, TMI, ammonia, Cp2Mg , a film thickness of 25

The fourth nitride semiconductor film 108b made of In _0.03 Ga _0.97 N doped with 1×10 ²⁰ /cm ³ Mg. Then, repeat the above operations repeatedly, stack 5 layers alternately in the order of the third + fourth, and finally grow a film with a thickness of 40

The third nitride semiconductor film 108a is grown into a multilayer film with a superlattice structure and has a film thickness of 365

The cladding layer 108 of the p-side multilayer film layer.

(p-side GaN contact layer 9)

Next, at 1050°C, using TMG, ammonia, and Cp2Mg, a film thickness of 700 p-side contact layer 9 made of p-type GaN doped with 1×10 ²⁰ /cm ³ Mg.

After the reaction, the temperature was lowered to room temperature, and then the wafer was placed in the reaction container, and annealed at 700° C. in a nitrogen atmosphere to further reduce the resistance of the p-type layer.

After the annealing, the wafer is taken out from the reaction vessel, and a mask of a predetermined shape is formed on the surface of the p-side contact layer 9 of the uppermost layer, and etched from the p-side contact layer with an RIE (reactive ion etching) device, As shown in FIG. 4, the surface of the n-side contact layer 4 is exposed.

的、含有Ni和Au的透光性p电极11，再在该p电极11上形成膜厚为0.5μm的、由键合用的Au构成的p焊盘电极11。另一方面，在由于蚀刻而暴露出来的n侧接触层4的表面上形成含W和Al的n电极12，从而制造出LED元件。After etching, a film thickness of 200 is formed on almost the entire surface of the uppermost p-side contact layer

A translucent p-electrode 11 containing Ni and Au was formed, and a p-pad electrode 11 made of Au for bonding was formed on the p-electrode 11 with a film thickness of 0.5 μm. On the other hand, an n-electrode 12 containing W and Al is formed on the surface of the n-side contact layer 4 exposed by etching, thereby manufacturing an LED element.

Under the forward voltage of 20mA, the LED element displays 520nm pure green light, and the Vf is only 3.5V. Compared with the previous multi-quantum well structure LED element, the Vf is reduced by nearly 1.0V, and the output power is increased by more than two times. . Therefore, it is possible to obtain an LED having substantially the same characteristics as a conventional LED element at 10 mA.

In addition, the conventional LED element is formed by sequentially laminating the following film layers on the first buffer layer made of GaN: the second buffer layer made of undoped GaN, and the n-side buffer layer made of Si-doped GaN. Contact layer, p-side active layer formed by the same multiple quantum well structure as in Example 12, single-layer Mg-doped Al _0.1 Ga _0.9 N layer, p-side contact layer formed by Mg-doped GaN .

Example 18

In this embodiment, except that the following changes are made to the active layer 7 in the embodiment 17, everything else is the same as that of the embodiment 17 to manufacture an LED element.

(active layer 7)

的由非掺杂的GaN构成的势垒层，然后，使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30的由非掺杂的In_0.3Ga_0.7N构成的阱层。然后，按照势垒层十阱层+势垒层+阱层+......+势垒层这样的顺序，将7层势垒层和6层阱层交替地层叠起来，从而生长出由总厚度为1930

的多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

The barrier layer made of non-doped GaN, then, keep the temperature at 800 ° C, use TMG, TMI, ammonia, grow a film thickness of 30 The well layer is composed of non-doped In _0.3 Ga _0.7 N. Then, according to the sequence of barrier layer + well layer + barrier layer + well layer + ... + barrier layer, 7 barrier layers and 6 well layers are stacked alternately to grow By total thickness of 1930

The active layer 7 is composed of multiple quantum well structures.

The obtained LED element exhibited pure blue light of 470 nm when the current in the forward direction was 20 mA, and the same good results as in Example 17 could be obtained.

Example 19

In this embodiment, except that the following changes are made to the active layer 7 in the embodiment 17, everything else is the same as that of the embodiment 17 to manufacture an LED element.

(active layer 7)

的由非掺杂的GaN构成的势垒层，然后，使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30

的由非掺杂的In_0.3Ga_0.7N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层+......+势垒层这样的顺序，将6层势垒层和5层阱层交替地层叠起来，从而生长出由总厚度为1650

的多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

The barrier layer made of non-doped GaN, then, keep the temperature at 800 ° C, use TMG, TMI, ammonia, grow a film thickness of 30

The well layer is composed of non-doped In _0.3 Ga _0.7 N. Then, in the order of barrier layer+well layer+barrier layer+well layer+...+barrier layer, 6 barrier layers and 5 well layers are alternately stacked to grow By total thickness of 1650

The active layer 7 is composed of multiple quantum well structures.

The obtained LED element displayed pure blue light of 470 nm when the forward current was 20 mA, and the same good results as in Example 17 could be obtained.

Example 20

In this embodiment, except that the active layer 7 in the embodiment 17 is changed as follows, everything else is the same as that of the embodiment 17 to manufacture an LED element.

(active layer 7)

的由非掺杂的GaN构成的势垒层，然后，使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30

的由非掺杂的In_0.35Ga_0.65构成的阱层。然后，按照势垒层+阱层+势垒层+阱层+......+势垒层这样的顺序，将7层势垒层和6层阱层交替地层叠起来，从而生长出由总厚度为1930

的多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

The barrier layer made of non-doped GaN, then, keep the temperature at 800 ° C, use TMG, TMI, ammonia, grow a film thickness of 30

A well layer composed of non-doped In _0.35 Ga _0.65 . Then, in the order of barrier layer+well layer+barrier layer+well layer+…+barrier layer, 7 barrier layers and 6 well layers are alternately stacked to grow By total thickness of 1930

The active layer 7 is composed of multiple quantum well structures.

The obtained LED element exhibited blue-green light of 500 nm when the forward current was 20 mA, and the same good results as in Example 17 could be obtained.

Example 21

In this embodiment, except that the following changes are made to the active layer 7 in the embodiment 17, everything else is the same as that of the embodiment 17 to manufacture an LED element.

(active layer 7)

的由非掺杂的GaN构成的势垒层，然后，使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30的由非掺杂的In_0.35Ga_0.65N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层+......+势垒层这样的顺序，将4层势垒层和3层阱层交替地层叠起来，从而生长出由总厚度为1090

的多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

The barrier layer made of non-doped GaN, then, keep the temperature at 800 ° C, use TMG, TMI, ammonia, grow a film thickness of 30 The well layer is composed of non-doped In _0.35 Ga _0.65 N. Then, in the order of barrier layer+well layer+barrier layer+well layer+…+barrier layer, 4 barrier layers and 3 well layers are alternately stacked to grow by total thickness of 1090

The active layer 7 is composed of multiple quantum well structures.

When the current in the forward direction was 20 mA, the obtained LED element displayed blue-green light of 500 nm, and the same good results as in Example 17 could be obtained.

Example 22

In this embodiment, except that the n-side second multi-layer film layer 6 is not grown, the others are the same as in the embodiment 17 to manufacture an LED element.

Although the obtained LED element was slightly inferior to Example 17 in terms of element characteristics and luminous output, it still had good luminous output compared with conventional LED elements.

Example 23

In this embodiment, except that the p-side multilayer coating layer 8 in the embodiment 17 is changed as follows, the others are the same as in the embodiment 17 to manufacture an LED element.

(p-side monolayer cladding layer 18)

的、由掺杂1×10²⁰/cm³的Mg的p型Al_0.16Ga_0.84N构成的p侧单层膜包覆层。At a temperature of 1050 ° C, using TMG, TMA, ammonia, Cp2Mg (dimagnesium), a film thickness of 300

A p-side single-layer film cladding layer composed of p-type Al _0.16 Ga _0.84 N doped with 1×10 ²⁰ /cm ³ Mg.

Although the obtained LED element did not make the cladding layer into a superlattice structure, but was grown as a single layer, it was combined with other layers of structures, although the performance was slightly worse than that of Example 1. , but almost equally good results can be obtained. In addition, if it is made into a single-layer film, its manufacturing process can be much simpler than that of a multi-layer film, so it is preferred.

Example 24

In this embodiment, except that the n-side first multi-layer film layer 105 in the embodiment 17 is changed as follows, everything else is the same as the embodiment 17 to manufacture an LED element.

(n-side first multilayer film layer 105)

的、由非掺杂的GaN构成的A层，然后生长出膜厚为25

的、由掺杂了1×10¹⁸/cm³的Si的Al_0.1Ga_0.9N构成的B层，然后将成对的A层和B层层叠20层，从而生长出厚度为2500

的n侧第一多层膜层105。A film thickness of 100

layer A made of undoped GaN, and then grow a film thickness of 25

A B layer composed of Al _0.1 Ga _0.9 N doped with Si at 1×10 ¹⁸ /cm ³ , and then the paired A layer and B layer are laminated for 20 layers to grow a thickness of 2500

The n-side first multilayer film layer 105.

The obtained LED element had substantially the same characteristics as Example 17, and good results were obtained.

Example 25

In this embodiment, except that the n-side contact layer 4 in the embodiment 17 is changed as follows, everything else is the same as that of the embodiment 17 to manufacture an LED element.

(n-side contact layer 4)

At 1050°C, using ammonia and TMG as raw material gases and silane gas as impurity gas, a 6μm-thick n-side contact made of GaN doped with Si at 4.5×10 ¹⁸ /cm ³ was grown. Layer 4.

The obtained LED element had substantially the same characteristics as Example 17, and good results were obtained.

Example 26

Example 26 is an example related to Embodiment 3 shown in FIG. 5 .

In the present embodiment 26, firstly, the substrate 1 made of sapphire (cut in such a way that the surface is C-plane) is placed in the reaction container, and the gas in the container is fully replaced with hydrogen gas, and then hydrogen gas is introduced while The temperature of the substrate 1 was raised to 1050° C. to clean the substrate. In addition, in the substrate 1, sapphire with the R plane or the A plane as the main surface other than the C plane can also be used, and an insulating substrate such as spinel (MgAl ₂ O ₄ ), and SiC (containing 6H, 4H , 3C), Si, ZnO, GaAs, GaN and other semiconductor substrates.

(buffer layer 202)

的、由GaN形成的缓冲层202。Next, lower the temperature to 510°C, use hydrogen as the carrier gas, and use ammonia and TMG (trimethylgallium) as the raw material gases to grow a film with a thickness of about 200 on the substrate 1.

buffer layer 202 formed of GaN.

(First n-side nitride semiconductor layer 203)

After the buffer layer 202 was grown, only the supply of TMG was stopped, and the temperature was raised to 1050°C. After reaching 1050° C., a first n-side nitride semiconductor layer 203 made of undoped GaN and having a film thickness of 5 μm was grown using ammonia gas and TMG (trimethylgallium) as raw material gases. The first n-side nitride semiconductor layer 203 is preferably grown at a higher temperature than the buffer layer 202, for example, 900° C. to 1100° C.; besides GaN, it can also be made of In _{x Aly} Ga _1-xy N (0≤x , 0≤y, x+y≤1), it is preferable to use GaN or _{AlxGa1 -xN} whose x value is 0.2 or less, so that it is easy to obtain a nitride semiconductor layer with few crystal defects. In addition, it is preferable to grow with a film thickness thicker than the buffer layer, usually with a film thickness of 0.1 μm or more. Since this layer is usually an undoped layer, its properties are close to those of an intrinsic semiconductor, and its resistivity is greater than 0.2Ω·cm, but it can also be doped with Si, Ge, etc. in an amount less than that of the second n-side nitride semiconductor layer n-type impurities, thereby reducing the resistivity.

(Second n-side nitride semiconductor layer 204)

的非掺杂GaN层，然后，再通入硅烷气，生长出膜厚为20

的掺杂了1×10¹⁹/cm³的Si的GaN层，然后，停止掺杂Si，再生长出膜厚为20

的非掺杂的GaN层。这样，就生长出由A层和B层构成的一对膜层，所述A层是由厚度为20

的非掺杂的GaN层构成的，所述B层是由厚度为20

的掺杂了Si的GaN层构成的。然后层叠这一对膜层，就生长出由调制掺杂的GaN构成的、厚度1μm的第二n侧氮化物半导体层204。Next, at a temperature of 1050°C, using TMG and ammonia gas, a film thickness of 20

The non-doped GaN layer, and then pass through silane gas to grow a film thickness of 20

GaN layer doped with 1×10 ¹⁹ /cm ³ Si, then, stop doping Si, and then grow a film thickness of 20

undoped GaN layer. In this way, a pair of film layers consisting of A layer and B layer are grown, and the A layer is made of a layer with a thickness of 20

Consisting of an undoped GaN layer, the B layer is composed of a thickness of 20

made of Si-doped GaN layers. Then, this pair of film layers is stacked to grow a second n-side nitride semiconductor layer 204 made of modulated doped GaN with a thickness of 1 μm.

(third n-side nitride semiconductor layer 205)

Next, only the supply of silane gas was stopped, and at 1050°C, a film with a thickness of 100 The third n-side nitride semiconductor layer 205 made of undoped GaN. In addition to GaN, the third n-side nitride semiconductor layer 205 may also be composed of _{InxAlyGa1 -xyN} (0≤x, 0≤y, x+y≤1), although its _composition is not particularly limited. , but preferably _{AlxGa1 -xN} whose x value is 0.2 or less, or _{InyGa1 -yN} whose y value is 0.1 or less, so that it is easy to obtain a nitride semiconductor layer with few crystal defects. If InGaN is grown, it is possible to prevent cracks from being generated in the Al-containing nitride semiconductor layer when the Al-containing nitride semiconductor is grown thereon.

(active layer 7)

的非掺杂的In_0.4Ga_0.6N层，从而生长出具有单量子阱结构的有源层7。另外，这一层也可以是具有由InGaN构成的阱层的多量子阱结构。Then, adjust the temperature to 800°C, change the carrier gas to nitrogen, and use TMG, TMI (trimethylindium) and ammonia to grow a film with a thickness of 30

The non-doped In _0.4 Ga _0.6 N layer, thereby growing the active layer 7 with a single quantum well structure. In addition, this layer may also have a multi-quantum well structure having a well layer made of InGaN.

(p-side cladding layer 108)

的、由掺杂了1×10²⁰/cm³的Mg的p型Al_0.1Ga_0.9N构成的膜层；然后，使用TMG、氨、Cp2Mg，生长出膜厚为20

的、由掺杂了1×10¹⁹/cm³的Mg的GaN构成的膜层。下面，通过交替重复同样的工序，形成总膜厚为0.8μm的超晶格结构层构成的p侧包覆层。Then, the temperature was raised to 1050°C, and a film thickness of 20

A film layer composed of p-type Al _0.1 Ga _0.9 N doped with 1×10 ²⁰ /cm ³ Mg; then, using TMG, ammonia, and Cp2Mg, grow a film with a thickness of 20

A film layer composed of GaN doped with 1×10 ¹⁹ /cm ³ Mg. Next, by repeating the same steps alternately, a p-side cladding layer composed of superlattice structure layers with a total film thickness of 0.8 μm was formed.

(p-side contact layer 208)

的、由非掺杂的In_0.1Ga_0.9N构成的第一氮化物半导体膜；接着，停止供应TMI，生长出膜厚为30

的、由掺杂了1×10²⁰/cm³的Mg的GaN构成的第二氮化物半导体膜。然后交替层叠，生长成总膜厚为600

的p侧接触层208。Next, at 800°C, a film thickness of 30

A first nitride semiconductor film composed of non-doped In _0.1 Ga _0.9 N; then, the supply of TMI was stopped, and a film thickness of 30

A second nitride semiconductor film made of GaN doped with 1×10 ²⁰ /cm ³ Mg. Then stacked alternately to grow a total film thickness of 600

The p-side contact layer 208.

After the reaction, the temperature was lowered to room temperature, and the wafer was placed in a reaction vessel in a nitrogen atmosphere, and annealed at 700° C. to further reduce the resistance of each p-side layer.

After the annealing, the wafer is taken out from the reaction vessel, a mask of a predetermined shape is formed on the surface of the uppermost p-side contact layer 208, and then etched from the p-side contact layer with RIE (reactive ion etching), as shown in Figure 5 As shown, the surface of the second n-side nitride semiconductor layer 204 is exposed.

的、含有Ni和Au的透光性的p电极10，然后在该p电极10上形成膜厚为0.5μm的由键合用的Au构成的p焊盘电极10。另一方面，在由蚀刻而露出来的第二n侧氮化物半导体层204的表面上形成含有W和Al的n电极12。最后，为了保护p电极10的表面，在以图5所示的方式形成由SiO₂构成的绝缘膜12之后，通过划线器将晶片分离，成为350μm见方的LED元件。After etching, a film thickness of 200 is formed on almost the entire surface of the uppermost p-side contact layer

A light-transmitting p-electrode 10 containing Ni and Au, and a p-pad electrode 10 made of Au for bonding with a film thickness of 0.5 μm was formed on the p-electrode 10 . On the other hand, the n-electrode 12 containing W and Al is formed on the surface of the second n-side nitride semiconductor layer 204 exposed by etching. Finally, in order to protect the surface of the p-electrode 10, after forming the insulating film 12 made of _SiO2 in the manner shown in FIG.

The LED element has a forward voltage of 3.2V at 20mA, emits 520nm green light, can reduce Vf at 20mA by 0.2-0.3V, and can increase output power by 10% or more. In addition, 100 LED elements shown in Example 21 were produced, and the forward voltage Vf at 20 mA was measured. As a result, the distribution of Vf was in the range of 3.2V to 3.3V, and the degree of dispersion was extremely small.

Example 27

In this embodiment, except that the stacking order of the non-doped In _0.1 Ga _0.9 N layer and GaN doped with 1×10 ²⁰ /cm ³ Mg is reversed when growing the p-side contact layer, other All were fabricated as LED elements in the same manner as in Example 26.

Example 28

In this embodiment, except that the composition of the second nitride semiconductor was changed to In _0.05 Ga _0.95 N when growing the p-side contact layer, the LED element was manufactured in the same manner as in Embodiment 26.

Example 29

In this embodiment, the second nitride semiconductor film is made into an In _0.05 Ga _0.95 N layer doped with 1×10 ²⁰ /cm ³ Mg when growing the p-side contact layer. In the same manner as in Example 26, an LED element was fabricated.

Example 30

In this embodiment, the second nitride semiconductor film is made into an Al _0.05 Ga _0.95 N layer doped with 1×10 ²⁰ /cm ³ Mg when growing the p-side contact layer. In the same manner as in Example 26, an LED element was fabricated.

Example 31

In this example, except that the first nitride semiconductor film was doped with 1×10 ²⁰ /cm ³ Mg when growing the p-side contact layer, the LED element was manufactured in the same manner as in Example 26. .

Example 32

In this embodiment, except when growing the p-side contact layer, the first nitride semiconductor film composed of In _0.1 Ga _0.9 N doped with Mg of 1×10 ²⁰ /cm ³ is used instead of the non-doped The first nitride semiconductor film made of In _0.1 Ga _0.9 N layer, and the second nitride semiconductor film made of GaN doped with 1×10 ¹⁹ /cm ³ Mg instead of the layer made of GaN doped with 1×10 ²⁰ The second nitride semiconductor film made of GaN with Mg/cm ³ , and the first nitride semiconductor film was formed as the uppermost layer, and the others were the same as in Example 26 to fabricate an LED element.

Example 33

In this example, except that the p-side contact layer 208 was formed in the following manner, the LED element was produced in the same manner as in Example 26.

的、由掺杂了1×10²⁰/cm³的Mg的GaN构成的第二氮化物半导体膜。然后，又逐渐增加TMI，形成组成在厚度方向上逐渐从GaN变化成In_0.1Ga_0.9N的组成渐变的膜层；之后，再形成膜厚为30

的、由非掺杂的In_0.1Ga_0.9N构成的第一氮化物半导体膜。然后重复该操作，直到第一氮化物半导体膜和第二氮化物半导体膜各自都成为10层，由此生长出p侧接触层208。That is, at a temperature of 800°C, a film thickness of 30 A first nitride semiconductor film composed of non-doped In _0.1 Ga _0.9 N; then, gradually reducing the TMI to form a film layer whose composition gradually changes from In _0.1 Ga _0.9 N to GaN in the thickness direction; After the TMI is 0, a film thickness of 30

A second nitride semiconductor film made of GaN doped with 1×10 ²⁰ /cm ³ Mg. Then, gradually increase the TMI to form a film layer whose composition gradually changes from GaN to In _0.1 Ga _0.9 N in the thickness direction; after that, form a film with a thickness of 30

A first nitride semiconductor film made of undoped In _0.1 Ga _0.9 N. This operation is then repeated until each of the first nitride semiconductor film and the second nitride semiconductor film becomes 10 layers, whereby the p-side contact layer 208 is grown.

The LED elements in the above-mentioned Examples 27 to 33 also obtained better light emission characteristics than those in the conventional example, as in Example 26.

In addition, in the conventional p-side contact layer made of InGaN, since InGaN absorbs a lot of light in the short wavelength region, the p-side contact layer is colored yellow, and the active layer may be damaged. However, since the p-side contact layer of the present invention has a superlattice structure, compared with the conventional p-side contact layer composed of a single layer of InGaN, the problem of shifting the wavelength of light to the longer wavelength side can be reduced. The absorption rate of light with small wavelengths and short wavelengths. Therefore, the p-side contact layer of the present invention can prevent shifting to a direction in which the wavelength of light is longer, and can also improve light transmittance.

)和InGaN(20

)交替层叠30个周期而成的、具有掺杂了4×10¹⁸/cm³的Mg的载流子浓度的p型膜层。另外，在图7中，为了进行比较，还显示了由单层的In_0.15Ga_0.85N(膜厚0.12μm)构成的以往例的光透过率。如图7所示，可以看到，本发明的超晶格结构的多层膜与以往例的单层膜的相对于波长400nm附近的光的吸收率明显不同，本发明的超晶格结构的多层膜的相对于400nm附近的光的透过率要优异得多。另外，图7中所示的本发明的超晶格结构的多层膜与以往例的单层膜的各自的电阻率ρ都是0.5Ω·cm。另外，图7中的透过率表示的是以蓝宝石的光透过率为100％的相对值。7 is a graph showing the transmittance with respect to light of different wavelengths of the multilayer film of the superlattice structure of the present invention composed of GaN and InGaN. The multilayer film is made of GaN (20

) and InGaN (20

) is alternately stacked for 30 cycles, and has a p-type film layer doped with Mg of 4×10 ¹⁸ /cm ³ . In addition, in FIG. 7 , for comparison, the light transmittance of a conventional example composed of a single layer of In _0.15 Ga _0.85 N (thickness: 0.12 μm) is also shown. As shown in FIG. 7 , it can be seen that the multilayer film of the superlattice structure of the present invention is significantly different from the single-layer film of the conventional example in terms of the absorptivity of light near a wavelength of 400 nm, and the superlattice structure of the present invention The transmittance of the multilayer film with respect to light around 400 nm is much excellent. In addition, the resistivity p of each of the multilayer film of the superlattice structure of the present invention shown in FIG. 7 and the single layer film of the conventional example is 0.5 Ω·cm. In addition, the transmittance in FIG. 7 shows the relative value when the light transmittance of sapphire is 100%.

Example 34

Example 34 is an example associated with Embodiment 5 shown in FIG. 8 .

In Example 34, first, the substrate 1 made of sapphire (C surface) was placed in a MOVPE reaction vessel, and the temperature of the substrate was raised to 1050° C. while hydrogen gas was passed through, to clean the substrate.

(buffer layer 102)

的、由GaN形成的缓冲层102。Next, lower the temperature to 510°C, use hydrogen as the carrier gas, and use ammonia and TMG (trimethylgallium) as the raw material gases to grow a film with a thickness of about 150 on the substrate 1.

buffer layer 102 formed of GaN.

(undoped GaN layer 103)

After growing into the buffer layer 102, only the supply of TMG was stopped, and the temperature was raised to 1050°C. After reaching 1050° C., a non-doped GaN layer 103 with a film thickness of 1.5 μm is grown by using ammonia and TMG as raw material gases.

(n-side contact layer 4)

Next, at 1050°C, using ammonia gas and TMG as the raw material gas and silane gas as the impurity gas, GaN doped with 4.5×10 ¹⁸ /cm ³ Si was grown with a film thickness of 2.25 μm. n-side contact layer 4.

(n-side first multilayer film layer 305)

的、由非掺杂的GaN构成的下层305a；然后，在同样的温度下，再添加硅烷气体，生长出膜厚为300

的、由掺杂了4.5×10¹⁸/cm³的Si的GaN层构成的中间层305b；然后，只停止供应硅烷气体，在同样的温度下生长出膜厚为50

的、由非掺杂的GaN构成的上层305c；这样就生长出由三层构成的、总膜厚为2350的第一多层膜层305。Next, only the supply of silane gas was stopped, and a film thickness of 2000

The lower layer 305a made of non-doped GaN; then, at the same temperature, add silane gas to grow a film with a thickness of 300

The intermediate layer 305b composed of a GaN layer doped with Si at 4.5×10 ¹⁸ /cm ³ ; then, only the supply of silane gas was stopped, and a film thickness of 50

An upper layer 305c made of undoped GaN; thus, a three-layered upper layer 305c with a total film thickness of 2350 The first multilayer film layer 305.

(n-side second multilayer film layer 306)

然后，将温度降到800℃，使用TMG、TMI、氨，生长出厚度为20

的、由非掺杂的In_0.13Ga_0.87构成的第二氮化物半导体膜。然后，重复以上的操作，以第一+第二的顺序交替地层叠，各层叠10层，最后生长出膜厚40

的由GaN构成的第二氮化物半导体膜，从而成长为由超晶格结构多层膜构成的、膜厚为640

的n侧第二多层膜层306。Next, at the same temperature, a second nitride semiconductor film made of undoped GaN is grown to 40

Then, the temperature was lowered to 800°C, and TMG, TMI, and ammonia were used to grow a thickness of 20

The second nitride semiconductor film made of non-doped In _0.13 Ga _0.87 . Then, repeat the above operation, stacking alternately in the order of first + second, each stacking 10 layers, and finally growing a film with a thickness of 40

The second nitride semiconductor film composed of GaN is grown into a multilayer film composed of a superlattice structure with a film thickness of 640

n-side second multilayer film layer 306 .

(active layer 7)

的、由非掺杂的GaN构成的势垒层；然后，继续使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30

的、由非掺杂的In_0.4Ga_0.6N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层这样的顺序，将5层势垒层和4层阱层交替地层叠起来，就生长成总厚度为1120

的、由多量子阱结构构成的有源层7。Next, a film thickness of 200

A barrier layer made of non-doped GaN; then, continue to keep the temperature at 800 ° C, use TMG, TMI, ammonia, and grow a film thickness of 30

A well layer composed of non-doped In _0.4 Ga _0.6 N. Then, in the order of barrier layer+well layer+barrier layer+well layer...+barrier layer, 5 barrier layers and 4 well layers are alternately stacked to grow the total Thickness is 1120

The active layer 7 is composed of multiple quantum well structures.

(p-side multilayer film cladding layer 8)

的第三氮化物半导体膜，从而成长为膜厚365

的由超晶格结构的多层膜所组成的p侧多层膜层包覆层8。Then, at 1050°C, using TMG, TMA, ammonia, Cp2Mg (dimagnesium), a film thickness of 40 A third nitride semiconductor film made of p-type Al _0.2 Ga _0.8 N doped with Mg of 1×10 ²⁰ /cm ³ ; then, the temperature was lowered to 800° C., using TMG, TMI, ammonia, Cp2Mg, A film thickness of 25 A fourth nitride semiconductor film composed of In _0.03 Ga _0.97 N doped with 1×10 ²⁰ /cm ³ Mg. Then, repeat the above operations, alternately stack 5 layers in the order of the third + fourth, and finally grow a film with a thickness of 40

The third nitride semiconductor film, thus grown to a film thickness of 365

The p-side multilayer film cladding layer 8 composed of a multilayer film of superlattice structure.

(p-side GaN contact layer 9)

Next, at 1050°C, using TMG, ammonia, and Cp2Mg, a film thickness of 700 p-side contact layer 9 made of p-type GaN doped with 1×10 ²⁰ /cm ³ Mg.

After the reaction, the temperature was lowered to room temperature, and then the wafer was placed in the reaction container in a nitrogen atmosphere, and annealed at 700°C to further reduce the resistance of the p-type film layer.

After the annealing, the wafer is taken out from the reaction vessel, and a mask of a predetermined shape is formed on the surface of the p-side contact layer 9 positioned at the uppermost layer, and a RIE (reactive ion etching) device is used to start from the p-side contact layer side Etching is performed to expose the surface of the n-side contact layer 4 as shown in FIG. 8 .

的、含有Ni和Au的透光性p电极11，然后再在该p电极11上形成膜厚为0.5μm的、由键合用的Au构成的p焊盘电极11。另一方面，在由蚀刻而露出来的n侧接触层4的表面上形成含有W和Al的n电极12，从而形成为LED元件。After etching, a film thickness of 200 is formed on almost the entire surface of the uppermost p-side contact layer

A translucent p-electrode 11 containing Ni and Au was formed, and a p-pad electrode 11 made of Au for bonding was formed on the p-electrode 11 with a film thickness of 0.5 μm. On the other hand, an n-electrode 12 containing W and Al is formed on the surface of the n-side contact layer 4 exposed by etching to form an LED element.

The LED element displays 520nm pure green light at a positive direction current of 20mA, and its Vf is 3.5V. Compared with the previous multi-quantum well structure LED element, the Vf is reduced by nearly 1.0V, and the output power is increased by more than two times. Therefore, it is possible to obtain an LED having substantially the same characteristics as a conventional LED element at 10 mA. Furthermore, from the n-layer and p-layer electrodes of the LED element, the voltage was gradually increased in the opposite direction to measure the electrostatic withstand voltage performance of the obtained LED. At this time, a good result of more than 1.5 times that of the conventional one can be obtained.

In addition, the composition of the conventional LED element is formed by sequentially laminating the following film layers on the first buffer layer made of GaN: the second buffer layer made of undoped GaN, the second buffer layer made of Si-doped GaN The n-side contact layer, the active layer formed by the same multi-quantum well structure as in Example 27, the single-layer Mg-doped Al _0.1 Ga _0.9 N layer, the p-side contact layer formed by Mg-doped GaN layer.

Example 35

In this embodiment, except that the following changes are made to the active layer 7 in the embodiment 34, everything else is the same as that of the embodiment 34 to manufacture an LED element.

(active layer 7)

的、由非掺杂的GaN构成的势垒层；然后，继续使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30的、由非掺杂的In_0.3Ga_0.7N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层这样的顺序，将7层势垒层和6层阱层交替地层叠起来，就生长成总厚度为1930

的、由多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

A barrier layer made of non-doped GaN; then, continue to keep the temperature at 800 ° C, use TMG, TMI, ammonia, and grow a film thickness of 30 A well layer composed of non-doped In _0.3 Ga _0.7 N. Then, in the order of barrier layer+well layer+barrier layer+well layer...+barrier layer, 7 barrier layers and 6 well layers are stacked alternately to grow the total Thickness is 1930

The active layer 7 is composed of multiple quantum well structures.

The obtained LED element emits pure blue light of 470 nm when the current in the forward direction is 20 mA, and the same good results as in Example 34 can be obtained.

Example 36

In this embodiment, except that the following changes are made to the active layer 7 in the embodiment 34, everything else is the same as that of the embodiment 34 to manufacture an LED element.

(active layer 7)

的、由非掺杂的GaN构成的势垒层；然后，继续使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30

的、由非掺杂的In_0.3Ga_0.7N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层这样的顺序，将6层势垒层和5层阱层交替地层叠起来，就生长成总厚度为1650的、由多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

A barrier layer made of non-doped GaN; then, continue to keep the temperature at 800 ° C, use TMG, TMI, ammonia, and grow a film thickness of 30

A well layer composed of non-doped In _0.3 Ga _0.7 N. Then, in the order of barrier layer+well layer+barrier layer+well layer...+barrier layer, 6 barrier layers and 5 well layers are stacked alternately to grow the total Thickness is 1650 The active layer 7 is composed of multiple quantum well structures.

The obtained LED element emits pure blue light of 470 nm when the current in the forward direction is 20 mA, and the same good results as in Example 34 can be obtained.

Example 37

In this embodiment, except that the following changes are made to the active layer 7 in the embodiment 34, everything else is the same as that of the embodiment 34 to manufacture an LED element.

(active layer 7)

的、由非掺杂的GaN构成的势垒层；然后，继续使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30

的、由非掺杂的In_0.35Ga_0.65N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层这样的顺序，将7层势垒层和6层阱层交替地层叠起来，就生长成总厚度为1930

的、由多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

A barrier layer made of non-doped GaN; then, continue to keep the temperature at 800 ° C, use TMG, TMI, ammonia, and grow a film thickness of 30

A well layer made of non-doped In _0.35 Ga _0.65 N. Then, in the order of barrier layer+well layer+barrier layer+well layer...+barrier layer, 7 barrier layers and 6 well layers are stacked alternately to grow the total Thickness is 1930

The active layer 7 is composed of multiple quantum well structures.

The obtained LED element emits blue-green light of 500 nm when the current in the forward direction is 20 mA, and the same good results as in Example 34 can be obtained.

Example 38

In this embodiment, except that the following changes are made to the active layer 7 in the embodiment 34, everything else is the same as that of the embodiment 34 to manufacture an LED element.

(active layer 7)

的、由非掺杂的GaN构成的势垒层；然后，继续使温度保持在800℃，使用TMG、TMI、氨，生长出膜厚为30

的、由非掺杂的In_0.35Ga_0.65N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层这样的顺序，将4层势垒层和3层阱层交替地层叠起来，就生长成总厚度为1090

的、由多量子阱结构构成的有源层7。Next, grow a film with a thickness of 250

A barrier layer made of non-doped GaN; then, continue to keep the temperature at 800 ° C, use TMG, TMI, ammonia, and grow a film thickness of 30

A well layer made of non-doped In _0.35 Ga _0.65 N. Then, in the order of barrier layer+well layer+barrier layer+well layer...+barrier layer, 4 barrier layers and 3 well layers are alternately stacked to grow the total Thickness is 1090

The active layer 7 is composed of multiple quantum well structures.

The obtained LED element emits blue-green light of 500 nm when the current in the forward direction is 20 mA, and the same good results as in Example 34 can be obtained.

Example 39

In this embodiment, except that the n-side second multi-layer film layer 306 is not formed, the others are the same as in the embodiment 34 to manufacture an LED element.

Compared with Example 34, the obtained LED element had slightly lower element characteristics and luminous output power, but the static voltage resistance characteristic was almost as good as that of Example 27.

Example 40

In this example, an LED element was produced in the same manner as in Example 34, except that the p-side multilayer film cladding layer 8 was changed as described below.

(p-side monolayer cladding layer 8)

的、由掺杂了1×10²⁰/cm³的Mg的p型Al_0.16Ga_0.84N构成的p侧单层膜包覆层8。At 1050°C, using TMG, TMA, ammonia, Cp2Mg (dimagnesium), a film thickness of 300

The p-side single-layer cladding layer 8 is composed of p-type Al _0.16 Ga _0.84 N doped with 1×10 ²⁰ /cm ³ Mg.

Although the obtained LED element does not grow the cladding layer into a superlattice structure but grows into a single layer, but through the combination with other film layer structures, although the performance such as luminous output power is slightly worse than that of Example 27, However, good results were obtained that were almost equivalent in static voltage resistance characteristics. In addition, if it is made into a single layer, the manufacturing process can be simplified compared with the case where it is made into a multilayer film layer, which is preferable.

Example 41

In this embodiment, except that the thickness of each layer of the n-side first multilayer film layer 305 in the embodiment 34 is changed in the following manner, other things are the same as the embodiment 34 to manufacture an LED element.

(n-side first multilayer film layer 305)

的、由掺杂了4.5×10¹⁸/cm³的Si的GaN层构成的中间层305b；然后，只停止供应硅烷气体，在同样的温度下生长出膜厚为50

的、由非掺杂GaN构成的上层305c；于是，就生长出由三层构成的、总膜厚为3350

的第一多层膜层305。Next, only the supply of silane gas was stopped, and a film thickness of 3000 was grown at 1050°C using ammonia and TMG. The lower layer 305a made of non-doped GaN layer; then, at the same temperature, add silane gas to grow a film with a thickness of 300

The intermediate layer 305b composed of a GaN layer doped with Si at 4.5×10 ¹⁸ /cm ³ ; then, only the supply of silane gas was stopped, and a film thickness of 50

The upper layer 305c made of non-doped GaN; thus, a three-layered upper layer 305c with a total film thickness of 3350

The first multilayer film layer 305.

The obtained LED element had almost the same characteristics as Example 34, and good results were obtained.

Example 42

In this embodiment, except that the n-side first multi-layer film layer 305 in the embodiment 41 is changed in the following way, other things are the same as the embodiment 41 to manufacture an LED element.

的非掺杂的Al_0.1Ga_0.9N作为下层305a，生长出膜厚为300

的、掺杂了4.5×10¹⁸/cm³的Si的Al_0.1Ga_0.9N作为中间层305b，生长出膜厚为50

的非掺杂的Al_0.1Ga_0.9N构成上层305c。如上述那样所获得的LED元件具有与实施例41大致同等的特性，可以取得良好的结果。That is, the grown film thickness is 3000

undoped Al _0.1 Ga _0.9 N as the lower layer 305a, grown with a film thickness of 300

Al _0.1 Ga _0.9 N doped with Si at 4.5×10 ¹⁸ /cm ³ is used as the intermediate layer 305b, grown with a film thickness of 50

Undoped Al _0.1 Ga _0.9 N constitutes the upper layer 305c. The LED element obtained as described above had almost the same characteristics as Example 41, and good results were obtained.

Comparative example 1

In this comparative example, except that the lower layer 305a made of undoped GaN constituting the n-side first multilayer film layer 305 was not formed, the LED element was manufactured in the same manner as in Example 34.

Compared with Example 34, the obtained LED element had significantly lower static voltage resistance characteristics, and the leakage current and Vf characteristics were not sufficiently satisfactory values.

Comparative example 2

In this comparative example, except that the intermediate layer 305b made of Si-doped GaN constituting the n-side first multilayer film layer 305 was not formed, an LED element was produced in the same manner as in Example 34.

Compared with Example 34, the obtained LED element had remarkably lower luminous output and static voltage resistance characteristics, and other characteristics were not sufficiently satisfactory values.

Comparative example 3

In this comparative example, except that the upper layer 305c made of undoped GaN constituting the n-side first multilayer film layer 305 was not formed, an LED element was produced in the same manner as in Example 34.

Compared with Example 34, the obtained LED element had an increased leakage current, and other characteristics were not sufficiently satisfactory.

Example 43

Example 43 is an example related to Embodiment 6 of the present invention.

(Substrate 1)

A substrate 1 made of sapphire (side C) was placed in a MOVPE reaction vessel, and the temperature of the substrate 1 was raised to 1050° C. to clean the substrate while flowing hydrogen gas.

(buffer layer 2)

的、由GaN形成的缓冲层2。另外，根据基板的种类和生长方法等，还可以省略掉该在低温下生长起来的第一缓冲层2。Next, lower the temperature to 510°C, use hydrogen as the carrier gas, and use ammonia and TMG (trimethylgallium) as the raw material gases to grow a film with a thickness of about 200 on the substrate 1.

buffer layer 2 formed of GaN. In addition, according to the type of the substrate and the growth method, etc., the first buffer layer 2 grown at low temperature may also be omitted.

(undoped GaN layer 3)

After growing into the buffer layer 2, only the supply of TMG was stopped, and the temperature was raised to 1050°C. After reaching 1050° C., a non-doped GaN layer 3 with a film thickness of 1 μm is grown by using ammonia gas and TMG as raw material gases.

(n-type contact layer 4)

Next, at 1050°C, using ammonia and TMG as raw material gases and silane gas as impurity gas, a 3 μm thick n-type contact formed of GaN doped with 3×10 ¹⁹ /cm ³ Si was grown. layer.

(undoped GaN layer 5)

的非掺杂的GaN层5。Then, only the supply of silane gas was stopped, and at 1050°C, a film with a thickness of 100 was grown in the same way.

undoped GaN layer 5 .

(n-type multilayer film layer 6)

的第二氮化物半导体膜；然后，提高温度，在其上生长出膜厚为25的、由非掺杂的GaN构成的第一氮化物半导体膜。然后重复以上的操作，生长成膜厚为500

的、由超晶格结构构成的n型多层膜，所述超晶格结构是按照第二+第一的顺序交替地各层叠10层而成的。Next, lower the temperature to 800°C, and use TMG, TMI, and ammonia to grow a non-doped In _0.03 Ga _0.97 N layer with a thickness of 25

The second nitride semiconductor film; then, increase the temperature, grow a film thickness of 25 A first nitride semiconductor film made of undoped GaN. Then repeat the above operations to grow a film with a thickness of 500

An n-type multilayer film composed of a superlattice structure, the superlattice structure is formed by stacking 10 layers alternately in the order of second + first.

(active layer 7)

的、由非掺杂的In_0.4Ga_0.6N构成的阱层。然后，按照势垒层+阱层+势垒层+阱层......+势垒层这样的顺序，将5层势垒层和4层阱层交替地层叠起来，就生长出总厚度为1120

的、由多量子阱结构构成的有源层7。Next, a film thickness of 200 A barrier layer made of non-doped GaN; then, continue to keep the temperature at 800 ° C, use TMG, TMI, ammonia, and grow a film thickness of 30

A well layer composed of non-doped In _0.4 Ga _0.6 N. Then, in the order of barrier layer+well layer+barrier layer+well layer...+barrier layer, 5 barrier layers and 4 well layers are stacked alternately to grow the total Thickness is 1120

The active layer 7 is composed of multiple quantum well structures.

(p-type multilayer film layer 8)

的、由掺杂了5×10¹⁹/cm³的Mg的p型Al_0.1Ga_0.9N构成的第三氮化物半导体膜。接着，停止Cp2Mg、TMA，生长出膜厚为25

的、由非掺杂的GaN构成的第四氮化物半导体膜。然后，重复以上的操作，以第三+第四氮化物半导体膜的顺序交替地层叠各4层，最后生长出膜厚为20

的、由超晶格结构构成的p型多层膜层8。Then, using TMG, TMA, ammonia, Cp2Mg (dimagnesium), a film thickness of 25

A third nitride semiconductor film made of p-type Al _0.1 Ga _0.9 N doped with 5×10 ¹⁹ /cm ³ Mg. Next, stop Cp2Mg and TMA, and grow a film with a thickness of 25

A fourth nitride semiconductor film made of undoped GaN. Then, repeat the above operation, stack each 4 layers alternately in the order of the third + fourth nitride semiconductor films, and finally grow a film with a thickness of 20

A p-type multilayer film layer 8 composed of a superlattice structure.

(p-type contact layer 9)

的、由掺杂了1×10²⁰/cm³的Mg的p型GaN构成的p型接触层8。Next, at 1050°C, using TMG, ammonia, and Cp2Mg, a film thickness of 700

p-type contact layer 8 made of p-type GaN doped with 1×10 ²⁰ /cm ³ Mg.

After the reaction, the temperature was lowered to room temperature, and then the wafer was placed in the reaction container in a nitrogen atmosphere, and annealed at 700°C to further reduce the resistance of the p-type film layer.

After the annealing, the wafer is taken out from the reaction vessel, and a mask of a predetermined shape is formed on the surface of the p-type contact layer 9 positioned on the uppermost layer, and an RIE (reactive ion etching) device is used to etch the p-type contact layer. , as shown in FIG. 1, the surface of the n-type contact layer 4 is exposed.

的、含有Ni和Au的透光性p电极10，然后在该p电极10上形成膜厚为0.5μm的、由键合用的Au构成的p焊盘电极11。另一方面，在由蚀刻而暴露出来的n型接触层4的表面上形成含有W和Al的n电极12，从而成为LED元件。After etching, a film thickness of 200 is formed on almost the entire surface of the uppermost p-type contact layer

A translucent p-electrode 10 containing Ni and Au was formed, and a p-pad electrode 11 made of Au for bonding was formed on the p-electrode 10 with a film thickness of 0.5 μm. On the other hand, an n-electrode 12 containing W and Al is formed on the surface of the n-type contact layer 4 exposed by etching to form an LED element.

The LED element can display 520nm pure green light at a forward voltage of 20mA, and its Vf is 3.5V. Compared with the previous multi-quantum well structure LED element, the Vf is reduced by nearly 0.5V, and the luminous output power is doubled. above. Therefore, it is possible to obtain an LED having substantially the same characteristics as a conventional LED element at 10 mA. Furthermore, the static voltage withstand characteristic of the obtained device was improved by about 1.2 times or more compared with the conventional device.

In addition, the composition of the conventional LED element is formed by sequentially laminating the following film layers on the first buffer layer made of GaN: the second buffer layer made of undoped GaN, the second buffer layer made of Si-doped GaN The n-side contact layer, the active layer formed by the same multi-quantum well structure as in Example 1, the single-layer Mg-doped Al _0.1 Ga _0.9 N layer, the p-type contact formed by Mg-doped GaN layer.

Example 44

In this embodiment, except that when growing the n-type multilayer film 6, only the first nitride semiconductor film is grown as GaN doped with 1×10 ¹⁸ /cm ³ Si, the others are the same as those in the embodiment. 43 are the same and made into LED elements. The obtained device had almost the same good device characteristics as Example 43.

Example 45

In this embodiment, except that when growing the n-type multilayer film layer 6, the second nitride semiconductor film is made into an In _0.03 Ga _0.97 N layer doped with 1×10 ¹⁸ /cm ³ Si, and the first An LED element was manufactured in the same manner as in Example 43 except that the nitride semiconductor film was a GaN layer doped with 5×10 ¹⁸ /cm ³ Si. The obtained LED element exhibited excellent characteristics with a Vf of 3.4V at 20mA and an output power more than 1.5 times higher than that of conventional elements. In addition, the electrostatic resistance characteristics were also good as in Example 43.

Example 46

In this embodiment, except that the fourth nitride semiconductor film is grown as p-type GaN doped with Mg at 1×10 ¹⁹ /cm ³ when growing the p-type multilayer film layer 8 , everything else is the same as in the implementation. An LED element was manufactured in the same manner as in Example 43, and thus an LED element having substantially the same characteristics as in Example 43 could be obtained.

Example 47

的由非掺杂的Al_0.1Ga_0.9N构成的第三氮化物半导体膜，和膜厚为25

的由非掺杂的GaN构成的第四氮化物半导体膜交替地各层叠两层从而使总膜厚为100

之外，其他都与实施例43相同而制作成LED元件，这样，就能够获得具有与实施例43大致同等的特性的LED元件。In this embodiment, except that when growing the p-type multilayer film layer 8, the film thickness is set to 25

The third nitride semiconductor film made of non-doped Al _0.1 Ga _0.9 N, and the film thickness is 25

The fourth nitride semiconductor film made of undoped GaN is alternately laminated in two layers so that the total film thickness is 100

Other than that, an LED element was produced in the same manner as in Example 43, so that an LED element having substantially the same characteristics as in Example 43 could be obtained.

Example 48

In this embodiment, except that the non-doped GaN layer 5 is replaced by forming multi-layer film layers, and the following changes are made to the following layers, the LED element is manufactured in the same manner as in Embodiment 43.

(n-side contact layer 4)

Next, at 1050°C, ammonia and TMG are also used as raw material gases, and silane gas is used as impurity gas to grow a 2.25 μm thick n-type GaN doped with 6×10 ¹⁸ /cm ³ Si. contact layer 4.

(Multilayer film layer)

的、由非掺杂GaN构成的下层305a；然后，在同样的温度下，再添加硅烷气体，生长出膜厚为300

的、由掺杂了6×10¹⁸/cm³的Si的GaN构成的中间层305b；然后，只停止供应硅烷气体，在同样的温度下生长出膜厚为50的、由非掺杂GaN构成的上层305c；于是，就生长出由三层组成的、总膜厚为2350的多层膜层。Next, only the supply of silane gas was stopped, and a film thickness of 2000

The lower layer 305a made of non-doped GaN; then, at the same temperature, add silane gas to grow a film with a thickness of 300

The intermediate layer 305b made of GaN doped with 6×10 ¹⁸ /cm ³ Si; then, only the supply of silane gas was stopped, and a film thickness of 50 An upper layer 305c made of non-doped GaN; thus, a three-layered upper layer 305c with a total film thickness of 2350 multilayer film.

(n-type multilayer film layer 6)

的、由非掺杂的In_0.02Ga_0.98N构成的第二氮化物半导体膜。然后，重复以上的操作，按照第一+第二的顺序，交替地层叠各10层，最后生长出膜厚40

的由GaN构成的第一氮化物半导体膜，从而成长为由超晶格结构的多层膜构成的、膜厚为640

的n型多层膜层6。Then, at the same temperature, a film thickness of 40 The first nitride semiconductor film made of non-doped GaN; then, the temperature was lowered to 800°C, and TMG, TMI, and ammonia were used to grow a film with a thickness of 20

A second nitride semiconductor film made of undoped In _0.02 Ga _0.98 N. Then, repeat the above operations, alternately stack 10 layers in the order of first + second, and finally grow a film with a thickness of 40

The first nitride semiconductor film composed of GaN is grown into a multilayer film composed of a superlattice structure with a film thickness of 640

The n-type multilayer film layer 6.

(p-type multilayer film 8)

的、由掺杂了5×10¹⁹/cm³的Mg的p型Al_0.2Ga_0.8N构成的第三氮化物半导体膜；接着，使温度下降到800℃，使用TMG、TMA、氨、Cp2Mg，生长出膜厚为25

的、由掺杂了5×10¹⁹/cm³的Mg的In_0.02Ga_0.98N构成的第四氮化物半导体膜。然后，重复以上的操作，按照第三+第四的顺序，交替地各层叠5层，最后生长出膜厚为40

的第三氮化物半导体膜，从而成长为膜厚365

的、由超晶格结构的多层膜所组成的p型多层膜层8。Then, at 1050°C, using TMG, TMA, ammonia, Cp2Mg (dimagnesium), a film thickness of 40

A third nitride semiconductor film composed of p-type Al _0.2 Ga _0.8 N doped with 5×10 ¹⁹ /cm ³ Mg; then, the temperature was lowered to 800°C, and TMG, TMA, ammonia, Cp2Mg was used, A film thickness of 25

A fourth nitride semiconductor film composed of In _0.02 Ga _0.98 N doped with 5×10 ¹⁹ /cm ³ Mg. Then, repeat the above operations, alternately stack 5 layers in the order of the third + fourth, and finally grow a film with a thickness of 40

The third nitride semiconductor film, thus grown to a film thickness of 365

A p-type multilayer film layer 8 composed of a multilayer film with a superlattice structure.

The obtained LED element showed excellent luminous output power and Vf approximately equal to those of Example 43. Furthermore, the obtained LED element was measured by gradually increasing the voltage from the n-layer and p-layer electrodes of the LED element in the opposite direction. At this time, the following effects can be obtained: compared with the conventional element used as a comparison of embodiment 43, the result is more than 1.5 times higher than the conventional element, and its electrostatic resistance characteristic is better than that of embodiment 43 .

In the above-mentioned embodiments, although the nitride semiconductor light-emitting element which is an LED element was used as an explanation, the present invention is not limited to the LED element, and can be applied to other light-emitting elements such as laser diode elements.

In addition, the present invention is not limited to light-emitting elements, but can also be applied to photosensitive elements such as solar cells and photosensors constructed using nitride semiconductors, or electronic devices such as triodes and power devices.

industrial availability

As described above, according to the present invention, in a nitride semiconductor, especially a nitride semiconductor light-emitting element, an output power equal to or higher than that of a conventional LED element can be obtained at a very low current, and the luminous output can be further improved. power.

In addition, according to the present invention, the antistatic voltage characteristic can be improved, a highly reliable nitride semiconductor device can be provided, and the applicable range of applicable products can be expanded.

In addition, the present invention is not limited to light-emitting elements, but can also be applied to various electronic devices using nitride semiconductors, such as photosensitive elements and solar cells.

Claims (28)

1. nitride semiconductor device, it is the nitride semiconductor device that has active layer between n side nitride semiconductor layer and p side nitride semiconductor layer, it is characterized in that:

Above-mentioned active layer is to have In _aGa _1-aN, the multi-quantum pit structure of 0≤a＜1 layer;

Said n side nitride semiconductor layer comprises:

N side second stratified film, its by first nitride semiconductor film that contains In with have different second nitride semiconductor films of forming and be laminated with this first nitride semiconductor film, the thickness of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film is

Or below,

N side first stratified film, it is 1 * 10 by n type impurity ¹⁷/ cm ³～1 * 10 ²¹/ cm ³The nitride semiconductor film of scope and at least two kinds of nitride semiconductor films that have with the nitride semiconductor film of this nitride semiconductor film same composition and or non-doping lower than this nitride semiconductor film impurity concentration be laminated,

The n side contact layer that contains n type impurity;

Have said n side contact layer, said n side first stratified film, said n side second stratified film, above-mentioned active layer in order.

2. nitride semiconductor device as claimed in claim 1 is characterized in that, 2 kinds of nitride semiconductor films of said n side first stratified film all are the GaN layers.

3. nitride semiconductor device as claimed in claim 1 is characterized in that, above-mentioned first nitride semiconductor film is by In _xGa _1-xN, 0＜x＜1 is formed, and above-mentioned second nitride semiconductor film is by In _yGa _1-yN, 0≤y＜1, y＜x form.

4. nitride semiconductor device as claimed in claim 3, it is characterized in that, the thickness of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film is between the first adjoining nitride semiconductor film or different between the second adjoining nitride semiconductor film.

5. nitride semiconductor device as claimed in claim 3 is characterized in that, above-mentioned first nitride semiconductor film and second nitride semiconductor film all are non-doping.

6. nitride semiconductor device as claimed in claim 3 is characterized in that, said n side second multilayer film is the multilayer film of modulation doping, is doped with n type impurity among any one party of above-mentioned first nitride semiconductor film or second nitride semiconductor film.

7. nitride semiconductor device as claimed in claim 1, it is characterized in that, said n side first stratified film has three-decker: the lower floor that is made of the nitride-based semiconductor of non-doping, the intermediate layer that constitutes by the nitride-based semiconductor of the n type impurity that mixed, and the upper strata that constitutes by the nitride-based semiconductor of non-doping.

8. nitride semiconductor device as claimed in claim 7 is characterized in that, above-mentioned three-decker comprises: by thickness be

The lower floor that constitutes of the nitride-based semiconductor of non-doping, by thickness be

Doping the intermediate layer that constitutes of the nitride-based semiconductor of n type impurity, and be by thickness

The upper strata that constitutes of the nitride-based semiconductor of non-doping.

9. nitride semiconductor device as claimed in claim 3, it is characterized in that, above-mentioned p side nitride semiconductor layer contains p side multilayer film coating layer, and described p side multilayer film coating layer and concentration p type impurity similar and different third and fourth nitride semiconductor layer different by band-gap energy is laminated.

10. nitride semiconductor device as claimed in claim 9, wherein, above-mentioned p side multilayer film coating layer has superlattice structure, and above-mentioned the 3rd nitride semiconductor layer is by Al _nGa _1-nN, 0＜n≤1 constitutes, and above-mentioned tetrazotization thing semiconductor layer is by Al _pGa _1-pN, 0≤p＜1, p＜n or In _rGa _1-rN, 0≤r≤1 constitutes.

11. nitride semiconductor device as claimed in claim 9, wherein, said n side nitride semiconductor layer has, by the Ga of 200～900 ℃ low-temperature epitaxies _dAl _1-dN, 0＜d≤1 resilient coating that is constituted, Jie is by the GaN layer of the non-doping of this resilient coating setting, the said n side contact layer is formed on the GaN layer of above-mentioned non-doping, and, on above-mentioned p side multilayer film coating layer, formed the p side GaN contact layer that contains Mg as p type impurity.

12. nitride semiconductor device as claimed in claim 3, wherein, above-mentioned p side nitride semiconductor layer comprises, by the Al that contains p type impurity _bGa _1-bN, the p side monofilm coating layer that 0≤b≤1 constitutes.

13. nitride semiconductor device as claimed in claim 12, above-mentioned p side nitride semiconductor layer has, p side monofilm coating layer and contain the p side GaN contact layer of Mg on above-mentioned p side monofilm coating layer as p type impurity.

14. nitride semiconductor device as claimed in claim 3 is characterized in that, said n side second stratified film and active layer join and form.

15. a nitride semiconductor device, it is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is n side first stratified film with three-decker: by the lower floor that the nitride semiconductor film of non-doping constitutes, n type impurity is 3 * 10 by having mixed ¹⁸/ cm ³～5 * 10 ²¹/ cm ³The intermediate layer that constitutes of the nitride semiconductor film of scope, and the upper strata that constitutes by the nitride semiconductor film of non-doping; And

Between said n side first stratified film and active layer, have by first nitride semiconductor film that contains In with have n side second stratified film that different second nitride semiconductor films of forming with this first nitride semiconductor film are laminated;

At least one deck nitride semiconductor layer in territory, above-mentioned p lateral areas is by p type impurity and the p side multilayer film coating layer that is laminated of the third and fourth different nitride semiconductor film of band-gap energy each other of having mixed respectively;

Above-mentioned active layer is by In _aGa _1-aN, the multi-quantum pit structure that 0≤a＜1 constitutes.

16. nitride semiconductor device as claimed in claim 15, wherein, the concentration of the p type impurity of above-mentioned the 3rd nitride semiconductor film is different with the concentration of the p type impurity of above-mentioned tetrazotization thing semiconductor film, and the concentration of the p type impurity of perhaps above-mentioned the 3rd nitride semiconductor film is identical with the concentration of the p type impurity of above-mentioned tetrazotization thing semiconductor film.

17. nitride semiconductor device as claimed in claim 15 is characterized in that, above-mentioned three-decker comprises: by thickness be

The lower floor that constitutes of the nitride-based semiconductor of non-doping, by thickness be

Doping the intermediate layer that constitutes of the nitride-based semiconductor of n type impurity, and be by thickness

The upper strata that constitutes of the nitride-based semiconductor of non-doping.

18. nitride semiconductor device as claimed in claim 17 is characterized in that, in territory, said n lateral areas, has the n side contact layer that contains n type impurity, is provided with said n side first stratified film between said n side contact layer and said n side second stratified film.

19. nitride semiconductor device as claimed in claim 15 is characterized in that, above-mentioned first nitride semiconductor film is by In _xGa _1-xN, 0＜x＜1 is formed, and above-mentioned second nitride semiconductor film is by In _yGa _1-yN, 0≤y＜1, y＜x form.

20. nitride semiconductor device as claimed in claim 19, it is characterized in that, the thickness of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film is between the first adjoining nitride semiconductor film or different between the second adjoining nitride semiconductor film.

21. nitride semiconductor device as claimed in claim 15 is characterized in that, said n side second stratified film and active layer join and form.

22. nitride semiconductor device as claimed in claim 15 is characterized in that, above-mentioned first nitride semiconductor film and second nitride semiconductor film all are non-doping.

23. nitride semiconductor device as claimed in claim 15, it is characterized in that, among any one party of above-mentioned first nitride semiconductor film or second nitride semiconductor film, be doped with n type impurity, perhaps the both sides at above-mentioned first nitride semiconductor film and second nitride semiconductor film are doped with n type impurity, and the impurity concentration of above-mentioned first nitride semiconductor film is different with the impurity concentration of above-mentioned second nitride semiconductor film.

24. a nitride semiconductor device, it is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is n side first stratified film with three-decker: by the lower floor that the nitride-based semiconductor of non-doping constitutes, n type impurity is 3 * 10 by having mixed ¹⁸/ cm ³～5 * 10 ²¹/ cm ³The intermediate layer that constitutes of the nitride-based semiconductor of scope, and the upper strata that constitutes by the nitride-based semiconductor of non-doping;

At least one deck nitride semiconductor layer in territory, above-mentioned p lateral areas is by the Al that contains p type impurity _bGa _1-bN, the p side monofilm coating layer that 0≤b≤1 constitutes;

Above-mentioned active layer is to contain In _aGa _1-aN, the multi-quantum pit structure that 0≤a＜1 constitutes.

25. nitride semiconductor device as claimed in claim 24 is characterized in that, above-mentioned three-decker comprises: by thickness be

The lower floor that constitutes of the nitride-based semiconductor of non-doping, by thickness be

Doping the intermediate layer that constitutes of the nitride-based semiconductor of n type impurity, and be by thickness The upper strata that constitutes of the nitride-based semiconductor of non-doping.

26. nitride semiconductor device as claimed in claim 25 is characterized in that, in territory, said n lateral areas, has the n side contact layer that contains n type impurity, the said n side contact layer is provided with said n side first stratified film.

27. nitride semiconductor device as claimed in claim 26 is characterized in that, territory, said n lateral areas also has, by the Ga of 200～900 ℃ low-temperature epitaxies _dAl _1-dN, 0＜d≤1 resilient coating that is constituted, Jie is by the GaN layer of the non-doping of this resilient coating setting, and the said n side contact layer is formed on the GaN layer of above-mentioned non-doping, and, on p side monofilm coating layer, formed the p side GaN contact layer that contains Mg as p type impurity.

28. nitride semiconductor device as claimed in claim 24 is characterized in that, has formed the p side GaN contact layer that contains Mg as p type impurity on above-mentioned p side monofilm coating layer.

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