WO2022261895A1 - Nitride semiconductor light-emitting element and manufacturing method therefor - Google Patents

Abstract

The present invention relates to the field of semiconductors, and in particular, to a nitride semiconductor light-emitting element and a manufacturing method therefor. The nitride semiconductor light-emitting element comprises an N-type semiconductor layer; a P-type semiconductor layer; an active layer, the active layer being located between the N-type semiconductor layer and the P-type semiconductor layer; a cover layer, the cover layer being located between the active layer and the P-type semiconductor layer; a hole injection layer, the hole injection layer being located between the cover layer and the P-type semiconductor layer; and an electron blocking layer, the electron blocking layer being located between the hole injection layer and the P-type semiconductor layer, wherein the hole injection layer comprises a first aluminum-containing layer, a second aluminum-containing layer, and a third aluminum-containing layer, and the aluminum content of the second aluminum-containing layer is higher than the aluminum content of the first aluminum-containing layer, and higher than the aluminum content of the third aluminum-containing layer. In the present invention, the second aluminum-containing layer having a high aluminum content is inserted into the hole injection layer, so that electron overflow can be blocked and the polarization electric field of the electron blocking layer can be improved.

Description

Nitride semiconductor light-emitting element and manufacturing method thereof technical field

The invention belongs to the field of semiconductors, in particular to a nitride semiconductor light-emitting element and a manufacturing method thereof.

Background technique

Nitride semiconductor light-emitting elements can convert electrical energy into light energy to achieve light emission. Its basic structure includes an N-type semiconductor layer, an active layer and a P-type semiconductor layer, wherein the electrons provided by the N-type semiconductor layer and the holes provided by the P-type semiconductor layer recombine and emit light in the active layer.

However, because the mobility of electrons is greater than that of holes, some of the electrons migrating to the active layer will overflow into the P-type semiconductor layer, so that electrons and holes will not emit light on the side of the P-type semiconductor layer. compound. Therefore, it is necessary to add a semiconductor layer on one side of the P-type semiconductor layer to prevent electrons from migrating into the P-type semiconductor layer. Therefore, an electron blocking layer with a higher energy level is generally inserted between the active layer and the P-type semiconductor layer to block electron migration.

However, the blocking effect of the electron blocking layer on electrons is still limited, especially as the current density increases, the blocking effect decreases, which affects the recombination efficiency of electrons and holes.

technical solution

According to the first aspect of the present invention, the nitride semiconductor light-emitting element disclosed in the present invention includes: a substrate; an N-type semiconductor layer located above the substrate; a P-type semiconductor layer located above the N-type semiconductor layer; an active layer , the active layer is located between the N-type semiconductor layer and the P-type semiconductor layer; a hole injection layer, the hole injection layer is located between the active layer and the P-type semiconductor layer; an electron blocking layer, The electron blocking layer is located between the hole injection layer and the P-type semiconductor layer; it is characterized in that: the hole injection layer includes a first aluminum-containing layer, a second aluminum-containing layer, and a third aluminum-containing layer, so The aluminum content of the second aluminum-containing layer is higher than the aluminum content of the first aluminum-containing layer, and higher than the aluminum content of the third aluminum-containing layer.

Preferably, the energy level of the second aluminum-containing layer is higher than the energy level of the first aluminum-containing layer and higher than the energy level of the third aluminum-containing layer.

Preferably, the impurity concentration of the hole injection layer is higher than that of the electron blocking layer and higher than that of the P-type semiconductor layer.

Preferably, the hole injection layer includes a first aluminum-containing layer close to the active layer, a third aluminum-containing layer close to the electron blocking layer, and a second aluminum-containing layer between the first aluminum-containing layer and the third aluminum-containing layer. Aluminum layer.

Preferably, the hole injection layer includes a second aluminum-containing layer close to the active layer, a third aluminum-containing layer close to the electron blocking layer, and a first aluminum-containing layer between the second aluminum-containing layer and the third aluminum-containing layer. aluminum layer.

Preferably, the hole injection layer includes a first aluminum-containing layer close to the active layer, a second aluminum-containing layer close to the electron blocking layer, and a third aluminum-containing layer between the first aluminum-containing layer and the second aluminum-containing layer. aluminum layer.

Preferably, the thickness of the second aluminum-containing layer is smaller than the thickness of the first aluminum-containing layer and smaller than the thickness of the third aluminum-containing layer.

Preferably, the thickness of the second aluminum-containing layer is less than 20 angstroms.

Preferably, the thickness of the first aluminum-containing layer is less than, greater than or equal to the thickness of the third aluminum-containing layer.

Preferably, the thickness of the first aluminum-containing layer is less than 150 angstroms.

Preferably, the thickness of the third aluminum-containing layer is less than 150 angstroms.

Preferably, the electron blocking layer is an aluminum-containing layer, and the aluminum content of the second aluminum-containing layer is lower than or equal to that of the electron blocking layer.

Preferably, the first aluminum-containing layer is a compound with a molecular formula of Alx1Iny1Ga1-x1-y1N, wherein 0<x1<1, 0≤y1<1.

Preferably, the second aluminum-containing layer is a compound with a molecular formula of Alx2Iny2Ga1-x2-y2N, wherein 0<x2<1, 0≤y2<1.

Preferably, the third aluminum-containing layer is a compound with a molecular formula of Alx3Iny3Ga1-x3-y3N, wherein 0<x3<1, 0≤y3<1.

Preferably, the electron barrier is a compound with a molecular formula of Alx4Iny4Ga1-x4-y4N, wherein 0<x4<1, 0≤y4<1.

Preferably, the light-emitting element further includes a capping layer, and the capping layer is located between the active layer and the hole injection layer.

Preferably, the capping layer is an aluminum-containing layer, and the aluminum content of the second aluminum-containing layer is higher than or equal to that of the capping layer.

Preferably, the capping layer is undoped or n-doped or p-doped.

Preferably, the impurity concentration of the capping layer is lower than that of the hole injection layer.

Preferably, the capping layer is a compound with a molecular formula of Alx5Iny5Ga1-x5-y5N, wherein 0<x5<1, 0≤y5<1.

Preferably, the impurity concentration of the hole injection layer is between 1E19cm ⁻³ and 2E20cm ⁻³ .

Preferably, a buffer layer is also included, and the buffer layer is located between the substrate and the N-type semiconductor layer.

Preferably, the buffer layer is selected from one or a combination of aluminum nitride, gallium nitride, aluminum gallium nitride, aluminum indium gallium nitride, indium nitride, and indium gallium nitride.

Preferably, a P-type contact layer located on the P-type semiconductor layer is further included, and the impurity concentration of the hole injection layer is lower than that of the P-type contact layer.

According to the second aspect of the present invention, a method for manufacturing a nitride semiconductor light-emitting element is disclosed, comprising the following steps: growing an N-type semiconductor layer on a substrate; growing an active layer on the N-type semiconductor layer; growing an active layer on the active layer growing a hole injection layer on the hole injection layer; growing an electron blocking layer on the hole injection layer; growing a P-type semiconductor layer on the electron blocking layer; it is characterized in that the hole injection layer includes a first aluminum-containing layer, a second An aluminum-containing layer and a third aluminum-containing layer, the aluminum content of the second aluminum-containing layer is higher than the aluminum content of the first aluminum-containing layer, and higher than the aluminum content of the second aluminum-containing layer.

Preferably, the growth temperature of the hole injection layer is lower than the growth temperature of the electron blocking layer and the P-type semiconductor layer.

According to the third aspect of the present invention, a method for manufacturing a nitride semiconductor light-emitting element is disclosed, comprising the following steps: growing an N-type semiconductor layer on a substrate; growing an active layer on the N-type semiconductor layer; growing an active layer on the active layer growing a capping layer; growing a hole injection layer on the capping layer; growing an electron blocking layer on the hole injection layer; growing a P-type semiconductor layer on the electron blocking layer; characterized in that the hole injection The layer includes a first aluminum-containing layer, a second aluminum-containing layer, and a third aluminum-containing layer, the aluminum content of the second aluminum-containing layer being higher than the aluminum content of the first aluminum-containing layer, and higher than the aluminum content of the second aluminum-containing layer Aluminum content.

Preferably, the growth temperature of the hole injection layer is higher than the growth temperature of the cap layer and lower than the growth temperature of the electron blocking layer and the P-type semiconductor layer.

Beneficial effect

Inserting the second aluminum-containing layer with higher aluminum content into the hole injection layer of the present invention can play an electron blocking effect, improve the polarization electric field of the electron blocking layer, finally improve luminous brightness, reduce voltage, and improve ESD antistatic ability.

Description of drawings

FIG. 1 is a schematic cross-sectional structure diagram of a nitride semiconductor light emitting device according to one embodiment of the present invention.

FIG. 1 a is a schematic cross-sectional structure diagram of an active layer according to one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional structure diagram of a hole injection layer according to one embodiment of the present invention.

FIG. 3 is a schematic cross-sectional structure diagram of a hole injection layer according to one embodiment of the present invention.

FIG. 4 is a schematic cross-sectional structure diagram of a hole injection layer according to one embodiment of the present invention.

FIG. 5 is a schematic cross-sectional structure diagram of a nitride semiconductor light emitting element according to another embodiment of the present invention.

Embodiments of the present invention

The following embodiments will illustrate the concepts of the present invention along with the drawings. In the drawings or descriptions, similar or identical parts use the same symbols, and in the drawings, the shape or thickness of elements can be enlarged or reduced. It should be noted that elements not shown in the figure or not described in the specification may be in forms known to those skilled in the art.

In the following embodiments, terms used to indicate directions, such as "upper", "lower", "front", "rear", "left", and "right", refer only to directions in the drawings. Accordingly, the directional terms are used to illustrate, not to limit, the invention.

The composition of each layer contained in the semiconductor device of the present invention and the dopant can be analyzed by any suitable means, such as secondary ion mass spectrometer (secondary ion mass spectrometer) mass spectrometer, SIMS).

The thickness of each layer included in the semiconductor element of the present invention can be analyzed by any suitable means, such as transmission electron microscope (transmission electron microscopy, TEM) or transmission electron microscope (scanning electron microscope, SEM), used to match, for example, the depth position of each layer on the SIMS map.

The nitride semiconductor light emitting device of the present invention includes a light emitting diode.

FIG. 1 is a schematic cross-sectional structure diagram of a nitride semiconductor light emitting device according to one embodiment of the present invention.

In this embodiment, the semiconductor light emitting element comprises a substrate 10, an N-type semiconductor layer 20, an active layer 30, a P-type semiconductor layer 40, and a hole injection layer 50 and An electron blocking layer 60 is provided between the hole injection layer 50 and the P-type semiconductor layer 40 .

The substrate 10 has a thickness enough to support the layers and structures on it. The substrate 10 can be made of conductive material or insulating material, and its manufacturing material can be selected from Al ₂ O ₃ single crystal, SiC, Si, GaAs, Any of GaN and a single crystal oxide whose lattice constant is close to that of a nitride semiconductor. In order to improve the light extraction efficiency of the substrate 10, it can also be patterned to form a series of concave-convex structures on its surface.

In another embodiment, a buffer layer 11 may be pre-grown between the substrate 10 and the N-type semiconductor layer 20 to reduce the lattice mismatch between the substrate 10 and the N-type semiconductor layer 20, so that the buffer layer 11 The lattice constant is between the substrate 10 and the N-type semiconductor layer 20, and can be made of materials including AlpInqGa1-p-qN, where 0≤p≤1, 0≤q≤1, specifically AlN layer, GaN layer layer, AlGaN layer, AlInGaN layer, InN layer and InGaN layer. The buffer layer 11 may be formed by MOCVD or PVD.

The N-type semiconductor layer 20, the present invention defines that the semiconductor layers between the buffer layer 11 and the active layer 30 are all N-type semiconductor layers 20, the purpose of which is to provide electrons. N-type impurities are doped into the N-type semiconductor layer 20 to provide electrons. The n-type impurities are such as Si, but not limited to Si. Some material layers in the N-type semiconductor layer 20 may also be substantially undoped material layers, but the N-type semiconductor layer 20 shows N-type doping as a whole, and Si signals can be clearly identified on the SIMS detection spectrum.

In another embodiment, a stress release layer 21 can be grown between the N-type semiconductor layer 20 and the active layer 30 to release the stress generated during the growth of the N-type semiconductor layer 20, and the size of the V-shaped pit can also be adjusted. Increase luminous brightness. The stress release layer 21 may be a superlattice structure, such as a superlattice structure formed by alternate lamination of InGaN and GaN, or may be a single layer structure.

FIG. 1 a is a schematic cross-sectional structure diagram of an active layer according to one embodiment of the present invention.

The active layer 30 has a well layer 31 and a barrier layer 32 . The energy level of the barrier layer 32 is higher than that of the well layer 31 , so that electrons and holes recombine and emit light in the well layer 31 . The active layer 30 closest to the N-type semiconductor layer 20 may be the well layer 31 or the barrier layer 32 , and the active layer 30 closest to the P-type semiconductor layer 40 may be the barrier layer 32 or the well layer 31 . The barrier layer 32 may be an aluminum-containing or aluminum-free nitride layer such that its energy level is higher than that of the well layer. The well layer 31 is usually a nitride layer containing indium, and its energy level is lower than that of the barrier layer. The barrier layer 32 may be an n-type doped layer or a non-doped layer substantially free of any impurities. In this embodiment, all the barrier layers 32 have approximately the same thickness; all the well layers 31 have approximately the same thickness. The last barrier layer 32 can be an undoped layer, can be a single layer structure or a multilayer structure, for example can be an undoped AlN layer, an undoped AlGaN layer, an undoped AlInGaN layer, an undoped GaN/undoped AlGaN multilayer structure, undoped InGaN/undoped AlInGaN/undoped AlGaN multilayer structure, or undoped GaN/AlN multilayer structure.

In another embodiment, the barrier layer 32 and the hole injection layer 50 also have a cover layer 321, the cover layer 321 is an aluminum-containing layer, and its energy level is higher than that of the barrier layer 32, which can block the N-type semiconductor layer Electrons 20 entering the active layer 30 without combining with holes flow out. The capping layer 321 is a compound with a molecular formula of Alx5Iny5Ga1-x5-y5N, wherein 0<x5<1, 0≤y5<1. The aluminum content of the cap layer 321 is relatively high. If the growth thickness is thicker, although the electron blocking effect is better, the growth quality of the cap layer 321 will be deteriorated, thereby affecting the growth quality of the subsequent hole injection layer 50, so its growth The thickness is relatively thin, less than 50 Angstroms. More preferably, the thickness of the capping layer 321 is between 5-20 Å, because when the thickness of the capping layer 321 is less than 5 Å, its electron blocking effect is weak. The capping layer 321 with high aluminum content is preferably an AlN layer. In one embodiment, the capping layer 321 is substantially an undoped layer without impurities, which can block electrons overflowing from the active layer 30 to a certain extent.

The hole injection layer 50 is a doped layer, the impurity concentration of the hole injection layer 50 is greater than the impurity concentration of the cover layer 321, and greater than the impurity concentration of the electron blocking layer 60 and greater than the impurity concentration of the P-type semiconductor layer 40, which can be an active Layer 30 provides a higher concentration of holes, improving hole injection efficiency. Since the purpose of the hole injection layer 50 is to improve hole injection efficiency, the hole injection layer 50 is a p-type impurity doped layer, and its p-type impurity concentration is between 1E19cm ⁻³ and 2E20cm ⁻³ . The p-type impurity may be, for example, magnesium, but not limited thereto. Other semiconductor layers may also be inserted between the hole injection layer 50 and the capping layer 321 , which is not limited in the present invention.

Referring to Figures 2, 3, and 4, the present invention incorporates a high-energy material layer into the hole injection layer 50, so that the hole injection layer 50 further blocks electrons overflowing from the capping layer 321. The hole injection layer 50 includes a first aluminum-containing layer 51, a second aluminum-containing layer 52, and a third aluminum-containing layer 53, wherein the aluminum content of the second aluminum-containing layer 52 is higher than that of the first aluminum-containing layer 51, and The aluminum content is higher than that of the third aluminum-containing layer 53 . The energy level of the second aluminum-containing layer 52 is higher than that of the first aluminum-containing layer 51 and higher than that of the third aluminum-containing layer 53 . The second aluminum-containing layer 52 with high aluminum content has a higher energy level, which can prevent electron overflow and reduce the polarization electric field generated by the subsequent electron blocking layer, and finally improve the luminous brightness, reduce the voltage, and improve the ESD antistatic ability. Moreover, the thickness of the second aluminum-containing layer 52 is relatively thin, and the light absorption of the semiconductor layer is almost negligible, which will not affect the luminous intensity.

The first aluminum-containing layer 51 is a compound with a molecular formula of Alx1Iny1Ga1-x1-y1N, wherein 0<x1<1, 0≤y1<1. The second aluminum-containing layer 52 is a compound with a molecular formula of Alx2Iny2Ga1-x2-y2N, wherein 0<x2<1, 0≤y2<1. The third aluminum-containing layer 53 is a compound with a molecular formula of Alx3Iny3Ga1-x3-y3N, wherein 0<x3<1, 0≤y3<1. In one embodiment, preferably, the first aluminum-containing layer 51 is AlGaN, the second aluminum-containing layer 52 is AlGaN or AlN, and the third aluminum-containing layer 53 is AlGaN.

The thickness of the second aluminum-containing layer 52 is smaller than the thickness of the first aluminum-containing layer 51 and smaller than the thickness of the third aluminum-containing layer 53 . Specifically, the thickness of the second aluminum-containing layer 52 is less than 20 angstroms, the thickness of the first aluminum-containing layer 51 is less than 150 angstroms, and the thickness of the third aluminum-containing layer 53 is also less than 150 angstroms. The relationship between the thickness of the first aluminum-containing layer 51 and the thickness of the third aluminum-containing layer 53 is not particularly limited, that is, the thickness of the first aluminum-containing layer 51 may be greater than, equal to, or smaller than the thickness of the third aluminum-containing layer 53 .

The specific position of the second aluminum-containing layer 52 with high aluminum content in the hole injection layer 50 is not particularly limited in the present invention, and it can be on the side close to the cap layer 321, or on the side close to the electron blocking layer 60, or on the side close to the electron blocking layer 60. The middle position of the hole injection layer 50 . No matter where the second aluminum-containing layer 52 with high aluminum content is located in the hole injection layer 50 , it has the effect of blocking electron overflow.

For example, referring to accompanying drawing 2, in one of the embodiments, the hole injection layer 50 comprises a first aluminum-containing layer 51 close to the capping layer, a third aluminum-containing layer 53 close to the electron blocking layer 60, and a The second aluminum-containing layer 52 between the layer 51 and the third aluminum-containing layer 53 . The aluminum content of the second aluminum-containing layer 52 is higher than that of the capping layer 321 , and lower than that of the electron blocking layer 60 .

3, in another embodiment, the hole injection layer 50 includes a second aluminum-containing layer 52 close to the capping layer 321, a third aluminum-containing layer 53 close to the electron blocking layer 60, and a and the first aluminum-containing layer 51 between the third aluminum-containing layer 53 . The aluminum content of the second aluminum-containing layer 52 is higher than or equal to that of the capping layer 321 , and lower than or equal to that of the electron blocking layer 60 .

4, in another embodiment, the hole injection layer 50 includes a first aluminum-containing layer 51 close to the capping layer 321, a second aluminum-containing layer 52 close to the electron blocking layer 60, and a layer located on the first aluminum-containing layer 51. and the third aluminum-containing layer 53 between the second aluminum-containing layer 52 . The aluminum content of the second aluminum-containing layer 52 is higher than or equal to that of the capping layer 321 , and lower than or equal to that of the electron blocking layer 60 .

Continuing to refer to FIG. 1 , the electron blocking layer 60 may be an undoped layer substantially free of impurities, or a doped layer containing impurities, for example doped with p-type impurities. Here, the non-doped layer refers to a layer formed without doping p-type or n-type impurities when the layer is grown (for example, in the case of growing the layer by organic metal vapor phase growth method, stop the source gas of the impurity and perform growing layer). Other semiconductor layers may also be inserted between the hole injection layer 50 and the electron blocking layer 60, which is not limited in the present invention. The electron blocking layer 60 can block the electrons flowing from the n-type semiconductor layer 20 into the active layer 30 without combining with holes in the well layer 31 , reducing the non-radiative recombination of electrons and holes. The electron blocking layer 60 is a compound layer containing aluminum, and can be a single-layer structure or a multi-layer structure. The aluminum content of the electron blocking layer 60 is higher than or equal to that of the second aluminum-containing layer, and higher than that of the capping layer, which has better electron blocking effect. The electron barrier is a compound with the molecular formula Alx4Iny4Ga1-x4-y4N, where 0<x4<1, 0≤y4<1.

For the P-type semiconductor layer 40 , the present invention defines the semiconductor layer above the electron blocking layer 60 as a P-type semiconductor layer for the purpose of providing holes. P-type impurities are doped into the P-type semiconductor layer 40 to provide holes. The p-type impurities are such as Mg, but not limited to Mg.

In another embodiment, there is a P-type contact layer 70 above the P-type semiconductor layer 40. The P-type contact layer 70 is located on the uppermost layer of the semiconductor light-emitting element and has a higher P-type impurity concentration, which is greater than that of hole injection. The impurity concentration of layer 50 makes it have a lower contact resistance and can act as an ohmic contact layer.

The present invention is aimed at the conventional light-emitting diode whose hole injection layer 50 is P-type AlGaN and the light-emitting diode whose hole injection layer 50 includes the first aluminum-containing layer 51/second aluminum-containing layer 52/third aluminum-containing layer 53 in the present invention. A comparative experiment was conducted on the tube structure, and the brightness of the present invention is increased by 0.3-0.5%, the voltage is decreased by 0.1-0.2%, and the antistatic ability is increased by 2-3%.

In another embodiment of the present invention, a method for manufacturing the above-mentioned semiconductor light-emitting element is disclosed, including growing an N-type semiconductor layer 20 on a substrate 10; growing an active layer 30 on the N-type semiconductor layer 20; growing an active layer 30 on the active A hole injection layer 50 is grown on the layer 30; an electron blocking layer 60 is grown on the hole injection layer 50; a P-type semiconductor layer 40 is grown on the electron blocking layer 60; the hole injection layer 50 includes a first aluminum-containing layer 51, a second aluminum-containing layer 52, and a third aluminum-containing layer 53, the aluminum content of the second aluminum-containing layer 52 is higher than the aluminum content of the first aluminum-containing layer 51, and higher than that of the third aluminum-containing layer 53 Aluminum content.

In another embodiment of the present invention, a method for manufacturing the above-mentioned semiconductor light-emitting element is disclosed, including growing an N-type semiconductor layer 20 on a substrate 10; growing an active layer 30 on the N-type semiconductor layer 20; growing an active layer 30 on the active growing a capping layer 321 on the layer 30; growing a hole injection layer 50 on the capping layer 321; growing an electron blocking layer 60 on the hole injection layer 50; growing a P-type semiconductor layer 40 on the electron blocking layer 60; The hole injection layer 50 includes a first aluminum-containing layer 51, a second aluminum-containing layer 52 and a third aluminum-containing layer 53, the aluminum content of the second aluminum-containing layer 52 is higher than that of the first aluminum-containing layer 51 content, and higher than the aluminum content of the third aluminum-containing layer 53.

The above-mentioned substrate 10 is an insulating substrate, and the N-type semiconductor layer 20, the active layer 30, the hole injection layer 50, the electron blocking layer 60, and the P-type semiconductor layer 40 can all be grown and formed by MOCVD. The growth temperature of the hole injection layer 50 is higher than that of the capping layer 321 and lower than that of the electron blocking layer 60 and the P-type semiconductor layer 40 .

In addition to the above steps, in another embodiment, the AlN buffer layer 11 can be grown between the substrate 10 and the N-type semiconductor layer 20 under low temperature growth conditions, or the GaN buffer layer 11 can be grown by MOCVD. A stress release layer 21 of superlattice structure is grown between the layer 20 and the active layer 30 by MOCVD, and a P-type contact layer 70 is grown on the P-type semiconductor layer 40 by MOCVD.

Referring to FIG. 5 , in another embodiment of the present invention, a light emitting diode based on the above semiconductor light emitting element is disclosed. The light-emitting diode of this embodiment also includes a P electrode P and an N electrode N, wherein the P electrode P is located above the P-type semiconductor layer 40 and is electrically connected to the P-type semiconductor layer 40, and the N electrode N is located on the N-type semiconductor layer 20. Above and electrically connected to the N-type semiconductor layer 20, the current is injected into the semiconductor light emitting element from the P electrode P, and flows to the N electrode N, so that the holes in the P-type semiconductor layer 40 migrate to the active layer 30, and the N-type semiconductor layer The electrons in the layer 20 migrate to the active layer 30 , and the holes and electrons in the active layer 30 recombine to emit, for example, visible light with a wavelength of 450-600 nm.

Wherein the P electrode P and the N electrode N can be on the same side of the substrate 10 to form a front-mounted light-emitting diode or a flip-chip light-emitting diode, and can also be on opposite sides of the substrate 10 to form a vertical light-emitting diode. At this time, the substrate 10 is a conductive substrate. , or the substrate 10 is peeled off, so that the N electrode N is directly in contact with the surface of the N-type semiconductor layer 20 away from the active layer 30 .

In order to promote the expansion of the current, a transparent conductive layer 80 can be inserted between the P-type semiconductor layer 40 and the P electrode P. The transparent conductive layer 80 needs to have a good current spreading effect on the one hand, and at the same time, the light transmittance of the material needs to be high. Potentially reduce light absorption by the material layer. Therefore, usually the transparent conductive layer 80 is an ITO layer.

At the same time, in order to prevent the current injected by the P electrode P from entering the active layer 30 vertically in the form of aggregation, a current blocking layer 90 can also be inserted between the transparent conductive layer 80 and the P-type semiconductor layer 40. The main purpose of the current blocking layer 90 is to block The current injected by the P electrode P, so the position of the current blocking layer 90 is usually located directly below the P electrode P, and its shape and size can be designed according to the shape and size of the P electrode P, as long as it can completely or partially block the P electrode P The effect of injecting current is sufficient. In order to achieve a current blocking effect, the material of the current blocking layer 90 is generally an insulating material, such as silicon dioxide, silicon carbide, silicon nitride, etc., preferably silicon dioxide.

Claims (26)

Nitride semiconductor light emitting elements, including: Substrate; an N-type semiconductor layer located above the substrate; a P-type semiconductor layer located above the N-type semiconductor layer; an active layer, the active layer is located between the N-type semiconductor layer and the P-type semiconductor layer; a hole injection layer, the hole injection layer is located between the active layer and the P-type semiconductor layer; an electron blocking layer, the electron blocking layer is located between the hole injection layer and the P-type semiconductor layer; It is characterized in that: the hole injection layer comprises a first aluminum-containing layer, a second aluminum-containing layer and a third aluminum-containing layer, the aluminum content of the second aluminum-containing layer is higher than that of the first aluminum-containing layer, And higher than the aluminum content of the third aluminum-containing layer. The nitride semiconductor light-emitting device according to claim 1, wherein the energy level of the second aluminum-containing layer is higher than the energy level of the first aluminum-containing layer and higher than the energy level of the third aluminum-containing layer. The nitride semiconductor light-emitting device according to claim 1, wherein the impurity concentration of the hole injection layer is higher than the impurity concentration of the electron blocking layer and higher than the impurity concentration of the P-type semiconductor layer. The nitride semiconductor light-emitting element according to claim 1, wherein the hole injection layer comprises a first aluminum-containing layer close to the active layer, a third aluminum-containing layer close to the electron blocking layer, and a third aluminum-containing layer located at the first A second aluminum-containing layer between the aluminum-containing layer and the third aluminum-containing layer. The nitride semiconductor light-emitting element according to claim 1, wherein the hole injection layer comprises a second aluminum-containing layer close to the active layer, a third aluminum-containing layer close to the electron blocking layer, and a third aluminum-containing layer located at the second The first aluminum-containing layer between the aluminum layer and the third aluminum-containing layer. The nitride semiconductor light-emitting element according to claim 1, wherein the hole injection layer comprises a first aluminum-containing layer close to the active layer, a second aluminum-containing layer close to the electron blocking layer, and a second aluminum-containing layer located in the first aluminum-containing layer. and a third aluminum-containing layer between the second aluminum-containing layer. The nitride semiconductor light-emitting device according to claim 1, wherein the thickness of the second aluminum-containing layer is smaller than the thickness of the first aluminum-containing layer and smaller than the thickness of the third aluminum-containing layer. The nitride semiconductor light-emitting device according to claim 1, wherein the thickness of the second aluminum-containing layer is less than 20 angstroms. The nitride semiconductor light-emitting element according to claim 1, wherein the thickness of the first aluminum-containing layer is less than, greater than or equal to the thickness of the third aluminum-containing layer. The nitride semiconductor light-emitting element according to claim 1, wherein the thickness of the first aluminum-containing layer is less than 150 angstroms. The nitride semiconductor light-emitting device according to claim 1, wherein the thickness of the third aluminum-containing layer is less than 150 angstroms. The nitride semiconductor light-emitting element according to claim 1, wherein the electron blocking layer is an aluminum-containing layer, and the aluminum content of the second aluminum-containing layer is lower than or equal to the aluminum content of the electron blocking layer. The nitride semiconductor light-emitting element according to claim 1, wherein the first aluminum-containing layer is a compound having a molecular formula of Alx1Iny1Ga1-x1-y1N, wherein 0<x1<1, 0≤y1<1. The nitride semiconductor light-emitting element according to claim 1, wherein the second aluminum-containing layer is a compound having a molecular formula of Alx2Iny2Ga1-x2-y2N, wherein 0<x2<1, 0≤y2<1. The nitride semiconductor light-emitting element according to claim 1, wherein the third aluminum-containing layer is a compound having a molecular formula of Alx3Iny3Ga1-x3-y3N, wherein 0<x3<1, 0≤y3<1. The nitride semiconductor light-emitting element according to claim 1, wherein the electron barrier is a compound having a molecular formula of Alx4Iny4Ga1-x4-y4N, wherein 0<x4<1, 0≤y4<1. The nitride semiconductor light-emitting device according to claim 1, further comprising a capping layer, the capping layer being located between the active layer and the hole injection layer. The nitride semiconductor light-emitting element according to claim 17, wherein the capping layer is an aluminum-containing layer, and the aluminum content of the second aluminum-containing layer is higher than or equal to the aluminum content of the capping layer. The nitride semiconductor light-emitting element according to claim 17, characterized in that, the capping layer is undoped or n-doped or p-doped. The nitride semiconductor light-emitting device according to claim 17, wherein the impurity concentration of the capping layer is lower than that of the hole injection layer. The nitride semiconductor light-emitting element according to claim 17, wherein the capping layer is a compound having a molecular formula of Alx5Iny5Ga1-x5-y5N, wherein 0<x5<1, 0≤y5<1. The nitride semiconductor light-emitting element according to claim 1 or 17, characterized in that the impurity concentration of the hole injection layer is between 1E19cm ^-3 and 2E20cm ^-3 . A method for manufacturing a nitride semiconductor light-emitting element, comprising the following steps: growing an N-type semiconductor layer on the substrate; growing an active layer on the N-type semiconductor layer; growing a hole injection layer on the active layer; growing an electron blocking layer on the hole injection layer; growing a P-type semiconductor layer on the electron blocking layer; It is characterized in that the hole injection layer comprises a first aluminum-containing layer, a second aluminum-containing layer and a third aluminum-containing layer, the aluminum content of the second aluminum-containing layer is higher than that of the first aluminum-containing layer, And higher than the aluminum content of the second aluminum-containing layer. A method for manufacturing a nitride semiconductor light-emitting element, comprising the following steps: growing an N-type semiconductor layer on the substrate; growing an active layer on the N-type semiconductor layer; growing a cap layer on the active layer; growing a hole injection layer on the capping layer; growing an electron blocking layer on the hole injection layer; growing a P-type semiconductor layer on the electron blocking layer; It is characterized in that the hole injection layer comprises a first aluminum-containing layer, a second aluminum-containing layer and a third aluminum-containing layer, the aluminum content of the second aluminum-containing layer is higher than that of the first aluminum-containing layer, And higher than the aluminum content of the second aluminum-containing layer. The method according to claim 23 or 24, wherein the growth temperature of the hole injection layer is lower than the growth temperature of the electron blocking layer and the P-type semiconductor layer. The method for manufacturing a nitride semiconductor light-emitting device according to claim 24, wherein the growth temperature of the hole injection layer is higher than the growth temperature of the capping layer.