KR20130113267A - Light emitting diode array with excellent light emtting efficiency - Google Patents

Abstract

Disclosed is a semiconductor light emitting device array having excellent current spreading effect and high luminous efficiency.
The semiconductor light emitting device array according to the present invention includes a substrate; An insulating layer formed on the substrate; A plurality of light emitting cells spaced apart from each other on the insulating layer and including a first semiconductor layer, an active layer, and a second semiconductor layer from above; A first electrode formed on a portion of the insulating layer, the first electrode of which one surface is in contact with a second semiconductor layer of each of the plurality of light emitting cells; And an insulating layer electrically separated from the first electrode, the active layer and the second semiconductor layer, one end of which is in contact with the first semiconductor layer of one of the light emitting cells. And a second electrode in contact with the first electrode in contact with the other one of the plurality of light emitting cells.

Description

Light emitting device array with excellent luminous efficiency {LIGHT EMITTING DIODE ARRAY WITH EXCELLENT LIGHT EMTTING EFFICIENCY}

The present invention relates to a light emitting device array, and more particularly to a light emitting device array having excellent luminous efficiency.

Since the semiconductor light emitting device has a beneficial advantage as a light source in terms of output, efficiency and reliability, it has been actively researched and developed as a high power, high efficiency light source that can replace the backlight of the lighting device or the display device.

A semiconductor light emitting device usually includes a p-type semiconductor and an n-type semiconductor together with an active layer capable of emitting light by electron / hole recombination therebetween. The semiconductor light emitting device may be classified into a horizontal structure and a vertical structure according to the position of the electrode for the semiconductor layer.

Typically, the horizontal structure and the vertical structure are determined by the electrical conductivity of the substrate used in the semiconductor light emitting device.

For example, a semiconductor light emitting device using a substrate having electrical insulation is mainly implemented in a horizontal structure. In this case, mesa etching for forming an n-type electrode connected to the n-type semiconductor layer is required. That is, the p-type semiconductor layer and the active layer are partially removed to expose a portion of the n-type semiconductor layer, and the p-side and n-side electrodes are formed on the upper surface of the p-type semiconductor layer and the exposed upper surface of the n-type semiconductor layer, respectively.

In such an electrode structure, since the light emitting area is lost by mesa etching and the current flow is formed laterally, it is difficult to achieve uniform current distribution over the entire area, thereby reducing the luminous efficiency.

In contrast, in the case of using a conductive substrate, the vertical semiconductor light emitting device can be provided by using the conductive substrate as an electrode part on one side. The vertical semiconductor light emitting device has a smaller light emission area than a horizontal structure and has a relatively uniform current flow, thereby improving the luminous efficiency.

However, in the case of realizing a large light emitting device for high power, The same electrode structure is provided to achieve uniform current distribution over the entire light emitting area. In this case, light extraction is limited by the finger or the like, or light absorption is caused by the electrode, thereby reducing the light emitting efficiency.

Prior art related to the present invention is Korean Patent Application Publication No. 10-0665302 (January 4, 2007.), which discloses a flip chip type light emitting device in which a plurality of light emitting cells are arranged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting device array in which a plurality of light emitting cells are arranged, which exhibits excellent current dispersing effect and can secure a maximum light emitting area to improve luminous efficiency.

Light emitting device array according to an embodiment of the present invention for achieving the above object is a substrate; An insulating layer formed on the substrate; A plurality of light emitting cells spaced apart from each other on the insulating layer and including a first semiconductor layer, an active layer, and a second semiconductor layer from above; A first electrode formed on a portion of the insulating layer, the first electrode of which one surface is in contact with a second semiconductor layer of each of the plurality of light emitting cells; And an insulating layer electrically separated from the first electrode, the active layer and the second semiconductor layer, one end of which is in contact with the first semiconductor layer of one of the light emitting cells. And a second electrode in contact with the first electrode in contact with the other one of the plurality of light emitting cells.

The light emitting device array according to the present invention is configured in the form of an array in which a plurality of light emitting cells are connected in series, so that a large current of the large light emitting device is possible.

Particularly, in the light emitting device array according to the present invention, an electrode for supplying electrons and power to each light emitting cell while connecting the light emitting cell and the light emitting cell is formed under each light emitting cell, thereby increasing the effective light emitting area as much as possible. The luminous efficiency can be improved.

1 is a cross-sectional view schematically showing a light emitting device array according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing a light emitting device array according to another embodiment of the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a light emitting device array having excellent luminous efficiency according to embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a cross-sectional view schematically showing a light emitting device array according to an embodiment of the present invention.

Referring to FIG. 1, the illustrated light emitting device array includes a substrate 110, an insulating layer 120, a plurality of light emitting cells 130, a first electrode 140, and a second electrode 150. In addition, the illustrated light emitting device array further includes a terminal electrode 150 ′ and an ohmic contact layer 180.

First, when looking at the overall array shape, the insulating layer 120 is formed on the substrate 110, the plurality of light emitting cells 130 are formed on the insulating layer 120 spaced apart from each other by a predetermined interval. In addition, the plurality of light emitting cells 130 are connected to each other in series by the first electrode 140 and the second electrode 150.

Each light emitting cell 130 includes a first semiconductor layer 131, a second semiconductor layer 135, and an active layer 133 interposed between the first semiconductor layer 131 and the second semiconductor layer 135. .

The first and second semiconductor layers 131 and 135 may be n-type and p-type, or p-type and n-type, respectively. Each of the first and second semiconductor layers 131 and 135 may be formed of, for example, an inorganic semiconductor such as a GaN based semiconductor, a ZnO based semiconductor, a GaAs based semiconductor, a GaP based semiconductor, or a GaAsP based semiconductor. In addition, each of the first and second semiconductor layers 131 and 135 may be appropriately selected from a group consisting of a group III-V semiconductor, a group II-VI semiconductor, and Si.

Each of the first and second semiconductor layers 131 and 135 may be formed as a single layer or as a multilayer, and may be formed using a molecular beam epitaxy (MBE) method.

The active layer 133 is a layer that activates light emission and may be formed of a material having an energy band gap less than the energy band gaps of the first and second semiconductor layers 131 and 135. For example, when the first and second semiconductor layers 131 and 135 are GaN compound semiconductors, the active layer 133 may be an InAlGaN compound semiconductor having an energy band gap smaller than that of GaN, that is, In _x. Al _y Ga _(1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).

The active layer 133 has a single-quantum well structure (SQW) structure or a plurality of quantum well layers and a quantum barrier layer alternately stacked between the first semiconductor layer 131 and the second semiconductor layer 135. It may be formed of a multi-quantum well (MQW) structure.

At this time, it is preferable that the impurities are not doped due to the characteristics of the active layer 133, and the wavelength of light emitted by controlling the composition ratio of the constituent material may be adjusted. Therefore, the light emitting device may emit light of any one of infrared rays, visible rays, and ultraviolet rays according to the characteristics of the active layer 133.

The light emitting cell 130 uses a phenomenon in which a small number of carriers (electrons or holes) are injected using a pn junction structure of a semiconductor, and light is emitted by recombination thereof.

In the present invention, the light emitting cell 130 includes a contact hole 137 that exposes a portion of the first semiconductor layer 131 through the second semiconductor layer 135 and the active layer 133 in some regions. That is, in the light emitting cell 130, some regions of the second semiconductor layer 135 and the active layer 133 are etched to expose the first semiconductor layer 131 in the downward direction.

Although the cross section of the contact hole 137 is illustrated as a circle, it is not limited thereto and may be variously modified in a polygonal shape such as a triangle or a square.

The light emitting cell 130 and the contact hole 137 may be formed of a first semiconductor layer 131, an active layer 133, and a second semiconductor layer 135 on a semiconductor growth substrate (not shown) such as sapphire. After the laminated film is formed, the laminated film may be patterned by a conventional photo-lithography process, which may be formed by using a conventionally known method, and thus a detailed description thereof will be omitted. After the light emitting cell 130 including the contact hole 137 is bonded to the substrate 110, the substrate for semiconductor growth is removed.

In the above, the substrate 110 may be a metal substrate or a semiconductor substrate. When the substrate 110 is a metal substrate, the substrate 110 may include at least one metal material such as gold (Au), nickel (Ni), copper (Cu), and tungsten (W). In addition, when the substrate 110 is a semiconductor substrate, the substrate 110 may include any one of silicon (Si), germanium (Ge), and gallium arsenide (GaAs). The substrate 110 may be formed by a plating method or separately provided and then bonded to the insulating layer 120 using a conductive adhesive.

The insulating layer 120 includes a first insulating layer 121 formed on the substrate 110 and a second insulating layer 123 formed on the first insulating layer 121 to fill the contact hole 137. The insulating layer 120 may be formed of silicon oxide, silicon nitride, silicon oxynitride, or the like, and may include a plasma enhanced chemical vapor deposition (PECVD) method, a sputtering method, an organic metal chemical vapor deposition (MOCVD) method, or an electron beam. It may be formed by an e-beam evaporation method.

The second insulating layer 123 is formed by protruding an area corresponding to the contact hole 137 to contact the bottom surface of the contact hole 137 and patterning the exposed area where the second contact pad 170 is to be exposed. Can be.

The first insulating layer 121 and the second insulating layer 123 may be formed of heterogeneous or the same material. For the second insulating layer 123, the second electrode 150 and the terminal electrode 150 ′ may be formed. The description will be further described.

On the insulating layer 120, a first electrode 140 having one surface contacting the second semiconductor layer 135 of each of the plurality of light emitting cells 130 is formed. That is, one surface of the first electrode 140 contacts the insulating layer 120, and the other surface of the first electrode 140 contacts the second semiconductor layer 135.

The first electrode 140 includes gold (Au), silver (Ag), copper (Cu), chromium (Cr), titanium (Ti), tungsten (W), nickel (Ni), silicon (Si), and aluminum (Al). ), A metal such as molybdenum (Mo), an alloy including one or more of these metals or a metal oxide may be formed including a conductive material capable of electrical connection, and is not particularly limited as long as it has a conductive material. The first electrode 140 may be formed of a material that reflects light generated from the active layer 133. For example, the first electrode 140 may include one or more materials such as silver (Ag), aluminum (Al), and platinum (Pt). Can be. In this case, the light reflected from the first electrode 140 is directed toward the light emitting surface, which is one surface of the first semiconductor layer 131, and as a result, the light emitting efficiency of the light emitting device may be increased.

The first electrode 140 is deposited on the insulating layer 120 using a PVD method or a MOCVD method to form a conductive film, and then the conductive film corresponds to the light emitting cell 130 by a photolithography process. It can be patterned and formed to provide an area.

Inside the insulating layer 120, one end of the plurality of light emitting cells 130 contacts the first semiconductor layer 131 of the light emitting cell 130, and the other end of the other of the plurality of light emitting cells 130. The second electrode 150 in contact with the first electrode 140 in contact with the light emitting cell 130 is formed. In this case, the first electrode 140 and the second electrode 150 are formed of n-side and p-side, or p-side and n-side electrodes.

Specifically, the second electrode 150 includes a horizontal portion formed on the upper surface of the first insulating layer 121 and a vertical portion extending in a direction perpendicular to both ends of the horizontal portion. At this time, one end of the vertical portion of the second electrode 150 is in electrical contact with the first semiconductor layer 131 of one of the light emitting cells 130 of the plurality of light emitting cells 130 through the contact hole 137, The other end is in electrical contact with the first electrode 140 in contact with the other one of the plurality of light emitting cells 130.

The second electrode 150 may be formed of the same material as the material of forming the first electrode 140. The second electrode 150 may include one or more materials such as silver (Ag), aluminum (Al), and platinum (Pt). The luminous efficiency of the light emitting device may be increased by increasing the amount of light reflected from the 150.

In addition, inside the insulating layer 120, one end of the terminal electrode 150 ′ having one end in contact with the first semiconductor layer 131 of the one of the light emitting cells 130 and the other end connected to the outside. ) Is formed. The terminal electrode 150 ′ may include a horizontal portion formed on the upper surface of the first insulating layer 121 and a vertical portion extending in a direction perpendicular to one end of the horizontal portion. In this case, one end of the vertical portion of the terminal electrode 150 ′ may be in electrical contact with the first semiconductor layer 131 of one of the light emitting cells 130 of the plurality of light emitting cells 130 through the contact hole 137.

The terminal electrode 150 ′ may be formed of the same material as the material of forming the second electrode 150, and may include one or more materials such as silver (Ag), aluminum (Al), and platinum (Pt). The light emitting efficiency of the light emitting device may be increased by increasing the amount of light reflected from the light beam 150 '.

Thus, the light emitting cells 130 adjacent to each other among the plurality of light emitting cells 130 formed on the substrate 110 are electrically connected in series through the second electrode 150. That is, the second electrode 150 is the first semiconductor layer 131 of one of the light emitting cells 130 of the plurality of light emitting cells 130 and the first electrode 140 of the other light emitting cell 130 adjacent thereto. Are electrically connected in series to form an array of light emitting cells 130. The second electrode 150 to which the first semiconductor layer 131 of the plurality of light emitting cells 130 is connected is electrically connected to an external power source (not shown) by the terminal electrode 150 '. In the light emitting device array, the plurality of light emitting cells 130 has a structure connected in series with each other as a whole.

The second electrode 150 and the terminal electrode 150 ′ may be formed through a separation process between the horizontal part and the vertical part. First, a conductive material is deposited on the upper surface of the first insulating layer 121 by a PVD method or a MOCVD method to form a conductive film (not shown), and then the conductive film is patterned to form a horizontal portion for the second electrode and a horizontal portion for the terminal electrode. An addition can be formed. Thereafter, an insulating film is formed on the horizontal portion for the second electrode or the terminal electrode by a CVD method, and then patterned to cover the horizontal portion for the second electrode or the terminal electrode, corresponding to the contact hole 137 of the light emitting cell 130. A second insulating layer 123 may be formed having a protrusion in a region to be exposed and exposing a horizontal portion for a terminal electrode in a region where the second contact pad 170 is to be formed.

Subsequently, a contact hole (not shown) penetrating the second insulating layer 123 corresponding to a region outside or inside of both side ends of the second electrode horizontal part and at least one end of at least one end of the horizontal part for the terminal electrode may be formed. After the formation, the vertical portion for the second electrode or the vertical portion for the terminal electrode may be formed to fill the contact hole. Here, patterning for forming contact holes for forming the horizontal portion for the second electrode or the terminal electrode, the second insulating layer 123, and the vertical portion for the second electrode or the terminal electrode is performed by a conventional known photolithography process. Can be.

In addition, the vertical portion for the second electrode or the terminal electrode is deposited by a conductive material (e.g., PVD method or MOCVD method) to fill the contact hole, and then a conductive film (not shown) is formed. It may be formed by etching back. The method of forming the second electrode 150 and the terminal electrode 150 ′ is not limited thereto, and may be variously modified using a conventional semiconductor process (etching, deposition, photolithography), or the like.

As described above, in the structure in which the second electrode 150 and the terminal electrode 150 ′ are formed under the light emitting cell 130, the conventional mesa etching process for forming the electrode may be performed as the process for forming the contact hole 137. Replaced. Accordingly, by minimizing the loss of the active layer 133 to increase the effective light emitting area, it is possible to improve the brightness of the light emitting device by improving the light emitting efficiency.

In addition, the current flowing through the first and second semiconductor layers 131 and 135 may be evenly distributed using the second electrode 150 and the terminal electrode 150 ′, thereby further improving luminous efficiency.

Meanwhile, the second insulating layer 123 is formed of the first insulating layer 121, the second electrode 150, and the second electrode 150 and the terminal electrode 150 ′ formed inside the insulating layer 120. The contact hole between the sidewall of the contact hole 137 and the vertical portion of the second electrode 150 or the sidewall of the contact hole 137 and the vertical portion of the terminal electrode 150 'with the upper portion of the terminal electrode 150'. 137 can be formed to fill. The second electrode 150 and the terminal electrode 150 ′ are electrically separated from the first electrode 140, the active layer 133, and the second semiconductor layer 135 by the insulating layer 120.

In addition, the light emitting device array may include a first electrode pad 160 and a terminal electrode 150 ′ in contact with the first electrode 140 in one region of each of the first electrode 140 and the terminal electrode 150 ′. It may further include a second electrode pad 170 in contact with.

The first and second electrode pads 160 and 170 may be generally provided to apply external power to the first and second electrodes 140 and 150. The first and second electrode pads 160 and 170 are made of metal, for example, gold (Au), silver (Ag), copper (Cu), chromium (Cr), titanium (Ti), tungsten (W), and nickel. (Ni), silicon (Si), or the like, and is not particularly limited as long as it is a conductive material. The first and second electrode pads 160 and 170 are After the conductive material is deposited on the first electrode 140 and the exposed terminal electrode 150 'by the PVD method or the MOCVD method to form a conductive film (not shown), the conductive film is patterned and formed by a photolithography process. Can be.

In addition, the light emitting device array includes an ohmic contact layer 180 between the exposed portion of the first semiconductor layer 131 and the second electrode 150 and between the exposed portion of the first semiconductor layer 131 and the terminal electrode 150 ′. ) May be further formed. The ohmic contact layer 180 is ohmic contacted to the first semiconductor layer 131 to lower the contact resistance. The ohmic contact layer 180 may be formed of a transparent conductive oxide, and the material may include elements such as In, Sn, Al, Zn, Ga, and the like, for example, ITO, CIO, ZnO, NiO, In ₂ O _{3, or the} like. It may be formed of one or more.

The ohmic contact layer 180 is deposited on the light emitting cell 130 including the contact hole 137 by a CVD method to form a transparent conductive oxide film, and the transparent conductive oxide film remains only at the bottom of the contact hole 137. It may be formed by etching.

The light emitting device array according to the present invention is a substrate including a first electrode 140, a second electrode 150 and a terminal electrode 150 'formed by applying a conventional semiconductor process (etching, deposition, photolithography) ( After bonding the light emitting cell 130 formed on the growth substrate (not shown) by using a conductive adhesive or eutectic bonding (110) on the 110, it may be formed by a method of removing the growth substrate. In addition, various methods may be applied in addition to this.

As a result, a series semiconductor stack array in which light emitting cells 130 adjacent to each other among the plurality of light emitting cells 130 formed on the substrate 110 are electrically connected in series is formed. .

As described above, according to the present invention, since a plurality of light emitting cells 130 may be configured in an array connected in series, high voltage driving is possible, and thus, in an application field requiring high light quantity such as a light or a head lamp requiring high light output. The array becomes available.

2 is a cross-sectional view schematically showing a light emitting device array according to another embodiment of the present invention.

Referring to FIG. 2, in the illustrated light emitting device array, a light emitting cell in which a terminal electrode 150 ′ in contact with the second electrode pad 170 is adjacent to the second electrode pad 170 and the second electrode pad 170 is shown. It may be formed in contact with the substrate 110 under a portion of the 130.

In this case, before forming the horizontal portion for the terminal electrode, the first insulating layer 121 corresponding to the region where the terminal electrode 150 ′ is to be contacted with the second electrode pad 170 is etched and removed by a photolithography process. Can be.

Except that the terminal electrode 150 'is in contact with the substrate 110, the light emitting device array according to another embodiment of the present invention is the same as the example shown in Figure 1 of the present invention, the effect is also the same. Therefore, duplicate description thereof will be omitted.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. These changes and modifications may be made without departing from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

110: substrate 120: insulating layer
121: first insulating layer 123: second insulating layer
130: light emitting cell 131: first semiconductor layer
133: active layer 135: second semiconductor layer
137 contact hole 140 first electrode
150: second electrode 150 ': terminal electrode
160: first electrode pad 170: second electrode pad
180: ohmic contact layer

Claims (11)

Board;
An insulating layer formed on the substrate;
A plurality of light emitting cells spaced apart from each other on the insulating layer and including a first semiconductor layer, an active layer, and a second semiconductor layer from above;
A first electrode formed on a portion of the insulating layer, the first electrode of which one surface is in contact with a second semiconductor layer of each of the plurality of light emitting cells; And
The insulating layer is formed to be electrically separated from the first electrode, the active layer, and the second semiconductor layer, one end of which is in contact with the first semiconductor layer of the one of the plurality of light emitting cells, and the other end thereof. And a second electrode in contact with the first electrode in contact with the other one of the plurality of light emitting cells.
The method of claim 1,
The light emitting device array
The insulating layer is formed to be electrically separated from the first electrode, the active layer, and the second semiconductor layer, one end of which is in contact with the first semiconductor layer of one of the light emitting cells, and the other end of which is external. The light emitting device array further comprises a terminal electrode connected with.
3. The method of claim 2,
The light emitting device array
And a first electrode pad in contact with the first electrode and a second electrode pad in contact with the terminal electrode in one region of each of the first electrode and the terminal electrode.
3. The method of claim 2,
The terminal electrode
The light emitting device array, characterized in that formed on the insulating layer.
3. The method of claim 2,
The terminal electrode
And a light emitting element array in contact with the substrate.
The method of claim 1,
The light emitting cell
And a contact hole for etching a portion of the second semiconductor layer and the active layer to expose the first semiconductor layer in a downward direction.
The method according to claim 6,
The insulating layer
Including a first insulating layer and a second insulating layer,
The first insulating layer is formed on the substrate,
And the second insulating layer is formed on the first insulating layer, the second electrode, and the terminal electrode, and fills the contact hole.
The method of claim 7, wherein
The second electrode
A horizontal portion formed on an upper surface of the first insulating layer and a vertical portion extending in a direction perpendicular to both ends of the horizontal portion,
One end of the vertical part contacts the first semiconductor layer of one of the light emitting cells of the plurality of light emitting cells through the contact hole, and the other end of the first electrode is in contact with the other light emitting cell of the plurality of light emitting cells. Light emitting element array characterized in that the contact.
3. The method of claim 2,
The light emitting device array
And an ohmic contact layer interposed between the exposed portion of the first semiconductor layer and the second electrode and between the exposed portion of the first semiconductor layer and the terminal electrode.
10. The method of claim 9,
The ohmic contact layer
ITO, CIO, ZnO, NiO, and In ₂ O ₃ Light emitting device array, characterized in that formed in at least one selected from.
The method of claim 1,
The substrate is a light emitting device array, characterized in that formed of a metal substrate or a semiconductor substrate.

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