JP2012253388A - Semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element with improved current injection density to a light-emitting region and with improved light-emitting efficiency.SOLUTION: A semiconductor light-emitting element comprises a supporting substrate, a first electrode, a first-conductivity-type layer, a light-emitting layer, a second-conductivity-type layer, and a second electrode. The first-conductivity-type layer includes a first contact sublayer, a window sublayer, and a first cladding sublayer. The second-conductivity-type layer includes a second cladding sublayer, a current diffusion sublayer, and a second contact sublayer. The second electrode includes a pad portion provided on a non-formation region of the second contact sublayer, and a narrow-line portion having a first region extending on the second contact sublayer and a second region provided in the non-formation region. The plane of the narrow-line portion and the plane of the pad portion are composed of a continuous metallic material. The band-gap energy of the first contact sublayer and the window sublayer is larger than that of the light-emitting layer. The first contact sublayer is selectively provided, and the first contact sublayer and the second contact sublayer are not overlapped.

Description

  Embodiments described herein relate generally to a semiconductor light emitting device.

  A light emitting element (LED: Light Emitting Diode) used for an illumination device, a display device, a traffic light or the like is required to have a high output.

  If a reflective metal layer is provided below the light emitting layer and the emitted light directed downward from the light emitting layer is reflected upward, the light extraction efficiency can be increased.

  However, for example, if the current injected from the electrode on the reflective metal layer side is excessively spread in the lateral direction, the effective current injection density in the light emitting layer is lowered and the light emission efficiency is lowered. For this reason, it becomes difficult to obtain a high light output.

JP 2009-65109 A

  Provided is a semiconductor light emitting device in which current injection density into a light emitting region and luminous efficiency are increased.

  The semiconductor light emitting device of the embodiment includes a support substrate, a first electrode provided on the support substrate, a first conductivity type layer provided on the first electrode, and a first conductivity type layer. A light emitting layer provided on the light emitting layer; a second conductive type layer provided on the light emitting layer; and a second electrode provided on the second conductive type layer. The first conductivity type layer has at least a first contact layer, a window layer having an impurity concentration lower than the impurity concentration of the first contact layer, and a first cladding layer in this order from the first electrode side. . The second conductivity type layer has at least a second cladding layer, a current diffusion layer, and a second contact layer in this order from the light emitting layer side. The second electrode includes a pad portion provided in a non-formation region of the second contact layer of the second conductivity type layer, a first region extending over the second contact layer, the pad portion, and the A thin line portion having a second region provided in the non-formation region between the first region and the first region. The surface of the fine line portion on the second conductivity type layer side and the surface of the pad portion on the second conductive layer side are made of a continuous metal material. The band gap energy of the first contact layer and the window layer is larger than the band gap energy of the light emitting layer. The first contact layer is selectively provided between the window layer and the first electrode, and the first contact layer and the second contact layer are provided so as not to overlap each other when viewed from above. It is characterized by that.

FIG. 1A is a schematic plan view of the semiconductor light emitting device according to the first embodiment, and FIG. 1B is a schematic cross-sectional view taken along the line AA. It is a schematic plan view of the semiconductor light emitting element concerning the modification of 1st Embodiment. 3A to 3F are process cross-sectional views of the method for manufacturing the semiconductor light emitting device according to the first embodiment. FIG. 3A is a schematic diagram of a semiconductor layer, and FIG. FIG. 3C is a schematic diagram in which ITO is formed, FIG. 3D is a schematic diagram of wafer bonding, FIG. 3E is a schematic diagram in which the second contact layer is patterned, FIG. 3F is a schematic diagram of a divided element. It is a schematic cross section of the semiconductor light emitting element concerning a comparative example. It is a schematic cross section of the semiconductor light emitting device according to the second embodiment. FIG. 6A is a schematic plan view of a semiconductor light emitting device according to the third embodiment, and FIG. 6B is a schematic cross-sectional view taken along the line BB.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a schematic plan view of the semiconductor light emitting device according to the first embodiment, and FIG. 1B is a schematic cross-sectional view taken along the line AA.
The semiconductor light emitting element includes a support substrate 10, a first electrode 20 provided on the support substrate 10, and a semiconductor layer 58 provided on the first electrode 20. The semiconductor layer 58 includes at least the light emitting layer 40, the window layer 34, and the first contact layer 32. Further, the window layer 34 is in contact with a part of the first electrode 20. In the present specification, the “window layer” is a layer having a band gap energy larger than that of the light emitting layer 40 and capable of transmitting light from the light emitting layer.

  The first contact layer 32 is selectively provided between the window layer 34 and the first electrode 20. Further, the first contact layer 32 is in contact with the window layer 34 and the first electrode 20 and has a conductivity higher than that of the window layer 34. In this way, the contact resistance between the first electrode 20 and the first contact layer 32 can be made lower than the contact resistance between the first electrode 20 and the window layer 34. For this reason, the first electrode 20 can inject carriers into the window layer 34 through the first contact layer 32.

  As shown in FIG. 1B, the semiconductor layer 58 includes, from the first electrode 20 side, the first contact layer 32, the window layer 34, the composition gradient layer 36, the first cladding layer 38, the light emitting layer 40, The second cladding layer 52, the current diffusion layer 54, the second contact layer 56, and the like can be included. Note that the structure of the semiconductor layer 58 is not limited to this. The second electrode 60 can include a pad portion 60a provided in a region where the second contact layer 56 is not formed, and a thin line portion 60b connected to the pad portion 60a. Although the fine line portion 60b is provided on the second contact layer 56, the fine line portion 60b can be provided in a region where the second contact layer 56 is not formed in the vicinity of the pad portion 60a. This is because there is no need to provide the second contact layer 56 because the first contact layer does not exist in the vicinity immediately below the pad portion 60a and no current is injected. When the light extraction surface 58a having unevenness is provided on the surface of the semiconductor layer 58 where the second electrode 60 is not provided, the light extraction efficiency can be increased.

  Further, by making the support substrate 10 conductive, the first electrode 20 and the back electrode 62 provided on the back surface of the support substrate 10 can be made conductive.

  The first electrode 20 is, for example, from the semiconductor layer 58 side, for example, a transparent conductive film 26, a reflective metal layer 25, a barrier metal layer 24, a second bonding metal layer 23, a first bonding metal layer 22, a barrier metal layer 21, and the like. It can be. The structure is not limited to this.

  As shown in the schematic plan view of FIG. 1A, the second contact layer 56 is provided so as not to overlap the first contact layer 32 represented by a broken line when viewed from above. In addition, the first contact layer 32 can include a plurality of regions provided in a distributed manner in the extending direction of the thin line portion 60b when viewed from above. That is, the current flows between the first electrode 20 and the second electrode 60 through the first contact layer 32 that is selectively provided. Moreover, the shortest distance seen from the upper direction between the thin wire | line part 60b and the 1st contact layer 32 can be 5 micrometers, for example. For this reason, when viewed from above, a region with high emission intensity in the light emitting layer 40 and the thin line portion 60b do not overlap with each other, and high luminance can be achieved. In FIG. 1A, the first contact layer 32 is rectangular, but the planar shape is not limited to this, and may be circular, elliptical, polygonal, or the like.

FIG. 2 is a schematic plan view of a semiconductor light emitting device according to a modification of the first embodiment.
The first contact layer 32 may have a rectangular shape with a width of several μm and a length of several tens of μm in the extending direction of the thin line portion 60b when viewed from above. In this case, when viewed from above, the first contact layer 32 and the second contact layer 56 represented by broken lines are provided so as not to overlap.

  3A to 3F are process cross-sectional views of the method for manufacturing the semiconductor light emitting device according to the first embodiment. FIG. 3A is a schematic diagram of a semiconductor layer, and FIG. FIG. 3C is a schematic diagram in which ITO is formed, FIG. 3D is a schematic diagram of wafer bonding, FIG. 3E is a schematic diagram in which the second contact layer is patterned, FIG. 3F is a schematic diagram of a divided element.

On the crystal growth substrate 70 made of GaAs, an n-type GaAs second contact layer 56 (carrier concentration of 1 × 10 ¹⁸ cm ⁻³ , thickness of 0.1 μm), n-type In _0.5 (Ga _{0. 3} Al _0.7 ) _0.5 P current diffusion layer 54 (1.6 × 10 ¹⁸ cm ⁻³ carrier concentration, 3.5 μm thickness), n-type In _0.5 Al _0.5 P first layer 2 clad layers 52 (carrier concentration of 4 × 10 ¹⁷ cm ⁻³ , thickness of 0.6 μm), light emitting layer 40, first clad layer 38 of p-type In _0.5 Al _0.5 P (3 × 10 ¹⁷ cm ⁻³ carrier concentration, 0.6 μm thickness), composition graded layer whose composition is gradually changed from p-type In _0.5 (Ga _0.7 Al _0.3 ) _0.5 P to p-type GaP 36 (thickness of 0.03 .mu.m), impure windows p-type GaP layer 34 (3 × ¹⁰ 18 ^{cm -3} Concentration, thickness of 0.3 [mu] m), the first impurity concentration of the contact layer 32 (5 × ¹⁰ 20 ^{cm -3} of p-type GaP, thickness of 0.1 [mu] m), but the semiconductor layer 58 which are laminated in this order form (FIG. 3A).

The light emitting layer 40 is made of, for example, In _0.5 Ga _0.5 P, a well layer 20 having a thickness of 4 nm, and In _0.5 (Ga _0.4 Al _0.6 ) _0.5 P. An MQW (Multi Quantum Well) structure having a barrier layer 21 having a thickness of 7 nm is provided. The light emitting layer 40 can emit light in a red light wavelength range of 0.61 to 0.7 μm, for example. Note that the structure of the semiconductor layer 58 is not limited thereto. The semiconductor layer 58 can be crystal-grown using, for example, a MOCVD (Metal Organic Chemical Vapor Deposition) method or an MBE (Molecular Beam Epitaxy) method.

  Subsequently, as shown in FIG. 3B, a region of the first contact layer 32 where current is injected into the window layer 34 is left as a convex portion by patterning, and other regions are removed. As a removal method, a wet etching method using an acid solution or a dry etching method such as RIE (Reactive Ion Etching) can be used.

  Subsequently, as shown in FIG. 3C, the patterned first contact layer (convex portion) 32 and the uneven surface of the semiconductor layer 58 including the window layer 34 serving as the bottom surface around the convex portion are formed on tin. A transparent conductive film 26 such as doped indium oxide (ITO), zinc oxide, or tin oxide is formed.

  Further, the reflective metal layer 25 containing at least one of Ag, Ag alloy, Au, etc., the barrier metal layer 24 containing Ti, Pt, Ni, etc., and the second bonding metal layer 23 such as Au or AuIn are arranged in this order. Form with. On the other hand, a barrier metal layer 21 containing Ti, Pt, Ni or the like and a first bonding metal layer 22 such as AuIn are formed in this order on the support substrate 10 made of conductive Si or the like. In this way, the adhesion between the first electrode 20 and the semiconductor layer 58 can be improved, and the light extraction efficiency can be increased by the unevenness.

  As shown in FIG. 3D, the surface of the second bonding metal layer 23 on the semiconductor layer 58 side formed on the crystal growth substrate 70 and the first bonding metal layer 22 on the support substrate 10 side are overlapped. At the same time, the wafer is bonded by heating and pressing.

  Subsequently, as shown in FIG. 3E, the crystal growth substrate 70 is removed. Further, the second contact layer 56 is left only in the region where current is injected into the thin line portion 60b.

  Subsequently, as shown in FIG. 3F, pad portions 60a are formed in the non-formation regions of the second contact layer 56 so that the thin line portions 60b extend to the patterned second contact layer 56 regions. Is done. The second electrode 60 including the pad portion 60a and the thin wire portion 60b can be formed by stacking, for example, AuGe and Au in this order from the semiconductor layer 58 side. Further, the surface of the semiconductor layer 58 on which the second electrode 60 is not formed is subjected to frost processing to form irregularities, thereby forming a light extraction surface 58a. Further, a back electrode 62 made of Ti / Pt / Au or the like is formed on the back surface of the support substrate 10.

When the light emitting layer 40 includes In _x (Ga _1-y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦ 0.6), light in the wavelength range of green to red is emitted. be able to. Further, when the light emitting layer 40 includes Al _z Ga _1-z As (0 ≦ z ≦ 0.45), light in the wavelength range from red to near infrared light can be emitted. Further, when the light emitting layer 40 includes In _s Ga _1-s As _t P _1-t (0 ≦ s ≦ 1, 0 ≦ t ≦ 1), light in the near-infrared wavelength range is emitted. be able to.

The first contact layer 32 and the window layer 34 made of p-type GaP have a band gap energy higher than that of the light emitting layer 40 and do not absorb light in a wavelength range longer than about 0.55 μm. The first contact layer 32 may be In _0.5 (Ga _1- x Al _x ) _0.5 P (0.3 ≦ x) or Al _x Ga _1-x As (0.5 ≦ x).

In the present embodiment, the second contact layer 56 is made of GaAs, but the second contact layer 56 is In _x (Ga _1-y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦ 0.6). ), Al _z Ga _1-z As (0 ≦ z ≦ 0.5), or In _s Ga _1-s As _t P _1-t (0 ≦ s ≦ 1, 0 ≦ t ≦ 1). . When considering ohmic contact between a semiconductor and a metal, generally, the contact resistance is lower when the band gap energy of the semiconductor is smaller. Therefore, the contact resistance can be lowered by using a material having a smaller band gap energy as the second contact layer 56 in the emission wavelength range of red to green (band gap energy: 2.0 to 2.2 eV). it can. For example, when a sinter process is performed at 400 ° C. using GaAs (band gap energy is 1.4 eV) as the second contact layer 56 and using an AuGe alloy as a material of the second electrode 60 in contact with the second contact layer 56. The contact resistance can be 5 × 10 ⁻⁵ Ω · cm ² .

Since the area where the thin line portion 60b and the second contact layer 56 are in contact (area where current is injected) is small, the contact resistance is set to 1 × 10 ^{−4 in} order not to increase the forward voltage during operation. It is desirable to set it to Ω · cm ² or less. For this purpose, the material of the second contact layer 56 is In _x (Ga ₁₋ ) having a band gap energy smaller than the band gap energy (2.0 to 2.2 eV) corresponding to red to green in the emission wavelength range. _y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦ 0.6), Al _z Ga _1-z As (0 ≦ z ≦ 0.5), In _s Ga _1-s As _t P _1-t (0 ≦ s ≦ 1, 0 ≦ t ≦ 1) is advantageous.

The light emitting layer 40 includes In _x Ga _1-x N (0 ≦ x ≦ 1), and the window layer 34 and the first contact layer 32 include Al _y Ga _1-y N (0 ≦ y ≦ 1). A semiconductor layer 58 made of a containing system may be used. In this case, the light emitting layer 40 can emit light in the ultraviolet to green wavelength range. In addition, the second contact layer 56 may include In _x Ga _1-x N (0 ≦ x ≦ 1).

  Since ITO and GaP hardly form an alloy layer, there is almost no absorption of emitted light in the alloy layer. On the other hand, when the window layer of Au and GaP and the first contact layer of Au and GaP are brought into contact with each other without interposing ITO, for example, in the sintering process of the second electrode 60, GaP and An alloy layer is formed at the interface with Au and absorbs part of the emitted light. As a result, the luminance is reduced.

The first contact layer 32 of p-type GaP is doped with carbon (C) or the like at a high concentration. According to experiments by the present inventors, when the impurity concentration of the first contact layer 32 is higher than 5 × 10 ¹⁹ cm ⁻³ , the contact resistance between the first contact layer 32 and ITO is 1 × 10 ⁻³ W · cm ^2. Turned out to be lower. On the other hand, the impurity concentration of the window layer 34 made of p-type GaP (the activation rate can be regarded as approximately 1 so that the carrier concentration and the impurity concentration are approximately equal) is in the range of 1 to 5 × 10 ¹⁸ cm ⁻³ or the like. I do. In addition to carbon, Zn can also be used as an impurity in the window layer. It has also been found that when the GaP layer has an impurity concentration lower than 5 × 10 ¹⁹ cm ⁻³ , the contact resistance between the first contact layer 32 and ITO is as high as 1 × 10 ⁻³ W · cm ² or more.

  Au can also be used as the reflective metal layer 25. However, since the light reflectance of Au decreases when the emission wavelength is 0.6 μm or less, it is possible to achieve higher luminance by using Ag that does not cause a significant decrease in light reflectance even in a short wavelength region. Further, when an Ag alloy in which In or the like is added to Ag is used, environmental resistance including moisture resistance can be improved.

FIG. 4 is a schematic cross-sectional view of a semiconductor light emitting device according to a comparative example.
A first electrode 120 is provided on a support substrate 110 made of Si. The first electrode 120 has a structure in which a barrier metal layer 121, a first bonding metal layer 122, a second bonding metal layer 123, a barrier metal layer 124, an Ag layer 125, and an ITO film 126 are stacked from the support substrate 110 side. It is.

The semiconductor layer 158 includes the second contact layer 156, the current diffusion layer 154, the second cladding layer 152, the light emitting layer 140, the first cladding layer 138, the composition gradient layer 136, the window layer 134, and the first contact layer 132 in this order. Laminated. The material, impurity concentration, and thickness of each layer are the same as those in the first embodiment shown in FIG. Note that after the crystal growth, an insulating layer 190 such as SiO ₂ is formed as a current blocking layer on the first contact layer 132, and an opening 190a is selectively provided. An ITO film 126, an Ag layer 125, a barrier metal layer 124, and a second bonding metal layer 123 are provided so as to cover the opening 190a. After that, the structure of FIG. 4 can be obtained through a wafer bonding process.

  In the comparative example, the holes injected from the first electrode 120 are highly doped in the first contact layer 132 and have a very low resistivity. As a result, a carrier flow F <b> 1 that spreads toward the center is generated. On the other hand, electrons injected from the thin line portion 160 b of the second electrode 160 generate a carrier flow F <b> 2 that spreads outward in the lateral direction by the current diffusion layer 154. That is, carriers spread above and below the light emitting layer 140. For this reason, the light emitting region EEG spreads in the horizontal direction, the effective current injection density is lowered, and the light emission efficiency is lowered.

  On the other hand, in the first embodiment, since the contact resistance between the window layer 34 and the transparent conductive film 26 is high in the region where the first contact layer 32 is removed, holes are not injected. Since the contact resistance between the first contact layer 32 and the transparent conductive film 26 is low, holes are injected and a carrier flow F1 is generated. In this case, the selectively provided first contact layer 32 makes it difficult for holes to spread in the lateral direction and suppresses the light emitting region ER from spreading in the lateral direction. The total thickness of the first conductivity type layer 30 that is the p-type and includes the first contact layer 32, the window layer 34, and the first cladding layer 38 is the second cladding layer 52, the current diffusion layer 54, and the first Since the total thickness of the second conductivity type layer 50 composed of the two contact layers 56 and being n-type is smaller and the effective mass of holes is larger than the effective mass of electrons, the holes are removed from the first electrode 20. It is injected toward the light emitting layer 40 immediately above.

  On the other hand, since the current diffusion layer 54 has a low resistance and the effective mass of electrons is small, electrons are injected from the second electrode 60 to generate a carrier flow F2, and flow into the light emitting layer 40 while spreading in the lateral direction. As a result, the light emitting region ER indicated by the broken line does not extend directly below the thin line portion 60b. For this reason, the current injection density in the light emitting layer 40 is effectively increased, and high light emission efficiency can be achieved. The inventors have confirmed that the luminance of the semiconductor light emitting device according to the first embodiment can be higher by 20% or more than the luminance of the semiconductor light emitting device of the comparative example. In this case, it was also confirmed that an increase in forward voltage was suppressed and the reliability of the element could be secured.

  In the first embodiment, the light Gd traveling downward from the light emitting layer 40 passes through the first cladding layer 38, the composition gradient layer 36, the window layer 34, and the transparent conductive film 26, and is reflected by the reflective metal layer 25. The reflected light Gr is directed upward. The reflected light Gr and the light traveling upward from the light emitting layer 40 are emitted from the light extraction surface 58a as output light Go. If the transparent conductive film 26 is too thick, the downwardly directed light Gd and the upwardly reflected light Gr may interfere with each other, resulting in a decrease in luminance. On the other hand, if the transparent conductive film 26 is too thin, the contact resistance between the first contact layer 32 and the transparent conductive film 26 may increase, and the forward voltage may increase. According to the experiments by the present inventors, it has been found that, when the thickness of the transparent conductive film 26 is in the range of 0.04 to 0.09 μm, the forward voltage can be kept low while the luminance is kept high.

  On the other hand, if the first contact layer 32 is too thin, the contact resistance between the transparent conductive film 26 and the first contact layer 32 increases, and the forward voltage increases. Therefore, in order not to increase the forward voltage, the thickness of the first contact layer 32 needs to be 0.03 μm or more. On the other hand, since the impurity concentration of the first contact layer 32 made of GaP is high, an impurity level is formed in the band gap, and the light from the light emitting layer 40 may be absorbed. That is, when the thickness of the first contact layer 32 is 0.2 μm or more, the luminance is liable to decrease. Further, when the first contact layer 32 is removed by etching, if the first contact layer 32 is too thick, the etching time becomes longer, resulting in a problem that the in-plane distribution of the depth of the removed portion becomes larger. For this reason, the thickness of the first contact layer 32 is preferably in the range of 0.03 to 0.2 μm.

  On the other hand, if the window layer 34 is too thick, the current spreads in the lateral direction even in the window layer 34, and the light emitting region ER spreads below the thin line portion 60b, resulting in a decrease in luminance. On the other hand, when the window layer 34 is too thin, shape control becomes insufficient. That is, when the first contact layer 32 is 0.1 μm, for example, when the first contact layer in a region where no current is injected is removed, if etching is performed under 100% over-etching conditions, the etching depth is 0. 2 μm. If the thickness of the window layer 34 is not 0.2 μm or more, etching may proceed to the composition gradient layer 36 and the first cladding layer 38. For this reason, the thickness of the window layer 34 is preferably in the range of 0.2 to 0.6 μm.

FIG. 5 is a schematic cross-sectional view of a semiconductor light emitting device according to the second embodiment.
In the second embodiment, an insulating film 90 such as SiO ₂ is provided on the surface of the window layer 34 in a region where the first contact layer 32 is not provided. The insulating film 90 is provided with an opening 90a, and the transparent conductive film 26 is provided so as to cover the first contact layer 32 exposed in the opening 90a and the insulating film 90 which is a region where the opening 90a is not formed. It is done. Further, the first electrode 20 is provided on the transparent conductive film 26. Since the holes are blocked by the current blocking layer 90, the holes are injected into the window layer 34 through the first contact layer 32.

  Also in the second embodiment, the thickness of the first conductivity type layer 30 is smaller than the thickness of the second conductivity type layer 50, and the effective mass of holes is heavier than the effective mass of electrons. The first conductive layer 30 is injected into the light emitting layer 40 immediately above the first contact layer 32 without spreading in the lateral direction. Therefore, as shown in FIG. 5, the light emitting region is directly above the first contact layer 32, and the current injection density can be kept high. The semiconductor light emitting device according to the second embodiment can increase the luminance by about 20% or more compared to the comparative example.

When SiO ₂ , SiON, or SiN (including Si ₃ N ₄ ) is used as the insulating film 90, absorption of light from the light emitting layer 40 can be suppressed. In addition, electrical insulation between the window layer 34 and the transparent conductive film 26 can be further ensured. In the case of an output LED having a high operating current density, for example, a high current drive higher than 1 A, it is preferable to provide the insulating film in this way.

FIG. 6A is a schematic plan view of a semiconductor light emitting device according to the third embodiment, and FIG. 6B is a schematic cross-sectional view taken along the line BB.
The semiconductor layer 58 includes the second contact layer 56, the current diffusion layer 54, the second cladding layer 52, the light emitting layer 40, the first cladding layer 38, the composition gradient layer 36, the window layer 34, and the first contact layer 32 in this order. Laminated. The material, impurity concentration, and thickness of each layer are the same as those in the first embodiment shown in FIG.

  As shown in FIGS. 1A and 1B, the first contact layers 32 are provided so as to be dispersed in the direction of the thin line portion 60b as viewed from above. On the other hand, the second contact layer 56 formed on the current diffusion layer 54 and made of GaAs or the like is also distributed along the thin line portion 60b. The fine line portion 60b extends on the second contact layer 56 and the current diffusion layer 54 provided in a distributed manner.

The contact resistance between the thin wire portion 60b and the second contact layer 56 is larger than the contact resistance between the thin wire portion 60b and the n-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P current diffusion layer 54. Low. Therefore, as shown in FIG. 6B, electrons are injected from the thin line portion 60 b into the second contact layer 56 and flow into the current diffusion layer 54 through the second contact layer 56. The electrons generate a carrier flow F2 that travels toward the light emitting layer 40 while spreading in the current diffusion layer 54 in the lateral direction. On the other hand, the holes travel from the first contact layer 32 toward the light emitting layer 40 immediately above. In this case, the region where the second contact layer 56 is provided has a longer distance to the light emitting region ER on the first contact layer 32, so light absorption in the second contact layer 56 is reduced, and light extraction efficiency is increased. Can be further enhanced. Even if only the second contact layer 56 is dispersed and the first contact layer 32 is provided continuously, light absorption can be reduced.

  The semiconductor light emitting devices according to the first to third embodiments and the modifications associated therewith remove at least one of the first and second contact layers provided with the light emitting layer sandwiched therebetween, The contact layer 32 and the second contact layer 56 are provided so as not to overlap each other when viewed from above. Further, when viewed from above, the region where the emission intensity is high and the thin wire electrode 60b are provided so as not to overlap. For this reason, the current injection density into the light emitting layer and the light emission efficiency can be increased, and the light extraction efficiency can be increased. The high-power LEDs obtained in this way are widely used in lighting devices, display devices, traffic lights and the like.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 Support substrate, 20 1st electrode, 25 Reflective metal layer, 26 Transparent electrically conductive film, 32 1st contact layer, 34 Window layer, 40 Light emitting layer, 56 2nd contact layer, 58 Semiconductor layer, 60 2nd electrode, 60a Pad Part, 60b Fine wire part, 90 Insulating layer

Claims (10)

A support substrate;
A first electrode provided on the support substrate and having at least a reflective metal layer and a transparent conductive film containing any of tin-doped indium oxide, zinc oxide, and tin oxide in this order;
A first conductivity type layer having a first contact layer containing GaP, a window layer containing GaP having an impurity concentration lower than that of the first contact layer, and a first cladding layer in this order, The surface on the side in contact with the transparent conductive film has a first conductivity type layer including a convex portion made of the first contact layer selectively provided, and the window layer serving as a bottom surface around the convex portion. ,
Provided on the first conductivity type layer, In _x (Ga _1-y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦ 0.6), Al _z Ga _1-z As ( 0 ≦ z ≦ 0.5), and In _s Ga _1-s As _t P _1-t (0 ≦ s ≦ 1, 0 ≦ t ≦ 1),
A second cladding layer, a current diffusion layer, In _x (Ga _1-y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦) provided on the light emitting layer from the light emitting layer side. 0.6), Al _z Ga _1-z As (0 ≦ z ≦ 0.5), In _s Ga _1-s As _t P _1-t (0 ≦ s ≦ 1, 0 ≦ t ≦ 1) A second conductivity type layer having at least a second contact layer in this order, the second conductivity type layer having a thickness larger than the thickness of the first conductivity type layer;
A pad portion provided on a non-formation region of the second contact layer of the second conductivity type layer; a first region extending on the second contact layer; the pad portion; and the first region; A thin line portion having a second region provided in the non-formation region between the second electrode and the surface of the thin line portion on the second conductivity type layer side and the second conductivity type layer A second electrode made of a metal material that is continuous with the surface of the pad portion on the side,
With
The band gap energy of the first contact layer and the window layer is larger than the band gap energy of the light emitting layer, respectively.
When viewed from above, the first contact layer and the second contact layer are provided so as not to overlap,
As viewed from above, the first contact layer includes a region dispersed along a direction in which the thin line portion extends. A support substrate;
A first electrode provided on the support substrate;
The first contact layer, the window layer having an impurity concentration lower than the impurity concentration of the first contact layer, and the first cladding layer are provided in this order from the first electrode side provided on the first electrode. A first conductivity type layer having at least;
A light emitting layer provided on the first conductivity type layer;
A second conductivity type layer provided on the light emitting layer and having at least a second cladding layer, a current diffusion layer, and a second contact layer in this order from the light emitting layer side;
A pad portion provided on a non-formation region of the second contact layer of the second conductivity type layer; a first region extending on the second contact layer; the first region; and the pad portion; A thin line portion having a second region provided in the non-formation region between the second electrode and the second conductive layer side of the second conductive layer side and the second conductive layer side A surface of the pad portion of the second electrode made of a continuous metal material,
With
The band gap energy of the first contact layer and the window layer is larger than the band gap energy of the light emitting layer, respectively.
The first contact layer is selectively provided between the window layer and the first electrode;
The semiconductor light emitting device, wherein the first contact layer and the second contact layer are provided so as not to overlap each other when viewed from above.   3. The semiconductor light emitting element according to claim 2, wherein the first contact layer includes a region dispersed in a direction in which the thin line portion extends as viewed from above.   4. The semiconductor light emitting element according to claim 2, wherein the second contact layer is provided in a dispersed manner in a direction in which the thin line portion extends as viewed from above. 5. The light emitting layer is composed of In _x (Ga _1-y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦ 0.6), Al _z Ga _1-z As (0 ≦ z ≦ 0.5). ), In _s Ga _1-s As _t P _1-t (0 ≦ s ≦ 1, 0 ≦ t ≦ 1),
The semiconductor light emitting element according to claim 2, wherein the first contact layer and the window layer each contain GaP. The light emitting layer and the first cladding layer include In _x (Ga _1-y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦ 1),
The first conductivity type layer is provided between the first cladding layer and the window layer, and In _x (Ga _1-y Al _y ) _1-x P (0 ≦ x ≦ 1, 0 ≦ y ≦ 1). The semiconductor light emitting device according to claim 5, further comprising a composition gradient layer in which the In composition ratio x and the Al composition ratio y approach zero as the first contact layer is approached. The light emitting layer includes In _x Ga _1-x N (0 ≦ x ≦ 1),
5. The semiconductor light emitting element according to claim 2, wherein the window layer and the first contact layer include Al _y Ga _1-y N (0 ≦ y ≦ 1).   An insulating layer provided to be in contact with the window layer and the first electrode in a region where the first contact layer is not provided between the window layer and the first electrode. The semiconductor light emitting element according to claim 2.   The first electrode is provided between the transparent conductive film and the support substrate, the transparent conductive film including any of tin-doped indium oxide, zinc oxide, and tin oxide in contact with the first contact layer, and the light emission A semiconductor light emitting element according to claim 2, further comprising a reflective metal layer capable of reflecting light from the layer.   The surface of the first conductivity type layer on the side in contact with the first electrode includes a selectively provided convex portion made of the first contact layer and the window layer serving as a bottom surface around the convex portion. The semiconductor light emitting element according to claim 2, wherein the semiconductor light emitting element is included.

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