JP2022184610A - Light-emitting device - Google Patents

Abstract

To provide a light-emitting device capable of increasing light extraction efficiency while suppressing an increase in forward voltage.SOLUTION: In a top view, a p-side electrode is provided around an n-side electrode, and a translucent conductive film has a first region that is outside the p-side electrode and positioned between the p-side electrode and an outer edge of a p-side semiconductor layer and a second region that is positioned inside the p-side electrode. In the top view, the first region has a plurality of first parts extending from the p-side electrode toward the outer edge of the p-side semiconductor layer and a second part positioned between the first parts. The film thickness of the first parts is greater than the film thickness of the second region and the film thickness of the second part.SELECTED DRAWING: Figure 2A

Description

The present invention relates to light emitting devices.

There is a light-emitting device in which a p-side electrode and an n-side electrode are arranged on the light extraction surface side, and a translucent conductive film is arranged between the p-side electrode and the p-side semiconductor layer (for example, Patent Document 1). In such a light-emitting element, thinning the light-transmitting conductive film suppresses light absorption by the light-transmitting conductive film and is advantageous for improving the light extraction efficiency, but causes an increase in the forward voltage. .

JP 2014-045108 A

An object of the present invention is to provide a light-emitting device capable of improving light extraction efficiency while suppressing an increase in forward voltage.

According to one aspect of the present invention, a light emitting device is a semiconductor laminate having a p-side semiconductor layer, an n-side semiconductor layer, and an active layer positioned between the p-side semiconductor layer and the n-side semiconductor layer. a translucent conductive film provided on the p-side semiconductor layer, a first connecting portion provided on the translucent conductive film, and a first extending portion extending from the first connecting portion. and an n-side electrode provided on the n-side semiconductor layer. When viewed from above, the p-side electrode is provided around the n-side electrode. When viewed from above, the translucent conductive film includes a first region located outside the p-side electrode and between the p-side electrode and the outer edge of the p-side semiconductor layer; and a second region located inside the electrode. As viewed from above, the first region has a plurality of first portions extending from the p-side electrode toward the outer edge of the p-side semiconductor layer, and second portions positioned between the first portions. The film thickness of the first portion is thicker than the film thickness of the second region and the film thickness of the second portion.
Further, according to one aspect of the present invention, the light emitting device is a semiconductor having a p-side semiconductor layer, an n-side semiconductor layer, and an active layer positioned between the p-side semiconductor layer and the n-side semiconductor layer. a laminate, a translucent conductive film provided on the p-side semiconductor layer, a first connecting portion provided on the translucent conductive film, and a first extending portion extending from the first connecting portion and an n-side electrode provided on the n-side semiconductor layer and having a second connecting portion and a second extending portion extending from the second connecting portion. A said 1st extending|stretching part is provided facing a said 2nd extending|stretching part. When viewed from the top, the translucent conductive film has an outer region positioned between the first extending portion and the outer edge of the p-side semiconductor layer, and between the first extending portion and the second extending portion. and an inner region located at the When viewed from above, the outer region has a plurality of first portions extending from the first extending portion toward the outer edge of the p-side semiconductor layer, and second portions located between the first portions. The film thickness of the first portion is thicker than the film thickness of the inner region and the film thickness of the second portion.

According to the light emitting device of the present invention, light extraction efficiency can be improved while suppressing an increase in forward voltage.

1 is a schematic top view of a light emitting device according to a first embodiment of the invention; FIG. It is an enlarged view of the A section in FIG. 1 is a schematic top view of a light emitting device according to a first embodiment of the invention; FIG. FIG. 2 is a schematic cross-sectional view taken along line III-III of FIG. 1; FIG. 2 is a schematic cross-sectional view taken along line IV-IV of FIG. 1; FIG. 4 is a table showing the total area of the first region of each sample, the width and area of each portion of the first region; FIG. 4 is a graph for explaining the forward voltage of each sample; 4 is a graph for explaining the output of each sample; FIG. 4 is a schematic top view of a light emitting device according to a second embodiment of the invention; FIG. 8 is an enlarged view of a B portion in FIG. 7; FIG. 8 is a schematic cross-sectional view taken along line IX-IX of FIG. 7; 1A to 1D are schematic cross-sectional views showing a first method for forming a translucent conductive film according to an embodiment of the present invention; 1A to 1D are schematic cross-sectional views showing a first method for forming a translucent conductive film according to an embodiment of the present invention; 1A to 1D are schematic cross-sectional views showing a first method for forming a translucent conductive film according to an embodiment of the present invention; FIG. 4A is a schematic cross-sectional view showing a second method of forming a translucent conductive film according to an embodiment of the present invention; FIG. 4A is a schematic cross-sectional view showing a second method of forming a translucent conductive film according to an embodiment of the present invention; FIG. 4A is a schematic cross-sectional view showing a second method of forming a translucent conductive film according to an embodiment of the present invention;

Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals. Note that the cross-sectional views also include those showing only the cut surface.

[First embodiment]
FIG. 1 is a schematic top view of a light emitting device 1 according to a first embodiment of the invention.
2A is an enlarged view of part A in FIG. 1. FIG.
FIG. 3 is a schematic cross-sectional view along line III-III in FIG.
FIG. 4 is a schematic cross-sectional view taken along line IV-IV of FIG.

The light emitting device 1 includes a substrate 100 , a semiconductor laminate 10 , a translucent conductive film 20 , a p-side electrode 50 , an n-side electrode 60 and an insulating film 81 . 1 and 2A show the top surface of the configuration excluding the insulating film 81 shown in FIGS. 3 and 4. FIG. A first direction X and a second direction Y are two directions parallel to the main surface of the substrate 100 and perpendicular to each other. A third direction Z is a direction perpendicular to the first direction X and the second direction Y and extending from the substrate 100 toward the semiconductor stack 10 .

The shape of the semiconductor stacked body 10 when viewed from above can be, for example, a square or a rectangle. In the light-emitting device 1 of the first embodiment, as shown in FIG. 1, the semiconductor laminate 10 has a square shape when viewed from above. The corners of this square may be right angles or rounded. The length of one side of the semiconductor laminate 10 can be, for example, 100 μm or more and 1500 μm or less. The shape of the light emitting element 1 when viewed from above is a square.

The semiconductor laminate 10 includes, for example, a nitride semiconductor such as In _x Al _y Ga _1-xy N (0≦x, 0≦y, x+y≦1). For the substrate 100, for example, an insulating substrate such as sapphire or spinel (MgAl ₂ O ₄ ) having any one of the C-plane, R-plane, and A-plane as the main surface can be used. Also, as the substrate 100, a conductive substrate such as GaN, SiC (including 6H, 4H, and 3C), ZnS, ZnO, GaAs, and Si may be used. When viewed from above, the length of one side of the substrate 100 can be, for example, 100 μm or more and 1500 μm or less.

As shown in FIGS. 3 and 4, the semiconductor laminate 10 includes an n-side semiconductor layer 11, a p-side semiconductor layer 12, and an active layer 13 positioned between the n-side semiconductor layer 11 and the p-side semiconductor layer 12. and An n-side semiconductor layer 11 is provided on a substrate 100 , an active layer 13 is provided on the n-side semiconductor layer 11 , and a p-side semiconductor layer 12 is provided on the active layer 13 . The active layer 13 is a light-emitting layer that emits light. The active layer 13 includes a plurality of barrier layers and a plurality of well layers, and can have a multiple quantum well structure in which the barrier layers and the well layers are alternately laminated.

The upper surface of the n-side semiconductor layer 11 is not provided with the active layer 13 and the p-side semiconductor layer 12 and has a first surface 11 a and a second surface 11 b exposed from the active layer 13 and the p-side semiconductor layer 12 . An n-side electrode 60 is provided on the first surface 11a.

As shown in FIG. 1 , the second surface 11 b is located at the outermost periphery of the n-side semiconductor layer 11 and continues along the outer edge 11 c of the n-side semiconductor layer 11 . An outer edge 11 c of the n-side semiconductor layer 11 constitutes an outer edge of the semiconductor stack 10 . The outer edge 12 a of the p-side semiconductor layer 12 is along the outer edge 11 c of the n-side semiconductor layer 11 inside the outer edge 11 c of the n-side semiconductor layer 11 . When viewed from above, the second surface 11b of the n-side semiconductor layer 11 is located between the outer edge 11c of the n-side semiconductor layer 11 and the outer edge 12a of the p-side semiconductor layer 12 .

As shown in FIGS. 3 and 4, a translucent conductive film 20 is provided on the p-side semiconductor layer 12 . The translucent conductive film 20 is not provided on the first surface 11 a and the second surface 11 b of the n-side semiconductor layer 11 . The translucent conductive film 20 diffuses the current supplied through the p-side electrode 50 in the planar direction of the p-side semiconductor layer 12 . The translucent conductive film 20 is electrically connected to the p-side semiconductor layer 12 and the p-side electrode 50 . Further, the translucent conductive film 20 has translucency with respect to the wavelength of the light from the active layer 13 . The translucent conductive film 20 preferably has a transmittance of 60% or more, preferably 70% or more, more preferably 80% or more with respect to the wavelength of light from the active layer 13 .

As the translucent conductive film 20, for example, oxide films such as ITO (Indium Tin Oxide), AZO (Aluminum Zinc Oxide), IZO (Indium Zinc Oxide), and Ga ₂ O ₃ can be used. The film thickness of the translucent conductive film 20 can be, for example, 10 nm or more and 100 nm or less.

A p-side electrode 50 is provided on the translucent conductive film 20 . The p-side electrode 50 is in contact with the translucent conductive film 20 . The resistivity of the p-side electrode 50 is lower than that of the translucent conductive film 20 . The transmittance of the p-side electrode 50 with respect to the wavelength of light from the active layer 13 is lower than the transmittance of the translucent conductive film 20 with respect to the wavelength of light from the active layer 13 . The p-side electrode 50 is made of a metal material. As the p-side electrode 50, for example, metal materials such as Au, Cu, Al, Ru, Ti, Cr, and Ni, or alloys containing these metal materials can be used. The film thickness of the p-side electrode 50 can be, for example, 0.3 μm or more and 5 μm or less.

As shown in FIG. 1 , the p-side electrode 50 has a first connecting portion 51 and a first extending portion 52 extending from the first connecting portion 51 . The first connecting portion 51 is positioned on a virtual line that bisects one side of the semiconductor stacked body 10 and is parallel to the first direction X. As shown in FIG. For example, two first extending portions 52 extend from the first connecting portion 51 . The two first extending portions 52 are located on both sides of an imaginary line passing through the first connecting portion 51 and parallel to the first direction X (which coincides with line IV-IV in FIG. 1) in the second direction Y. As shown in FIG. The two first extending portions 52 are arranged line-symmetrically with respect to an imaginary line passing through the first connecting portion 51 and parallel to the first direction X. As shown in FIG.

An n-side electrode 60 is provided on the first surface 11 a of the n-side semiconductor layer 11 . The n-side electrode 60 is in contact with the n-side semiconductor layer 11 . The resistivity of the n-side electrode 60 is lower than that of the translucent conductive film 20 . The resistivity of the n-side electrode 60 can be, for example, 1 μΩ·cm or more and 100 μΩ·cm or less. The resistivity of the translucent conductive film 20 can be 10 μΩ·cm or more and 300 μΩ·cm or less. The transmittance of the n-side electrode 60 with respect to the wavelength of light from the active layer 13 is lower than the transmittance of the translucent conductive film 20 with respect to the wavelength of light from the active layer 13 . The n-side electrode 60 is made of a metal material. As the n-side electrode 60, for example, the same metal material as the p-side electrode 50 described above can be used. The film thickness of the n-side electrode 60 can be, for example, 0.3 μm or more and 5 μm or less.

The n-side electrode 60 has a second connecting portion 61 and a second extending portion 62 extending from the second connecting portion 61 . The second connection portion 61 is located on a virtual line that bisects one side of the semiconductor stacked body 10 and is parallel to the first direction X. As shown in FIG. The second connection portion 61 is arranged in the first direction X so as to face the first connection portion 51 of the p-side electrode 50 . For example, two second extensions 62 extend from the second connection 61 . The two second extensions 62 are located between the two first extensions 52 of the p-side electrode 50 in the second direction Y. As shown in FIG. In addition, the two second extending portions 62 extend in the second direction Y along an imaginary line that passes through the first connecting portion 51 and the second connecting portion 61 and is parallel to the first direction X (which coincides with line IV-IV in FIG. 1). positioned across. The two second extending portions 62 are arranged line-symmetrically with respect to an imaginary line parallel to the first direction X passing through the first connecting portion 51 and the second connecting portion 61 .

When viewed from above, the first connection portion 51 and the two first extension portions 52 of the p-side electrode 50 are provided around the n-side electrode 60 . The tip portion 54 a of the first extending portion 52 of the p-side electrode 50 is located closer to the outer edge 12 a of the p-side semiconductor layer 12 than the second connection portion 61 of the n-side electrode 60 in the first direction X. That is, the distance in the first direction X between the tip portion 54 a of the first extending portion 52 and the outer edge 12 a of the p-side semiconductor layer 12 is equal to the distance between the second connecting portion 61 and the outer edge 12 a of the p-side semiconductor layer 12 . shorter than the distance in the first direction X;

The p-side electrode 50 further has a third extending portion 53 . The third extending portion 53 extends from the first connecting portion 51 toward the second connecting portion 61 of the n-side electrode 60 . A tip portion 53 a of the third extension portion 53 is located between two second extension portions 62 of the n-side electrode 60 in the second direction Y. As shown in FIG.

As shown in FIGS. 3 and 4, the insulating film 81 covers the semiconductor laminate 10, the translucent conductive film 20, the p-side electrode 50, and the n-side electrode 60. As shown in FIGS. As shown in FIG. 4 , part of the upper surface 51 a of the first connection portion 51 of the p-side electrode 50 and part of the upper surface 61 a of the second connection portion 61 of the n-side electrode 60 are exposed from the insulating film 81 . there is Wires, for example, are joined to the upper surface 51a of the first connection portion 51 and the upper surface 61a of the second connection portion 61, and the p-side electrode 50 and the n-side electrode 60 are electrically connected to an external circuit via the wires.

As viewed from above, the translucent conductive film 20 has a first region 21 , a second region 22 and a third region 23 . FIG. 2B is a schematic top view similar to FIG. 1. In FIG. 2B, the first area 21 and the third area 23 are hatched with dots. The first region 21 is outside the p-side electrode 50, between the first extending portion 52 and the outer edge 12a of the p-side semiconductor layer 12, and between the first connecting portion 51 and the outer edge 12a of the p-side semiconductor layer 12. located between The second region 22 is located inside the first extending portion 52 and the first connecting portion 51 of the p-side electrode 50 . When viewed from above, the first connecting portion 51 and the first extending portion 52 of the p-side electrode 50 are positioned between the first region 21 and the second region 22 .

As shown in FIG. 2, in top view, the first region 21 of the translucent conductive film 20 has a plurality of first portions 21a, a plurality of second portions 21b, and a plurality of third portions 21c. The first portion 21 a extends from the first extending portion 52 of the p-side electrode 50 toward the outer edge 12 a (shown in FIG. 1) of the p-side semiconductor layer 12 . Also, the first portion 21 a extends from the first connecting portion 51 of the p-side electrode 50 toward the outer edge 12 a of the p-side semiconductor layer 12 . The second portions 21b are positioned between the plurality of first portions 21a. The third portion 21c is connected to the first portion 21a and positioned between two adjacent first portions 21a among the plurality of first portions 21a. When viewed from above, one second portion 21b is surrounded by the first portion 21a and the third portion 21c.

In this specification, the film thickness represents the thickness in the third direction Z. The first portion 21a has a first film thickness. The first film thickness is the maximum film thickness of the first portion 21a. The second portion 21b has a second film thickness that is thinner than the first film thickness. The second film thickness is the maximum film thickness of the second portion 21b. Hereinafter, the first film thickness is simply referred to as the film thickness of the first portion 21a, and the second film thickness is simply referred to as the film thickness of the second portion 21b. In addition, the film thicknesses of other regions and portions described below also represent the maximum film thickness.

The film thickness of the first portion 21a is thicker than the film thickness of the second region 22 and the film thickness of the second portion 21b. The film thickness of the third portion 21c is thicker than the film thickness of the second region 22 and the film thickness of the second portion 21b. For example, the thickness of the first portion 21a and the thickness of the third portion 21c are the same. In the first region 21, the translucent conductive films 20 having the same film thickness are arranged in a grid pattern. For example, the film thickness of the second region 22 and the film thickness of the second portion 21b are the same. The film thickness of the first portion 21a can be, for example, 50 nm or more and 100 nm or less. The film thickness of the second portion 21b can be, for example, 10 nm or more and 50 nm or less. The difference between the first film thickness of the first portion 21a and the second film thickness of the second portion 21b can be, for example, 20 nm or more and 40 nm or less. When an inclined surface or curved surface is formed between the first portion 21a and the second portion 21b in a cross-sectional view, for example, a portion having a thickness of 60% or less of the first thickness of the first portion 21a is the second thickness. Let it be the portion 21b.

The cross section of the first region 21 of the translucent conductive film 20 in FIG. 3 shows the cross section of the first portion 21a. The cross section of the first region 21 of the translucent conductive film 20 in FIG. 4 represents the cut surface of the first portion 21a and the cut surface of the fifth portion 21d, which will be described later. As shown in FIG. 2A , the first portion 21 a extends from the first extending portion 52 along the second direction Y toward the outer edge 12 a of the p-side semiconductor layer 12 . On line IV-IV in FIG. 1 , the first portion 21 a extends from the first connecting portion 51 along the first direction X toward the outer edge 12 a of the p-side semiconductor layer 12 .

As shown in FIGS. 1, 2A, and 2B, when viewed from above, the translucent conductive film 20 is continuous with the first region 21 and between the tip portion 54a of the first extending portion 52 and the second region 22. It further has a third region 23 located at . The third region 23 is also located between the distal end portion 54 of the first extending portion 52 and the second region 22 . The tip side portion 54 of the first extending portion 52 is a portion including the tip portion 54a. The distal end portion 54 is a portion of the first extending portion 52 between the portion parallel to the first direction X and the distal end portion 54a. The length of the tip side portion 54 is, for example, 20% or more and 30% or less of the entire length of one first extending portion 52 .

When viewed from above, the third region 23 is adjacent to the distal end portion 54 of the first extending portion 52 . When viewed from above, the third region 23 is positioned between the second region 22 and the distal end portion 54 , and the distal end portion 54 is positioned between the third region 23 and the first region 21 .

As shown in FIG. 2B , the first boundary 91 between the second region 22 and the third region 23 is located closer to the first extending portion 52 of the p-side electrode 50 than the n-side electrode 60 is. The shortest distance between the first boundary 91 between the second region 22 and the third region 23 and the tip portion 54a is shorter than the shortest distance between

It is preferable that the width of the third region 23 in the direction orthogonal to the extending direction of the distal end portion 54 gradually decreases from the distal end portion 54 a along the distal end portion 54 toward the first connecting portion 51 .

As shown in FIG. 2A, in top view, the third region 23 has a plurality of fourth portions 23a and a plurality of sixth portions 23b. The fourth portion 23 a extends from the distal end portion 54 of the first extending portion 52 toward the n-side electrode 60 . The sixth portion 23b is positioned between the plurality of fourth portions 23a. When viewed from above, for example, the fourth portions 23a are arranged in a grid pattern.

The thickness of the fourth portion 23a is thicker than the thickness of the second region 22, the thickness of the second portion 21b, and the thickness of the sixth portion 23b. For example, the film thickness of the fourth portion 23a is the same as the film thickness of the first portion 21a and the film thickness of the third portion 21c. For example, the film thickness of the sixth portion 23b is the same as the film thickness of the second region 22 and the film thickness of the second portion 21b.

As shown in FIG. 2B, when viewed from above, the first region 21 extends between the tip portion 54a of the first extending portion 52 and the outer edge 12a of the p-side semiconductor layer 12 in the first direction X, and the third region 23 and the outer edge 12 a of the p-side semiconductor layer 12 . Also, in the first direction X, the second region 22 and the first region 21 are positioned between the n-side electrode 60 and the outer edge 12 a of the p-side semiconductor layer 12 . A second region 22 and a first region 21 are formed on the side of the outer edge 12a of the p-side semiconductor layer 12 in the first direction X from an imaginary line 93 connecting the tip portions 54a of the two first extending portions 52 and parallel to the second direction Y. A second boundary 92 with is located. The second boundary 92 may be continuous with the first boundary 91 . As shown in FIG. 2B, the second boundary 92 is provided by a single curve. The second boundary 92 may be provided with a plurality of curved lines corresponding to the shapes of the second connecting portion 61 and the second extending portion 62, for example. A boundary between the first area 21 and the third area 23 is located on the virtual line 93 .

The first region 21 located between the second connection portion 61 of the n-side electrode 60 and the outer edge 12a of the p-side semiconductor layer 12 is located between the second connection portion 61 and the outer edge 12a of the p-side semiconductor layer 12. It is positioned closer to the outer edge 12 a of the p-side semiconductor layer 12 than the second region 22 . The shortest distance between the second boundary 92 between the second region 22 and the first region 21 located between the second connecting portion 61 and the outer edge 12a of the p-side semiconductor layer 12 and the outer edge 12a of the p-side semiconductor layer 12 The distance is shorter than the shortest distance between the second boundary 92 and the second connecting portion 61 .

When viewed from above, the first region 21 located between the second connecting portion 61 and the outer edge 12a of the p-side semiconductor layer 12 further has a fifth portion 21d. The fifth portion 21d extends at least on a virtual line (matching the IV-IV line) passing through the second connection portion 61 of the n-side electrode 60 and parallel to the first direction X, the second connection portion 61 and p It is located between the outer edge 12 a of the side semiconductor layer 12 . The film thickness of the fifth portion 21 d is thinner than the film thickness of the first portion 21 a and the film thickness of the third portion 21 c , and the film thickness of the second portion 21 b and the film thickness of the second region 22 .

In the first region 21 located between the second connecting portion 61 and the outer edge 12a of the p-side semiconductor layer 12, the fifth portions 21d may be arranged in a grid pattern. In addition, in the first region 21 located between the second connecting portion 61 and the outer edge 12a of the p-side semiconductor layer 12, a portion located between the plurality of fifth portions 21d and having a thinner film thickness than the fifth portions 21d. may be placed.

The translucent conductive film 20 has a thick film portion and a thin film portion thinner than the thick film portion. The thick film portion includes a first portion 21a. The thick film portion may include a third portion 21c, a fourth portion 23a, and a fifth portion 21d. The thin film portion includes a second region 22 and a second portion 21b. The thin film portion may include a sixth portion 23b. For example, in the translucent conductive film 20, the thickness of the thick film portion is 1.5 to 3.0 times the thickness of the thin film portion.

Also, the film thickness of the translucent conductive film 20 arranged directly under the p-side electrode 50 is preferably thicker than the film thickness of the thin film portion. For example, the film thickness of the translucent conductive film 20 arranged directly under the p-side electrode 50 is the same as the film thickness of the thick film portion. A thin film portion of the translucent conductive film 20 may be arranged immediately below the p-side electrode 50 .

In the light-emitting device 1 of this embodiment, light from the active layer 13 is extracted to the outside of the light-emitting device 1 mainly through the p-side semiconductor layer 12 and the translucent conductive film 20 .

A first region of the translucent conductive film 20 positioned between the p-side electrode 50 and the outer edge 12a of the p-side semiconductor layer 12 in a configuration in which the p-side electrode 50 is provided around the n-side electrode 60 as viewed from above. Reference numeral 21 denotes a region in which the current is more difficult to diffuse than the second region 22 located inside the p-side electrode 50 .

According to this embodiment, the first portion 21a, which is a thick film portion thicker than the second region 22, is arranged in the first region 21. As shown in FIG. As a result, the sheet resistance of the first region 21 can be reduced and the current can be easily diffused in the first region 21 as compared with the case where the entire first region 21 is a thin film portion such as the second region 22 . In addition, by arranging the second portion 21b, which is a thin film portion thinner than the first portion 21a, in the first region 21, compared to the case where the entire first region 21 is a thick film portion, Light absorption can be suppressed. Further, by setting the film thickness of the second region 22, in which the current is more likely to diffuse than the first region 21, to be thinner than the thick film portion of the first region 21, when the entire region of the translucent conductive film 20 is thickened, In comparison, light absorption by the translucent conductive film 20 can be suppressed. Therefore, according to the light-emitting element 1 of the present embodiment, it is possible to improve the light extraction efficiency while suppressing an increase in the forward voltage.

In order to facilitate the diffusion of the current from the p-side electrode 50 in the plane direction of the translucent conductive film 20, the translucent conductive film 20 in the region immediately below the p-side electrode 50 and in contact with the p-side electrode 50 is formed. The thickness is preferably the same as the thickness of the thick film portion such as the first portion 21a.

In the first region 21, by disposing the third portion 21c as a thick film portion between the adjacent first portions 21a, the current can be diffused in the first region 21 more than when only the first portions 21a are disposed. It can be done easily.

A current is supplied to the light emitting element 1 from an external circuit via wires provided in the first connection portion 51 and the second connection portion 61, for example. The current supplied to the first connecting portion 51 flows through the first extending portion 52 from the first connecting portion 51 toward the tip portion 54a. The distal end portion 54a is positioned farthest from the first connection portion 51 in the path through which the current flows among the first extension portions 52 . Therefore, in the translucent conductive film 20 , the region near the distal end portion 54 including the distal end portion 54 a of the first extending portion 52 receives more current than the region closer to the first connecting portion 51 than the distal end portion 54 . This is an area where diffusion is difficult.

In such a region where the current is difficult to diffuse, by providing the third region 23 including the fourth portion 23a as the thick film portion of the translucent conductive film 20 inside the first extending portion 52, translucent conductive Current can be easily diffused to the region near the tip side portion 54 in the film 20, and an increase in forward voltage can be suppressed.

In the first direction X, the first connection portion 51 of the p-side electrode 50 and the second connection portion 61 of the n-side electrode 60 are arranged to face each other. In such an arrangement, the current tends to be biased in the translucent conductive film 20 between the first connection portion 51 and the second connection portion 61, and the second connection portion 61 and the outer edge 12a of the p-side semiconductor layer 12 It becomes difficult for the current to diffuse in the region between

According to the present embodiment, by arranging the fifth portion 21d as the thick film portion of the translucent conductive film 20 in the region between the second connection portion 61 and the outer edge 12a of the p-side semiconductor layer 12, the Current can be easily diffused in the region between the second connection portion 61 and the outer edge 12a of the p-side semiconductor layer 12, and an increase in forward voltage can be suppressed.

Note that current tends to diffuse more easily in the region between the second connecting portion 61 and the outer edge 12a of the p-side semiconductor layer 12 than in the region between the first extending portion 52 and the outer edge 12a of the p-side semiconductor layer 12. There is Therefore, even if the film thickness of the fifth portion 21d is not as thick as the film thickness of the first portion 21a, it is possible to suppress the increase in the forward voltage. Therefore, by making the film thickness of the fifth portion 21d thinner than the film thickness of the first portion 21a and thicker than the film thickness of the second region 22 and the film thickness of the second portion 21b, the forward voltage can be reduced. At the same time, light absorption can also be suppressed.

In the present embodiment, the form in which the insulating film 81 is provided has been described, but the insulating film 81 may not be provided. In the present embodiment, a configuration in which the third extending portion 53 is provided has been described, but the third extending portion 53 may not be provided. In the present embodiment, the configuration in which the third portion 21c is provided has been described, but the third portion 21c may not be provided. In the present embodiment, the form in which the third region 23 is provided has been described, but the third region 23 may not be provided. For example, when the distance between the distal end portion 54 and the second extending portion 62 is the same in top view, the third region 23 may not be provided. In the present embodiment, the first connection portion 51 and the second connection portion 61 are arranged on a virtual line that bisects one side of the semiconductor stacked body 10 and is parallel to the first direction X. The first connection portion 51 and the second connection portion 61 may be arranged on diagonal lines of the semiconductor stacked body 10 .

Next, the results of measuring the forward voltage and output of each sample will be described.

FIG. 5 is a table showing the overall area of the first regions of Sample A, Sample B, and Sample C of the light emitting device of the first embodiment, and the width and area of each portion of the first regions.

The width of the first portion 21a is the width in the direction perpendicular to the direction in which the first portion 21a extends. The width of the third portion 21c is the width in the direction orthogonal to the direction in which the third portion 21c extends.

The width of the first portion 21a and the width of the third portion 21c of Sample A are 5 μm. The width of the first portion 21a and the width of the third portion 21c of Sample B are 7 μm. The width of the first portion 21a and the width of the third portion 21c of Sample C are 9 μm. The width of the first extending portion 52 of the p-side electrode 50 in the direction orthogonal to the direction in which the first extending portion 52 extends is 6 μm.

The total area of the first region 21 is 400 μm ² . The area of the second portion 21 b represents the total area of the plurality of second portions 21 b in the first region 21 . The area of the second portion 21b of sample A is 225 μm ² . The area of the second portion 21b of sample B is 169 μm ² . The area of the second portion 21b of sample C is 121 μm ² .

The area of the first portion 21 a and the third portion 21 c represents the total area of the multiple first portions 21 a and the multiple third portions 21 c in the first region 21 . The area of the first portion 21a and the third portion 21c of Sample A is 175 μm ² . The area of the first part 21a and the third part 21c of sample B is 231 μm ² . The area of the first portion 21a and the third portion 21c of Sample C is 279 μm ² .

The ratio of the area of the first portion 21a and the third portion 21c to the total area of the first region 21 of Sample A is 43.75%. The ratio of the area of the first portion 21a and the third portion 21c to the total area of the first region 21 of Sample B is 57.75%. The ratio of the area of the first portion 21a and the third portion 21c to the total area of the first region 21 of Sample C is 69.75%.

The thickness of the thick film portion (first portion 21a, third portion 21c) of the translucent conductive film 20 in each sample A to C is 60 nm, and the film thickness of the thin film portion (second portion 21b, second region 22) is 60 nm. The thickness is 30 nm.

FIG. 6A is a graph for explaining forward voltages Vf [V] of sample A, sample B, sample C, comparative sample Ref1, and comparative sample Ref2.
FIG. 6B is a graph for explaining the output Po [mW] of sample A, sample B, sample C, comparative sample Ref1, and comparative sample Ref2.
The forward voltage difference and power difference shown in FIGS. 6A and 6B are the difference between the forward voltage and power of Ref2 and the forward voltage and power of Sample A, Sample B, Sample C and Comparative Sample Ref1. Also, the values shown in FIGS. 6A and 6B are calculated from the average of three measurements for each sample.

The translucent conductive films of Comparative Sample Ref1 and Comparative Sample Ref2 do not include a thick film portion and a thin film portion. The film thickness of the entire region of the translucent conductive film of the comparative sample Ref1 is 60 μm, which is the same as the film thickness of the thick film portions of the samples AC. The thickness of the entire region of the translucent conductive film of the comparative sample Ref2 is 30 μm, which is the same as the thickness of the thin film portions of the samples AC. Samples A to C, comparative sample Ref1, and comparative sample Ref2 are the same except for the translucent conductive film.

From the results of FIG. 6A, according to the samples A to C of the embodiment, the forward voltage Vf can be made lower than that of the comparative sample Ref2. That is, compared to the comparative sample Ref2 in which the entire region of the translucent conductive film is the thin film portion, the samples A to C of the embodiment in which the translucent conductive film has a thick film portion and a thin film portion have a lower forward voltage. can do. In samples A to C, the width of the thick film portion (first portion 21a, third portion 21c) is increased, and the area of the thick film portion (first portion 21a, third portion 21c) with respect to the total area of first region 21 is The forward voltage Vf decreases as the ratio of .

From the results of FIG. 6B, according to the samples A to C of the embodiment in which the light-transmitting conductive film is provided with the thick film portion and the thin film portion, the light-transmitting conductive film has a thick film portion in the entire region, compared to the comparative sample Ref1. A large output Po is also obtained, and an output Po equal to or greater than that of the comparative sample Ref2 is obtained.

Therefore, according to the samples A to C of the embodiment, it is possible to improve the light extraction efficiency while suppressing the increase of the forward voltage Vf.

In particular, in the samples B and C, the forward voltage Vf can be made lower than that of the sample A, and a larger output Po than that of the comparative sample Ref2 can be obtained. Therefore, the width of the thick film portion (the first portion 21a and the third portion 21c) in the first region 21 of the translucent conductive film 20 is wider than the width (6 μm) of the first extending portion 52 of the p-side electrode 50. , In the first region 21, the area per unit area of the thick film portions (the first portion 21a and the third portion 21c) is preferably larger than the area of the second portion 21b.

[Second embodiment]
FIG. 7 is a schematic top view of the light emitting device 2 of the second embodiment of the invention.
8 is an enlarged view of a portion B in FIG. 7. FIG.
9 is a schematic cross-sectional view taken along line IX-IX in FIG. 7. FIG.

The light emitting device 2 of the second embodiment includes a substrate 100 , a semiconductor laminate 10 , a translucent conductive film 20 , a p-side electrode 150 , an n-side electrode 160 and an insulating film 81 . 7 shows the top surface of the configuration excluding the insulating film 81 shown in FIG.

In the light emitting device 2 of the second embodiment, as shown in FIG. 7, the shape of the semiconductor laminate 10 is rectangular when viewed from above. The corners of this rectangle may be right angles or rounded. The longitudinal direction of the semiconductor stack 10 is parallel to the first direction X, and the lateral direction is parallel to the second direction Y. As shown in FIG. The shape of the light emitting element 2 in top view is rectangular.

Also in the second embodiment, as shown in FIG. 9, the semiconductor stacked body 10 includes an n-side semiconductor layer 11, a p-side semiconductor layer 12, and a position between the n-side semiconductor layer 11 and the p-side semiconductor layer 12. and an active layer 13 that The n-side semiconductor layer 11 is not provided with the active layer 13 and the p-side semiconductor layer 12 and has an exposed surface 11 d exposed from the active layer 13 and the p-side semiconductor layer 12 .

As shown in FIG. 7, the outer edge of the n-side semiconductor layer 11 has a pair of long-side outer edges 11c1 extending in the first direction X and a pair of short-side outer edges 11c2 extending in the second direction Y. As shown in FIG. The exposed surface 11d of the n-side semiconductor layer 11 is positioned between the outer edges 11c1 and 11c2 of the n-side semiconductor layer 11 and the outer edge 12a of the p-side semiconductor layer 12 when viewed from above. The exposed surface 11 d is continuous along the outer edges 11 c 1 and 11 c 2 of the n-side semiconductor layer 11 .

As shown in FIG. 9, a translucent conductive film 20 is provided on the p-side semiconductor layer 12 . The translucent conductive film 20 is not provided on the exposed surface 11 d of the n-side semiconductor layer 11 . The translucent conductive film 20 diffuses the current supplied through the p-side electrode 150 in the planar direction of the p-side semiconductor layer 12 . The translucent conductive film 20 is electrically connected to the p-side semiconductor layer 12 and the p-side electrode 150 .

A p-side electrode 150 is provided on the translucent conductive film 20 . The p-side electrode 150 is in contact with the translucent conductive film 20 . The resistivity of the p-side electrode 150 is lower than that of the translucent conductive film 20 . The transmittance of the p-side electrode 150 to light from the active layer 13 is lower than the transmittance of the translucent conductive film 20 to the wavelength of light from the active layer 13 . The p-side electrode 150 is made of a metal material.

As shown in FIG. 7 , the p-side electrode 150 has a first connecting portion 151 and a first extending portion 152 extending from the first connecting portion 151 . The first connecting portion 151 is located on one end side in the first direction X, and the first extending portion 152 extends from the first connecting portion 151 toward the other end side in the first direction X. As shown in FIG.

An n-side electrode 160 is provided on the exposed surface 11 d of the n-side semiconductor layer 11 . The n-side electrode 160 is in contact with the n-side semiconductor layer 11 . The resistivity of the n-side electrode 160 is lower than that of the translucent conductive film 20 . The transmittance of the n-side electrode 160 for light from the active layer 13 is lower than the transmittance of the translucent conductive film 20 for the wavelength of light from the active layer 13 . The n-side electrode 160 is made of a metal material.

The n-side electrode 160 has a second connecting portion 161 and a second extending portion 162 extending from the second connecting portion 161 . The second connection portion 161 is located on the other end side opposite to the one end in the first direction X where the first connection portion 151 is located. The second connection portion 161 is located near one of the four corners of the n-side semiconductor layer 11 . The second extending portion 162 extends from the second connecting portion 161 toward one end on the exposed surface 11 d on the long side of the n-side semiconductor layer 11 .

As shown in FIG. 9, the insulating film 81 covers the semiconductor laminate 10, the translucent conductive film 20, the p-side electrode 150, and the n-side electrode 160. As shown in FIG. A portion of the upper surface of the first connection portion 151 of the p-side electrode 150 and a portion of the upper surface of the second connection portion 161 of the n-side electrode 160 are exposed from the insulating film 81 . Wires, for example, are joined to the exposed upper surfaces, and the p-side electrode 150 and the n-side electrode 160 are electrically connected to an external circuit via the wires.

As shown in FIG. 7, the first extending portion 152 of the p-side electrode 150 faces the second extending portion 162 of the n-side electrode 160 when viewed from above. When viewed from the top, the translucent conductive film 20 includes an outer region 26 located between the first extending portion 152 and the outer edge 12a of the p-side semiconductor layer 12, and the first extending portion 152 and the second extending portion 162. and an inner region 25 located therebetween. The p-side electrode 150 is located between the inner region 25 and the outer region 26 when viewed from above.

As shown in FIG. 8, in top view, the outer region 26 of the translucent conductive film 20 has a plurality of first portions 26a, a plurality of second portions 26b, and a plurality of third portions 26c. The first portion 26 a extends from the first extending portion 152 toward the outer edge 12 a of the p-side semiconductor layer 12 . Also, the first portion 26 a extends from the first connecting portion 151 toward the outer edge 12 a of the p-side semiconductor layer 12 . The second portions 26b are located between the plurality of first portions 26a. The third portion 26c is connected to the first portion 26a and positioned between two adjacent first portions 26a among the plurality of first portions 26a. The first portion 26a and the third portion 26c are arranged in a grid pattern. When viewed from above, one second portion 26b is surrounded by the first portion 26a and the third portion 26c.

The film thickness of the first portion 26a is thicker than the film thickness of the inner region 25 and the film thickness of the second portion 26b. The film thickness of the third portion 26c is thicker than the film thickness of the inner region 25 and the film thickness of the second portion 26b. For example, the thickness of the first portion 26a and the thickness of the third portion 26c are the same. In the outer region 26, the translucent conductive films 20 having the same film thickness are arranged in a grid pattern. For example, the film thickness of the inner region 25 and the film thickness of the second portion 26b are the same. The film thickness of the first portion 26a can be, for example, 50 nm or more and 100 nm or less. The film thickness of the second portion 26b can be, for example, 10 nm or more and 50 nm or less.

The cross section of the outer region 26 of the translucent conductive film 20 in FIG. 9 shows the cross section of the first portion 26a.

As in the first embodiment, in the second embodiment, the translucent conductive film 20 includes thick film portions (first portion 26a and third portion 26c) and thin film portions (thin film portions) thinner than the thick film portions. an inner region 25 and a second portion 26b). For example, the film thickness of the thick film portion is 1.5 to 3.0 times the film thickness of the thin film portion.

Also, the film thickness of the translucent conductive film 20 arranged directly under the p-side electrode 150 is thicker than the film thickness of the thin film portion. For example, the film thickness of the translucent conductive film 20 arranged directly under the p-side electrode 150 is the same as the film thickness of the thick film portion.

Also in the second embodiment, light from the active layer 13 is extracted to the outside of the light emitting device 2 mainly through the p-side semiconductor layer 12 and the translucent conductive film 20 .

In the light-transmitting conductive film 20 of the light-emitting element 2 , the outer region 26 draws more current than the inner region 25 located between the first extension 152 of the p-side electrode 150 and the second extension 162 of the n-side electrode 160 . is the area where diffusion is difficult.

By arranging the first portion 26a, which is a thick film portion thicker than the inner region 25, in such an outer region 26, compared to the case where the entire outer region 26 is a thin portion like the inner region 25, The sheet resistance of the outer region 26 can be reduced, and the current can be easily diffused in the outer region 26 . In addition, by arranging the second portion 26b, which is a thin film portion thinner than the first portion 26a, in the outer region 26, light absorption in the outer region 26 is reduced compared to the case where the entire outer region 26 is a thick film portion. can be suppressed. In addition, by setting the film thickness of the inner region 25, in which current is more likely to diffuse than the outer region 26, to be thinner than the thick film portion of the outer region 26, compared to the case where the entire region of the translucent conductive film 20 is thickened, Light absorption by the translucent conductive film 20 can be suppressed. Therefore, according to the light emitting element 2 of the second embodiment, it is possible to improve the light extraction efficiency while suppressing the increase in the forward voltage.

In order to facilitate the diffusion of the current from the p-side electrode 150 in the plane direction of the translucent conductive film 20, the translucent conductive film 20 in the region directly below the p-side electrode 150 and in contact with the p-side electrode 150 is formed. The thickness is preferably the same as the thickness of the thick film portion such as the first portion 26a.

By disposing the third portion 26c as a thick film portion between the adjacent first portions 26a in the outer region 26, current can be more easily diffused to the outer region 26 than when only the first portions 26a are disposed. .

10A to 10C are schematic cross-sectional views showing a first method of forming the translucent conductive film 20 according to each embodiment of the present invention.

As shown in FIG. 10A, a translucent conductive film 20 is formed on the p-side semiconductor layer 12 . A resist 200 is formed on the upper surface of the translucent conductive film 20 , and the resist 200 is left on a part of the upper surface of the translucent conductive film 20 by photolithography and development processing for the resist 200 . The resist 200 is left on the part of the translucent conductive film 20 that is to be the thick film portion. Then, as shown in FIG. 10B, the translucent conductive film 20 is etched using the resist 200 as a mask to remove the portion of the translucent conductive film 20 exposed from the resist 200 . Thereafter, the resist 200 is removed, and as shown in FIG. 10C, a light-transmitting film is again formed so as to cover the upper surface of the translucent conductive film 20 left in the step shown in FIG. 10B and the upper surface of the p-side semiconductor layer 12 . A conductive film 20 is deposited. Through these steps, the thin film portion 20b formed in the portion where the light-transmitting conductive film 20 was etched in the above-described step and the thickness formed in the portion covered with the resist 200 and not etched in the light-transmitting conductive film 20 are formed. The translucent conductive film 20 including the film portion 20a can be formed.

11A to 11C are schematic cross-sectional views showing a second method of forming the translucent conductive film 20 according to each embodiment of the present invention.

As shown in FIG. 11A, a translucent conductive film 20 is formed on the p-side semiconductor layer 12 . A resist 200 is formed on the upper surface of the translucent conductive film 20 , and the resist 200 is left on a part of the upper surface of the translucent conductive film 20 by photolithography and development processing for the resist 200 . As shown in FIG. 11B, the resist 200 is left on the part of the translucent conductive film 20 that will be the thick film portion. Then, using the resist 200 as a mask, the translucent conductive film 20 exposed from the resist 200 is etched. As shown in FIG. 11C, the translucent conductive film 20 exposed from the resist 200 is etched halfway in the thickness direction. As a result, the translucent conductive film 20 including the thin film portion 20b etched halfway in the thickness direction and the thick film portion 20a covered with the resist 200 and not etched can be formed.

If the film thickness of the translucent conductive film 20 is relatively thin and it is difficult to control the film thickness by etching, the first forming method is preferable to the second forming method. In addition, since the surface of the light-transmitting conductive film 20 is easily damaged after etching, it is necessary to prevent the surface condition of the upper surface of the light-transmitting conductive film 20 from deteriorating. The first method of forming the photosensitive conductive film 20 is preferred.

The embodiments of the present invention have been described above with reference to specific examples. However, the invention is not limited to these specific examples. Based on the above-described embodiment of the present invention, all forms that can be implemented by those skilled in the art by appropriately designing and changing are also included in the scope of the present invention as long as they include the gist of the present invention. In addition, within the scope of the idea of the present invention, those skilled in the art can conceive of various modifications and modifications, and these modifications and modifications also belong to the scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 2... Light-emitting element 10... Semiconductor laminated body 11... n-side semiconductor layer 12... p-side semiconductor layer 13... Active layer 20... Translucent conductive film 21... First region 21a... First first region Part 21b...Second part 21c...Third part 21d...Fifth part 22...Second area 23...Third area 23a...Fourth part 23b...Sixth part 25...Inner area 26 Outer region 26a First portion 26b Second portion 50, 150 p-side electrode 51, 151 First connection portion 52, 152 First extending portion 54 Tip side portion 54a Tip part 60, 160... n-side electrode 61, 161... Second connection part 62, 162... Second extension part 100... Substrate

Claims (9)

a semiconductor laminate having a p-side semiconductor layer, an n-side semiconductor layer, and an active layer positioned between the p-side semiconductor layer and the n-side semiconductor layer;
a translucent conductive film provided on the p-side semiconductor layer;
a p-side electrode provided on the translucent conductive film and having a first connecting portion and a first extending portion extending from the first connecting portion;
an n-side electrode provided on the n-side semiconductor layer;
with
When viewed from above, the p-side electrode is provided around the n-side electrode,
When viewed from above, the translucent conductive film includes a first region located outside the p-side electrode and between the p-side electrode and the outer edge of the p-side semiconductor layer; a second region located inside the electrode;
When viewed from above, the first region has a plurality of first portions extending from the p-side electrode toward the outer edge of the p-side semiconductor layer and second portions located between the first portions,
The film thickness of the first portion is thicker than the film thickness of the second region and the film thickness of the second portion. When viewed from above, the first region further includes a third portion connected to the first portion and positioned between two adjacent first portions among the plurality of first portions,
2. The light emitting device according to claim 1, wherein the film thickness of the third portion is thicker than the film thickness of the second region and the film thickness of the second portion. the n-side electrode has a second connection portion arranged to face the first connection portion in a first direction;
a tip portion of the first extending portion is located closer to an outer edge of the p-side semiconductor layer than the second connecting portion in the first direction;
When viewed from above, the translucent conductive film further has a third region that is continuous with the first region and positioned between the tip of the first extending portion and the second region,
When viewed from above, the third region has a fourth portion extending from the tip portion toward the n-side electrode,
The film thickness of the fourth portion is thicker than the film thickness of the second region and the film thickness of the second portion,
3. The light-emitting device according to claim 1, wherein a boundary between said second region and said third region is located closer to said p-side electrode than said n-side electrode. When viewed from above, the first region is a fifth portion located between the second connection portion and the outer edge of the p-side semiconductor layer on a virtual line passing through the second connection portion and parallel to the first direction. further having
4. The light emitting device according to claim 3, wherein the thickness of the fifth portion is thinner than the thickness of the first portion and thicker than the thickness of the second portion. Claims 1 to 4, wherein the width of the first portion in the direction orthogonal to the direction in which the first portion extends is wider than the width of the first extension portion in the direction orthogonal to the direction in which the first extension portion extends. The light-emitting device according to any one of . The light emitting device according to any one of claims 1 to 5, wherein in the first region, the area of the first portion per unit area is larger than the area of the second portion. The light emitting device according to any one of claims 1 to 6, wherein the translucent conductive film arranged directly under the p-side electrode has a thickness equal to that of the first portion. The light emitting device according to any one of claims 1 to 7, wherein the film thickness of the first portion is 1.5 times or more and 3.0 times or less the film thickness of the second region. a semiconductor laminate having a p-side semiconductor layer, an n-side semiconductor layer, and an active layer positioned between the p-side semiconductor layer and the n-side semiconductor layer;
a translucent conductive film provided on the p-side semiconductor layer;
a p-side electrode provided on the translucent conductive film and having a first connecting portion and a first extending portion extending from the first connecting portion;
an n-side electrode provided on the n-side semiconductor layer and having a second connecting portion and a second extending portion extending from the second connecting portion;
with
The first extending portion is provided facing the second extending portion,
When viewed from the top, the translucent conductive film has an outer region positioned between the first extending portion and the outer edge of the p-side semiconductor layer, and between the first extending portion and the second extending portion. and an inner region located at
When viewed from above, the outer region has a plurality of first portions extending from the first extending portion toward the outer edge of the p-side semiconductor layer, and second portions positioned between the first portions,
The thickness of the first portion is thicker than the thickness of the inner region and the thickness of the second portion.

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