Light-emitting element

• US 9,887,323 B2
• Filed: 05/27/2015
• Issued: 02/06/2018
• Est. Priority Date: 05/27/2014
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Nagamatsu, Yuichi, Shinohara, Hironao
• Primary Examiner(s): Kim, Su C
• Assistant Examiner(s): Wilbert, David S
• Application Number:
  US14/723,322
• Publication Number:
  US 20150349209A1
• Time in Patent Office: 986 Days
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/486 adapted for surface mounting

Abstract

A light-emitting element includes a semiconductor laminate including a light-emitting layer, a transparent electrode layer formed on the semiconductor laminate, the transparent electrode layer including an oxide including indium, a pad electrode formed on the transparent electrode layer so as to connect to the transparent electrode layer, and a reflective layer including aluminum. The reflective layer is formed under the pad electrode so as not to contact the transparent electrode layer.

Claims

1. A light-emitting element, comprising:

a semiconductor laminate comprising a light-emitting layer;

a transparent electrode layer formed on the semiconductor laminate, the transparent electrode layer comprising an oxide including indium;

a pad electrode formed on the transparent electrode layer so as to connect to the transparent electrode layer;

a reflective layer including aluminum, the reflective layer being formed under the pad electrode so as not to contact the transparent electrode layer, and comprising a plurality of separate reflective layer parts; and

a barrier layer formed on and contacting an uppermost surface of the reflective layer so as not to contact the transparent electrode layer, the pad electrode being formed on and contacting an uppermost surface of the barrier layer, and an outermost sidewall of the barrier layer being aligned in a thickness direction with a sidewall of the reflective layer.

2. The light-emitting element according to claim 1, further comprising an insulating current blocking layer formed between the reflective layer and the semiconductor laminate so as to block a current to the semiconductor laminate in a region directly below the pad electrode.

3. The light-emitting element according to claim 1, wherein the reflective layer is formed inside a hole formed on the transparent electrode layer.

4. The light-emitting element according to claim 1, wherein the reflective layer comprises an Al film.

5. The light-emitting element according to claim 1, wherein the transparent electrode layer comprises one of IZO, In₂O₃, ITO and IFO.

6. The light-emitting element according to claim 1, further comprising a substrate,

wherein the semiconductor laminate further comprises:

a first conductivity-type semiconductor layer formed on the substrate, the light-emitting layer being formed on the first conductivity-type semiconductor layer; and

a second conductivity-type semiconductor layer formed on the light-emitting layer.

7. The light-emitting element according to claim 6, wherein the first conductivity-type semiconductor layer, the light-emitting layer and the second conductivity-type semiconductor layer comprise group III nitride compound semiconductor.

8. The light-emitting element according to claim 7, wherein the group III nitride compound semiconductor comprises a quaternary group-III nitride compound semiconductor represented by Al_xGa_yIn_1-x-yN (0<

x<

1, 0<

y<

1, 0<

x+y<

1).

9. The light-emitting element according to claim 6, further comprising:

a current blocking layer formed on a surface of the second conductivity-type semiconductor layer.

13. The light-emitting element according to claim 9, wherein the transparent electrode layer is formed on an outermost portion of the current blocking layer.

14. The light-emitting element according to claim 9, wherein the current blocking layer has an area which is greater than an area of the pad electrode in a plan view, and the pad electrode is surrounded by the current blocking layer in a plan view.

15. The light-emitting element according to claim 9, wherein the current blocking layer has an area which is greater than an area of the reflective film in a plan view, and the reflective film is surrounded by the current blocking layer in a plan view.

16. The light-emitting element according to claim 1, wherein the current blocking layer comprises a line-shaped current blocking layer portion,

wherein the plurality of separate reflective layer parts comprise a line shape and are formed on the line-shaped current blocking layer portion, and

wherein the pad electrode comprises a line-shaped pad electrode portion which is formed on the plurality of separate reflective layer parts and on the line-shaped current blocking layer portion.

17. The light-emitting element according to claim 1, further comprising:

a sapphire substrate, the semiconductor laminate being formed on the sapphire substrate.

19. The light-emitting element according claim 1, wherein the surface of the reflective layer comprises an upper surface of the reflective layer.

20. The light-emitting element according to claim 1, wherein the barrier layer comprises a metal barrier layer.

21. The light-emitting element according to claim 1, wherein a pattern of the barrier layer is the same as a pattern of the reflective layer.

22. The light-emitting element according to claim 2, wherein the transparent electrode layer comprises a portion formed on the insulating current blocking layer, and

wherein a thickness of the reflective layer is less than a thickness of the portion of the transparent electrode layer.

23. The light-emitting element according to claim 1, wherein the pad electrode comprises a line-shaped pad electrode, and the plurality separate reflective layer parts comprise a plurality of separate line-shaped reflective layer parts which are aligned lengthwise under the line-shaped pad electrode.

24. The light-emitting element according to claim 1, wherein the barrier layer contacts an entirety of the uppermost surface of the reflective layer, such that the pad electrode is separated from the entirety of the uppermost surface of the reflective layer by the barrier layer.

25. The light-emitting element according to claim 1, wherein the outermost sidewall of the barrier layer and the sidewall of the reflective layer face a sidewall of the transparent electrode layer.

26. The light-emitting element according to claim 25, wherein a width of the pad electrode is greater than a width of the barrier layer, such that the pad electrode is formed between the outermost sidewall of the barrier layer and the sidewall of the transparent electrode layer.

10. A light-emitting element, comprising:

a semiconductor laminate comprising a light-emitting layer;

a transparent electrode layer formed on the semiconductor laminate, the transparent electrode layer comprising an oxide including indium;

a pad electrode formed on the transparent electrode layer so as to connect to the transparent electrode layer;

a reflective layer including aluminum, the reflective layer being formed under the pad electrode so as not to contact the transparent electrode layer, and comprising a plurality of separate reflective layer parts;

a substrate, the semiconductor laminate further comprising;

a first conductivity-type semiconductor layer formed on the substrate, the light-emitting layer being formed on the first conductivity-type semiconductor layer; and

a second conductivity-type semiconductor layer formed on the light-emitting layer;

a current blocking layer formed on a surface of the second conductivity-type semiconductor layer, the reflective layer being formed on a surface of the current blocking layer; and

a barrier layer formed on and contacting an uppermost surface of the reflective layer so as not to contact the transparent electrode layer, the pad electrode being formed on and contacting an uppermost surface of the barrier layer, and an outermost sidewall of the barrier layer being aligned in a thickness direction with a sidewall of the reflective layer.

11. The light-emitting element according to claim 10, further comprising:

an other current blocking layer formed on a surface of the first conductivity-type semiconductor layer;

an other reflective layer formed on the other current blocking layer;

an other barrier layer formed on the other reflective layer; and

an other pad electrode formed on the other barrier layer.

12. The light-emitting element according to claim 11, further comprising:

a protective film formed on the transparent electrode layer, a sidewall of the pad electrode, and a sidewall of the other pad electrode, and separating the other pad electrode from the light-emitting layer, the second conductivity-type semiconductor layer and the transparent electrode layer.

18. A light-emitting element comprising:

a light-emitting layer;

a transparent electrode thrilled on the light-emitting layer and comprising an oxide including indium;

a reflective layer which comprises aluminum and is formed on the light-emitting layer and separated from the transparent electrode layer, the reflective layer comprising a plurality of separate reflective layer parts;

a pad electrode formed on the plurality of separate reflective layer parts and the transparent electrode layer; and

a barrier layer formed on and contacting an uppermost surface of the reflective layer so as not to contact the transparent electrode layer, the pad electrode being formed on and contacting an uppermost surface of the barrier layer, and an outermost side wall of the barrier layer being aligned in a thickness direction with a sidewall of the reflective layer.