Light emitting devices having light coupling layers with recessed electrodes

• US 8,664,679 B2
• Filed: 09/29/2011
• Issued: 03/04/2014
• Est. Priority Date: 09/29/2011
• Status: Active Grant

• Current Assignee: Seoul Semiconductor Co., Ltd.
• Original Assignee: Toshiba Techno Center Inc. (Toshiba Corporation)
• Inventors: Yan, Li, Lin, Chao-Kun, Chuang, Chih-Wei
• Primary Examiner(s): NGUYEN, THANH T
• Application Number:
  US13/249,196
• Publication Number:
  US 20130082290A1
• Time in Patent Office: 887 Days
• Field of Search: 257 13- 15, 257 98- 99
• US Class Current: 257/98
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A light emitting device comprises a first layer of an n-type semiconductor material, a second layer of a p-type semiconductor material, and an active layer between the first layer and the second layer. A light coupling structure is disposed adjacent to one of the first layer and the second layer. In some cases, the light coupling structure is disposed adjacent to the first layer. An orifice formed in the light coupling structure extends to the first layer. An electrode formed in the orifice is in electrical communication with the first layer.

Claims

1. A light emitting device, comprising:

a substrate;

a p-type Group III-V semiconductor layer adjacent to the substrate;

an active layer adjacent to the p-type semiconductor layer;

an n-type Group III-V semiconductor layer adjacent to the active layer;

a light coupling structure adjacent to the n-type Group III-V semiconductor layer, the light coupling structure comprising one or more Group III-V semiconductor materials, wherein the light coupling structure has a corrugated surface including a first corrugation portion and comprises an orifice extending to the n-type Group III-V semiconductor layer, the orifice including a second corrugation portion different from the first corrugation portion; and

an electrode formed on the second corrugation portion in the orifice, the electrode in electrical communication with the n-type Group III-V semiconductor layer.

2. The light emitting device of claim 1, wherein the orifice exposes a portion of the n-type Group III-V semiconductor layer.

3. The light emitting device of claim 2, wherein the exposed portion of the n-type semiconductor layer has a corrugation less than or equal to about 300 nanometers (nm).

4. The light emitting device of claim 1, wherein the orifice has a circular, elliptical, triangular, square, rectangular, pentagonal, hexagonal, heptagonal or nonagonal cross-section.

5. The light emitting device of claim 1, wherein the orifice is a channel extending along at least a portion of the light coupling structure.

6. The light emitting device of claim 1, wherein the one or more Group III-V semiconductor materials of the light coupling structure are selected from the group consisting of n-type gallium nitride, u-type gallium nitride, aluminum gallium nitride and aluminum nitride.

7. The light emitting device of claim 1, wherein the n-type Group III-V semiconductor layer comprises n-type gallium nitride.

8. The light emitting device of claim 1, wherein the p-type Group III-V semiconductor layer comprises p-type gallium nitride.

9. The light emitting device of claim 1, wherein the electrode comprises one or more elemental metals selected from the group consisting of titanium, aluminum, nickel, platinum, gold, silver, rhodium, copper and chromium.

10. The light emitting device of claim 1, wherein the light coupling structure comprises one or more light coupling moieties, an individual light coupling moiety having a decreasing width along an axis oriented away from the active layer.

11. The light emitting device of claim 1, wherein the substrate is selected from the group consisting of silicon, germanium, silicon oxide, silicon dioxide, titanium oxide, titanium dioxide, sapphire, silicon carbide, a ceramic material and a metallic material.

12. The light emitting device of claim 1, wherein the light coupling structure has protrusions sized between about 10 nanometers (nm) and 3 micrometers (μ

m).

13. The light emitting device of claim 1, further comprising an optical reflector between the substrate and the p-type Group III-V semiconductor layer.

14. The light emitting device of claim 13, wherein the optical reflector is formed of one or more of silver, platinum, gold, rhodium, aluminum and nickel.

15. The light emitting device of claim 1, wherein the light coupling structure comprises at least two layers of different materials, at least one of the layers comprising a u-type semiconductor layer.

16. The light emitting device of claim 15, wherein the u-type semiconductor layer is a u-type gallium nitride layer.

17. The light emitting device of claim 15, wherein the u-type semiconductor layer is a buffer layer used to form the light emitting device.

18. The light emitting device of claim 1, wherein the second corrugation portion is smaller than the first corrugation portion.

19. A light emitting device, comprising:

a first layer of a first type of Group III-V semiconductor material;

a second layer adjacent to the first layer, the second layer having an active material configured to generate light upon the recombination of electrons and holes;

a third layer adjacent to the second layer, the third layer comprising a second type of Group III-V semiconductor material;

a light coupling structure adjacent to the third layer, the light coupling structure comprising a third type of Group III-V semiconductor material, wherein the light coupling structure has a corrugated surface including a first corrugation portion and comprises an opening extending through at least a portion of the light coupling structure, the opening including a second corrugation portion being different from the first corrugation portion; and

an electrode adjacent to said light coupling structure, the electrode in electrical communication with said one of the first layer and the second layer.

20. The light emitting device of claim 19, wherein the third type of Group III-V semiconductor material is different from the first type of Group III-V semiconductor material and the second type of Group III-V semiconductor material.

21. The light emitting device of claim 19, wherein the first type of Group III-V semiconductor material includes one of an n-type Group III-V semiconductor and a p-type Group III-V semiconductor.

22. The light emitting device of claim 21, wherein the second type of Group III-V semiconductor material includes the other of the n-type Group III-V semiconductor and the p-type Group III-V semiconductor.

23. The light emitting device of claim 19, wherein the second corrugation portion is smaller than the first corrugation portion.

24. A light emitting device, comprising:

a substrate;

a p-type Group III-V semiconductor layer adjacent to the substrate;

an active layer adjacent to the p-type semiconductor layer;

an n-type Group III-V semiconductor layer adjacent to the active layer;

a light coupling structure adjacent to the n-type Group III-V semiconductor layer, the light coupling structure comprising one or more Group III-V semiconductor materials, wherein the light coupling structure comprises a corrugated surface including a first corrugation portion and a second corrugation portion different from the first corrugation portion; and

an electrode formed on the second corrugation portion of the light coupling structure, the electrode in electrical communication with the n-type Group III-V semiconductor layer.

25. The light emitting device of claim 24, wherein the light coupling structure comprises an orifice exposing a portion of the n-type Group III-V semiconductor layer, the electrode formed in the orifice.

26. The light emitting device of claim 25, wherein the exposed portion of the n-type semiconductor layer has a corrugation less than or equal to about 300 nanometers (nm).

27. The light emitting device of claim 24, wherein the light coupling structure comprises an orifice having a circular, elliptical, triangular, square, rectangular, pentagonal, hexagonal, heptagonal or nonagonal cross-section.

28. The light emitting device of claim 24, wherein the light coupling structure comprises an orifice, and the orifice is a channel extending along at least a portion of the light coupling structure.

29. The light emitting device of claim 24, wherein the one or more Group III-V semiconductor materials of the light coupling structure are selected from the group consisting of n-type gallium nitride, u-type gallium nitride, aluminum gallium nitride and aluminum nitride.

30. The light emitting device of claim 24, wherein the n-type Group III-V semiconductor layer comprises n-type gallium nitride.

31. The light emitting device of claim 24, wherein the p-type Group III-V semiconductor layer comprises p-type gallium nitride.

32. The light emitting device of claim 24, wherein the electrode comprises one or more elemental metals selected from the group consisting of titanium, aluminum, nickel, platinum, gold, silver, rhodium, copper and chromium.

33. The light emitting device of claim 24, wherein the light coupling structure comprises one or more light coupling moieties, an individual light coupling moiety having a decreasing width along an axis oriented away from the active layer.

34. The light emitting device of claim 24, wherein the substrate is selected from the group consisting of silicon, germanium, silicon oxide, silicon dioxide, titanium oxide, titanium dioxide, sapphire, silicon carbide, a ceramic material and a metallic material.

35. The light emitting device of claim 24, wherein the light coupling structure has protrusions sized between about 10 nanometers (nm) and 3 micrometers (μ

m).

36. The light emitting device of claim 24, further comprising an optical reflector between the substrate and the p-type Group III-V semiconductor layer.

37. The light emitting device of claim 36, wherein the optical reflector is formed of one or more of silver, platinum, gold, rhodium, aluminum and nickel.

38. The light emitting device of claim 24, wherein the light coupling structure comprises at least two layers of different materials, at least one of the layers comprising a u-type semiconductor layer.

39. The light emitting device of claim 38, wherein the u-type semiconductor layer is a u-type gallium nitride layer.

40. The light emitting device of claim 38, wherein the u-type semiconductor layer is a buffer layer used to form the light emitting device.

41. The light emitting device of claim 24, wherein the second corrugation portion is smaller than the first corrugation portion.