Methods and devices for light extraction from a group III-nitride volumetric LED using surface and sidewall roughening

• US 9,000,466 B1
• Filed: 02/28/2013
• Issued: 04/07/2015
• Est. Priority Date: 08/23/2010
• Status: Active Grant

• Current Assignee: Korrus Incorporated (MKD Electric, Inc.)
• Original Assignee: Soraa, Inc.
• Inventors: Aldaz, Rafael, David, Aurelien, Feezell, Daniel F., Katona, Thomas M., Sharma, Rajat
• Primary Examiner(s): ARMAND, MARC ANTHONY
• Application Number:
  US13/781,633
• Time in Patent Office: 768 Days
• Field of Search: 257/98, 257/94, 257/E33.001
• US Class Current: 257/98
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/18 within the light emitting region
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

Embodiments of the present disclosures are directed to improved approaches for achieving high-performance light extraction from a Group III-nitride volumetric LED chips. More particularly, disclosed herein are techniques for achieving high-performance light extraction from a Group III-nitride volumetric LED chip using surface and sidewall roughening.

Claims

1. A light emitting diode comprising:

a gallium and nitrogen containing substrate comprising a surface region;

an n-type epitaxial material overlying the surface region;

one or more active regions overlying the n-type epitaxial material;

a p-type epitaxial material overlying the one or more active regions;

a first electrode coupled to the n-type epitaxial material, to the substrate, or to both the n-type epitaxial material and to the substrate;

a second electrode coupled to the p-type epitaxial material;

a top surface region comprising a top textured surface characterized by a top surface roughness of about 80 nm to about 10,000 nm;

a base; and

at least three lateral surface regions coupling the top surface region to the base, wherein at least one of the three lateral surface regions is characterized by a lateral surface roughness, wherein the at least one lateral surface region comprises a first portion and a second portion, wherein, the first portion comprise a one-dimensional surface roughness; and

the second portion comprises a two-dimensional surface roughness.

2. The light emitting diode of claim 1, wherein,

the top surface region is triangular;

the base is triangular; and

the at least three lateral surface regions comprise three lateral surface regions.

3. The light emitting diode of claim 1, wherein the light emitting diode has a thickness of at least 20 μ

m.

4. The light emitting diode of claim 1, wherein the lateral surface roughness ranges from 80 nm to about 1000 nm.

5. The light emitting diode of claim 1, wherein the lateral surface roughness ranges from about 1001 nm to about 10000 nm.

6. The light emitting diode of claim 1, wherein the top surface roughness is configured to extract a substantial portion of electromagnetic radiation derived from the one or more active regions.

7. The light emitting diode of claim 1, wherein the lateral surface roughness is configured to extract a substantial portion of electromagnetic radiation derived from the one or more active regions.

8. The light emitting diode of claim 1, wherein the one or more active regions comprises two or more of indium, gallium, aluminum, and nitrogen.

9. The light emitting diode of claim 1, wherein the at least one lateral surface region is configured in a non-polar orientation.

10. The device of claim 1, wherein the at least one lateral surface region is configured in a semi-polar orientation.

11. The device of claim 1, wherein the at least one lateral surface region is configured in a polar orientation.

12. The light emitting diode of claim 1, wherein the at least one lateral surface region is slanted with respect to the base.

13. The light emitting diode of claim 1, wherein the at least one lateral surface region is slanted at an angle from 5 degrees to 20 degrees with respect to the base.

14. The light emitting diode of claim 1, wherein the average lateral size of the one-dimensional surface roughness is from 1 μ

m to 10 μ

m.

15. The light emitting diode of claim 1, wherein the average vertical size of the one-dimensional surface roughness is between 100 nm and 10 μ

m.

16. The light emitting diode of claim 1, wherein the top surface roughness is characterized by a two-dimensional surface roughness.

17. The light emitting diode of claim 1, wherein the top surface roughness comprises greater than 15% of the area of the top surface region.

18. The light emitting diode of claim 1, wherein the one-dimensional surface roughness is characterized by vertical striations.

19. The light emitting diode of claim 1, wherein the one-dimensional surface roughness comprises vertical striations having a characteristic distance from 1 μ

m to 5 μ

m.

20. The light emitting diode of claim 1, wherein each of the at least three lateral surface regions comprises:

a first portion comprising p-type gallium and nitrogen containing material characterized by a first surface roughness; and

a second portion comprising an n-type gallium and nitrogen containing material characterized by a second surface roughness,

wherein the first surface roughness is different than the second surface roughness.

21. The light emitting diode of claim 1, wherein the at least one lateral surface region is misaligned with a crystallographic plane of the gallium and nitrogen containing substrate.

22. The light emitting diode of claim 1, wherein the at least one lateral surface region is misaligned within +/−

20 degrees with respect to a crystallographic plane of the gallium and nitrogen containing substrate.

23. The light emitting diode of claim 20, wherein,

the first surface roughness is characterized by a two-dimensional surface roughness;

and

the second surface roughness is characterized by a one-dimensional surface roughness.

24. The light emitting diode of claim 23, wherein,

the one-dimensional surface roughness comprises vertical striations.

25. A light emitting diode comprising:

a gallium and nitrogen containing substrate comprising a surface region;

an n-type epitaxial material overlying the surface region;

one or more active regions overlying the n-type epitaxial material;

a p-type epitaxial material overlying the one or more active regions;

a first electrode coupled to the n-type epitaxial material, to the substrate, or to both the n-type epitaxial material and to the substrate;

a second electrode coupled to the p-type epitaxial material;

a triangular top surface region comprising a top textured surface;

a triangular base; and

three lateral surface regions coupling the top surface region to the base, wherein each of the at least three lateral surface regions comprises a first portion and a second portion, wherein, the first portion comprise a one-dimensional surface roughness; and

the second portion comprises a two-dimensional surface roughness.