Non-polar and semi-polar light emitting devices

• US 9,130,119 B2
• Filed: 12/11/2007
• Issued: 09/08/2015
• Est. Priority Date: 12/11/2006
• Status: Active Grant

• Current Assignee: Japan Science & Technology Trading Co. Limited
• Original Assignee: Japan Science & Technology Trading Co. Limited, Regents of the University of California (University of California)
• Inventors: Schmidt, Mathew C., Kim, Kwang Choong, Speck, James S., Nakamura, Shuji, DenBaars, Steven P.
• Primary Examiner(s): Islam, Mohammad
• Assistant Examiner(s): Dulka, John P
• Application Number:
  US12/001,227
• Publication Number:
  US 20080179607A1
• Time in Patent Office: 2,828 Days
• Field of Search: 257/94, 257/E33.001, 257/79, 257/E21.113, 257/E21.463, 257/13, 257/76, 257/80, 257/82, 257/88, 257/96, 257/97, 257/103, 438/46, 438/47, 438/479, 148/33
• US Class Current: 1/1
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• 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: H01S 5/2201 in a specific crystallographic orientation
• CPC Class Codes: H01S 5/2231 with inner confining structure only between the active layer and the upper electrode
• CPC Class Codes: H01S 5/3404 influencing the polarisation
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

An (Al, Ga, In)N light emitting device, such as a light emitting diode (LED), in which high light generation efficiency is realized by fabricating the device on non-polar or semi-polar III-Nitride crystal geometries. Because non-polar and semi-polar emitting devices have significantly lower piezoelectric effects than c-plane emitting devices, higher efficiency emitting devices at higher current densities can be realized.

Claims

1. A III-nitride light emitting device, comprising:

a plurality of III-nitride layers comprising at least one p-type layer, an active region, and at least one n-type layer,

wherein the III-nitride layers are not c-plane III-nitride layers, and

wherein the active region is comprised of at least one III-nitride quantum well layer having a thickness that achieves a current density such that light is emitted at an output power of at least 25 milliWatts (mW) when a current input at 20 milliAmps (mA) is applied.

2. The device of claim 1, wherein the at least one quantum well layer has a thickness of approximately 8-12 nanometers.

3. The device of claim 1, wherein the at least one quantum well layer has a thickness of approximately 10 nanometers.

4. The device of claim 1, wherein one or more emitting surfaces of the device is roughened, textured, patterned or shaped.

5. The device of claim 4, wherein more than one emitting surface of the device is roughened, textured, patterned or shaped.

6. The device of claim 4, wherein the emitting surface of the device is a cone shaped surface.

7. The device of claim 1, wherein the active region is comprised of multiple emitting layers emitting light at more than one wavelength.

8. The device of claim 1, further comprising a transparent electrode layer is formed adjacent the III-nitride layers.

9. The device of claim 8, wherein the transparent electrode layer is an electrically conductive contact layer.

10. The device of claim 8, wherein a surface of the transparent layer is roughened, textured, patterned or shaped.

11. The device of claim 8, wherein a current spreading layer is deposited before the transparent electrode layer.

12. The device of claim 1, wherein the device is placed on a transparent mounting structure.

13. The device of claim 1, wherein the active region includes at least one quantum well layer having a thickness greater than 5 nanometers to increase emitting efficiency as compared to non-polar or semi-polar III-nitride quantum well layers having a thickness of 5 nanometers or less and the light-emitting device has increased light emitting efficiency as the thickness is increased.

14. A method of fabricating a III-nitride light emitting device, comprising:

forming a plurality of III-nitride layers comprising at least one p-type layer, an active region, and at least one n-type layer,

wherein the III-nitride layers are not c-plane III-nitride layers, and

wherein the active region is comprised of at least one III-nitride quantum well layer having a thickness that achieves a current density such that light is emitted at an output power of at least 25 milliWatts (mW) when a current input at 20 milliAmps (mA) is applied.

15. The method of claim 14, wherein the at least one quantum well layer has a thickness of approximately 8-12 nanometers.

16. The method of claim 14, wherein the at least one quantum well layer has a thickness of approximately 10 nanometers.

17. The method of claim 14, wherein one or more emitting surfaces of the device is roughened, textured, patterned or shaped.

18. The method of claim 17, wherein more than one emitting surface of the device is roughened, textured, patterned or shaped.

19. The method of claim 17, wherein the emitting surface of the device is a cone shaped surface.

20. The method of claim 14, wherein the active region is comprised of multiple emitting layers emitting light at more than one wavelength.

21. The method of claim 14, further comprising forming a transparent electrode layer adjacent the III-nitride layers.

22. The method of claim 21, wherein the transparent electrode layer is an electrically conductive contact layer.

23. The method of claim 21, wherein a surface of the transparent layer is roughened, textured, patterned or shaped.

24. The method of claim 21, wherein a current spreading layer is deposited before the transparent electrode layer.

25. The method of claim 14, wherein the device is placed on a transparent mounting structure.

26. The method of claim 14, wherein the active region includes at least one III-nitride quantum well layer having a thickness greater than 5 nanometers to increase emitting efficiency as compared to non-polar or semi-polar III-nitride quantum well layers having a thickness of 5 nanometers or less and the light-emitting device has increased light emitting efficiency as the thickness is increased.