Light emitting diodes (LEDs) with improved light extraction by roughening

• US 8,466,479 B2
• Filed: 01/07/2011
• Issued: 06/18/2013
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Original Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Inventors: Liu, Wen-Huang, Cheng, Chao-Chen, Chu, Chen-Fu, Cheng, Hao-Chun, Fan, Feng-Hsu
• Primary Examiner(s): Lee, Calvin
• Application Number:
  US12/986,946
• Publication Number:
  US 20110101400A1
• Time in Patent Office: 893 Days
• Field of Search: 438/22, 438/29, 438/42, 438/48, 257 88- 98, 257/E21.125, 257/E21.216
• US Class Current: 257/98
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

Systems and methods are disclosed for fabricating a semiconductor light-emitting diode (LED) device by forming an n-doped gallium nitride (n-GaN) layer on the LED device and roughening the surface of the n-GaN layer to extract light from an interior of the LED device.

Claims

1. A light-emitting diode (LED) structure, comprising:

a multilayer semiconductor structure for emitting light, an upper surface of the structure having a plurality of protuberances, wherein the upper surface of the structure and surfaces of the protuberances comprise submicron-dimensioned objects; and

an electrically conductive substrate disposed beneath a lower surface of the structure.

2. The LED structure of claim 1, wherein the submicron-dimensioned objects comprise spheres.

3. The LED structure of claim 2, wherein the spheres comprise polystyrene spheres.

4. The LED structure of claim 1, wherein lateral surfaces of the protuberances form an angle greater than 90°

with the upper surface of the multilayer semiconductor structure.

5. The LED structure of claim 1, wherein the protuberances comprise one of dots, studs, or bumps.

6. The LED structure of claim 1, wherein the protuberances are uniformly patterned protuberances.

8. The LED structure of claim 1, wherein the surfaces of the structure and of the protuberances comprise polystyrene spheres.

9. The LED structure of claim 1, wherein the multilayer semiconductor structure comprises:

a p-doped layer;

an active layer for emitting light disposed above the p-doped layer; and

an n-doped layer disposed above the active layer, such that the surface of the structure having the plurality of protuberances is a surface of the n-doped layer.

10. The LED structure of claim 1, wherein the protuberances have a shape akin to a frustum of a cone or a pyramid.

11. The LED structure of claim 1, wherein the protuberances comprise one of dots, studs, or bumps.

7. A light-emitting diode (LED) structure, comprising:

a multilayer semiconductor structure for emitting light, an upper surface of the structure having a plurality of patterned protuberances, wherein lateral surfaces of the protuberances form an angle greater than 90°

with the upper surface of the multilayer semiconductor structure and wherein the surfaces of the structure and of the protuberances comprise rough or textured surfaces; and

an electrically conductive substrate disposed beneath a lower surface of the structure.

12. The LED structure of claim 7, wherein the electrically conductive substrate comprises a plurality of metal layers.

13. A light-emitting diode (LED) structure, comprising:

a multilayer semiconductor structure for emitting light, an upper surface of the structure having a plurality of protuberances, wherein the upper surface of the structure and surfaces of the protuberances comprise rough or textured surfaces and wherein the protuberances have a shape akin to a frustum of a cone or a pyramid; and

an electrically conductive substrate disposed beneath a lower surface of the structure.

14. The LED structure of claim 13, wherein lateral surfaces of the protuberances form an angle greater than 90°

with the upper surface of the multilayer semiconductor structure.

15. The LED structure of claim 13, wherein the upper surface of the structure and the surfaces of the protuberances comprise submicron-dimensioned objects.

16. The LED structure of claim 15, wherein the submicron-dimensioned objects comprise spheres.

17. The LED structure of claim 16, wherein the spheres comprise polystyrene spheres.

18. The LED structure of claim 13, wherein the protuberances comprise one of dots, studs, or bumps.

19. The LED structure of claim 13, wherein the protuberances are patterned protuberances.

20. The LED structure of claim 13, wherein the electrically conductive substrate comprises at least one of a metal or a metal alloy.