LED with current confinement structure and surface roughening

• US 8,410,490 B2
• Filed: 11/09/2007
• Issued: 04/02/2013
• Est. Priority Date: 01/24/2005
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Denbaars, Steven P., Nakamura, Shuji, Batres, Max
• Primary Examiner(s): Huynh, Andy
• Application Number:
  US11/983,515
• Publication Number:
  US 20080061311A1
• Time in Patent Office: 1,971 Days
• Field of Search: 257/79, 257/98, 257/99, 257/103, 257/E33.068, 257/E33.074
• US Class Current: 257/79
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

An LED having a p-type layer of material with an associated p-contact, an n-type layer of material with an associated n-contact and an active region between the p-type layer and the n-type layer, includes a confinement structure that is formed within one of the p-type layer of material and the n-type layer of material. The confinement structure is generally aligned with the contact on the top and primary emission surface of the LED and substantially prevents the emission of light from the area of the active region that is coincident with the area of the confinement structure and the top-surface contact. The LED may include a roughened emitting-side surface to further enhance light extraction.

Claims

1. A light emitting diode (LED) comprising:

a first layer of semiconductor material having an associated first contact and first surface through which light is emitted;

a second layer of semiconductor material having an associated continuous, metal second contact layer in direct contact with said second layer;

an active region between the first layer and the second layer;

a confinement structure in the continuous, metal second contact layer, the confinement structure being completely surrounded by said continuous, metal second contact layer and directing current flowing toward the active region away from an area of the active region that is substantially coincident with an area of the confinement structure; and

a roughened surface of said light emitting diode.

2. The LED of claim 1 wherein the confinement structure comprises an insulating, non-conducting material.

3. The LED of claim 2 wherein the insulating, non-conducting material comprises one of SiO₂, AlN and SiN.

4. The LED of claim 1 wherein the confinement structure is generally axially aligned with the first contact.

5. The LED of claim 1 wherein the continuous, metal second contact layer is formed of a reflective material.

6. The LED of claim 1 wherein said roughened surface comprises at least a portion of the first surface.

7. The LED of claim 1 wherein said roughened surface comprises a layer of at least partially roughened transparent conducting material adjacent the first surface.

8. The LED of claim 7 wherein the transparent material comprises one of ZnO, In₂O₃ and indium tin oxide (ITO).

9. A light emitting diode (LED) comprising:

a base LED structure comprising;

a first semiconductor material;

a first contact associated with said first semiconductor material;

a second semiconductor material;

a continuous, reflective second contact layer in direct contact with said second semiconductor material; and

an active region interposed between said first and second semiconductor materials;

a confinement structure comprising an insulating material disposed in said continuous, reflective second contact layer, the confinement structure being completely surrounded by said continuous, reflective second contact layer and reducing current flow around an area of said active region that is generally axially aligned with said first contact; and

a roughened surface of said LED.

10. The LED of claim 9, further comprising:

a transparent conductive material on a primary light emitting surface of said first semiconductor material.

11. The LED of claim 10, said transparent conductive material comprising at least one material selected from the list consisting of ZnO, In₂O₃ and indium tin oxide (ITO).

12. The LED of claim 10, wherein said roughened surface comprises a roughened surface of said transparent conductive material.

13. The LED of claim 9, further comprising a transparent conductive oxide interposed between said primary light emitting surface of said first semiconductor material and said first contact.

14. The LED of claim 13, wherein said transparent conductive oxide is indium tin oxide.

15. The LED of claim 9, wherein said continuous, reflective second contact layer comprises metal.

16. The LED of claim 9, wherein said second semiconductor material is p-type.

17. The LED of claim 9, wherein said first semiconductor material comprises an n-type semiconductor material and said second semiconductor material comprises a p-type semiconductor material.

18. The LED of claim 9, wherein said first semiconductor material comprises a p-type semiconductor material and said second semiconductor material comprises an n-type semiconductor material.

19. The LED of claim 9, wherein said roughened surface comprises at least a portion of said first semiconductor material.

20. A light emitting diode (LED) comprising:

a base LED structure comprising;

a first semiconductor material;

a first contact associated with said first semiconductor material;

a second semiconductor material;

a continuous, metal second contact layer associated with said second semiconductor material; and

an active region interposed between said first and second semiconductor materials;

a confinement structure disposed in said continuous, metal second contact layer and being completely surrounded by said continuous, metal second contact layer, such that current flows around an area of said active region that is generally axially aligned with said first contact, reducing the radiative recombination in said area;

a transparent conductive material different from said first and second semiconductor materials on said first material and said first contact; and

a roughened surface of said light emitting diode.

21. The LED of claim 20, wherein said first semiconductor material is p-type, said transparent conductive material is on said first semiconductor material, and said first semiconductor material comprises a primary light emitting surface.

22. The LED of claim 21, wherein said roughened surface comprises a roughened surface of said transparent conductive material.

23. The LED of claim 20, said transparent conductive material comprising at least one material selected from the list consisting of ZnO, In₂O₃ and indium tin oxide (ITO).

24. The LED of claim 20, wherein said roughened surface comprises a roughened surface of said transparent conductive material opposite said p-type material.

25. A light emitting diode (LED) comprising:

a base LED structure comprising;

a first semiconductor material comprising a primary light emitting surface;

a first contact associated with said first semiconductor material;

a second semiconductor material; and

an active region interposed between said first and second semiconductor materials;

a confinement structure disposed directly on said second semiconductor material such that current flows around an area of said active region that is generally axially aligned with said first contact, reducing the radiative recombination in said area;

a continuous, reflective layer disposed directly on said second semiconductor material and completely surrounding said confinement structure; and

a roughened surface of said light emitting diode.

26. The LED of claim 25, further comprising a support structure disposed on the opposite side of said LED from said primary light emitting surface.

27. The LED of claim 25, further comprising a transparent conductive material of a material different from said first and second semiconductor materials.

28. The LED of claim 27, said transparent conductive material comprising at least one material selected from the list consisting of ZnO, In₂O₃ and indium tin oxide (ITO).

29. The LED of claim 27, wherein said transparent conductive material is on said primary light emitting surface of said first semiconductor material.

30. The LED of claim 29 wherein said roughened surface comprises a roughened surface of said transparent conductive material.

31. The LED of claim 25, wherein said first semiconductor material is n-type and said second semiconductor material is p-type.

32. The LED of claim 31, wherein said roughened surface comprises a roughened surface of said first semiconductor material.

33. The LED of claim 31, wherein said continuous, reflective layer is a second contact associated with said second semiconductor material.

34. The LED of claim 25, wherein said first semiconductor material is p-type and said second semiconductor material is n-type.

35. The LED of claim 34, further comprising a transparent conducting material different from said first semiconductor material on said first semiconductor material.

36. The LED of claim 35, wherein said roughened surface comprises a roughened surface of said transparent conducting material.

37. The LED of claim 36, further comprising a support structure on said second semiconductor material, said continuous, reflective layer being on said support structure opposite said second semiconductor material.