LED with current confinement structure and surface roughening

• US 7,335,920 B2
• Filed: 01/24/2005
• Issued: 02/26/2008
• 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: Nakamura, Shuji, Denbaars, Steven P., Batres, Max
• Primary Examiner(s): Huynh; Andy
• Application Number:
  US11/042,030
• Publication Number:
  US 20060163586A1
• Time in Patent Office: 1,128 Days
• Field of Search: 257/79, 257/98, 257/E33.011, 257/E33.021, 257/E33.027
• 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 base LED structure comprising;

a p-type layer of material having an associated p-contact;

an n-type layer of material having an associated n-contact;

an active region sandwiched between and in adjacent contact with the p-type layer and the n-type layer;

a confinement structure formed within at least one of the p-type layer of material and the n-type layer of material, the confinement structure substantially preventing the emission of light from the area of the active region coincident with the area of the confinement structure; and

a roughened surface associated with one of the p-type layer of material and the n-type layer of material.

2. The LED of claim 1 wherein the confinement structure comprises an ion implanted region of at least one of the p-type layer of material and the n-type layer of material.

3. The LED of claim 1 wherein the confinement structure comprises an oxidation region of at least one of the p-type layer of material and the n-type layer of material.

4. The LED of claim 1 wherein the confinement structure comprises a current blocking region in at least one of the p-type layer of material and the n-type layer of material.

5. The LED of claim 1 wherein the current confinement structure is within the p-type layer of material.

6. The LED of claim 1 wherein the current confinement structure is within the n-type layer of material.

7. The LED of claim 1 further comprising a conducting substrate adjacent the n-layer of material, wherein the n-contact is in adjacent contact with the substrate.

8. A light emitting diode (LED) comprising:

a base LED structure comprising;

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

a second layer of material having a dopant opposite to that of said first layer and having an associated second contact;

an active region sandwiched between and in adjacent contact with the first layer and the second layer; and

a confinement structure integral with one of the first layer and the second layer and generally axially aligned with the first contact, the confinement structure substantially preventing the emission of light in the area of the active region coincident with the area of the confinement structure.

9. The LED of claim 8 wherein the confinement structure comprises a portion of one of the first layer and second layer, the portion subjected to ion implantation.

10. The LED of claim 8 wherein the confinement structure comprises a portion of one of the first layer and second layer, the portion subjected to oxidation.

11. The LED of claim 8 wherein the confinement structure comprises a portion of one of first layer and second layer, the portion implanted with a semi-insulating material.

12. The LED of claim 11 wherein the material of the first layer and second layer comprises GaN and the semi-insulating material comprises one of Al and Ga.

13. The LED of claim 8 wherein the first surface is at least partially roughened.

14. The LED of claim 8 further comprising a layer of at least partially roughened transparent conducting material adjacent the first surface.

15. The LED of claim 14 wherein the transparent material comprises one of ZnO, In₂O₃ and indium tin oxide (ITO).

16. The LED of claim 8 wherein the second contact is formed of a reflective material.

17. The LED of claim 8 wherein the area of the confinement structure is substantially the same as the area of the first contact.

18. A light emitting diode (LED) comprising:

a base LED structure comprising;

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

a second layer of material;

an active region sandwiched between and in adjacent contact with the first layer and the second layer;

a conducting substrate adjacent the second layer of material and having an associated substrate contact; and

at least one confinement structure fully within one of the first layer, the second layer and the substrate and generally axially aligned with the first contact, the at least one confinement structure directing current flowing toward the active region away from the area of the active region that is coincident with the area of the confinement structure.

19. The LED of claim 18 wherein the first layer of material comprises a p-type material, the second layer of material comprises an n-type material and the at least one current confinement structure is within the p-type material.

20. The LED of claim 18 wherein the first layer of material comprises a p-type material, the second layer of material comprises an n-type material and the at least one current confinement structure is within the n-type material.

21. The LED of claim 18 wherein the first layer of material comprises a p-type material, the second layer of material comprises an n-type material and the at least one current confinement structure is within the substrate.

22. The LED of claim 18 wherein the first layer of material comprises an n-type material, the second layer of material comprises a p-type material and the at least one current confinement structure is within the n-type material.

23. The LED of claim 18 wherein the first layer of material comprises an n-type material, the second layer of material comprises a p-type material and the at least one current confinement structure is within the p-type material.

24. The LED of claim 18 wherein the first layer of material comprises an n-type material, the second layer of material comprises a p-type material and the at least one current confinement structure is within the substrate.

25. The LED of claim 18 wherein at least a portion of the first surface is roughened.

26. The LED of claim 18 further comprising a layer of at least partially roughened transparent conducting material adjacent the first surface.