LED WITH CURRENT CONFINEMENT STRUCTURE AND SURFACE ROUGHENING

• US 20100032704A1
• Filed: 10/19/2009
• Published: 02/11/2010
• 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
• Granted Patent: US 8,541,788 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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. In a light emitting diode having a vertical orientation with an ohmic contact on portions of a top surface of said diode and a reflective layer adjacent the light emitting region of said diode;

the improvement comprising;

an opening in said reflective layer beneath said top ohmic contact that defines a non-contact area between said reflective layer and said light emitting region of said diode to encourage current flow to take place other than at said non-contact area to in turn decrease the number of light emitting recombinations beneath said ohmic contact and increase the number of light emitting recombinations in the areas not beneath said ohmic contact.

2. A light emitting diode according to claim 1 formed on a substrate and having an ohmic contact to said substrate that is larger in area than said top ohmic contact.

4. A light emitting diode according to claim 1 wherein said light emitting region comprises a plurality of Group III nitride layers, including at least one p-type layer and at least one n-type layer.

5. The light emitting diode according to claim 1, further comprising a roughened layer on a surface of said light emitting diode.

6. The light emitting diode according to claim 1, wherein said reflective layer comprises silver, aluminum or rhodium.

7. The light emitting diode according to claim 1, further comprising a insulating, non conductive material in said opening in said reflective layer.

8. The light emitting diode according to claim 1, further comprising a material in said opening in said reflective layer that comprise SiO₂, AlN or SiN.

9. The light emitting diode according to claim 1, wherein said opening in said reflective area has an area essentially the same as the area covered by said top ohmic contact.

3. A light emitting diode according to claim 3 wherein said reflective layer is positioned between said substrate and said light emitting region.

10. In a light emitting diode having a vertical orientation with an ohmic contact on portions of a top surface of said diode and a reflective layer adjacent the light emitting region of said diode;

the improvement comprising;

a passivated portion of said light emitting region beneath said top ohmic contact that defines a less conductive area between said reflective layer and said light emitting region of said diode to encourage current flow to take place other than at said passivated portion to in turn decrease the number of light emitting recombinations beneath said ohmic contact and increase the number of light emitting recombinations not beneath said top ohmic contact.

11. A light emitting diode according to claim 10, formed on a substrate and having an ohmic contact to said substrate that is larger in area than said top ohmic contact.

12. A light emitting diode according to claim 11, wherein said reflective layer is positioned between said substrate and said light emitting region.

13. A light emitting diode according to claim 10, wherein the size of said passivated portion is substantially the same area as the size of said top ohmic contact.

14. A light emitting diode according to claim 10, wherein said light emitting region comprises a plurality of Group III nitride layers, including at least one p-type layer and at least one n-type layer.

15. A light emitting diode according to claim 10, wherein said light emitting region comprises a plurality of Group III nitride layers, including at least one p-type layer and at least one n-type layer.

16. A light emitting diode according to claim 10, wherein said passivation portion comprises an ion implanted region.

17. A light emitting diode according to claim 10, wherein said passivation portion comprises an oxidation region.

18. A light emitting diode according to claim 10, wherein said passivation portion comprises a current blocking region.

19. The light emitting diode according to claim 10, further comprising a roughened layer on a surface of said light emitting diode.