LED with current confinement structure and surface roughening

• US 8,541,788 B2
• Filed: 10/19/2009
• Issued: 09/24/2013
• 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:
  US12/581,759
• Publication Number:
  US 20100032704A1
• Time in Patent Office: 1,436 Days
• Field of Search: 257/79, 257/98, 257/99, 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

A light emitting diode having a vertical orientation with an ohmic contact on portions of a top surface of the diode and a reflective layer adjacent the light emitting region of the diode. This light emitting diode includes a confinement structure. The confinement structure may be an opening in the reflective layer generally beneath the top ohmic contact that defines a non-contact area between the reflective layer and the light emitting region of the diode to encourage current flow to take place other than at the non-contact area to in turn decrease the number of light emitting recombinations beneath the ohmic contact and increase the number of light emitting recombinations in the areas not beneath said ohmic contact. The LED may include roughened emitting surfaces to further enhance light extraction.

Claims

1. A light emitting diode having a vertical orientation, comprising:

a top ohmic contact on portions of a top surface of said diode;

a reflective layer adjacent a semiconductor material layer of said diode;

a passivated portion embedded in, and completely surrounded by, said semiconductor material layer beneath said top ohmic contact that defines a less conductive area between said reflective layer and an active region of said diode; and

a roughened surface of said light emitting diode.

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

3. The light emitting diode according to claim 2, wherein said reflective layer is positioned between said substrate and said semiconductor material layer.

4. The light emitting diode according to claim 1, wherein the size of said passivated portion is substantially the same area as the size of said top ohmic contact.

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

6. The light emitting diode according to claim 1, wherein said passivation portion comprises an ion implanted region.

7. The light emitting diode according to claim 1, wherein said passivation portion comprises an oxidation region.

8. The light emitting diode according to claim 1, wherein said passivation portion comprises a current blocking region.

9. The light emitting diode according to claim 1, wherein said roughened surface comprises a roughened top surface of said light emitting diode.

10. The light emitting diode according to claim 9, wherein said roughened top surface comprises a roughened semiconductor material layer.

11. The light emitting diode according to claim 9, further comprising a transparent conducting layer on said light emitting diode and wherein said roughened top surface comprises a roughened top surface of said transparent conducting layer.

12. The light emitting diode according to claim 1, wherein said semiconductor material layer is a unitary semiconductor material layer and wherein said passivated portion is embedded in said unitary semiconductor layer.