High output group III nitride light emitting diodes

• US 9,905,731 B2
• Filed: 06/08/2010
• Issued: 02/27/2018
• Est. Priority Date: 09/22/2004
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Edmond, John Adam, Bergmann, Michael J., Emerson, David T., Haberern, Kevin Ward
• Primary Examiner(s): HSIEH, HSIN YI
• Application Number:
  US12/796,365
• Publication Number:
  US 20100244052A1
• Time in Patent Office: 2,821 Days
• Field of Search: 257 79, 257 94, 257103
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/325 characterised by the doping materials

Abstract

A light emitting diode is disclosed that includes a silicon carbide substrate and a light emitting structure formed from the Group III nitride material system on the substrate. The diode has an area greater than 100,000 square microns and has a radiant flux at 20 milliamps current of at least 29 milliwatts at its dominant wavelength between 390 and 540 nanometers.

Claims

1. A light emitting diode comprising:

a light emitting layer that comprises a Group III nitride material system;

a first ohmic contact on said light emitting layer;

a silver-based layer between said first ohmic contact and said light emitting layer, said silver-based layer including a first face of said silver-based layer adjacent said first ohmic contact, a second face of said silver-based layer adjacent and directly contacting said light emitting layer and a sidewall of said silver-based layer that extends between said first and second faces;

a barrier layer between said first ohmic contact layer and said silver-based layer and directly contacting said first ohmic contact layer, said barrier layer extending on said first face of said silver-based layer and further extending on said sidewall of said silver-based layer to directly contact said light emitting layer;

a transparent conductive substrate on said light emitting layer opposite said silver-based layer; and

a second ohmic contact directly on said transparent conductive substrate opposite said light emitting layer.

2. A light emitting diode according to claim 1 wherein said transparent conductive substrate comprises a silicon carbide single crystal substrate.

3. A light emitting diode according to claim 2 further comprising a buffer layer between said silicon carbide substrate and said light emitting layer, said buffer layer comprising the Group III nitride material system.

4. A light emitting diode according to claim 3 further comprising at least two layers of opposite conductivity type comprising the Group III nitride material system for providing carriers for recombination and light emission under an applied current.

5. A light emitting diode according to claim 4 wherein said light emitting layer includes at least one layer of indium gallium nitride.

6. A light emitting diode according to claim 2 wherein said silicon carbide substrate is n-type and has a polytype selected from the 3C, 4H, 6H, and 15R polytypes of silicon carbide.

7. A light emitting diode according to claim 1 wherein said light emitting layer comprises a doped semiconductor layer, said silver-based layer is directly on said doped semiconductor layer and said barrier layer is directly on said first face of said silver-based layer and completely encloses said sidewall of said silver-based layer.

8. A light emitting diode according to claim 7 wherein said doped semiconductor layer is a p-type semiconductor layer.

9. A light emitting diode according to claim 1 wherein said transparent conductive substrate includes an oblique sidewall.

10. A light emitting diode according to claim 9;

wherein said second ohmic contact is directly on a face of said transparent conductive substrate that is opposite said light emitting layer, and

wherein said second ohmic contact extends on only a first portion of said face and exposes a second portion of said face.