Led with current confinement structure and surface roughening

• US 20080061311A1
• Filed: 11/09/2007
• Published: 03/13/2008
• 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, Batres, Max
• Granted Patent: US 8,410,490 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. A light emitting diode (LED) comprising:

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

a second layer of material having an associated second contact in direct contact with said second layer;

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

a confinement structure in the second contact, the 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.

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 second contact is formed of a reflective material.

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

7. The LED of claim 1 further comprising 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).