Light emitting diodes including two reflector layers

• US 8,426,881 B2
• Filed: 01/27/2009
• Issued: 04/23/2013
• Est. Priority Date: 02/01/2001
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Slater, David B. Jr., Glass, Robert C., Swoboda, Charles M., Keller, Bernd, Ibbetson, James, Thibeault, Brian, Tarsa, Eric J.
• Primary Examiner(s): Jackson, Jr., Jerome
• Application Number:
  US12/360,216
• Publication Number:
  US 20090166658A1
• Time in Patent Office: 1,547 Days
• Field of Search: 257/98
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/32014 the layer connector being smaller than the bonding area, e.g. bond pad
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A light emitting diode includes a diode region having a gallium nitride based n-type layer, an active region and a gallium nitride based p-type layer. A first reflector layer is provided on the gallium nitride based p-type layer, and a second reflector layer is provided on the gallium nitride based n-type layer. Bonding layers, a mounting support, a wire bond and/or transparent oxide layers also may be provided.

Claims

1. A light emitting diode comprising:

a diode region comprising a gallium nitride based n-type layer, an active region on the gallium nitride based n-type layer and a gallium nitride based p-type layer on the active region opposite the gallium nitride based n-type layer;

a first reflector layer that comprises silver on the gallium nitride based p-type layer opposite the active region and oriented to reflect light that emerges from the diode region and impinges on the first reflector layer that comprises silver back towards the diode region; and

a second reflector layer that comprises aluminum on the gallium nitride based n-type layer opposite the active region and oriented to reflect light that emerges from the diode region and impinges on the second reflector layer that comprises aluminum back towards the diode region.

2. A light emitting diode according to claim 1 further comprising:

a first bonding layer on the first reflector layer opposite the gallium nitride based p-type layer; and

a mounting support on the first bonding layer opposite the first reflector layer.

3. A light emitting diode according to claim 1 further comprising:

a second bonding layer on the second reflector layer opposite the gallium nitride based n-type layer; and

a wire bond on the second bonding layer opposite the second reflector layer.

4. A light emitting diode according to claim 2 further comprising:

a second bonding layer on the second reflector layer opposite the gallium nitride based n-type layer; and

a wire bond on the second bonding layer opposite the second reflector layer.

5. A light emitting diode according to claim 1 further comprising:

a bonding layer on the second reflector layer opposite the gallium nitride based n-type layer, wherein the bonding layer and the second reflector layer are congruent to one another.

6. A light emitting diode according to claim 1 wherein the second reflector layer is directly on an underlying layer and wherein the second reflector layer is of smaller area than the underlying layer.

7. A light emitting diode according to claim 1 further comprising:

a bonding layer on the second reflector layer opposite the gallium nitride based n-type layer, wherein the bonding layer and the second reflector layer each comprise a plurality of fingers.

8. A light emitting diode according to claim 1 further comprising:

a bonding layer on the second reflector layer opposite the gallium nitride based n-type layer, wherein the bonding layer and the second reflector layer each comprise a grid.

9. Alight emitting diode according to claim 1 wherein the second reflector layer comprises a plurality of fingers.

10. A light emitting diode according to claim 1 wherein the second reflector layer comprises a grid.

11. A light emitting diode according to claim 5 further comprising:

a wire bond on the bonding layer opposite the second reflector layer.

12. A light emitting diode according to claim 1 further comprising:

a transparent oxide layer between the gallium nitride based p-type layer and the first reflector layer.

13. A light emitting diode according to claim 1 further comprising:

a transparent oxide layer between the gallium nitride based n-type layer and the second reflector layer.

14. A light emitting diode according to claim 12 wherein the transparent oxide layer comprises Indium Tin Oxide (ITO).

15. A light emitting diode according to claim 13 wherein the transparent oxide layer comprises Indium Tin Oxide (ITO).

16. A light emitting diode comprising:

a vertical gallium nitride based light emitting diode structure; and

a pair of reflector layers, a respective one of which is on an opposite side of the vertical gallium nitride based light emitting diode structure, and is oriented to reflect light that emerges from the vertical gallium nitride based light emitting diode structure and impinges on a respective one of the pair of reflective layers back towards the vertical gallium nitride based light emitting diode structure, wherein one of the reflector layers comprises silver and the other of the reflector layers comprises aluminum.

17. A light emitting diode according to claim 16 wherein the pair of reflector layers have different sizes and/or shapes.

18. A light emitting diode according to claim 16 further comprising a mounting support on one of the pair of reflector layers.

19. A light emitting diode according to claim 18 further comprising a wire bond on the other of the pair of reflector layers.