LIGHT EMITTING DIODES INCLUDING TRANSPARENT OXIDE LAYERS

• US 20070284604A1
• Filed: 08/21/2007
• Published: 12/13/2007
• Est. Priority Date: 02/01/2001
• Status: Active Grant

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd, Ibbetson, James, Thibeault, Brian, Glass, Robert, Slater, David, Swoboda, Charles, Tarsa, Eric
• Granted Patent: US 7,420,222 B2
• Time in Patent Office: Days
• 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

Light emitting diodes include a substrate having first and second opposing faces and that is transparent to optical radiation in a predetermined wavelength range and that is patterned to define, in cross-section, a plurality of pedestals that extend into the substrate from the first face towards the second face. A diode region on the second face is configured to emit light in the predetermined wavelength range, into the substrate upon application of voltage across the diode region. A mounting support on the diode region, opposite the substrate is configured to support the diode region, such that the light that is emitted from the diode region into the substrate, is emitted from the first face upon application of voltage across the diode region. A reflector is provided between the mounting support and the diode region, that is configured to reflect light that is emitted from the diode region back into the diode region, through the substrate that is transparent to optical radiation in the predetermined wavelength range and from the plurality of pedestals, upon application of voltage across the diode region. A layer of Indium Tin Oxide (ITO) is provided between the reflector and the diode region.

Claims

1. A light emitting diode comprising:

a substrate having first and second opposing faces, that is transparent to optical radiation in a predetermined wavelength range and that is patterned to define, in cross-section, a plurality of pedestals that extend into the substrate from the first face towards the second face;

a diode region on the second face that is configured to emit light in the predetermined wavelength range into the substrate that is transparent to optical radiation in the predetermined wavelength range, upon application of voltage across the diode region;

a mounting support on the diode region, opposite the substrate that is transparent to optical radiation in the predetermined frequency range, the mounting support being configured to support the diode region such that the light that is emitted from the diode region into the substrate that is transparent to optical radiation in the predetermined wavelength range, is emitted from the plurality of pedestals, upon application of voltage across the diode region;

a reflector between the mounting support and the diode region, that is configured to reflect light that is emitted from the diode region back into the diode region, through the substrate that is transparent to optical radiation in the predetermined wavelength range and from the plurality of pedestals, upon application of voltage across the diode region; and

a layer comprising Indium Tin Oxide (ITO) between the reflector and the diode region.

2. A light emitting diode according to claim 1 wherein the layer comprising ITO is several microns or more thick.

3. A light emitting diode comprising:

a substrate having first and second opposing faces, that is transparent to optical radiation in a predetermined wavelength range and that is patterned to define, in cross-section, a plurality of pedestals that extend into the substrate from the first face towards the second face;

a diode region on the second face that is configured to emit light in the predetermined wavelength range into the substrate that is transparent to optical radiation in the predetermined wavelength range, upon application of voltage across the diode region;

a mounting support on the diode region, opposite the substrate that is transparent to optical radiation in the predetermined frequency range, the mounting support being configured to support the diode region such that the light that is emitted from the diode region into the substrate that is transparent to optical radiation in the predetermined wavelength range, is emitted from the plurality of pedestals, upon application of voltage across the diode region;

a reflector between the mounting support and the first face, that is configured to reflect light that is emitted from the first face back into the substrate that is transparent to optical radiation in the predetermined wavelength range, upon application of voltage across the diode region; and

a layer comprising Indium Tin Oxide (ITO) between the reflector and the first face.

4. A light emitting diode according to claim 3 wherein the layer comprising ITO is several microns or more thick.

5. A light emitting diode comprising:

a substrate having first and second opposing faces, that is transparent to optical radiation in a predetermined wavelength range;

a diode region on the second face that is configured to emit light in the predetermined wavelength range into the substrate that is transparent to optical radiation in the predetermined wavelength range, upon application of voltage across the diode region; and

a layer comprising Indium tin Oxide (ITO) on the diode region opposite the second face and/or on the first face opposite the second face.

6. A light emitting diode according to claim 5 wherein the layer comprising ITO is several microns or more thick.

7. A light emitting diode according to claim 6 further comprising a reflector on the layer comprising ITO.

8. A light emitting diode comprising:

a silicon carbide substrate;

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

a first transparent oxide layer on the gallium nitride based p-type layer; and

a second transparent oxide layer on the silicon carbide substrate.

9. A light emitting diode according to claim 8 further comprising a first reflector on the gallium nitride based p-type layer and a second reflector on the silicon carbide substrate.

10. A light emitting diode according to claim 8 wherein the first transparent oxide layer and the second transparent oxide layer both comprise Indium Tin Oxide (ITO).

11. A light emitting diode according to claim 10 wherein the ITO is several microns or more thick.

12. A light emitting diode according to claim 8 further comprising a first reflector on the first transparent oxide layer opposite the gallium nitride based p-type layer and a second reflector on the second transparent oxide layer opposite the silicon carbide substrate.

13. A light emitting diode comprising:

a substrate having a first face and a second face;

a gallium nitride based diode region on the first face; and

a transparent oxide layer on the second face.

14. A light emitting diode according to claim 13 further comprising a reflector on the transparent oxide layer opposite the second face.

15. A light emitting device according to claim 13 wherein the transparent oxide layer comprises Indium Tin Oxide.

16. A light emitting diode according to claim 15 wherein the ITO is several microns or more thick.