LEDs with efficient electrode structures

• US 9,105,815 B2
• Filed: 11/11/2012
• Issued: 08/11/2015
• Est. Priority Date: 05/19/2006
• Status: Active Grant

• Current Assignee: Bridgelux Incorporated
• Original Assignee: Bridgelux Incorporated
• Inventors: Shum, Frank T., So, William W., Lester, Steven D.
• Primary Examiner(s): Nguyen, Dao H
• Application Number:
  US13/674,050
• Publication Number:
  US 20130270573A1
• Time in Patent Office: 1,003 Days
• Field of Search: 257/79, 257/88, 257/98, 257/99, 257/103, 257/E27.121, 257/E33.005, 257/E33.068, 372/38.09, 372/43.01, 372/50.124, 438/25, 438/29, 438/35
• US Class Current: 1/1
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/385 the electrode extending at least partially onto a side surface of the semiconductor body
• CPC Class Codes: H01L 33/387 with a plurality of electrode regions in direct contact with the semiconductor body and being electrically interconnected by another electrode layer
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• 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

Aspects include Light Emitting Diodes that have a GaN-based light emitting region and a metallic electrode. The metallic electrode can be physically separated from the GaN-based light emitted region by a layer of porous dielectric, which provides a reflecting region between at least a portion of the metallic electrode and the GaN-based light emitting region.

Claims

1. A Light Emitting Diode (LED) device, comprising:

a Gallium-Nitride (GaN) based semiconductor structure comprising an active region, the active region being in electrical contact with a P doped region formed to have a generally planar surface, through which light generated in the active region can be emitted; and

a metallic electrode structure, comprising a bonding pad area, the metallic electrode structure formed in electrical contact with the planar surface of the P-doped region, wherein a physical interface between the bonding pad area and the planar surface comprises a single layer of dielectric material interposed between the planar surface and the bonding pad area, the single layer of dielectric material being non-perforated and porous, and defining a region of total internal reflection between the metallic electrode structure and the GaN based semiconductor structure.

2. The Light Emitting Diode (LED) device of claim 1, wherein the interface of the reflection region is capable of reflecting at least 90% of light incident at angles between about zero degrees and about thirteen degrees.

3. The Light Emitting Diode (LED) device of claim 1, wherein the interface is capable of reflecting at least 92% of light incident at angles between about zero degrees and about ten degrees.

4. The Light Emitting Diode (LED) device of claim 1, wherein the interface of the reflection region is further capable of reflecting at least 82% of light incident at angles between about twenty-two degrees and about twenty-seven degrees.

5. The Light Emitting Diode (LED) device of claim 1, wherein the interface of the reflection region is further capable of reflecting at least 85% of light incident at angles between about twenty-three degrees and about twenty-six degrees.

6. The Light Emitting Diode (LED) device of claim 1, wherein the interface of the reflection region is capable of reflecting at least 85% of light incident for a total angular range of at least about 20 degrees within a range of zero to forty degrees.

7. The Light Emitting Diode (LED) device of claim 1, wherein the interface of the reflection region is capable of reflecting at least 85% of light incident within a total of at least about 22 degrees within a range of incident angles between zero and forty degrees.

8. The Light Emitting Diode (LED) device of claim 1, wherein the physical interface between the bonding pad area and the planar surface further comprises a current spreading layer.

9. The Light Emitting Diode (LED) device of claim 1, wherein the interface of the reflection region is capable of reflecting at least 90% of light incident within a total of at least about 16 degrees for a range of incident angles between zero and forty degrees.

10. An electrode for a Light Emitting Diode (LED) semiconductor device, the electrode structure comprising:

a metallic structure formed in electrical contact with a surface of a P-doped region of the semiconductor, and comprising a bonding pad area; and

a porous layer of dielectric material physically disposed between the bonding pad area and the planar surface of the P-doped region, wherein the porous layer of material forms a physical interface comprising a reflective region capable of reflecting at least 85% of light incident at angles between about zero degrees and about fifteen degrees.

11. The electrode for a Light Emitting Diode (LED) device of claim 10, wherein the reflective region is capable of reflecting at least 90% of light incident at angles between about zero degrees and about thirteen degrees.

12. The electrode for a Light Emitting Diode (LED) device of claim 10, wherein the porous layer of dielectric material is nano-porous Silicon Dioxide.

13. The electrode for a Light Emitting Diode (LED) device of claim 10, wherein the reflective region is capable of reflecting at least 92% of light incident at angles between about zero degrees and about ten degrees.

14. The electrode for a Light Emitting Diode (LED) device of claim 10, wherein the reflective region is capable of reflecting at least 82% of light incident at angles between about twenty-two degrees and about twenty-seven degrees.

15. The electrode for a Light Emitting Diode (LED) device of claim 10, wherein the reflective region is capable of reflecting at least 85% of light incident at angles between about twenty-three degrees and about twenty-six degrees.

16. The electrode for a Light Emitting Diode (LED) device of claim 10, wherein the reflective region is capable of reflecting at least 85% of light incident within a total of at least about 20 degrees for a range of incident angles between zero and forty degrees.