Luminescent ceramic for a light emitting device

Patent metadata

Field	Value
Publication number	US-9359260-B2
Application number	US-3458808-A
Country	US
Kind code	B2
Filing date	Feb 20, 2008
Priority date	Jun 3, 2004
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

A semiconductor light emitting device comprising a light emitting layer disposed between an n-type region and a p-type region is combined with a ceramic layer which is disposed in a path of light emitted by the light emitting layer. The ceramic layer is composed of or includes a wavelength converting material such as a phosphor. Luminescent ceramic layers according to embodiments of the invention may be more robust and less sensitive to temperature than prior art phosphor layers. In addition, luminescent ceramics may exhibit less scattering and may therefore increase the conversion efficiency over prior art phosphor layers.

First claim

What is being claimed is:

1. A device comprising:
a light emitting structure comprising a light emitting layer;
a first ceramic phosphor disposed in a path of light emitted by the light emitting layer;
a second ceramic phosphor disposed in a path of light emitted by the light emitting layer; and
a heat extraction structure;
wherein:
one of the first ceramic phosphor and the second ceramic phosphor is directly connected to the heat extraction structure;
a surface of the first ceramic phosphor is roughened;
one of the first ceramic phosphor and the second ceramic phosphor is a transparent or translucent ceramic slab formed by sintering;
the light emitting structure is disposed between a mount and the first ceramic phosphor and directly connected to the mount; and
the heat extraction structure is disposed between the mount and the first ceramic phosphor and directly connected to the mount.

2. The device of claim 1 wherein the second ceramic phosphor is disposed between the first ceramic phosphor and the light emitting structure.

3. The device of claim 1 wherein the first ceramic phosphor and the second ceramic phosphor are different phosphors.

4. The device of claim 1 wherein one of the first ceramic phosphor and the second ceramic phosphor is formed by heating powder phosphor particles until surfaces of the phosphor particles melt and stick together to form a rigid agglomerate of phosphor particles.

5. The device of claim 1 wherein one of the first ceramic phosphor and the second ceramic phosphor comprises a ceramic slab that is substantially free of binder material other than the phosphor itself.

6. The device of claim 1 wherein one of the first ceramic phosphor and the second ceramic phosphor comprises a ceramic slab with very little space or material with a refractive index different from a refractive index of a phosphor that forms the ceramic slab.

7. The device of claim 1 wherein the heat extraction structure is disposed adjacent to the light emitting structure and is spaced apart from the light emitting structure.

8. The device of claim 1 wherein the heat extraction structure comprises one of metal, Cu foil, Mo, Cu/Mo, Cu/W, ceramic, and compressed diamond.

9. The device of claim 1 wherein the first ceramic phosphor is wider than the second ceramic phosphor.

10. The device of claim 1 wherein the light emitting structure is a flip chip device.

11. A device comprising:
a light emitting structure comprising a light emitting layer;
a first ceramic phosphor disposed in a path of light emitted by the light emitting layer;
a second ceramic phosphor disposed in a path of light emitted by the light emitting layer; and
a heat extraction structure;
wherein:
one of the first ceramic phosphor and the second ceramic phosphor is directly connected to the heat extraction structure;
the first ceramic phosphor is textured;
one of the first ceramic phosphor and the second ceramic phosphor is a transparent or translucent ceramic slab formed by sintering;
the light emitting structure is disposed between a mount and the first ceramic phosphor and directly connected to the mount; and
the heat extraction structure is disposed between the mount and the first ceramic phosphor and directly connected to the mount.

12. The device of claim 11 wherein the first ceramic phosphor is textured with a photonic crystal structure.

13. The device of claim 11 wherein the first ceramic phosphor is textured with a Fresnel lens structure.

14. The device of claim 11 wherein the heat extraction structure is disposed adjacent to the light emitting structure and is spaced apart from the light emitting structure.

15. The device of claim 11 wherein the heat extraction structure comprises one of metal, Cu foil, Mo, Cu/Mo, Cu/W, ceramic, and compressed diamond.

16. The device of claim 11 wherein the first ceramic phosphor is wider than the second ceramic phosphor.

17. The device of claim 11 wherein the light emitting structure is a flip chip device.

Assignees

• Mueller Gerd O
• Mueller-Mach Regina B
• Krames Michael R
• Schmidt Peter J
• Bechtel Hans-Helmut
• Meyer Joerg
• De Graaf Jan
• Kop Theo Arnold
• Lumileds Llc

Inventors

• Mueller Gerd O
• Mueller-Mach Regina B
• Krames Michael R
• Schmidt Peter J
• Bechtel Hans-Helmut
• Meyer Joerg
• De Graaf Jan
• Kop Theo Arnold

Classifications

• C04B2235/662

  Annealing after sintering · CPC title

• C04B35/64

  Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F}) · CPC title

• C04B2235/6027

  Slip casting · CPC title

• C04B35/584 Primary

  based on silicon nitride · CPC title

• C04B2235/3229

  Cerium oxides or oxide-forming salts thereof · CPC title