HIGH EFFICIENCY LIGHT EMITTING DIODE (LED)

• US 20070145397A1
• Filed: 12/08/2006
• Published: 06/28/2007
• Est. Priority Date: 12/08/2005
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Nakamura, Shuji, DenBaars, Steven, Speck, James
• Granted Patent: US 7,956,371 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

An (Al, Ga, In)N light emitting diode (LED), wherein light extraction from chip and/or phosphor conversion layer is optimized. By novel shaping of LED and package optics, a high efficiency light emitting diode is achieved.

Claims

1. An optical device, comprising:

a light emitting device comprised of at least an active region;

at least one first shaped optical element coupled to at least one side of the light emitting device;

at least one second shaped optical element encapsulating both the light emitting device and the at least one first shaped optical element for extracting light emitted by the active region and the first shaped optical elements; and

a phosphor, optically coupled to the at least one second shaped optical element, wherein light in at least a first wavelength region emitted by the III-nitride light emitting region passes through the at least one second shaped optical elements and excites the phosphor to emit light in at least a second wavelength region.

2. The optical device of claim 1, wherein the at least one first optical element is wafer bonded to the light emitting device.

3. The optical device of claim 1, wherein at least one of the at least one first shaped optical elements comprises a ZnO optical element.

4. The optical device of claim 1, wherein at least one of the at least one first shaped optical elements is shaped to increase light extraction from the III-nitride light emitting region.

5. The optical device of claim 1, wherein the at least one first shaped optical elements include angles adjusted for light extraction efficiency from the III-nitride light emitting region.

6. The optical device of claim 1, wherein at least one of the at least one first shaped optical elements is cone-shaped.

7. The optical device of claim 1, wherein the at least one second shaped optical element comprises a lens.

8. The optical device of claim 1, wherein the at least one second shaped optical element is shaped for light extraction.

9. The optical device of claim 1, wherein the at least one second shaped optical element includes angles that are adjusted for light extraction efficiency.

10. The optical device of claim 1, wherein a layer that forms an interface between the III-nitride light emitting region and the at least one first shaped optical elements has a roughened surface.

11. The optical device of claim 1, further comprising an additional phosphor layer coupled to the phosphor layer.

12. The optical device of claim 1, further comprising a third shaped optical element encapsulating the III-nitride light emitting region, the at least one first shaped optical elements and the at least one second shaped optical elements for extracting light emitted by the III-nitride light emitting region, the first shaped optical elements, and the second shaped optical elements.

13. The optical device of claim 11, wherein the third shaped optical element comprises a reflector cup.

14. The optical device of claim 1, wherein the phosphor layer is shaped for light extraction efficiency.

15. The optical device of claim 1, wherein the light emitting device comprises at least one of the group consisting of:

(Al, Ga, In)N materials, (Al, Ga, In)As materials, (Al, Ga, In)P materials, compound semiconductor material from (Al, Ga, In)AsPNSb materials, and compound semiconductor material from ZnGeN₂ or ZnSnGeN₂ materials.

16. The optical device of claim 1, further comprising a reflective coating coupled to the at least one first optical element.

17. The optical device of claim 1, further comprising a reflector positioned between the phosphor layer and the light emitting region which passes at least the first wavelength region and reflects at least a portion of light in the second wavelength region.

18. The optical device of claim 17, wherein the reflector is a distributed Bragg reflector.

19. A Light Emitting Diode (LED) assembly, comprising:

a substrate;

a light emitting device, comprising;

an n-type Group III nitride layer coupled to the substrate;

an active layer, coupled to the n-type Group III nitride layer, wherein the active layer emits light in at least a first wavelength region; and

a p-type Group III nitride layer, coupled to the active layer;

at least one oxide layer, coupled to the light emitting device, the at least one oxide layer being shaped into a form that increases the efficiency of the light emitting device by reducing internal reflection of the light in the light emitting device;

an optical element, coupled to the at least one oxide layer; and

a phosphor, optically coupled to the at least one oxide layer, wherein light in at least the first wavelength region emitted by the light emitting device passes through the phosphor and excites the phosphor to emit light in at least a second wavelength region.

21. The LED of claim 19, further comprising a lens, coupled between the oxide layer and the phosphor, wherein the lens increases the efficiency of the LED by reducing light absorption in the LED.

20. A Light Emitting Diode (LED) emitting multiple wavelength regions of light, comprising:

an active Group III nitride layer, wherein the active Group III nitride layer emits light in at least a first wavelength region;

at least one oxide layer, coupled to the light emitting device, wherein the at least one oxide layer is substantially transparent in the first wavelength region, the at least one oxide layer being shaped into a form that increases the efficiency of the LED by reducing internal reflection of the light in the LED; and

a phosphor, optically coupled to the at least one oxide layer such that light in at least the first wavelength region strikes the phosphor and excites the phosphor to emit light in at least a second wavelength region, such that light in at least the first wavelength region and the second wavelength region are emitted by the LED.