Phosphor-converted light emitting device

• US 20020185965A1
• Filed: 06/11/2001
• Published: 12/12/2002
• Est. Priority Date: 06/11/2001
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Martin van Leth, Nicolaas Joseph, Krames, Michael R., Verhoeckx, Godefridus Johannes, Collins, William David III
• Granted Patent: US 6,642,652 B2
• Time in Patent Office: Days
• US Class Current: 313/501
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01039 Yttrium [Y]
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil

Abstract

A light source is disclosed that includes a light emitting device such as a III-nitride light emitting diode covered with a luminescent material structure, such as a single layer or multiple layers of phosphor. Any variations in the thickness of the luminescent material structure are less than or equal to 10% of the average thickness of the luminescent material structure. In some embodiments, the thickness of the luminescent material structure is less than 10% of a cross-sectional dimension of the light emitting device. In some embodiments, the luminescent material structure is the only luminescent material through which light emitted from the light emitting device passes. In some embodiments, the luminescent material structure is between about 15 and about 100 microns thick. The luminescent material structure is selectively deposited on the light emitting device by, for example, stenciling or electrophoretic deposition.

Claims

1. A light source comprising:

a light emitting device, the light emitting device comprising a stack of semiconductor layers including an n-type region, an active region, and a p-type region; and

a luminescent material structure covering the light emitting device, wherein any variation in a thickness of the luminescent material structure is less than or equal to 10% of an average thickness of the luminescent material structure.

2. The light source of claim 1 wherein any variation in the thickness of the luminescent material structure is less or equal to 5% of an average thickness of the luminescent material structure.

3. The light source of claim 1 wherein the average thickness of the luminescent material structure is about 15 microns to about 100 microns.

4. The light source of claim 1 wherein the thickness of the luminescent material structure is less than or equal to the larger of 100 microns and 10% of a cross-sectional dimension of the light emitting device.

5. The light source of claim 1 wherein the luminescent material structure comprises a plurality of phosphor layers.

6. The light source of claim 1 wherein the light emitting device is a III-nitride device.

7. The light source of claim 1 wherein the luminescent material structure comprises a layer selected from the group consisting of yttrium aluminum garnet doped with gadolinium, cerium, and praseodymium;

strontium sulfide; and

strontium thiogallate.

8. The light source of claim 1 wherein the luminescent material layer is selected from the group consisting of silicone polymer and glass.

9. The light source of claim 1 wherein the luminescent material layer comprises silica particles.

10. The light source of claim 1 wherein the light emitting device further comprises a transparent electroconductive layer.

11. The light source of claim 9 wherein the electroconductive layer comprises a transparent metal oxide.

12. The light source of claim 1 wherein the luminescent material layer covering the light emitting device is the only luminescent material layer through which light emitted from the light emitting device passes.

13. The light source of claim 1 wherein the layer of luminescent material emits light, such that when combined with light emitted by said light emitting device, the light source generates white light.

14. The light source of claim 1 wherein the layer of luminescent material comprises phosphors that emit red and green light when energized by light emitted by the light emitting device.

15. The light source of claim 1 wherein the layer of luminescent material comprises one or more phosphors that emit yellow light when energized by light emitted by the light emitting device.

16. The light source of claim 1 further comprising a submount connected to the light emitting device by connectors.

17. The light source of claim 16 wherein the submount comprises a conducting material, the light source further comprising a layer of poorly-conducting material coating a portion of the submount.

18. The light source of claim 16 wherein a portion of the luminescent material layer covers a first portion of the submount, an outer edge of the first portion of the submount being located within 100 microns of a second portion of the submount underlying the light emitting device.

19. The light source of claim 1 wherein the luminescent material layer comprises a plurality of sublayers of luminescent material.

20. The light source of claim 19 wherein a first sublayer has a different composition than a second sublayer.

21. The light source of claim 1 further comprising a reflective member underlying the LED.

22. The light source of claim 21 wherein the reflective member has a shape selected from the group consisting of planar, convex, and concave.

23. The light source of claim 1 wherein the LED emits light in the UV through blue portion of the electomagnetic spectrum.

24. The light source of claim 1 wherein the luminescent material structure comprises a plurality of phosphor types.

25. The light source of claim 1 wherein the luminescent material structure covers top and side surfaces of said light emitting device, a bottom surface of said light emitting device not being covered.