Light emitting element and light emitting device

• US 20050093008A1
• Filed: 10/28/2004
• Published: 05/05/2005
• Est. Priority Date: 10/31/2003
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Nakajo, Naoki, Suehiro, Yoshinobu
• Granted Patent: US 7,388,232 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/06102 the bonding areas being at different heights
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/1703 Bump connectors having different sizes, e.g. different diameters, heights or widths
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/181 Encapsulation
• 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 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

A light emitting element has: a light emitting layer of semiconductor; and a diffusion layer that has a refractive index equal to or greater than that of the light emitting layer and that diffuses light emitted from the light emitting layer to increase the external radiation efficiency of the light emitting element. The light emitting layer has a refractive index equal to or greater than that of any layers formed between the light emitting layer and the diffusion layer.

Claims

1. A light emitting element, comprising:

a light emitting layer of semiconductor; and

a diffusion layer that diffuses light emitted from the light emitting layer to increase the external radiation efficiency of the light emitting element.

3. The light emitting element according to claim 1, wherein:

the diffusion layer is of a porous material.

5. The light emitting element according to claim 1, wherein:

the diffusion layer comprises a coat layer with a refractive index equal to or greater than that of the light emitting layer, and a light diffusing particle, and

the coat layer comprises an uneven surface.

7. The light emitting element according to claim 1, wherein:

the diffusion layer comprises a phosphor.

9. The light emitting element according to claim 5, wherein:

the diffusion layer comprises a phosphor.

11. The light emitting element according to claim 7, wherein:

the phosphor comprises a phosphor particle with a light diffusion property.

13. The light emitting element according to claim 9, wherein:

the phosphor comprises a phosphor particle with a light diffusion property.

15. The light emitting element according to claim 11, wherein:

the diffusion layer comprises a phosphor particle and a bead-shaped light transmitting particle.

17. The light emitting element according to claim 13, wherein:

the diffusion layer comprises a phosphor particle and a bead-shaped light transmitting particle.

19. The light emitting element according to claim 1, wherein:

the diffusion layer comprises a resin material with a high refractive index.

21. The light emitting element according to claim 19, wherein:

the diffusion layer further comprises a phosphor.

2. A light emitting element, comprising:

a light emitting layer of semiconductor; and

a diffusion layer that has a refractive index equal to or greater than that of the light emitting layer and that diffuses light emitted from the light emitting layer to increase the external radiation efficiency of the light emitting element,

wherein the light emitting layer has a refractive index equal to or greater than that of any layers formed between the light emitting layer and the diffusion layer.

4. The light emitting element according to claim 2, wherein:

the diffusion layer is of a porous material.

6. The light emitting element according to claim 2, wherein:

the diffusion layer comprises a coat layer with a refractive index equal to or greater than that of the light emitting layer, and a light diffusing particle, and

the coat layer is provided with an uneven surface.

8. The light emitting element according to claim 2, wherein:

the diffusion layer comprises a phosphor.

10. The light emitting element according to claim 6, wherein:

the diffusion layer comprises a phosphor.

12. The light emitting element according to claim 8, wherein:

the phosphor comprises a phosphor particle with a light diffusion property.

14. The light emitting element according to claim 10, wherein:

the phosphor comprises a phosphor particle with a light diffusion property.

16. The light emitting element according to claim 12, wherein:

the diffusion layer comprises a phosphor particle and a bead-shaped light transmitting particle.

18. The light emitting element according to claim 14, wherein:

the diffusion layer comprises a phosphor particle and a bead-shaped light transmitting particle.

20. The light emitting element according to claim 2, wherein:

the diffusion layer comprises a resin material with a high refractive index.

22. The light emitting element according to claim 20, wherein:

the diffusion layer further comprises a phosphor.

23. A light emitting device, comprising:

a light emitting element that comprises semiconductor layers including a light emitting layer, an electrode to supply electric power to the light emitting layer, and a transparent protection layer for protecting the semiconductor layers and the electrode, the protection layer having a refractive index substantially equal to that of the semiconductor layers; and

a light extraction portion that is disposed on the protection layer to coat the surface of the light emitting element and to enhance the external radiation efficiency of light emitted from the light emitting layer.

26. The light emitting device according to claim 23, wherein:

the light extraction portion comprises an uneven surface.

28. The light emitting device according to claim 23, wherein:

the light extraction portion comprises a light diffusing particle.

30. The light emitting device according to claim 23, wherein:

the light extraction portion comprises a phosphor.

32. The light emitting device according to claim 23, wherein:

the protection layer is formed avoiding the electrode on a light radiation surface of the light emitting element.

34. The light emitting device according to claim 23, wherein:

the semiconductor layers comprises a GaN-based semiconductor.

36. The light emitting device according to claim 34, wherein:

the light extraction portion comprises a light transmitting material with a refractive index of 1.7 or greater.

38. The light emitting device according to claim 23, wherein:

the light extraction portion comprises a resin material with a high refractive index.

24. A light emitting device, comprising:

a light emitting element that comprises semiconductor layers including a light emitting layer, an electrode to supply electric power to the light emitting layer, and a transparent protection layer for protecting the semiconductor layers and the electrode;

a light extraction portion that is disposed on the protection layer to coat the surface of the light emitting element and to enhance the external radiation efficiency of light emitted from the light emitting layer; and

a light transmitting material portion that is disposed on the surface of the light extraction portion,

wherein the light extraction portion and the protection layer have a refractive index greater than that of the light transmitting material portion.

25. The light emitting device according to claim 24, wherein:

the protection layer has a refractive index equal to or greater than that of the semiconductor layers.

27. The light emitting device according to claim 24, wherein:

the light extraction portion comprises an uneven surface.

29. The light emitting device according to claim 24, wherein:

the light extraction portion comprises a light diffusing particle.

31. The light emitting device according to claim 24, wherein:

the light extraction portion comprises a phosphor.

33. The light emitting device according to claim 24, wherein:

the protection layer is formed avoiding the electrode on a light radiation surface of the light emitting element.

35. The light emitting device according to claim 24, wherein:

the semiconductor layers comprises a GaN-based semiconductor.

37. The light emitting device according to claim 35, wherein:

the light extraction portion comprises a light transmitting material with a refractive index of 1.7 or greater.

39. The light emitting device according to claim 24, wherein:

the light extraction portion comprises a resin material with a high refractive index.