Light emitting element and light emitting device

• US 7,388,232 B2
• Filed: 10/28/2004
• Issued: 06/17/2008
• Est. Priority Date: 10/31/2003
• Status: Expired due to Fees

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Nakajo, Naoki, Suehiro, Yoshinobu
• Primary Examiner(s): Hu; Shouxiang
• Application Number:
  US10/974,945
• Publication Number:
  US 20050093008A1
• Time in Patent Office: 1,328 Days
• Field of Search: 257/98, 257/95, 257/81, 257/103, 257/E33.074
• 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:

plural GaN-based semiconductor layers comprising a light emitting layer; and

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

wherein the plural GaN-based semiconductor layers further comprise a light extraction face,

wherein the diffusion layer comprises a TiO₂ coating film that substantially wraps phosphor particles and has an uneven surface, and has a refractive index substantially equal to or greater than that of the light extraction face,

wherein the TiO₂ coating film contacts directly the light extraction face, and

wherein said TiO₂ coating film has a thickness substantially smaller than sizes of the phosphor particles, such that the uneven surface of the TiO₂ coating film at least partially conforms with top surfaces of the phosphor particles.

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

the diffusion layer further substantially wraps light diffusing particles.

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

the phosphor particles comprise a light diffusion property.

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

the light diffusing particles comprise a bead-shaped light transmitting particle.

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

the phosphor particles comprise a light diffusion property.

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

the diffusion layer further substantially wraps a bead-shaped light transmitting particle.

7. The light emitting element according to claim 1, wherein at least a part of the diffusion layer is formed by a sol-gel method using an alkoxide.