Light emitting device

• US 20050199887A1
• Filed: 03/09/2005
• Published: 09/15/2005
• Est. Priority Date: 03/10/2004
• Status: Abandoned Application

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Ito, Jun, Suehiro, Yoshinobu
• Application Number:
  US11/074,939
• Publication Number:
  US 20050199887A1
• Time in Patent Office: Days
• US Class Current: 257/79
• 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 2224/49107 on the semiconductor or solid-state body
• 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 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A light emitting device has an LED element and a transparent material that covers the periphery of the LED element. The LED element has a semiconductor layer that has a light emitting layer and has a refractive index substantially equal to that of the light emitting layer, an electrode to supply electric power to the light emitting layer, a light scattering portion formed in the semiconductor layer, and an optical system that is formed with a convex surface on the semiconductor layer so as to externally radiate light scattered by the light scattering portion. A material composing the light emitting layer to the optical system has a refractive index of 10% or greater than that of the transparent material and of 1.7 or greater.

Claims

1. A light emitting device, comprising:

an LED element comprising a semiconductor layer that includes a light emitting layer and has a refractive index substantially equal to that of the light emitting layer, an electrode to supply electric power to the light emitting layer, a light scattering portion formed in the semiconductor layer, and an optical system that is formed with a convex surface on the semiconductor layer so as to externally radiate light scattered by the light scattering portion; and

a transparent material that covers the periphery of the LED element,

wherein a material composing the light emitting layer to the optical system has a refractive index of 10% or greater than that of the transparent material and of 1.7 or greater.

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

the light scattering portion is disposed corresponding to the optical system.

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

the light scattering portion is formed below the light emitting layer above which the optical system is formed.

4. The light emitting device according to claim 1 further comprising:

a substrate on which the semiconductor layer is formed and which has a refractive index substantially different from that of the light emitting layer,

wherein the light scattering portion is formed at an interface of the substrate and the semiconductor layer.

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

the light scattering portion and the optical system comprises a plurality of light scattering portions and optical systems, respectively, which are densely formed.

6. The light emitting device according to claim 1 further comprising:

a passivation film that is formed between the light emitting layer and the optical system.

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

the electrode comprises a transparent electrode formed between the light emitting layer and the optical system.

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

the electrode comprises a plurality of electrodes that are formed locally corresponding to a plurality of the optical systems.

9. The light emitting device according to claim 4, wherein:

the substrate comprises an Al₂O₃ substrate,

the semiconductor layer comprises a GaN based semiconductor layer, and

the light scattering portion is formed at the interface of the Al₂O₃ substrate and the GaN based semiconductor layer.

10. The light emitting device according to claim 4, wherein:

the light scattering portion comprises a concave portion formed on the substrate, the concave portion comprising the same material as the semiconductor layer formed on the substrate.

11. The light emitting device according to claim 4, wherein:

the light scattering portion comprises a convex portion formed on the substrate, the convex portion comprising the same material as the substrate.

12. The light emitting device according to claim 4, wherein:

the light scattering portion comprises a local region with a plurality of minute concaves and convexes formed on the substrate corresponding to the optical system.