Light-Emitting Device Substrate

• US 20110272734A1
• Filed: 11/11/2009
• Published: 11/10/2011
• Est. Priority Date: 01/16/2009
• Status: Abandoned Application

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Yoshimura, Masashi, Nakamura, Takao, Hachigo, Akihiro
• Application Number:
  US13/144,696
• Publication Number:
  US 20110272734A1
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: H01L 33/007 comprising nitride compounds

Abstract

The present invention is a minimal-defect light-emitting device substrate that enables emitted light to issue from a device'"'"'s substrate side, and is a light-emitting device 100 substrate furnished with a transparent substrate 10 that is transparent to light of wavelengths between 400 nm and 600 nm, inclusive, and a nitride-based compound semiconductor thin film 1c formed onto one of the major surfaces of the transparent substrate 10 by a join. Letting the thermal expansion coefficient of the transparent substrate along a direction perpendicular to the major surface of the transparent substrate be α₁, and the thermal expansion coefficient of the nitride-based compound semiconductor thin film be α₂, then (α₁−α₂)/α₂ is between −0.5 and 1.0, inclusive, and at up to 1200° C. the transparent substrate does not react with the nitride-based compound semiconductor thin film 1c. The absolute index of refraction of the transparent substrate 10 preferably is between 60% and 140%, inclusive, of the absolute index of refraction of the nitride-based compound semiconductor thin film.

Claims

1. A light-emitting device substrate comprising:

a transparent substrate that is transparent to light of wavelengths between 400 nm and 600 nm, inclusive; and

a nitride-based compound semiconductor thin film formed onto one of the major surfaces of the transparent substrate by a join;

being a light-emitting device substrate wherein

letting the thermal expansion coefficient of said transparent substrate along a direction perpendicular to the major surface of said transparent substrate be α

₁, and the thermal expansion coefficient of said nitride-based compound semiconductor thin film be α

₂, then (α

₁−

α

₂)/α

₂ is between −

0.5 and 1.0, inclusive, and

said transparent substrate is not reactive with said nitride-based compound semiconductor thin film at temperatures of up to 1200°

C.

2. The light-emitting device substrate set forth in claim 1, wherein the absolute index of refraction of said transparent substrate is between 60% and 140%, inclusive, of the absolute index of refraction of said nitride-based compound semiconductor thin film.

3. The light-emitting device substrate set forth in claim 1, wherein said transparent substrate is of at least one material selected from the group consisting of spinel, magnesium oxide, titanium oxide, alumina, sapphire, and aluminum nitride.

4. The light-emitting device substrate set forth in claim 1, wherein the surface roughness R_max of the major surface of said transparent substrate is not greater than 2 nm.

5. The light-emitting device substrate set forth in claim 1, further comprising, in between said transparent substrate and said nitride-based compound semiconductor thin film, a transparent thin film having an absolute index of refraction of between 60% and 140%, inclusive, of the absolute index of refraction of said nitride-based compound semiconductor thin film, and being transparent to light of wavelengths between 400 nm and 600 nm, inclusive,

6. The light-emitting device substrate set forth in claim 5, wherein said transparent thin film is of at least one material selected from the group consisting of spinel, magnesium oxide, titanium oxide, alumina, and aluminum nitride.