Light emitting element, light emitting device using the light emitting element and method for manufacturing light emitting element

• US 20070228409A1
• Filed: 04/03/2007
• Published: 10/04/2007
• Est. Priority Date: 04/04/2006
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Uemura, Toshiya
• Granted Patent: US 7,687,817 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/01004 Beryllium [Be]
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/0102 Calcium [Ca]
• CPC Class Codes: H01L 2924/01025 Manganese [Mn]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• 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 33/52 Encapsulations

Abstract

To provide a light emitting element that can extract substantially all the light emitted from a luminous layer structure to the outside, a GaN substrate and a luminous layer structure are formed by growing III nitride compound semiconductor on a sapphire substrate that is a growth substrate. Thereafter, the sapphire substrate is lifted off and minute irregularities are formed on the exposed GaN substrate. The pitch of irregularities is shorter than the wavelength of light emitted from the luminous layer structure.

Claims

1. A III nitrogen compound semiconductor light emitting element, comprising:

a substrate made of III nitride compound semiconductor;

a luminous layer structure made of III nitride compound semiconductor formed on a first surface of said substrate; and

an irregular surface formed on a second surface of said substrate, the pitch of said irregular surface being shorter than the wavelength of light emitted from said luminous layer structure.

2. A light emitting device, comprising:

a light emitting element according to claim 1, with a principal light emission surface being said second surface; and

a translucent sealing member for sealing said light emitting element, said sealing member being separated from said second surface.

3. The light emitting device according to claim 2, wherein a translucent gel material is filled between said light emitting element and said sealing member.

4. A method for manufacturing a light emitting element, including:

a step of growing a substrate made of III nitride semiconductor on a growth substrate made of sapphire;

a step of forming a luminous layer structure by growing a III nitride compound semiconductor layer on a first surface of said substrate;

a step of removing said growth substrate from said substrate; and

a step of forming irregularities having a shorter pitch than the wavelength of light emitted from said luminous layer structure on the second surface of said substrate with said growth substrate removed.

5. The manufacturing method according to claim 4, wherein said step of forming irregularities includes soaking the second surface of said substrate in an alkali solution and applying light having a shorter wavelength than the wavelength corresponding to the band gap of a material forming said second surface to said second surface.

6. The manufacturing method according to claim 4, wherein said step of forming irregularities includes soaking the second surface of said substrate in an alkali solution and raising the temperature of said second surface.

7. The manufacturing method according to any one of claims 4, wherein characterized in that said alkali solution is KOH solution.

8. The manufacturing method according to claim 5, wherein said alkali solution is KOH solution.

9. The manufacturing method according to claim 6, wherein said alkali solution is KOH solution.