Gallium nitride-based compound semiconductor light-emitting device

• US 8,258,541 B2
• Filed: 12/13/2006
• Issued: 09/04/2012
• Est. Priority Date: 12/13/2005
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Showa Denko KK
• Inventors: Muraki, Noritaka, Shinohara, Hironao
• Primary Examiner(s): Pizarro, Marcos D.
• Assistant Examiner(s): SALERNO, SARAH KATE
• Application Number:
  US12/097,139
• Publication Number:
  US 20090045434A1
• Time in Patent Office: 2,092 Days
• Field of Search: 257/103, 257/98, 438/42
• US Class Current: 257/103
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02573 Conductivity type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

A gallium nitride-based compound semiconductor light-emitting device including a positive electrode having openings, which is excellent in light extraction efficiency. The gallium nitride-based compound semiconductor light-emitting device includes a substrate; an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer, the layers being formed of a gallium nitride-based compound semiconductor and being stacked in this order on the substrate; a positive electrode which is provided so as to contact the p-type semiconductor layer; and a negative electrode which is provided so as to contact the n-type semiconductor layer, where the positive electrode is a positive electrode having openings, and at least a portion of the surface of the p-type semiconductor layer corresponding to the openings are roughened surface derived from spherical particulates.

Claims

1. A gallium nitride-based compound semiconductor light-emitting device comprising a substrate;

an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer, the layers being formed of a gallium nitride-based compound semiconductor and being stacked in this order on the substrate;

a positive electrode which is provided so as to contact the p-type semiconductor layer; and

a negative electrode which is provided so as to contact the n-type semiconductor layer, wherein the positive electrode is a positive electrode having openings, and at least a portion of the surface of the p-type semiconductor layer corresponding to the openings are roughened surfaces whose apical portions are semispherical,

wherein a density of protruding portions (particulates) of the roughened surface is from 1×

10⁵ pieces/mm² to 1×

10⁸ pieces/mm².

2. The gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein the positive electrode having the openings is in a lattice pattern or a comb-like pattern.

3. The gallium nitride-based compound semiconductor light-emitting device according to claim 2, wherein widths of bars of the lattice pattern or teeth of the comb-like pattern are from 1 pm to 50 pm.

4. The gallium nitride-based compound semiconductor light-emitting device according to claim 2, wherein a distance between bars of the lattice pattern or teeth of the comb-like pattern is from 1 pm to 50 gm.

5. The gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein diameters of protruding portions (particulates) of the roughened surface are from 0.01 to 3 μ

m.

6. The gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein heights of upper ends of the roughened surface are from 0.1 to 2 μ

m from a surface at which the negative electrode is formed.

7. The gallium nitride-based compound semiconductor light-emitting device according to claim 6, wherein the heights of upper ends of the roughened surface are the same height as the surface of the p-type semiconductor layer.

8. The gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein heights of the protruding portions of the roughened surface are from 0.01 to 1 μ

m.

9. A lamp comprising the gallium nitride-based compound semiconductor light-emitting device according to claim 1.

10. The gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein the roughened surface also exists at four sides of the light-emitting device.

11. The gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein the roughened surface also exists between the positive electrode and the negative electrode.

16. An electronic equipment incorporating the lamp according to claim 9.

17. A mechanical device incorporating the electronic equipment according to claim 16.

12. A method for manufacturing a gallium nitride-based compound semiconductor light-emitting device, comprising the following steps (1) to (4) of:

(1) stacking an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer which are formed of a gallium nitride-based compound semiconductor, in this order on a substrate;

(2) forming a positive electrode having openings on the p-type semiconductor layer;

(3) forming a mask formed of metal microparticles on the p-type semiconductor layer corresponding to the openings; and

(4) performing dry etching onto the gallium nitride-based compound semiconductor from above the mask so that at least a portion of the surface of the p-type semiconductor layer corresponding to the openings are roughened surfaces whose apical portions are semispherical,

wherein a density of protruding portions (particulates) of the roughened surface is from 1×

10⁵ pieces/mm² to 1×

10⁸ pieces/mm².

13. The method according to claim 12, wherein the step (3) comprises the step of forming a metal thin film on the p-type semiconductor layer and the step of a thermal treatment thereafter.

14. The method according to claim 12, wherein the metal microparticles are made of metal selected from the group consisting of Ni, Au, Sn, and Ge, or a low melting point alloy containing at least one kind of these metals.

15. A gallium nitride-based compound semiconductor light-emitting device manufactured by the method according to claim 12.