GALLIUM NITRIDE-BASED COMPOUND SEMICONDUCTOR LIGHT-EMITTING DEVICE

• US 20090045434A1
• Filed: 12/13/2006
• Published: 02/19/2009
• 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
• Granted Patent: US 8,258,541 B2
• Time in Patent Office: Days
• 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 surface derived from spherical particulates.

4. 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.

5. The gallium nitride-based compound semiconductor light-emitting device according to claim 4, wherein widths of bars of the lattice pattern or teeth of the comb-like pattern are from 1 pm to 50 pm.

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

7. 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.

8. 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.

9. The gallium nitride-based compound semiconductor light-emitting device according to claim 8, wherein the heights of upper ends of the roughened surface are the same height as the surface of the p-type semiconductor layer.

10. 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.

11. The gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein a density of the protruding portions (particulates) of the roughened surface is from 1×

10⁵ pieces/mm² to 1×

10⁸ pieces/mm².

12. 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.

13. 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.

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

19. An electronic equipment incorporating the lamp according to claim 18.

20. A mechanical device incorporating the electronic equipment according to claim 19.

2. 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.

3. 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 formed from curved surfaces.

14. 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.

15. The method according to claim 14, 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.

16. The method according to claim 14, 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.

17. A gallium nitride-based compound semiconductor light-emitting device manufactured by the method according to claim 14.