Gallium Nitride Based Compound Semiconductor Light-Emitting Device and Method for manufacturing Same

• US 20090309119A1
• Filed: 12/12/2006
• Published: 12/17/2009
• Est. Priority Date: 12/14/2005
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Showa Denko KK
• Inventors: Shinohara, Hironao, Osawa, Hiroshi
• Granted Patent: US 8,026,118 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• 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 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• 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
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

The present invention provides a gallium nitride based compound semiconductor light-emitting device having high light emission efficiency and a method of manufacturing the same. The gallium nitride based compound semiconductor light-emitting device includes: a substrate 11; an n-type semiconductor layer 13, a light-emitting layer 14, and a p-type semiconductor layer 15 that are composed of gallium nitride based compound semiconductors and formed on the substrate 11 in this order; a transparent positive electrode 16 that is formed on the p-type semiconductor layer 15; a positive electrode bonding pad 17 that is formed on the transparent positive electrode 16; a negative electrode bonding pad 18 that is formed on the n-type semiconductor layer 13; and an uneven surface that has random convex portions formed thereon and is provided on at least a portion of the surface 16a of the transparent positive electrode 16.

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 that are composed of gallium nitride based compound semiconductors and formed on the substrate in this order;

a transparent positive electrode that is formed on the p-type semiconductor layer;

a positive electrode bonding pad that is formed on the transparent positive electrode;

a negative electrode bonding pad that is formed on the n-type semiconductor layer; and

an uneven surface that has random convex portions formed thereon and is provided on at least a portion of the surface of the transparent positive electrode.

2. The gallium nitride based compound semiconductor light-emitting device according to claim 1:

wherein the average distance between the centers of the convex portions on the uneven surface that is formed on the surface of the transparent positive electrode is in the range of 0.01 μ

m to 3 μ

m.

3. The gallium nitride based compound semiconductor light-emitting device according to claim 1:

wherein the average distance between the centers of the convex portions on the uneven surface that is formed on the surface of the transparent positive electrode is in the range of 0.05 μ

m to 1.5 μ

m.

4. The gallium nitride based compound semiconductor light-emitting device according to claim 2:

wherein the standard deviation of the distances between the convex portions with respect to the average distance between the convex portions is in the range of 10% to 80%.

5. The gallium nitride based compound semiconductor light-emitting device according to claim 1:

wherein the transparent positive electrode is formed of a conductive oxide.

6. The gallium nitride based compound semiconductor light-emitting device according to claim 1:

wherein the transparent positive electrode is formed of at least one of ITO(In₂O₃—

SnO₂), AZO(ZnO—

Al₂O₃), IZO(In₂O₃—

ZnO), and GZO(ZnO—

Ga₂O₃).

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

7. A method of manufacturing a gallium nitride based compound semiconductor light-emitting device, the method comprising:

(1) a process of sequentially forming on a substrate an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer, and a transparent positive electrode, the n-type semiconductor layer, the light-emitting layer, and the p-type semiconductor layer each composed of a gallium nitride based compound semiconductor;

(2) a process of forming a mask made of metal particles on the surface of the transparent positive electrode; and

(3) a process of performing dry etching on the transparent positive electrode using the mask.

8. The method of manufacturing a gallium nitride based compound semiconductor light-emitting device according to claim 7,

wherein the process (2) includes:

forming a metal thin film on the surface of the transparent positive electrode; and

performing a heat treatment.

9. The method of manufacturing a gallium nitride based compound semiconductor light-emitting device according to claim 7,

wherein the metal particles of the mask are made of Ni, or a Ni alloy.

10. The method of manufacturing a gallium nitride based compound semiconductor light-emitting device according to claim 7,

wherein the metal particles of the mask are made of a metal with a low melting point or an alloy with a low melting point having a melting point in the range of 100°

C. to 450°

C.

11. The method of manufacturing a gallium nitride based compound semiconductor light-emitting device according to claim 7,

wherein the metal particles of the mask are made of a metal with a low melting point selected from Ni, Au, Sn, Ge, Pb, Sb, Bi, Cd, and In, or an alloy with a low melting point including at least one of the metallic materials.

12. The method of manufacturing a gallium nitride based compound semiconductor light-emitting device according to claim 7,

wherein the uneven surface is formed on at least a portion of the surface of the transparent positive electrode by wet etching.

14. A lamp comprising the gallium nitride based compound semiconductor light-emitting device manufactured by the method according to claim 7.