Group III Nitride Semiconductor Light-Emitting Device

• US 20080035908A1
• Filed: 11/14/2005
• Published: 02/14/2008
• Est. Priority Date: 11/16/2004
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Showa Denko KK
• Inventors: Sakai, Hiromitsu
• Granted Patent: US 7,514,707 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 5/0213 Sapphire, quartz or diamond based substrates
• CPC Class Codes: H01S 5/3201 incorporating bulkstrain effects, e.g. strain compensation, strain related to polarisation
• CPC Class Codes: H01S 5/3211 characterised by special cladding layers, e.g. details on band-discontinuities
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

An object of the present invention is to provide a Group III nitride semiconductor light-emitting device with high emission efficiency.

The inventive Group III nitride semiconductor light-emitting device has an n-type layer, a light-emitting layer and a p-type layer composed of a Group III nitride semiconductor on a substrate, with the light-emitting layer sandwiched between the n-type layer and p-type layer, wherein the range for Δa as the ratio of the difference between the a-axis lattice constant of the layer between the light-emitting layer and substrate (or in the case of multiple layers with different compositions between the light-emitting layer and substrate, where each layer is grouped according to composition, the a-axis lattice constant of the group having the maximum thickness considering all of the layers belonging to the group) a₁ and the a-axis lattice constant of the light-emitting layer (or if the light-emitting layer has a multiple quantum well structure, the a-axis lattice constant determined from the zero-order peak representing the average composition of the well layers and barrier layers) a₂, represented by the following formula (I), is −0.05≦Δa≦0.05 (unit: %).
Δa=100(a₁−a₂)/a₁  (I)

Claims

1. A Group III nitride semiconductor light-emitting device having an n-type layer, a light-emitting layer and a p-type layer composed of a Group III nitride semiconductor on a substrate, with the light-emitting layer sandwiched between the n-type layer and p-type layer, wherein the range for Δ

a as the ratio of the difference between the a-axis lattice constant of the layer between the light-emitting layer and substrate (or in the case of multiple layers with different compositions between the light-emitting layer and substrate, where each layer is grouped according to composition, the a-axis lattice constant of the group having the maximum thickness considering all of the layers belonging to the group) a₁ and the a-axis lattice constant of the light-emitting layer (or if the light-emitting layer has a multiple quantum well structure, the a-axis lattice constant determined from the zero-order peak representing the average composition of the well layers and barrier layers) a₂, represented by the following formula (I), is −

0.05≦

Δ

a≦

0.05 (unit;

%)

Δ

a=100(a₁−

a₂)/a₁ 

 

(I)

2. A Group III nitride semiconductor light-emitting device according to claim 1, wherein the Group III nitride semiconductor is represented by the formula Al_XGa_YIn_ZN_1-AM_A (0≦

X≦

1, 0≦

Y≦

1, 0≦

Z≦

1 and X+Y+Z=1, wherein M represents a Group V element different from nitrogen (N), and 0≦

A<

1).

3. A Group III nitride semiconductor light-emitting device according to claim 1, wherein the substrate is sapphire.

4. A Group III nitride semiconductor light-emitting device according to claim 1, wherein the layer between the light-emitting layer and the substrate (or in the case of multiple layers with different compositions between the light-emitting layer and substrate, where each layer is grouped according to composition, the group having the maximum thickness considering all of the layers belonging to the group) is an n-type GaN layer.

5. A Group III nitride semiconductor light-emitting device according to claim 1, wherein the light-emitting layer has a multiple quantum well structure.

6. A Group III nitride semiconductor light-emitting device according to claim 5, wherein the barrier layer of the multiple quantum well structure is composed of Al_XGa_YIn_ZN (0≦

X≦

1, 0≦

Y≦

1, 0≦

Z≦

1, X+Y+Z=1), and the well layer is composed of Ga_YIn_ZN (0≦

Y≦

1, 0≦

Z≦

1, Y+Z=1).

7. A Group III nitride semiconductor light-emitting device according to claim 1, wherein the substrate is sapphire, the layer between the light-emitting layer and the substrate (or in the case of multiple layers with different compositions between the light-emitting layer and substrate, where each layer is grouped according to composition, the group having the maximum thickness considering all of the layers belonging to the group) is an n-type GaN layer, the light-emitting layer has a multiple quantum well structure wherein the barrier layer is composed of Al_XGa_YIn_ZN (0≦

X≦

1, 0≦

Y≦

1, 0≦

Z≦

1, X+Y+Z=1) and the well layer is composed of Ga_YIn_ZN (0≦

Y≦

1, 0≦

Z≦

1, Y+Z=1), and the lattice constants a₁ and a₂ are larger than 3.181 Å

.

8. A Group III nitride semiconductor light-emitting device according to claim 1, wherein the thickness of the layer between the light-emitting layer and the substrate (or in the case of multiple layers with different compositions between the light-emitting layer and substrate, where each layer is grouped according to composition, the group having the maximum thickness considering all of the layers belonging to the group) is 1-20 μ

m.

9. A lamp comprising a Group III nitride semiconductor light-emitting device according to claim 1.