GROUP III NITRIDE SEMICONDUCTOR LIGHT-EMITTING DEVICE

• US 20120248407A1
• Filed: 03/28/2012
• Published: 10/04/2012
• Est. Priority Date: 03/30/2011
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Okuno, Koji, TOYODA, Yusuke, Nishijima, Kazuki
• Granted Patent: US 8,586,965 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence

Abstract

A Group III nitride semiconductor light-emitting device includes a light-emitting layer having a multiple quantum structure including an Al_xGa_1-xN (0<x<1) layer as a barrier layer. When the light-emitting layer is divided into three blocks including first, second and third blocks in the thickness direction from the n-type-layer-side cladding layer to the p-type-layer-side cladding layer, the number of barrier layers are the same in the first and third blocks, and the Al composition ratio of each light-emitting layer is set to satisfy a relation x+z=2y and z<x where an average Al composition ratio of the barrier layers in the first block is represented as x, an average Al composition ratio of the barrier layers in the second block is represented as y, and an average Al composition ratio of the barrier layers in the third block is represented as z.

Claims

1. A Group III nitride semiconductor light-emitting device comprising at least an n-type-layer-side cladding layer, a light-emitting layer having a multiple quantum structure including an Al_xGa_1-xN (0<

x<

1) layer as a barrier layer, and a p-type-layer-side cladding layer, each of the layers being formed of a Group III nitride semiconductor, wherein when the light-emitting layer is divided into three blocks of a first block, a second block, and a third block in the thickness direction from the n-type-layer-side cladding layer to the p-type-layer-side cladding layer, an Al composition ratio of the barrier layer in each block is set to satisfy a relation z<

y<

x where an average Al composition ratio of the barrier layers in the first block is represented as x, an average Al composition ratio of the barrier layers in the second block is represented as y, and an average Al composition ratio of the barrier layers in the third block is represented as z.

2. A Group III nitride semiconductor light-emitting device according to claim 1, wherein the number of the barrier layers in the first block is equal to the number of the barrier layers in the third block, and the Al composition ratio of the barrier layer in each block is set so as to satisfy a relation x+z=2y.

3. A Group III nitride semiconductor light-emitting device according to claim 2, wherein a ratio x/y is set so as to satisfy a relation 1.1≦

x/y≦

2.2.

4. A Group III nitride semiconductor light-emitting device according to claim 1, wherein a thickness of the barrier layer in each block is set so as to satisfy at least one of relations a<

b<

c and c<

b<

a when an average thickness of the barrier layers in the first block is represented as a, an average thickness of the barrier layers in the second block as b, and an average thickness of the barrier layers in the third block as c.

5. A Group III nitride semiconductor light-emitting device according to claim 2, wherein a thickness of the barrier layer in each block is set so as to satisfy at least one of relations a<

b<

c and c<

b<

a when an average thickness of the barrier layers in the first block is represented as a, an average thickness of the barrier layers in the second block as b, and an average thickness of the barrier layers in the third block as c.

6. A Group III nitride semiconductor light-emitting device according to claim 3, wherein a thickness of the barrier layer in each block is set so as to satisfy at least one of relations a<

b<

c and c<

b<

a when an average thickness of the barrier layers in the first block is represented as a, an average thickness of the barrier layers in the second block as b, and an average thickness of the barrier layers in the third block as c.

7. A Group III nitride semiconductor light-emitting device according to claim 4, wherein the number of the barrier layers in the first block is equal to the number of the barrier layers in the third block, and the thickness of the barrier layer in each block is set to so as to satisfy a relation a+c=2b.

8. A Group III nitride semiconductor light-emitting device according to claim 5, wherein the number of the barrier layers in the first block is equal to the number of the barrier layers in the third block, and the thickness of the barrier layer in each block is set to so as to satisfy a relation a+c=2b.

9. A Group III nitride semiconductor light-emitting device according to claim 6, wherein the number of the barrier layers in the first block is equal to the number of the barrier layers in the third block, and the thickness of the barrier layer in each block is set to so as to satisfy a relation a+c=2b.

10. A Group III nitride semiconductor light-emitting device according to claim 7, wherein the thickness of the barrier layer in each block is set to so as to satisfy a relation a<

c.

11. A Group III nitride semiconductor light-emitting device according to claim 8, wherein the thickness of the barrier layer in each block is set to so as to satisfy a relation a<

c.

12. A Group III nitride semiconductor light-emitting device according to claim 9, wherein the thickness of the barrier layer in each block is set to so as to satisfy a relation a<

c.

13. A Group III nitride semiconductor light-emitting device according to claim 7, wherein a ratio a/b is 0.7≦

a/b≦

0.9 in the case of a<

b<

c, and a ratio c/b is 0.7≦

c/b≦

0.9 in the case of c<

b<

a.

14. A Group III nitride semiconductor light-emitting device according to claim 8, wherein a ratio a/b is 0.7≦

a/b≦

0.9 in the case of a<

b<

c, and a ratio c/b is 0.7≦

c/b≦

0.9 in the case of c<

b<

a.

15. A Group III nitride semiconductor light-emitting device according to claim 9, wherein a ratio a/b is 0.7≦

a/b≦

0.9 in the case of a<

b<

c, and a ratio c/b is 0.7≦

c/b≦

0.9 in the case of c<

b<

a.

16. A Group III nitride semiconductor light-emitting device comprising at least an n-type-layer-side cladding layer, a light-emitting layer having a multiple quantum structure including an Al_xGa_1-xN (0<

x<

1) layer as a barrier layer, and a p-type-layer-side cladding layer, each of the layers being formed of a Group III nitride semiconductor, wherein when the light-emitting layer is divided into three blocks of a first block, a second block, and a third block in the thickness direction from the n-type-layer-side cladding layer to the p-type-layer-side cladding layer, the Al composition ratio of the barrier layer in each block is the same in the first, second, and third blocks, and the thickness of the barrier layer in each block is set so as to satisfy at least one of relations a<

b<

c and c<

b<

a where an average thickness of the barrier layers in the first block is represented as a, an average thickness of the barrier layers in the second block as b, and an average thickness of the barrier layers in the third block as c.

17. A Group III nitride semiconductor light-emitting device according to claim 16, wherein the number of the barrier layers in the first block is equal to the number of the barrier layers in the third block, and the thickness of the barrier layer in each block is set so as to satisfy a relation a+c=2b.

18. A Group III nitride semiconductor light-emitting device according to claim 17, wherein the thickness of the barrier layer in each block is set so as to satisfy a<

c.

19. A Group III nitride semiconductor light-emitting device according to claim 17, wherein a ratio a/b is 0.7≦

a/b≦

0.9 in the case of a<

b<

c, and a c/b is 0.7≦

c/b≦

0.9 in the case of c<

b<

a.