Semiconductor light emitting device and illuminating device using it

• US 7,723,739 B2
• Filed: 09/04/2006
• Issued: 05/25/2010
• Est. Priority Date: 09/05/2005
• Status: Expired due to Fees

• Current Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation), Riken
• Original Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation), Riken
• Inventors: Takano, Takayoshi, Ikeda, Junji, Hirayama, Hideki, Kondo, Yukihiro
• Primary Examiner(s): NGO, NGAN V
• Application Number:
  US11/991,418
• Publication Number:
  US 20090001409A1
• Time in Patent Office: 1,359 Days
• Field of Search: 257/95, 257/96, 257/97, 257/103, 257/E33.026, 257/E33.028
• US Class Current: 257/95
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A semiconductor light emitting device includes an n-type nitride semiconductor layer 3 formed on one surface side of a single-crystal substrate 1 for epitaxial growth through a first buffer layer 2, an emission layer 5 formed on a surface side of the n-type nitride semiconductor layer 3, and a p-type nitride semiconductor layer 6 formed on a surface side of the emission layer 5. The emission layer 5 has an AlGaInN quantum well structure, and a second buffer layer 4 having the same composition as a barrier layer 5a of the emission layer 5 is provided between the n-type nitride semiconductor layer 3 and the emission layer 5. In the semiconductor light emitting device, it is possible to increase emission intensity of the ultraviolet radiation as compared with a conventional configuration while using AlGaInN as a material of the emission layer.

Claims

1. A semiconductor light emitting device comprising:

an n-type nitride semiconductor layer formed on one surface side of a single-crystal substrate for epitaxial growth through a first buffer layer;

an emission layer formed on a surface side of said n-type nitride semiconductor layer;

a p-type nitride semiconductor layer formed on a surface side of said emission layer;

wherein

said emission layer has an AlGaInN quantum well structure and includes at least a pair of a barrier layer and a well layer,

a second buffer layer having the same composition as said barrier layer included in the emission layer being provided between said n-type nitride semiconductor layer and said barrier layer.

2. The semiconductor light emitting device as set forth in claim 1, wherein

said first buffer layer is comprises of an AlN layer.

3. The semiconductor light emitting device as set forth in claim 1, wherein

said n-type nitride semiconductor layer is comprised of an AlGaN layer.

4. The semiconductor light emitting device as set forth in claim 1, wherein

said first buffer layer and said second buffer layer have different lattice constants from each other,

relative proportions of said n-type nitride semiconductor layer being changed so that a lattice constant of said n-type nitride semiconductor layer approaches from a lattice constant of said first buffer layer to a lattice constant of said second buffer layer with distance from said first buffer layer.

5. The semiconductor light emitting device as set forth in claim 4, wherein

said second buffer layer has a film thickness which is larger than that of said barrier layer.

6. The semiconductor light emitting device as set forth in claim 1, wherein

a concave-convex structure for increasing light output efficiency is formed on an exposed surface of at least one of said single-crystal substrate, said n-type nitride semiconductor layer, and said p-type nitride semiconductor layer.

7. An illuminating device comprising:

said semiconductor light emitting device as set forth in claim 1.

8. An illuminating device comprising:

said semiconductor light emitting device as set forth in claim 2.

9. An illuminating device comprising:

said semiconductor light emitting device as set forth in claim 3.

10. An illuminating device comprising:

said semiconductor light emitting device as set forth in claim 4.

11. An illuminating device comprising:

said semiconductor light emitting device as set forth in claim 5.

12. An illuminating device comprising:

said semiconductor light emitting device as set forth in claim 6.