Nitride semiconductor light emitting device

• US 7,705,364 B2
• Filed: 10/23/2006
• Issued: 04/27/2010
• Est. Priority Date: 10/25/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Lee, Dong Yul, Song, Keun Man, Kang, Sang Won, Kim, Je Won, Hong, Sang Su
• Primary Examiner(s): SEFER, AHMED N
• Application Number:
  US11/584,504
• Publication Number:
  US 20070090339A1
• Time in Patent Office: 1,282 Days
• Field of Search: 257/94, 257 96- 97, 257/79, 257 88- 90, 257/14, 257/103, 257/13, 257/104
• US Class Current: 257/96
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• 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 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

A nitride semiconductor light emitting device has high internal quantum efficiency but low operating voltage. The nitride semiconductor light emitting device includes an n-nitride semiconductor layer; an active layer of multi-quantum well structure formed on the n-nitride semiconductor layer, and having a plurality of quantum well layers and a plurality of quantum barrier layers; and a p-nitride semiconductor layer formed on the active layer. One of the quantum well layers adjacent to the n-nitride semiconductor layer has an energy band gap greater than that of another one of the quantum well layers adjacent to the p-nitride semiconductor layer.

Claims

1. A nitride semiconductor light emitting device comprising:

an n-nitride semiconductor layer;

an active layer of multi-quantum well structure formed on the n-nitride semiconductor layer, and having three or more quantum well layers and a plurality of quantum barrier layers; and

a p-nitride semiconductor layer formed on the active layer,

wherein one of the three or more quantum well layers adjacent to the n-nitride semiconductor layer has an energy band gap greater than those of another one of the three or more quantum well layers adjacent to the p-nitride semiconductor layer, and one of the three or more of quantum well layers proximate to the n-nitride semiconductor layer has a smaller thickness than another one of the three or more quantum well layers less proximate to the n-nitride semiconductor layer.

2. The nitride semiconductor light emitting device according to claim 1, wherein one of the three or more quantum well layers adjacent to the n-nitride semiconductor layer has an In content lower than that of another one of the quantum well layers adjacent to the p-nitride semiconductor layer.

3. The nitride semiconductor light emitting device according to claim 1, wherein the three or more quantum well layers and the quantum barrier layers alternate with each other, the three or more quantum well layers having a composition of In_xGa_1-yN, where 0≦

x≦

1, and the quantum barrier layers having a composition of In_yGa_1-yN, where 0≦

y<

1, x>

y.

4. The nitride semiconductor light emitting device according to claim 1, wherein the three or more quantum well layers have a composition of InGaN, and the quantum barrier layers have a composition of GaN excluding In.

5. The nitride semiconductor light emitting device according to claim 1, wherein the three or more quantum well layers have a energy band gap increasing with increase of proximity to the n-nitride semiconductor layer.

6. The nitride semiconductor light emitting device according to claim 1, wherein the three or more quantum well layers have an In content decreasing with increase of proximity to the n-nitride semiconductor layer.

7. The nitride semiconductor light emitting device according to claim 1, wherein each of the three or more quantum well layers has a thickness ranging from 10 Å

to 100 Å

.