Nitride semiconductor laser device

• US 7,496,124 B2
• Filed: 11/28/2005
• Issued: 02/24/2009
• Est. Priority Date: 03/04/1999
• Status: Expired due to Fees

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Nakamura, Shuji, Sano, Masahiko, Nagahama, Shinichi, Kozaki, Tokuya
• Primary Examiner(s): Rodriguez; Armando
• Application Number:
  US11/287,339
• Publication Number:
  US 20060078022A1
• Time in Patent Office: 1,184 Days
• Field of Search: 372/39, 372/43.01, 372/45.01, 372/50.1
• US Class Current: 372/39
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01S 2304/00 Special growth methods for semiconductor lasers
• CPC Class Codes: H01S 5/04252 characterised by the material
• CPC Class Codes: H01S 5/04257 having positive and negative electrodes on the same side of the substrate
• CPC Class Codes: H01S 5/0655 Single transverse or lateral mode emission
• CPC Class Codes: H01S 5/2004 Confining in the direction perpendicular to the layer structure
• CPC Class Codes: H01S 5/2031 characterized by special waveguide layers, e.g. asymmetric waveguide layers or defined bandgap discontinuities
• CPC Class Codes: H01S 5/22 having a ridge or stripe structure
• CPC Class Codes: H01S 5/2214 based on oxides or nitrides
• CPC Class Codes: H01S 5/2216 nitrides
• CPC Class Codes: H01S 5/223 Buried stripe structure H01S5/227 takes precedence
• CPC Class Codes: H01S 5/2231 with inner confining structure only between the active layer and the upper electrode
• CPC Class Codes: H01S 5/3213 asymmetric clading layers
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP
• 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 laser device has an improved stability of the lateral mode under high output power and a longer lifetime, so that the device can be applied to write and read light sources for recording media with high capacity. The nitride semiconductor laser device includes an active layer, a p-side cladding layer, and a p-side contact layer laminated in turn. The device further includes a waveguide region of a stripe structure formed by etching from the p-side contact layer. The stripe width provided by etching is within the stripe range of 1 to 3 μm and the etching depth is below the thickness of the p-side cladding layer of 0.1 μm and above the active layer. Particularly, when a p-side optical waveguide layer includes a projection part of the stripe structure and a p-type nitride semiconductor layer on the projection part and the projection part of the p-side optical waveguide layer has a thickness of not more than 1 μm, an aspect ratio is improved in far field image. Moreover, the thickness of the p-side optical waveguide layer is greater than that of an n-side optical waveguide layer.

Claims

1. A nitride semiconductor laser device comprising:

an n-type semiconductor layer;

an active layer having a multi-quantum well (MQW) structure, including a plurality of well layers, each containing In, and a plurality of barrier layers, the active layer being provided on the n-type semiconductor layer; and

a p-type semiconductor layer provided on the active layer;

wherein the active layer comprises at least one three-layered structure, each said three-layered structure having one of the well layers, a middle layer having a band gap energy larger than that of one of the barrier layers, the middle layer being adjacent to said one of the well layers residing on the side of the p-type semiconductor layer, said one of the barrier layers being adjacent to the middle layer residing on the side of the p-type semiconductor layer.

2. The nitride semiconductor laser device according to claim 1, wherein a thickness of the middle layer is smaller than that of the barrier layer.

3. The nitride semiconductor laser device according to claim 1, wherein a thickness of the middle layer is within a range of one atomic layer to 100 angstroms.

4. The nitride semiconductor laser device according to claim 1, wherein said middle layer is composed of Al_uGa_1-uN (0≦

u≦

1).

5. The nitride semiconductor laser device according to claim 1, wherein said middle layer is composed of Al_uGa_1-uN (0.3≦

u≦

1).

6. The nitride semiconductor laser device according to claim 1, wherein a stripe-shaped waveguide region is provided in the p-type semiconductor layer.

7. The nitride semiconductor laser device according to claim 1, wherein an oscillation wavelength of the laser device is within a range of 450 nm to 520 nm.

8. The nitride semiconductor laser device according to claim 1, wherein another one of the barrier layers is adjacent to the n-type semiconductor layer.