GaN single-crystal substrate, nitride type semiconductor epitaxial substrate, nitride type semiconductor device, and methods of making the same

• US 6,841,274 B2
• Filed: 05/08/2003
• Issued: 01/11/2005
• Est. Priority Date: 05/13/2002
• Status: Active Grant

• Current Assignee: Institute of Materials Research and Engineering, Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Institute of Materials Research and Engineering, Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Ueno, Masaki, Chen, Peng, Takasuka, Eiryo, Chua, Soo-Jin
• Primary Examiner(s): STEIN, STEPHEN J
• Application Number:
  US10/431,431
• Publication Number:
  US 20030209185A1
• Time in Patent Office: 614 Days
• Field of Search: 428/698, 428/697, 117/952, 117/953
• US Class Current: 428/698
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 21/3245 of AIIIBV compounds
• CPC Class Codes: H01L 21/3247 for altering the shape, e.g. smoothing the surface

Abstract

The GaN single-crystal substrate 11 in accordance with the present invention has a polished surface subjected to heat treatment for at least 10 minutes at a substrate temperature of at least 1020° C. in a mixed gas atmosphere containing at least an NH₃ gas. As a consequence, an atomic rearrangement is effected in the surface of the substrate 11 in which a large number of minute defects are formed by polishing, so as to flatten the surface of the substrate 11. Therefore, the surface of an epitaxial layer 12 formed on the substrate 11 can be made flat.

Claims

1. A GaN single-crystal substrate having a polished surface flattened by heat treatment for at least 10 minutes at a substrate temperature of at least 1020°

C. in a mixed gas atmosphere containing at least an NH₃ gas, and a nitride type compound semiconductor layer epitaxially grown on said GaN single-crystal substrate, and said nitride type compound semiconductor layer has an x-ray diffraction half width of 100 seconds or less.

2. A GaN single-crystal substrate having a polished surface flattened by heat treatment for at least 10 minutes at a substrate temperature of at least 1020°

C. in a mixed gas atmosphere containing at least an NH₃ gas, and a nitride type compound semiconductor layer epitaxially grown on said GaN single-crystal substrate, and said nitride type compound semiconductor layer has a threading dislocation density of 1×

10⁶ cm<sup>−

2</sup> or less.

3. A nitride type semiconductor device comprising a GaN single-crystal substrate having a polished surface flattened by heat treatment for at least 10 minutes at a substrate temperature of at least 1020°

C. in a mixed gas atmosphere containing at least an NH₃ gas, and said substrate having an n-type conductivity;

an n-type cladding layer, laminated on said substrate, the n-type cladding layer comprising Al_xGa_1-xN (0<

x<

1);

an active layer laminated on said cladding layer;

a p-type cladding layer, laminated on said active layer, the p-type cladding layer comprising Al_xGa_1-xN (0<

x<

1) and a p-type GaN layer laminated on said p-type cladding layer.