| 摘要 |
PROBLEM TO BE SOLVED: To provide a self-standing group III-V nitride-based semiconductor substrate almost free from warp. SOLUTION: A GaN layer 33 is epitaxially grown on a sapphire substrate 31 through a GaN low-temperature buffer layer 32. Then the substrate is taken out of a reaction tube, and a self-standing GaN substrate 35 is obtained by removing the sapphire substrate 31, the GaN low-temperature buffer layer 32 and a portion of the GaN layer 33. Thereafter, the self-standing GaN substrate 35 is put in an electric furnace and heat-treated at 1,200°C for 24 h in an NH<SB>3</SB>atmosphere. Thereby, a self-standing GaN substrate having surface dislocation density of 4×10<SP>7</SP>cm<SP>-2</SP>, rear surface dislocation density of 8×10<SP>5</SP>cm<SP>-2</SP>, and a dislocation density ratio of 50 can be obtained. COPYRIGHT: (C)2008,JPO&INPIT
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