| 摘要 |
PROBLEM TO BE SOLVED: To provide a GaN substrate whose front and back surfaces are identifiable without reducing the morphology of the semiconductor layer grown on a GaN crystal substrate. SOLUTION: The GaN substrate has a roughness Ra<SB>(C)</SB>on crystal growth surface 10c of≤10 nm and a roughness Ra<SB>(R)</SB>on the back surface 10r being the opposite surface of the crystal growth surface 10c of≥0.5μm and≤10μm. The ratio of the surface roughness Ra<SB>(R)</SB>to the surface roughness Ra<SB>(C)</SB>, Ra<SB>(R)</SB>/Ra<SB>(C)</SB>is≥50. COPYRIGHT: (C)2008,JPO&INPIT
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