| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a GaN single crystal substrate having a flat surface, a nitride-based semiconductor epitaxial substrate, a nitride-based semiconductor device and method for manufacturing them. <P>SOLUTION: The GaN single-crystal substrate 11 has a polished surface subjected to heat treatment for at least 10 minutes at a substrate temperature of ≥1,020°C in a mixed gas atmosphere containing at least an NH<SB>3</SB>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 the GaN single crystal substrate 11 exhibits a root-mean-square roughness of ≤0.2 nm and has steps and terraces corresponding to one atomic layer, such that the surface of a GaN epitaxial layer 12 formed on the substrate 11 can be made flat. <P>COPYRIGHT: (C)2009,JPO&INPIT |
