| 摘要 |
PROBLEM TO BE SOLVED: To provide a nitride semiconductor substrate having a protective film formed on a surface where a high-quality epitaxial wafer can be produced.SOLUTION: A protective film essentially comprising gallium oxide and/or indium oxide and having a surface roughness of not more than 5 nm in terms of a square mean value is formed on the surface of a nitride semiconductor substrate by heat treating the nitride semiconductor substrate in an atmosphere containing air or oxygen or by exposing the surface of the nitride semiconductor substrate to oxygen plasma. The protective film prevents a contaminant from depositing on the substrate surface and can be easily removed only by keeping the substrate at a temperature of not higher than 1,200°C in a hydrogen atmosphere, and thereby, unusual growth of an epitaxial growth film or generation of crystal defects caused by contaminants can be prevented. |
