Patent ID: 7659190

Claim:
A method for producing a Group III-V compound semiconductor with a crystal layer, comprising forming a buffer layer of the general formula In u Ga v Al w N (wherein 0≦u≦1, 0≦v≦1, 0≦w≦1, u+v+w=1) directly on a substrate to give a buffer layer thickness of at least about 5 Å and not more than about 90 Å at temperatures lower than a growing temperature of the compound semiconductor crystal layer before growing the compound semiconductor crystal layer, then growing a Group III-V compound semiconductor crystal layer of the general formula In x Ga y Al z N (wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, x+y+z=1) on the buffer layer, wherein there is no intermediate layer between the buffer and the substrate, and wherein the substrate consists essentially of sapphire and comprises pits having a ratio of a maximum depth to a major axis of 0.05 to 0.5.