Semiconductor substrate made of group III nitride, and process for manufacture thereof

摘要

To provide a semiconductor substrate of a group III nitride with low defect density and little warp,
a process comprises the steps of:
forming a GaN layer 2 on a sapphire substrate 1 of the C face ((0001) face); forming a titanium film 3 thereon; heat-treating the substrate in an atmosphere containing hydrogen gas or a gas of a compound containing hydrogen to form voids in the GaN layer 2; and thereafter forming a GaN layer 4 on the GaN layer 2'.