GROUP ? NITRIDE BASED SEMICONDUCTOR SUBSTRATE AND PROCESS FOR MANUFACTURE THEREOF

摘要

To provide a semiconductor substrate of a group III nitride with a little warp, this invention provides a process comprising such steps of: epitaxial-growing a GaN layer 33 with a GaN low temperature grown buffer layer 32 upon a sapphire substrate 31; removing the sapphire substrate 31 , the GaN buffer layer 32 and a small portion of the GaN layer 33 from the substrate taken out of a growth reactor to obtain a self-supporting GaN substrate 35 ; and after that, heat-treating the GaN substrate 35 by putting it into an electric furnace under the NH₃ atmosphere at 1200° C. for 24 hours; which leads to a marked reduction of the warp of the self-supporting GaN substrate 35 such that dislocation densities of its obverse and reverse surface are 4x10⁷ cm^-2 and 8x10⁵ cm^-2, and thereby such a low ratio of dislocation densities of 50 is well-controlled.