Growth of GaN quasi‐substrates by hydride vapor phase epitaxy

To grow high quality GaN heteroepitaxially is a difficult task due to the lattice mismatch and differences in thermal expansion coefficients between the films and the foreign substrates. A large number of structural defects form in the films, which lateron may limit the performance in the devices. Hydride vapor phase epitaxy is a high-growth-rate technique which has the potential to faciliate large area, low defect density “GaN quasi-substrates” for subsequent growth by MOCVD or MBE. We report on a flow modulated growth process which includes a nitridation of the sapphire substrate and the growth of high temperature buffer layers. The strucutral and optical properties of the films are presented and compared at different stages of the growth process.