The influence of substrate etched on the quality of GaN epilayers

We report the growth of GaN epilayers on the sapphire substrate etched by MOCVD. Sapphire substrate is etched by H3PO4 and NaOH. The Raman scattering spectroscopy and photoetching analyses show that the substrate etched can effectively decrease the residual stress and the dislocations density in these epilayers. The X-ray diffraction analysis shows the process can reduce the value of the FWHM. Therefore, the quality of GaN epilayers should be improved by substrate etched.