MOCVD-epitaxy on free-standing HVPE-GaN substrates

Free-standing GaN substrates of up to 2 " diameter can be produced hy delam ination of thick HVPE (hydride vapour phase epitaxy) films from sapphire wi th a laser-induced liftoff process. Homoepitaxial films of up to 2 mu m thi ckness were grown on the Ga-face and N-face of these substrates with a low- pressure MOCVD system. The pre-overgrowth polishing of the substrates influ ences the final surface morphology and growth modus, which also depend on t he crystal polarity. PL spectra resolve the bound and free exciton peaks fr om the overgrown GaN.