▎ 摘　　要

A conventional two-step growth process is still the state-of-the-art technology for the epitaxy of GaN, even if graphene is used as a substrate. Lowtemperature buffer layers play a decisive role in forming a continuous film In this work, the informative characterization of low-temperature (550 *C) GaN buffer layers grown on graphene by hydride vapor phase epitaxy (HVPE) was performed High-density and sixfold-symmetry structures of GaN nucleation sites formed the primary morphology of buffer layers The E-2 (high) Raman shift of GaN buffer layers on graphene was 568 cm(-1), illustrating that GaN was free of stress We also captured nonfoeusing photoluminescence (PL) spectra and observed the high intensity of nearband-edge emission of wurtzite GaN and the absence of yellow luminescence in the visible band. Thermally induced quantum effects could be found in low-temperature PL. The elementary and detailed characterizations offer referenced values for the growth of GaN films on graphene (C) 2018 The Japan Society of Applied Physics