In this work,the GaN thin films were directly deposited on multilayer graphene (MLG) by plasma-enhanced atomic layer deposition.The deposition was carried out at a low temperature using triethylgallium (TEGa) precursor and Ar/N2/H2 plasma.Chemical properties of the bulk GaN and GaN-graphene interface were analyzed using X-ray photoelectron spectroscopy.The sharp interface between GaN and graphene was verified via X-ray reflectivity and transmission electron microscope.The microstructures and the nucleation behaviors of the GaN grown on graphene have been also studied.The results of grazing incidence X-ray diffraction and Raman spectrum indicate that the as-deposited sample is polycrystalline with wurtzite structure and has a weakly tensile stress.Optical properties of the sample were investigated by photoluminescence (PL) at room temperature.The successful growth of GaN on MLG at a low temperature opens up the possibility of ameliorating the performance of electronic and optical devices based on GaN/graphene heterojunction.