Characterization of GaN thin film growth on 3C–SiC/Si(1 1 1) substrate using various buffer layers

GaN thin films have been grown by MOCVD on GaN, AlN, and superlattice buffer layers predeposited on 3C–SiC/Si(111) substrates. The growth of 3C–SiC intermediate layer was carried out by CVD on the Si(111) substrates using tetramethylsilane single source precursor. In the results of X-ray diffraction, GaN films grown with a superlattice buffer layer showed only c-oriented (0002) plane of GaN. From the Raman spectra, the E2 high mode, agreed with the selection rule, was well observed in all GaN films. But, the A1(TO) and E1(TO) mode and the E1(TO) mode were additionally appeared in the GaN films grown without buffer layer and with GaN buffer layer, respectively. In the photoluminescence spectra at low temperature, the peaks associated with band edge emission and donor–accepter pair (D0A0) were observed in GaN films grown without buffer layer or with GaN buffer layer and AlN buffer layer. GaN films grown with superlattice buffer layer showed band edge and very weak D0A0 emission. The root mean square (RMS) roughness of the GaN film grown on superlattice buffer layer was only 4.21Å. The surface morphology and structural and optical qualities of GaN films were extremely improved using superlattice buffer layer.