Structural characterization of hexagonal GaN thin films grown by MOCVD on 4H-SiC substrate

A Si-doped GaN films was, grown on 4H-SiC by metal-organic chemical vapor deposition. It was found that the compressively strained layer of the film can be relaxed and surface structural quality can be improved by increasing the thickness of Si-doped GaN film. The critical thickness of beginning of two-dimension growth of GaN on 4H-SiC substrate by metal-organic chemical vapor deposition (MOCVD) has been systematically studied. We optimized growth time of GaN layer so that the GaN layer structral quality can be improved and the root mean square (RMS) roughness of surface can be reduced. With suitable growth time of GaN layer, crack-free 600 nm GaN was obtained and the full-width at half-maximum (FWHM) of (0 0 2) plane rocking curve measured by double crystal X-ray diffraction (DCXRD) was as low as 279.6 arcsec. This kind of film can be used as a high-quality buffer layer between the substrate and epitaxial layer.