TEM study of the morphology of GaN/SiC (0001) grown at various temperatures by MBE

GaN films grown on SiC (0001) by MBE at various substrate temperatures (600 -750 degreesC) were characterized by RHEED, STM, x-ray diffraction, AFM and TEM. This work focuses on the TEM analysis of the films' features, such as stacking faults and dislocations, which are related to the substrate tempe rature. There are several basal plane stacking faults in the form of cubic inclusions for samples grown at low temperatures compared to those grown at high temperatures. The dislocation density is greatest for the film grown at 600 degreesC, and it steadily decreases with increasing growth temperatu res. Despite the presence of various defects, x-ray analysis shows that the GaN films are of high quality. The double crystal rocking curve full width at half maximum (FWHM) for the GaN (0002) peak is less than 2 are-minutes for all of the films we measured and it decreases with increasing growth te mperature.