Characterization of GaN grown on SiC on Si/SiO2/Si by metalorganic chemical vapor deposition

SiC (3C-SiC) was grown on the top Si layer of SIMOX (Si/SiO2/Si) by carbonization followed by chemical vapor deposition (CVD). Subsequently, GaN was deposited on the SiC by metalorganic (IVIO) CVD to produce a GaN/SiC/Si/SiO2/Si multilayer structure. This multilayer film was investigated by conventional transmission electron microscopy (TEM) and high-resolution (HR) TEM from cross-sectional view. The GaN layer was found to consist of predominately hexagonal gallium nitride (h-GaN), and a small fraction of cubic GaN (c-GaN) crystallites. The orientation relationship between most of the h-GaN grains and SiC (3C-SiC) was found to be (0001)(GaN)parallel to(111)SiC; [11 (2) over bar 0](GaN)parallel to[1 (1) over bar 0](SiC) while most of the c-GaN grains had an orientation relationship (001)(GaN)parallel to(001)sic; [1 (1) over bar 0](GaN)parallel to[1 (1) over bar 0](SiC) With respect to 3C-SiC substrate. The hexagonal grains of GaN were found to grow as two variants. The defects in both h-GaN and c-GaN are also discussed.