CRYSTAL-STRUCTURE OF GAN GROWN ON 3C-SIC SUBSTRATES BY METALORGANIC VAPOR-PHASE EPITAXY

GaN films were grown on 3C-SiC substrates by metalorganic vapor phase epitaxy (MOVPE) using 1,1-dimethylhydrazine (DMHy) as the N source. Th e crystal structure was strongly affected by both the growth temperatu re and the V/III ratio. At 600 degrees C, only hexagonal GaN films wit h their c-axis perpendicular to the substrate surface were grown. At 8 00 degrees C, relatively high V/III ratios resulted in the growth of h exagonal GaN with their c-axis oriented in the [111] direction while c ubic GaN films were obtained at lower V/III ratios. The origin of [111 ]-oriented hexagonal GaN is also discussed.