SCANNING CAPACITANCE MICROSCOPY IMAGING OF THREADING DISLOCATIONS IN GAN FILMS GROWN ON (0001) SAPPHIRE BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

A combination of atomic force microscopy and scanning capacitance micr oscopy was used to investigate the relationship between the surface mo rphology and the near-surface electrical properties of GaN alms grown on c-axis sapphire substrates by metalorganic chemical vapor depositio n. Local regions surrounding the surface termination of threading disl ocations displayed a reduced change in capacitance with applied voltag e relative to regions that contained no dislocations. Capacitance-volt age characteristics obtained from these regions indicated the presence of negative charge in the vicinity of dislocations. (C) 1998 American Institute of Physics.