Microstructural Characterization of GaN on (0001) Sapphire

III-V nitrides grown on (0001) sapphire substrates often contain a very high density of defects; this high density is usually attributed to the poor lattice and thermal match between the nitride and the sapphire [1]. There is thus a need to understand the defect structures in these materials. In the present study, a microstructural characterization of MBE-grown GaN films on (0001) sapphire using various TEM techniques was performed to evaluate defect structures in this material. This paper will outline some of the different types of defects found in these films and suggest some possible mechanisms by which they were formed.