Study of Threading Dislocations in Wurtzite GaN Films Grown on Sapphire by Metalorganic Chemical Vapor Deposition

Abstract
The threading dislocations in GaN films grown on Al2O3 substrates were studied by plan view transmission electron microscopy (TEM). A pure edge dislocation and a mixed dislocation with different kinds of screw components, could be distinguished by taking the images near and far-away from the zone. The experimental results show that some pure edge dislocations form low-angle boundaries and other pure edge dislocations as well as mixed dislocations are randomly distributed in GaN films. The randomly distributed dislocations result from reactions of partial dislocations. Partial dislocations, on the other hand, is formed to eliminate the stacking disorder near the interface of GaN/Al2O3 films.