Threading dislocations in films which had been grown onto Al2O3 substrates were studied by means of plan-view transmission electron microscopy. A pure edge dislocation, and a mixed dislocation with various screw components, could be distinguished by taking images near to, and far from, the <00•1> zone. The results showed that some pure edge dislocations formed low-angle boundaries and that other pure edge dislocations, as well as mixed dislocations, were randomly distributed in the films. The randomly distributed dislocations resulted from reactions between partial dislocations. The latter, in turn, formed in order to eliminate stacking disorder near to the film/substrate interface.

Study of threading dislocations in Wurtzite GaN films grown on sapphire M.Hao, T.Sugahara, H.Sato, Y.Morishima, Y.Naoi, L.T.Romano, S.Sakai: Japanese Journal of Applied Physics - 2, 1998, 37[3A], L291-3