The Ga-N bond extensions and compressions at the cores of various types of dislocation in hexagonal GaN films, grown onto Si(111) substrates, were studied by means of high-

resolution transmission electron microscopy. The relative bond extension and compression were about 6.4 and 7.4%, respectively, around the cores of mixed dislocations and about 9.6 and 12.7%, respectively, around the cores of pure edge dislocations. The core structure of a pure edge dislocation was deduced to be an 8-fold atom-column ring.

Dislocation Core Structures in GaN Grown on Si(111) Substrate. D.Wang, M.Ichikawa, S.S.Yoshida: Philosophical Magazine Letters, 2002, 82[3], 119-24