TOPOLOGY OF TWIN JUNCTIONS IN EPITAXIAL BETA-SIC

The island growth of beta-SiC on vicinal (001) Si is studied by HREM a nd AFM. The initial nuclei have the morphology of tetragonal pyramids, Growth proceeds by a dendritic mechanism resulting in a large density of primary twins and stacking faults. The density of planar defects i s reduced dramatically with increasing distance from the substrate. Mu tual twin annihilation was studied taking into account interfacial con nectivity principles developed recently. The secondary defects that ar e geometrically necessary for such a mechanism were identified. It has been shown that, for the formation of closed defect topologies, junct ion lines of planar defects are introduced. This has been verified usi ng computer simulation of HREM images. (C) 1997 Elsevier Science S.A.