MICROPIPES AND POLYTYPISM AS A SOURCE OF LATERAL INHOMOGENEITIES IN SIC SUBSTRATES

Structural and electrical inhomogeneities in SIC bulk crystals grown b y the modified Lely sublimation method [1] in (0001) direction are inv estigated. Inclusions of different polytypes such as 15R in 6H materia l are observed on a macroscopic as well as a microscopic scale. Their size and number can be associated with the growth rate of the crystal. Beside the familiar micropipes, 'nanopipes' were observed by atomic f orce microscopy. Micropipes and nanopipes form centers of growth spira ls related to the growth mechanism of the crystals under study. These micro- and nanopipes are a major source of structural and electrical i nhomogeneities of SiC which are discussed in this paper. (C) 1997 Publ ished by Elsevier Science S.A.