The Formation of Helical Dislocations in Silicon Substrates During Epitaxial Deposition of β- SiC

Abstract

ABSTRACTA study is presented of the dislocation content of (001) Si substrates after the formation of thin epitaxial “buffer layers” of beta-SiC by the pyrolysis of propane. Helical dislocations are observed running parallel to the interface and extending for many microns. The dislocation helices emanate from the substrate, have 1/2<110> Burgers vectors which are inclined to the interface, and do not lie on the {111} glide planes. This is consistent with the extension of dislocations in the substrate by climb. The extended segments are subsequently pinned and further climb gives rise to the observed helical configuration. These climb effects are presumably due to an excess of vacancies which are produced when Si interstitials migrate to the deposit in order to form SiC.