THREADING DISLOCATIONS IN CHEMICAL-VAPOR-DEPOSITED BETA-SIC ON (001)SI

The threading dislocations in hétéroépitaxial β-SiC films grown on (001)Si by chemical vapour deposition have been studied. A large number of threading dislocations are present and these are dissociated into two partial dislocations which bound a planar fault. The introduction of these threading dislocations is attributed to residual coherency stresses present in the deposited films. This occurs by the formation of half-loops at the deposit surface which subsequently glide toward the film/substrate interface. It is proposed that the threading dislocations are dissociated into two partial dislocations with Burgers vectors, b, given by b=1/4<111> which bound an antiphase boundary according to the reaction 1/2<101>=>1/4<111> + APB + 1/4<111> and that this dissociation is stabilized by a low antiphase-boundary energy in β-SiC. © 1991 Taylor & Francis Group, LLC.