DISLOCATION GLIDE MOTION IN HETEROEPITAXIAL THIN-FILMS OF SI1-XGEX/SI(100)

Measurements of dislocation glide velocity in heteroepitaxial Si1-xGex thin films grown on Si(100) substrates revealed that the velocity of threading dislocations penetrating the epitaxial layers depends almost linearly on the film thickness (dislocation length) in very thin films and shows saturation as the film thickness exceeds about 1 mum, in agreement with results of a similar experiment performed by Tuppen and Gibbings in 1990. The activation energy of dislocation motion is unaltered over this transition, which is incompatible with the view that such saturation is brought about by commencement of kink collision in long dislocations. This fact, together with other findings in the present study, supports an interpretation that the dislocation glide in bulk crystals of Si, even though the segment of straight dislocation is of a macroscopic dimension, proceeds without kink collision and is controlled solely by the formation rate of double kinks.