Dislocation glide motion in heteroepitaxial thin films of Si_1-xGe_x/Si(100)

Measurements of dislocation glide velocity in heteroepitaxial Si_1-xGe_x thin films grown on Si(100) substrates revealed that the velocity of threading dislocationspenetrating the epitaxial layers depends almost linearly on the film thickness(dislocation length) in very thin films and shows saturation as the film thicknessexceeds about 1 pm, in agreement with results of a similar experiment performed byTuppen and Gibbings in 1990. The activation energy of dislocation motion isunaltered over this transition, which is incompatible with the view that suchsaturation is brought about by commencement of kink collision in long dislocations. This fact, together with other findings in the present study, supports aninterpretation that the dislocation glide in bulk crystals of Si, even though thesegment of straight dislocation is of a macroscopic dimension, proceeds withoutkink collision and is controlled solely by the formation rate of double kinks.