The formation of partial dislocations in Ge/Si(001) structures was investigated theoretically by using an atomistic model. The equilibrium critical thickness for the nucleation of a 90 partial, with an extrinsic stacking fault, was equal to about half of that for 60 perfect dislocations in the shuffle-set configuration. A 60 dislocation was predicted to be in the narrowly dissociated glide-set configuration, with an intrinsic stacking fault, when interaction with another dislocation was absent. It was predicted to be in the dissociated glide-set configuration, with an extrinsic stacking fault, when there was another 60 dislocation with a parallel screw component in its vicinity. It was predicted to be in the undissociated configuration, or in the narrowly dissociated configuration with an intrinsic fault, when there was another 60 dislocation with an opposite screw component in its vicinity. In the dissociated configurations, the 90 partial remained at the interface and the 30 partial was displaced into the Ge layer in the case of extrinsic fault dissociation, and into the substrate in the case of intrinsic fault dissociation.

M.Ichimura, J.Narayan: Philosophical Magazine A, 1996, 73[3], 767-78