Inclusion of Dislocation Pinning Interactions in a Model for Plastic Flow in II-VI Semiconductors

Plastic flow models for lattice relaxation in II-VI heterostructures have increased in sophistication, including thermal strains as well as dislocation multiplication, annihilation, coalescence, and compensation. However, despite evidence for the importance of pinning interactions, existing plastic flow models have not accounted for these interactions, whereby a gliding threading dislocation associated with a misfit dislocation along a < 110 > type direction is impeded by interaction with a misfit dislocation along the orthogonal < 110 > type direction. Such an impediment to glide will tend to reduce the extent of strain relaxation, perhaps appreciably in layers which are thin or exhibit low residual strain; in these cases, the motion of a gliding dislocation could be arrested altogether. In this paper we present a practical model for pinning interactions which can be used to extend the usefulness of plastic flow models, and we compare this model against experimental results for ZnSySe1y/GaAs (001) heterostructures.