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In-situ TEM studies of the interaction between dislocations in SiGe heterostructures

Abstract

The rate of strain relaxation in SiGe heterostructures by misfit dislocation introduction depends strongly on the kinetics of dislocation nucleation, propagation and interaction. In this work we present data regarding the effect of dislocation interactions on strain relaxation, delineating the growth regimes where they strongly affect relaxation rates, and specifics regarding the dislocation geometry and interaction stresses. Utilizing an ultrahigh vacuum transmission electron microscope equipped with chemical vapor deposition capability, we have systematically determined the epilayer thicknesses and compositions at which the interaction between propagating threading segments and pre-existing interfacial segments results in blocking of the threading segment. We find that the data shows broad agreement with the existing numerical simulations of the phenomenon, but we find that the subtleties of the dislocation geometry are significantly different than the theories predict. We explore herein the role of dislocation Burgers vectors, interaction stresses and the effects of further growth on the dislocation blocking process

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