Misfit dislocation cross-slip at the first stages of plastic relaxation in low-mismatch heterostructures

Abstract

Cross-slip events during the first stages of plastic relaxation have been investigated in low-mismatch semiconductor heterostructures using X-ray topography. It is shown that common and uncommon cross-slip as well as multiple cross-slip occur at very low misfit dislocation densities (less than 10³ cm cm⁻²) in GaAs/Ge and Si_1−xGe_x/Si epitaxial layers. The results are discussed in terms of the image force and the resolved shear stress that act on the emerging segment of threading dislocations. In particular, the image force is evaluated in the case of cross-slip in the {111} glide planes, and it is shown that this force can favour the local shrinkage of the fault ribbon, leading to cross-slip and multiple cross-slip events. In the case of the {101} and {131} uncommon glide planes, the effects of both the image force and the resolved shear stress have to be taken into account.