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

Cross-slip events during the first stages of plastic relaxation have been i nvestigated in low-mismatch semiconductor heterostructures using X-ray topo graphy. It is shown that common and uncommon cross-slip as well as multiple cross-slip occur at very low misfit dislocation densities (less than 10(3) cm cm(2)) in GaAs/Ge and Si1,xGex/Si epitaxial layers. The results are dis cussed in terms of the image force and the resolved shear stress that act o n 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 ri bbon, 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 fo rce and the resolved shear stress have to be taken into account.