THE SURFACE AND INTERFACE NUCLEATION OF MISFIT DISLOCATIONS AS A POSSIBLE SOURCE OF ASYMMETRIC STRAIN RELAXATION IN VICINAL HETEROSTRUCTURES

The surface nucleation of misfit dislocations in vicinal (001) oriente d heterostructures with compressive and tensile stresses is discussed. It is shown that beside the asymmetrical stressing of opposite disloc ation slip planes due to the vicinal substrate, the surface steps have a similar effect. The effect of the steps has the same-sign asymmetry for a compressive stressed epilayer, but opposite for the tensile cas e. The effect on dislocation nucleation energy is calculated. For misc ut angles used normally, the step energy contribution exceeds that of due to the vicinal substrate. The extension to interface nucleation is treated qualitatively.