GROWTH INSTABILITIES INDUCED BY ELASTICITY IN A VICINAL SURFACE

We study the effect of elasticity on the step-bunching instability in heteroepitaxial growth on a vicinal substrate. Three main effects are taken into account: the Schwoebel barrier and the step-step and the st ep-adatom elastic interactions. The first one is always stabilizing, t he second one generally destabilizing and the last one, stabilizing or not according to the sign of the misfit with the substrate. At very l ow values of the flux F, only the step-step interaction is effective: the stabilization is provided by the broken bond mechanism and the des tabilization by the misfit mechanism. At increasing F, the stabilizati on is governed by the Schwoebel effect and only the misfit mechanism n eeds to be taken into account. A stability phase diagram, taking into account also a possible instability for island nucleation, is drawn in the plane (F,T) = (flux,temperature): a stable region appears, at int ermediate values of F.