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 step-adatom elastic interactions. The first one is always stabilizing, the second one generally destabilizing and the last one, stabilizing or not according to the sign of the misfit with the substrate. At very low values of the flux F, only the step-step interaction is effective: the stabilization is provided by the broken bond mechanism and the destabilization by the misfit mechanism. At increasing F, the stabilization is governed by the Schwoebel effect and only the misfit mechanism needs 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 intermediate values of F.