Enhancement of alloy segregation due to strain assisted atomic diffusion in heteroepitaxy

Strain fields have proved to play a very important role in the self-organization of 3D islands which appear during highly mismatched epitaxy (e.g. for InAs deposited on GaAs, or SiGe/Si). In this work we focus on stress-driven atomic exchanges in inhomogeneously strained systems in order to derive — from a self consistent treatment — the stable equilibrium atomic distribution. For this we first calculate the energy of an atom, as a function of the local average strain. Then we combine this relation with the strain distribution calculated for a starting atomic configuration using a valence force field approach. Surface effects are also taken into account in a simple way. This study applies to alloy segregation in 3D quantum ☐es before, as well as during, their burying process, or to alloy segregation due to surface roughening during the deposition of very thick lattice-matched alloy 2D layers. Some results are compared with recent experimental observations of surface segregation in (Ga, In)As/GaAs quantum ☐es.