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 boxes 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 boxes. (C) 1998 Elsevier Science B.V.