Determination of segregation, elastic strain and thin-foil relaxation in InxGa-1-x As islands on GaAs(001) by high resolution transmission electron microscopy

Abstract

Lattice-parameter mismatch-induced strains in three-dimensional coherent InxGa1-xAs islands grown on GaAs(001) substrates have been determined experimentally on an atomic scale by a digital analysis of images obtained by high-resolution transmission electron microscopy. The strain distributions in the islands were simulated by finite-element calculations. The simulated strain distributions are found to be in good agreement with measured data, taking into account the thin-foil relaxation of electron-transparent specimens in addition to the well known elastic strain relief. Clear evidence is given for an indium segregation causing a misfit gradient between the interface and the islands' surface.