Strain profiles in overcritical (001) ZnSe/GaAs heteroepitaxial layers

Abstract

ZnSe layers of various thicknesses have been grown epitaxially on (001)-oriented GaAs substrates by metalorganic vapor phase epitaxy and studied by x-ray diffraction and Raman scattering. Consistent results have been found for the in-plane strains of both, ZnSe layers below and above the critical value of plastic relaxation. The experimental results are well described by strain profiles which are evaluated by an energy model and a geometrical model including the effects of strain and work hardening. The thickness-dependent full widths at half maximum of the x-ray reflections and the Raman resonances are accounted for by assuming uncorrelated misfit dislocations in the layers.