On the microstructure and interfacial structure of InSb layers grown on GaAs(100) by molecular beam epitaxy

Abstract

InSb films grown directly on GaAs(100) substrates by molecular beam epitaxy have been examined by transmission electron microscopy (TEM). High-quality epitaxial InSb layers were deposited despite the 14-6% lattice mismatch between film and substrate. Almost all the misfit strain was accommodated by a square array of (a/2){011} edge-type misfit dislocations, spaced on average 29 Å apart. A model for the formation of these dislocation arrays is presented. Pure edge-type dislocations are favoured over 60°-type dislocation arrays because they are more efficient at relieving misfit strain and consequently allow more coherent interface area to form. Several types of growth defect, namely Sb inclusions, microtwins and dislocation tangles, were observed in the InSb layers. Various methods for reducing the overall defect density are discussed. Finally, results on the extent of electron beam damage of InSb layers occurring during TEM observation are presented.