The Interaction of Extended Defects as the Origin of Step Bunching in Epitaxial III–V Layers on Vicinal Si(001) Substrates

Abstract

Several nanometer high steps are observed by (scanning) transmission electron microscopy at the surface and interfaces in heteroepitaxially grown III–Sb layers on vicinal Si(001) substrates. Their relations with antiphase boundaries (APBs) and threading dislocations (TDs) are elaborated. An asymmetric number density of TDs on symmetry-equivalent {111} lattice planes is revealed and explained according to the substrate miscut and the lattice misfit in the heteroepitaxial material system. Finally, a step bunching mechanism is proposed based on the interplay of APBs, TDs, and the vicinal surface of the miscut substrate.