Two-level model of heterojunction band offsets

Abstract

We introduce a new method for studying band offsets in heterostructure junctions. We ‘‘break’’ the junction bond and use the ‘‘broken’’ states as reference states. If only valence states plus broken bond states are allowed to interact they expel an ‘‘antibonding’’ state from the valence manifold. The charge transfer ρanti is the negative of the antibonding charge. The conduction–valence interactions give a further small charge transfer ρpert which can be calculated by perturbation theory. We develop a rigorous two-level model for calculating ρanti. When the hybrid levels of this model match exactly, ρanti=0.