Ultrathin quantum wells of HgTe in CdTe: Interface states

We present an exact calculation of the electronic structure of systems composed by a small number of HgTe layers into CdTe. Layer Green Functions are calculated from which interface state energies and density of states are obtained. We employ a realistic tight-binding method. Special attention is drawn to the anisotropic dispersion relation through the entire two-dimensional Brillouin zone for a monolayer of HgTe. Interface states depend sensitively on the valence-band-offset. A comparison is made with the single heterojunction case showing that the coupling between interfaces in the quantum well plays a minor role in determining the main features of such cases.