Pseudopotential approach to long-period narrow-gap superlattices.

Abstract

The pseudopotential method is used to calculate the electronic structures of long-period narrow-gap InAs-GaSb and HgTe-CdTe superlattices. The variations of the energy gaps with the layer thicknesses and the band offsets, the subband dispersion along the ${k}_{x}$ direction, the charge distributions along the lines connecting atoms in the [011] direction, and the optical-transition matrix elements are obtained. It is found that the crossing of the lowest electronic level and the highest hole level for the superlattice (InAs${)}_{\mathrm{n}}$(GaSb${)}_{\mathrm{n}}$ occurs at the period of 160 A\r{}. The band offset has an essential effect on the energy gaps of the superlattice (HgTe${)}_{\mathrm{n}}$(CdTe${)}_{\mathrm{n}}$ with longer periods. The behavior of the interface states in the HgTe-CdTe superlattice is also discussed.