Tight-binding study of the electronic structure of the InAs–GaSb (001) superlattice

We present tight-binding model calculations for the InAs–GaSb (001) superlattice including second nearest-neighbor interactions. The tight-binding parameters used were obtained by fitting to the bulk band structure of InAs, GaSb, InSb, and GaAs. The parameters were required to be consistent with each other, to yield accurate energy values at the symmetry points, and to reproduce well the overall dispersion. Results for the behavior of the energy gap of the superlattice as a funcion of layer thickness, and of the conduction-band–valence-band edge discontinuity at the Γ point have been obtained. With increasing magnitude of the discontinuity, the nature of the superlattice changes from a direct gap semiconductor to an indirect gap semiconductor, to a semimetal. These results are compared with recent experimental studies.