Self-consistent electronic structure method for broken-gap superlattices

We present a novel charge self-consistent eight-band k.p envelope function method for the calculation of the electronic structure of type-II broken-gap heterostructures. Standard multiband k.p approaches fail to yield the correct occupation of electronic states in broken-gap heterostructures, because the strong hybridization of conduction band and valence band states is incompatible with the separate occupation of electron and hole states that is common to envelope function approaches. In our method, we occupy all included subbands with electrons according to the Fermi statistics and subsequently subtract a positive background ionic charge that guarantees charge neutrality. With this procedure, we have calculated local charge densities and subband dispersions of periodically n and p doped GaAs layers as well as effective band gaps of intrinsic InAs/GaSb superlattices.