INTERBAND RESONANT TUNNELING AND TRANSPORT IN INAS/ALSB/GASB HETEROSTRUCTURES

The nonequilibrium Green-function Keldysh formalism is used to analyze resonant interband tunneling in double-barrier structures and nonresonant interband transport in polytype heterostructures of InAs, GaSb, and AlSb. The systems are modeled by a multiband tight-binding Hamiltonian that incorporates mixing of electron, light-hole, and heavy-hole states. The model is solved by the real-space renormalization technique, which is very rapid and numerically stable for any size of the system. The large difference in effective masses and the opposite curvature of the energy dispersion of the conduction band in InAs and valence bands in GaSb are reflected in the transport properties. The I-V characteristics of double-barrier structures show quite different features according to whether the well is InAs or GaSb. For the latter case, the current intensity peaks and the peak-to-valley current ratios are much larger than for the former case. The calculated I-V characteristics are generally in very good agreement with the experimental data. The density of states and the dispersion relation of the resonant states as a function of the in-plane wave vector are also discussed.