Influence of band folding in InAs/GaSb superlattices

We demonstrate the importance of accurate full zone fits for the band diagrams of constituent materials in the superlattice empirical pseudopotential method (SEPM) modeling of InAs/GaSb type-II strained superlattices. In particular, we show that inaccurate fits to X-valley energies in the constituent GaSb conduction band can lead to significant errors in the prediction of the primary band gaps of these superlattices. Specifically, we examine a set of five samples, each with a fixed InAs layer thickness of six monolayers. These samples show a strong blueshift of the band gap as the GaSb layer thickness is systematically increased. We demonstrate that the superlattice-induced band folding of the GaSb conduction band X valley significantly influences our theoretically predicted results for the shorter-period superlattice samples. This result helps shed light on the proper domain of application of heterostructure theories, such as effective mass theories, that only involve zone center properties of the constituent materials. (C) 2003 American Institute of Physics.