Abstract
Calculated electronic properties of compound semiconductor hetero structures are presented and compared with experimental results. Model theories used to obtain the discontinuity in the valence-band edge at the interface between two semiconductors are compared with results from first-principles supercell calculations. The so-called ‘dielectric midgap energy’ model yields good estimates of the band offsets in junctions where interface states have little influence on the charge transfer. These cases are simultaneously those where the transitivity rule applies. Lattice matched cases as well as systems with built-in strain are discussed. Strain effects are included in lattice mismatched systems, and also externally applied pressures can be taken into account. As an example of the latter we examine the type I-II conversion in ZnS/ZnSe superlattices under pressure. Superlattice band structures are derived within the density-functional theory, local approximation. The valence bands are well described, but optical properties can only be extracted after the application of shifts in the conduction-band structure. This is done by adding external potentials, transferred from calculations on the constituent bulk materials.