Electronic structure of two-dimensional semiconductor systems

The motion of two-dimensional carriers in semiconductor heterojunctions, quantum wells and superlattices is discussed, with emphasis on subband dispersion parallel to the interfaces and on quantization in a perpendicular magnetic field. The envelope function approximation is shown to provide an efficient and accurate method for the calculation of electronic states. It is shown that for states derived from degenerate or coupled bulk bands (valence bands, k . p-coupled conduction and valence bands in narrow-gap semiconductors) striking non-parabolicities of the subband dispersion and non-linearities of the Landau levels versus magnetic field occur. Results for GaAs-AlGaAs and InAs-GaSb systems are presented and compared with experiment.