Electronic structure of AlAs-GaAs superlattices

The electronic structure of (001) AlAs-GaAs superlattices is studied for (2,2)≤(n,m)≤(22,22), where n (m) is the number of principal layers of AlAs (GaAs). Four distinct regions are identified in the (n,m) chart. Only one has an indirect gap. Besides energy eigenvalues, especially band-edge levels, attention is paid to confinement problems and the spatial dependence of the local amplitude of several representative states. The results show a very diversified spectral phenomenology. The calculation is based on an ${\mathrm{sp}}^3$ $s^{\mathrm{*}}$ model and on a surface Green-function matching analysis, partly using formalism previously developed and partly based on further formal developments presented and used here.