Similarity of (Ga, Al, As) alloys and ultrathin heterostructures: Electronic properties from the empirical pseudopotential method

The energy-band structures of ${\left(\mathrm{GaAs}\right)}_n{\left(\mathrm{AlAs}\right)}_m$ heterostructures with $2\le n+m\le 8$ and of the corresponding virtual-crystal alloys are calculated with the empirical pseudopotential method. Our results indicate that cation order effects do not play a significant role for these heterostructures and can be handled in perturbation theory. Our picture is in agreement with all the available experimental data. The use for heterostructure calculations of empirical pseudopotentials derived from a fit to the band structures of the pure GaAs and AIAs compounds is critically discussed.