ELECTRONIC-STRUCTURES AND OPTICAL-PROPERTIES OF SHORT-PERIOD GAAS/ALAS SUPERLATTICES

Electronic and optical properties of short-period superlattices are investigated with an empirical tight-binding model, which includes second-neighbor interactions. The "- and X-like electronic energy levels are obtained as functions of the number of GaAs monolayers, the applied electric field, and the parallel wave vector. The calculated "-X crossover is in good agreement with the experimental observation. Short-period superlattices grown in the [111] direction are also examined. Dielectric functions of superlattices over the full energy range are calculated by using a newly developed empirical method to obtain optical matrix elements. Dielectric functions of short-period superlattices are found to be quite different from those of bulk GaAs and AlAs, but fairly close to their average when the number of monolayers of GaAs and AlAs in the superlattice are the same and larger than six. © 1990 The American Physical Society.