Bulk and surface electronic states in semiconductor superlattices

Abstract

We study the bulk and surface electronic states of semiconductor superlattices with the help of a simple two-band model. The superlattice has a larger periodicity in the direction perpendicular to the slabs and therefore many electronic branches in the folded Brillouin zone. In the gaps existing between the bulk branches appear the surface localized modes. The simplicity of the model used here allows one to obtain in closed form the bulk and (001) surface Green function for this superlattice. The analytic knowledge of these functions enables us to study easily the bulk and surface electronic bands of this semiconductor superlattice, which otherwise require important numerical calculations. We give here for the first time the analytic expression we obtained for the folded bulk electronic bands and also the expression that gives the surface electronic states. A few figures, especially for InAsGaSb and GaAsAlAs superlattices illustrate these results.