Theory of direct optical transitions in an optical indirect semiconductor with a superlattice structure

Abstract

Starting from a model of an indirect optical semiconductor with two bands, the electron states are calculated in the presence of an additional periodic one-dimensional potential (superlattice) in the semiconductor material. These states are used to determine the transition probability connected with the absorption of a photon. This transition corresponds to an optical direct transition — no phonon takes part in this process. The optical direct and optical indirect transitions are compared. For optical frequencies near the band gap one expects only direct transitions, whereby the optical indirect transitions may be neglected.