Energy Spectrum of the Cross Motion of Excitons in a Superlattice

Abstract

On the basis of the exact expression for the potential of a point charge in a superlattice, consisting of alternating layers with two different values of the dielectric constant, the energy spectrum is found of an exciton motion, perpendicular to the superlattice layer direction, a t small values of the exciton quasi-momentum component parallel to the layer plane. An evident form of an exciton energy dependence on the cross component of quasi-momentum which is perpendicular to the layer plane is adduced. The exciton energy has a maximum a t the centre of the Brillouin zone of the cross quasi-momentum and a minimum a t its boundaries.