Confined electron states in corrugated GaAs/AlAs superlattices

Abstract
The electronic and optical properties of GaAs/AlAs superlattices grown in the [311] direction are investigated in the framework of an empirical tight-binding mode1 which includes second-neighbor interactions. The [311] superlattices are of great interest because of their non-flat interfaces and because the periodic corrugation which appears gives rise to a lateral confinement. This results in the formation of quantum wires which present a pronounced degree of optical anisotropy. The characteristics and the energy gap value of these wires are studied as functions of the layer thickness and the differences with [001]-grown superlattices are discussed. The calculated cross-over of T- and X-like levels is in good agreement with the experimental observations. The nature of the lowest conduction states is explained in terms of the symmetry of the superlattice.