Spectroscopy on Lateral Superlattices

Abstract

Field-effect devices on GaAs and Si with laterally periodic gates serve to impose widely tuneable one- and two-dimensional superlattice potentials on two-dimensional electron systems and make it possible to investigate all regimes between weakly perturbing and strongly confining lateral superlattices. Studies of the intraband electronic excitations at far-infrared frequencies provide information on collective modes in lateral superlattices, on strength and form of the lateral confining potentials, as well as on the mechanisms of electronic interactions. A magnetic field applied perpendicularly to the plane of the electron system is used to study the transition from lateral confinement to quasi-two-dimensional behavior. Here recent results are discussed that show the effects of anisotropy and non-parabolicity of the confining potential on the intraband modes. With these experiments one spectroscopically gains information on electronic interactions both within a wire or dot as well as across the superlattice period. Most experimental results are discussed in terms of semiclassical models based on ballistic electron motion in the lateral superlattices.