Lateral Electronic Superlattices on Semiconductors

Summary

The effects of a voltage-tunable lateral superlattice potential on the electronic properties of a two-dimensional electron system are reviewed in the ballistic regime in which the electronic mean free path is longer than the super-lattice period for the particular case of square superlattices. Field-effect devices with laterally periodic gates serve to tune the ratio of Fermi energy to superlattice potential and make it possible to investigate all regimes between weakly perturbing and strongly confining superlattices. A magnetic field applied perpendicular to the plane of the electron system is used to provide a tunable length scale, namely the cyclotron radius at the Fermi energy. Magnetoresistance features that are observed when the diameter of the cyclotron orbit is equal to or a multiple of the superlattice period are shown to be quantitatively explainable in a semiclassical trajectory model of deterministic diffusion of ballistic electrons. The intraband response of lateral superlattices at infrared frequencies is demonstrated to provide information about the unscreened confining potential. Here the trajectory model can also serve to give a better understanding of the effects of a lateral superlattice on the dynamic electronic properties.