Dynamics of a superlattice with an impurity in an ac electric field

Abstract

Within a single-band tight-binding model, we investigate the dynamics of a one-dimensional semiconductor superlattice with an impurity under the action of an ac electric field. The long-time mean-square displacement is analytically obtained and the quasienergy spectrum is numerically calculated. We find that although the dynamic localization condition is not destroyed by the impurity, the quasienergy spectrum and corresponding local dynamics of the system are tuned dramatically by the ratio of the impurity potential to the ac field frequency. In particular, when the ratio becomes an integer, avoided crossing in the quasienergy spectrum occurs and the dynamics of the system is dominated by resonant oscillations between the impurity and its two nearest-neighbor sites. Such an effect is more favorable for experimental investigations of coherent oscillations of charged carriers.