LATERAL SUPERLATTICES AS VOLTAGE-CONTROLLED TRAPS FOR EXCITONS

We demonstrate the localization of quantum-well excitons in a periodic array of linear traps using photoluminescence experiments. The excito nic traps are induced by applying spatially alternating external volta ges via interdigitated metal gates. The localization originates from t he periodical modulation of the strength of the quantum-confined Stark effect in the plane of the quantum well. In our experiments, the trap depth is easily tuned by the voltages applied to the interdigitated g ates. Furthermore, we find that a perpendicular magnetic field reduces the exciton diffusion length. In short-period lateral superlattices, we observe a magnetic-field-induced stabilization of excitons in the p resence of strong in-plane electric fields.