Voltage-controlled trapping of excitons and “storage of light” in lateral superlattices

Abstract

Voltage-controlled lateral superlattices of various periods are employed to demonstrate the trapping of photogenerated excitons in quasi-one-dimensional regions and to store light in form of ionised excitons in the quantum well of a semiconductor heterostructure. The superlattices are induced by applying spatially alternating external voltages via interdigitated metal gates. Exciton localisation arises from a periodical modulation of the strength of the quantum confined Stark effect in the plane of the quantum well. At large superlattice potential amplitudes the excitons are ionised due to the strong lateral electric fields. The thus spatially separated electrons and holes can be stored efficiently in the structure. Resetting the potential amplitude to zero induces their radiative recombination after very long storage times.