Spatially resolved exciton trapping in a voltage-controlled lateral superlattice

Abstract

With spatially resolved photoluminescence experiments we demonstrate voltage-controlled trapping of excitons in a submicron scale lateral potential superlattice imposed on a semiconductor quantum well. The potential modulation is achieved by two interdigitated field-effect electrodes on top of the sample surface. Both parallel and vertical electric field components strongly modify the optical properties of the quantum well. We show that the lateral modulation of the strength of the quantum confined Stark effect results in an effective lateral exciton potential that can be probed by spatially resolved measurements of the excitonic luminescence. We demonstrate that excitons may be confined to the regions of strongest vertical fields, in which the effective exciton energy is lowest. Spatial resolution of the observed photoluminescence signal allows for a qualitative understanding of the exciton transport and trapping process.