Lateral superlattices as voltage-controlled traps for excitons

TL;DR

This paper demonstrates voltage-controlled localization of quantum well excitons in a periodic array of traps, showing tunable trap depth and magnetic field effects on exciton diffusion, advancing exciton manipulation techniques.

Contribution

It introduces a method to create and control exciton traps using interdigitated gates and external voltages, with insights into magnetic field effects on exciton stability.

Findings

Trap depth is tunable via applied voltages.

Magnetic field reduces exciton diffusion length.

Magnetic stabilization of excitons in strong electric fields.

Abstract

We demonstrate the localisation of quantum well excitons in a periodic array of linear traps using photoluminescence experiments. The excitonic traps are induced by applying spatially alternating external voltages via interdigitated metal gates. The localisation originates from the 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 gates. Furthermore, we find that a perpendicular magnetic field reduces the exciton diffusion length. In short-period lateral superlattices, we observe a magnetic-field-induced stabilisation of excitons in the presence of strong in-plane electric fields.