Electrical control of inter-layer excitons in van der Waals heterostructures

TL;DR

This study demonstrates that applying an external electric field to TMDC heterostructures allows precise control over inter-layer excitons, enhancing their binding energy and oscillator strength, which is promising for optoelectronic applications.

Contribution

The paper provides a detailed theoretical analysis showing how electric fields can tune charge distribution and excitonic properties in TMDC heterostructures, a novel approach for exciton manipulation.

Findings

Electric field modulates charge carrier distribution between layers.

Moderate electric fields increase exciton binding energy.

Electric fields enhance oscillator strength of inter-layer excitons.

Abstract

We investigate excitons in stacked transition metal dichalcogenide (TMDC) layers under perpendicularly applied electric field, herein MoSe$_2$/WSe$_2$ van der Waals heterostructures. Band structures are obtained with density functional theory calculations, along with the electron and hole wave functions in conduction and valence bands, respectively. Although the type-II nature of the heterostructure leads to fully charge separated inter-layer excitons, charge carriers distribution among the layers is shown to be easily tunable by external field. Our results show that moderate values of electric field produce more evenly distributed wave functions along the heterostructure, thus enhancing both the inter-layer exciton binding energy and, most notably, its oscillator strength.