Electric Field Tuning of Band Offsets in Transition Metal Dichalcogenides

TL;DR

This study uses first-principles calculations to explore how perpendicular electric fields can tune or invert the band alignments in W$X_2$/Mo$X_2$ heterobilayers, affecting their electronic and excitonic properties.

Contribution

It demonstrates how stacking configurations and electric fields influence band offsets and hybridization in transition metal dichalcogenide heterobilayers, providing insights for electronic tuning.

Findings

Band offset variations > 0.1 eV due to stacking differences

Electric fields can hybridize bands crossing at the K point

External fields enable tuning of excitonic properties

Abstract

We use first-principles calculations to investigate the band structure evolution of W$X_2$/Mo$X_2$ ($X$ = S, Se) heterobilayers under a perpendicular electric field. We characterize the extent to which the type-II band alignment in these compounds can be tuned or inverted electrostatically. Our results demonstrate two effects of stacking configuration. First, different stackings produce different net dipole moments, resulting in band offset variations that are larger than 0.1 eV. Second, based on symmetry constraints that depend on stacking, a perpendicular electric field may hybridize W$X_2$ and Mo$X_2$ bands that cross at the Brillouin Zone corner $K$. Our results suggest that external electric fields can be used to tune the physics of intralayer and interlayer excitons in heterobilayers of transition metal dichalcogenides.