Electrical control of excitons in van der Waals heterostructures with type-II band alignment

摘要

We investigate excitons in stacked transition-metal dichalcogenide layers under a perpendicularly applied electric field, herein MoSe2/WSe2 van der Waals heterostructures (vdWHs). Band structures are obtained with density functional theory (DFT), along with electron and hole wave functions in conduction and valence bands, respectively. A minimal continuum model, parametrized by the DFT results, is presented, allowing for the calculation of the excitonic states. Although the type-II nature of the heterostructure leads to a fully charge separated interlayer exciton on the ground states, our results show that moderate values of electric field produce more evenly distributed wave functions along the vdWH, namely, hybrid inter/intralayer exciton states, where both the interlayer exciton binding energy and, most notably, its oscillator strength are enhanced.