Control of the orbital character of indirect excitons in MoS2/WS2 heterobilayers

TL;DR

This paper demonstrates electric field control over the orbital character, layer index, lifetime, and emission energy of indirect excitons in MoS2/WS2 heterobilayers, enabling tunable van der Waals heterostructures.

Contribution

It introduces a method to electrically manipulate the orbital and layer properties of interlayer excitons in MoS2/WS2 heterobilayers, revealing hybridization effects and tunable exciton dynamics.

Findings

Electric field induces level anticrossing in excitonic states.

Exciton lifetime varies from 400 ns to 100 ns with electric field.

Hybridized excitons are delocalized between layers.

Abstract

Valley selective hybridization and residual coupling of electronic states in commensurate van der Waals heterobilayers enable the control of the orbital character of interlayer excitons. We demonstrate electric field control of layer index, orbital character, lifetime and emission energy of indirect excitons in MoS2/WS2 heterobilayers embedded in an vdW field effect structure. Different excitonic dipoles normal to the layers are found to stem from bound electrons and holes located in different valleys of MoS2/WS2 with a valley selective degree of hybridization. For the energetically lowest emission lines, coupling of electronic states causes a field-dependent level anticrossing that goes along with a change of the IX lifetime from 400 ns to 100 ns. In the hybridized regime the exiton is delocalized between the two constituent layers, whereas for large positive or negative electric fields, the layer index of the bound hole is field-dependent. Our results demonstrate the design of novel van der Waals solids with the possibility to in-situ control their physical properties via external stimuli such as electric fields.