Electrostatic control of exciton flux in van der Waals heterostructures

Large exciton binding energy in recently discovered two-dimensional semiconductors makes exciton physics accessible even at room temperature in these materials. Particular interest has been given to the interlayer excitons in van der Waals heterostructures based on transition metal dichalcogenides (TMDCs) with type-II band alignment. Whereas individual two-dimensional materials have short exciton diffusion lengths, the spatial separation of electrons and holes in different layers in heterostructures increases exciton lifetime and thus helps to overcome this limitation. In addition, this charge separation realizes built-in out-of-plane electric dipole moment, allowing exciton manipulation via an external electric field, showing promise for next-generation photonic devices relying on excitonic effects. Here, we present van der Waals devices made of TMDCs heterostructures encapsulated in h-BN with graphene control gates, which allow us to manipulate exciton dynamics by creating electrically reconfigurable potential profiles for the exciton flux. Our excitonic device demonstrates electrically controlled transistor actions at room temperature, that holds great promise for realizing small and efficient interconnects between optical data transmission and electrical processing systems.