Optical detection of electrostatically generated interlayer excitons

Interlayer excitons in transition metal dichalcogenide (TMD) heterostructures have been of great interest because of their potential to form a high temperature exciton condensate. Their large binding energies and long lifetimes allow interlayer excitons to exist within a large phase space of densities and temperatures. In a type-II band aligned MoSe₂/hBN/WSe₂ heterostructure, we electrostatically create interlayer excitons by independently controlling the charge densities in the electron and hole layers. The electron and hole densities in the exciton regime are calibrated by optical absorption in the uncorrelated regime. From the calibrated densities we observe a non-linear increase of the exciton density as a function of the bias voltage. Our observations can be qualitatively explained by a model consisting of permanent out-of-plane dipoles with a finite binding energy. The ability to create interlayer excitons in the electrostatic equilibrium limit lays the foundation towards systematically studying interlayer exciton transport in the condensate phase.