Signature of correlated electron–hole pair tunneling in multilayer WSe2 at room temperature

Abstract

Van der Waals (vdW) heterostructures provide a promising platform for high-temperature exciton condensates due to a strong Coulomb interaction, but the fabrication of very clean interface structures with precisely aligned 2D crystals is challenging. Here, we propose that correlated electron–hole pair tunneling can occur at room temperature in a monolithic multilayer WSe2 device with bottom Au contacts. Electron and hole conducting channels separated by an intrinsic, insulating region in the center of the crystal are defined by doping. The monolithic vertical homojunction formed naturally in the bulk vdW crystal provides a defect-free interface structure which shows clear indications of correlated tunneling at room temperature. We interpret zero-bias peaks in the differential conductance curves as a signature of electron–hole pairing when their densities balance. The conductance peak vanishes when the electron and hole densities are unbalanced, which can be controlled by the external electrical field, magnetic field, or temperature. Our results open an opportunity for realization of room-temperature superfluidity in vdW materials with a simple, clean, and effective approach.