Charge Transport in MoS/WSe van der Waals Heterostructure with Tunable Inversion Layer.

Despite numerous studies on two-dimensional van der Waals heterostructures, a full understanding of the charge transport and photoinduced current mechanisms in these structures, in particular, associated with charge depletion/inversion layers at the interface remains elusive. Here, we investigate transport properties of a prototype multilayer MoS/WSe heterojunction via a tunable charge inversion/depletion layer. A charge inversion layer was constructed at the surface of WSe due to its relatively low doping concentration compared to that of MoS, which can be tuned by the back-gate bias. The depletion region was limited within a few nanometers in the MoS side, while charges are fully depleted on the whole WSe side, which are determined by Raman spectroscopy and transport measurements. Charge transport through the heterojunction was influenced by the presence of the inversion layer and involves two regimes of tunneling and recombination. Furthermore, photocurrent measurements clearly revealed recombination and space-charge-limited behaviors, similar to those of the heterostructures built from organic semiconductors. This contributes to research of various other types of heterostructures and can be further applied for electronic and optoelectronic devices.