Optimizing Charge Injection across Transition Metal Dichalcogenide Heterojunctions: Theory and Experiment.

Abstract

In search of an improved strategy to form low-resistance contacts to semiconducting transition metal dichalcogenides, we combine ab initio density functional electronic structure calculations for an NbSe₂/WSe₂ interface with quantum transport measurements of the corresponding heterojunction between a few-layer WSe₂ semiconductor and a metallic NbSe₂ layer. Our theoretical results suggest that, besides a rigid band shift associated with charge transfer, the presence of NbSe₂ does not modify the electronic structure of WSe₂. Since the two transition metal dichalcogenides are structurally similar and display only a small lattice mismatch, their heterojunction can efficiently transfer charge across the interface. These findings are supported by transport measurements for WSe₂ field-effect transistors with NbSe₂ contacts, which exhibit nearly ohmic behavior and phonon-limited mobility in the hole channel, indicating that the contacts to WSe₂ are highly transparent.