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

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 NbSe 2 /WSe 2 interface with quantum transport measurements of the corresponding heterojunction between a few-layer WSe 2 semiconductor and a metallic NbSe 2 layer. Our theoretical results suggest that, besides a rigid band shift associated with charge transfer, the presence of NbSe 2 does not modify the electronic structure of WSe 2 . 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 WSe 2 field-effect transistors with NbSe 2 contacts, which exhibit nearly ohmic behavior and phonon-limited mobility in the hole channel, indicating that the contacts to WSe 2 are highly transparent.