Low work-function contact engineering for transition metal dichalcogenides (TMDs)

Atomically thin transition metal dichalcogenides (TMDs) are an exciting platform to study strongly correlated excitonic and electronic physics. However, electrical transport measurements in monolayer TMDs are limited by the ability to fabricate reliable electrodes, particularly n-type contacts to MoSe₂, MoS₂, and MoTe₂, due to Schottky barrier formation and metal-induced gap states. Efficient n-type contacts to these materials typically require work-function matching at the metal-semiconductor interface and heavy electron doping. Inspired by recent advances in p-type contacts to WSe₂ by RuCl₃ van der Waals ‘modulation’ doping, we investigate interfacing TMDs with very low work-function metals to explore interfacial charge transfer. These efforts can be combined with an atomically clean monolayer hBN insertion barrier between the metal-semiconductor interface that has been demonstrated to lower the metal work function and reduce in-gap states. We present electrical transport measurements to characterize the performance of these contacts to TMDs such as MoSe₂ and MoS₂.