# One-dimensional edge contacts to a monolayer semiconductor

## TL;DR

This paper demonstrates a scalable method for creating low-resistance edge contacts to monolayer MoS₂ encapsulated in hBN, enabling high-performance 2D electronic devices with preserved material quality.

## Contribution

It introduces a novel fabrication process combining reactive ion etching, Ar+ sputtering, and annealing for effective edge contact formation to encapsulated monolayer MoS₂.

## Key findings

- Achieved low edge contact resistance and high mobility (~30 cm²/Vs).
- Demonstrated high on-current density (>50 μA/μm at 3V).
- Maintained intrinsic channel quality with steep subthreshold swing (116 mV/dec).

## Abstract

Integration of electrical contacts into van der Waals (vdW) heterostructures is critical for realizing electronic and optoelectronic functionalities. However, to date no scalable methodology for gaining electrical access to buried monolayer two-dimensional (2D) semiconductors exists. Here we report viable edge contact formation to hexagonal boron nitride (hBN) encapsulated monolayer MoS$_2$. By combining reactive ion etching, in situ Ar$^+$ sputtering and annealing, we achieve a relatively low edge contact resistance, high mobility (up to ~30 cm$^2$/Vs) and high on-current density (>50 uA/um at V$_{\rm DS}$ = 3V), comparable to top contacts. Furthermore, the atomically smooth hBN environment also preserves the intrinsic MoS$_2$ channel quality during fabrication, leading to a steep subthreshold swing of 116 mV/dec with a negligible hysteresis. Hence, edge contacts are highly promising for large-scale practical implementation of encapsulated heterostructure devices, especially those involving air sensitive materials, and can be arbitrarily narrow, which opens the door to further shrinkage of 2D device footprint.