Making one‐dimensional electrical contacts to molybdenum disulfide‐based heterostructures through plasma etching

Abstract

A “passivation first, metallization second” technique is developed for fabricating edge contacts to a multi‐layer MoS 2 sample encapsulated under an Al 2 O 3 thin film. The in‐time sealing of the newly exfoliated MoS 2 under a dielectric ensures a complete isolation from the environment. CF 4 plasma is used to open trenches in the passivation layer and to expose the atoms at the edges of MoS 2 . Edge contacts are next made to h‐BN/MoS 2 /h‐BN 3‐level heterostructures, earlier assembled through a solvent‐free 2D material transfer procedure. Both types of MoS 2 ‐based heterostructures are further fabricated into back‐gated FETs and show n‐type doping behavior. In particular, trends of field‐effect mobility with respect to a varying drain voltage are analyzed based on the I D – V DS data measured from each device. The result verifies the effect of Schottky barrier on channel conduction, which is, only at the presence of a highly transparent contact interface, the field‐effect mobility can manifest the intrinsic material property by staying constant against the changes in drain voltage. The wide applicability of the processing sequence makes edge contacts an appealing option to future nanoelectronics on 2D heterostructures.