Monolayer MoS₂ Nanoribbon Transistors Fabricated by Scanning Probe Lithography.

Abstract

Monolayer MoS₂ is a promising material for nanoelectronics; however, the lack of nanofabrication tools and processes has made it very challenging to realize nanometer-scale electronic devices from monolayer MoS₂. Here, we demonstrate the fabrication of monolayer MoS₂ nanoribbon field-effect transistors as narrow as 30 nm using scanning probe lithography (SPL). The SPL process uses a heated nanometer-scale tip to deposit narrow nanoribbon polymer structures onto monolayer MoS₂. The polymer serves as an etch mask during a XeF₂ vapor etch, which defines the channel of a field-effect transistor (FET). We fabricated seven devices with a channel width ranging from 30 to 370 nm, and the fabrication process was carefully studied by electronic measurements made at each process step. The nanoribbon devices have a current on/off ratio > 10⁴ and an extrinsic field-effect mobility up to 8.53 cm²/(V s). By comparing a 30 nm wide device with a 60 nm wide device that was fabricated on the same MoS₂ flake, we found the narrower device had a smaller mobility, a lower on/off ratio, and a larger subthreshold swing. To our knowledge, this is the first published work that describes a working transistor device from monolayer MoS₂ with a channel width smaller than 100 nm.