Boltzmann Switching MoS 2 Metal-semiconductor Field-effect Transistors Enabled by Monolithic-oxide-gapped Metal Gates at the Schottky-Mott Limit.

A gate stack that facilitates a high-quality interface and tight electrostatic control is crucial for realizing high-performance and low-power field-effect transistors (FETs). However, when constructing conventional metal-oxide-semiconductor structures with two-dimensional (2D) transition metal dichalcogenide channels, achieving these requirements becomes challenging due to inherent difficulties in obtaining high-quality gate dielectrics through native oxidation or film deposition. Here, we report a gate-dielectric-less device architecture of van der Waals Schottky gated metal-semiconductor FETs (vdW-SG MESFETs) using a molybdenum disulfide (MoS 2 ) channel and surface-oxidized metal gates such as nickel and copper. Benefiting from the strong SG coupling, our MESFETs operate at remarkably low gate voltages, <0.5 V. Notably, they also exhibit Boltzmann-limited switching behavior featured by a subthreshold swing of ∼60 mV/dec and negligible hysteresis. These ideal FET characteristics are attributed to the formation of a Fermi-level (E F ) pinning-free gate stack at the Schottky-Mott limit. Furthermore, we experimentally and theoretically confirm that E F depinning can be achieved by suppressing both metal-induced and disorder-induced gap states at the interface between the monolithic-oxide-gapped metal gate and the MoS 2 channel. This work paves a new route for designing high-performance and energy-efficient 2D electronics. This article is protected by copyright. All rights reserved.