Boltzmann Switching MoS2 Metal–Semiconductor Field-Effect Transistors Enabled by Monolithic-Oxide-Gapped Metal Gates at the Schottky–Mott Limit

Yeon Ho Kim, Wei Jiang, Donghun Lee, Donghoon Moon, Hyun Young Choi, June Chul Shin, Yeonsu Jeong, Jong Chan Kim, Jaeho Lee, Woong Huh, Chang Yong Han, Jae Pil So, Tae Soo Kim, Seong Been Kim, Hyun Cheol Koo, Gunuk Wang, Kibum Kang, Hong Gyu Park, Hu Young Jeong, Seongil ImGwan Hyoung Lee, Tony Low, Chul Ho Lee

Research output: Contribution to journalArticlepeer-review

Abstract

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, a gate-dielectric-less device architecture of van der Waals Schottky gated metal–semiconductor FETs (vdW-SG MESFETs) using a molybdenum disulfide (MoS2) channel and surface-oxidized metal gates such as nickel and copper is reported. Benefiting from the strong SG coupling, these 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−1 and negligible hysteresis. These ideal FET characteristics are attributed to the formation of a Fermi-level (EF) pinning-free gate stack at the Schottky–Mott limit. Furthermore, authors experimentally and theoretically confirm that EF 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 MoS2 channel. This work paves a new route for designing high-performance and energy-efficient 2D electronics.

Original languageEnglish
JournalAdvanced Materials
DOIs
Publication statusAccepted/In press - 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. Advanced Materials published by Wiley-VCH GmbH.

Keywords

  • 2D semiconductors
  • Fermi-level pinning
  • low-power electronics
  • metal–semiconductor field-effect transistors
  • MoS

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering

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