Contact optimisation strategy for wafer-scale field-effect transistors based on two-dimensional semiconductors

Two-dimensional (2D) semiconductors can be utilized to continually miniaturize nanoscale electronic de-vices. However, achieving a practical solution for satisfying electrical contact with 2D semiconductors remains challenging. In this study, we developed a novel contact structure with transferred multilayer (t-ML) MoS2 by integrating both edge and top contact. After in-situ plasma treatment for the edge of the MoS2 channel and successive metal deposition, we achieved 16 times lower contact resistivity (22.8 k Omega mu m) than that of the top contacted devices. The thickness-dependent electrical measurement indicates that edge contact is highly effective with thick MoS2 due to the alleviated current-crowding effect re-sulting from the small contact area. The temperature-dependent transport measurement further confirms the effective minimization of the influence from the Schottky barrier and tunnelling barrier. Finally, the simplified resistor network model and energy-band diagram were proposed to understand the carrier transport mechanism. Our work provides a practical strategy for achieving excellent electrical contact between bulk metals and 2D semiconductors, paving the way for future large-scale 2D electronic devices. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study developed a novel contact structure with transferred multilayer MoS2, achieving low contact resistivity through in-situ plasma treatment and metal deposition on the edge of the MoS2 channel. Thickness-dependent electrical measurement showed that edge contact is highly effective with thick MoS2, alleviating current-crowding effect. Temperature-dependent transport measurement further confirmed the advantages of this contact structure. Finally, a simplified resistor network model and energy-band diagram were proposed to explain the carrier transport mechanism.