Intrinsic carrier mobility of multi-layered MoS$_2$ field-effect transistors on SiO$_2$

TL;DR

This study demonstrates that four-terminal measurements reveal higher intrinsic carrier mobility in multi-layer MoS$_2$ FETs on SiO$_2$ than two-terminal measurements, highlighting contact effects.

Contribution

The paper provides a quantitative comparison between two- and four-terminal measurements, showing that contact barriers cause underestimation of mobility in two-terminal configurations.

Findings

Four-terminal measurements yield higher mobility values than two-terminal.

Intrinsic mobility of MoS$_2$ on SiO$_2$ is significantly larger than previously reported.

Contact effects are critical in accurately assessing charge transport.

Abstract

By fabricating and characterizing multi-layered MoS$_2$-based field-effect transistors (FETs) in a four terminal configuration, we demonstrate that the two terminal-configurations tend to underestimate the carrier mobility $\mu$ due to the Schottky barriers at the contacts. For a back-gated two-terminal configuration we observe mobilities as high as 125 cm$^2$V$^{-1}$s$^{-1}$ which is considerably smaller than 306.5 cm$^2$V$^{-1}$s$^{-1}$ as extracted from the same device when using a four-terminal configuration. This indicates that the intrinsic mobility of MoS$_2$ on SiO$_2$ is significantly larger than the values previously reported, and provides a quantitative method to evaluate the charge transport through the contacts.