Carrier transport at the metal–MoS2 interface

Abstract

This study illustrates the nature of electronic transport and its transition from one mechanism to another between a metal electrode and MoS₂ channel interface in a field effect transistor (FET) device. Interestingly, measurements of the contact resistance (R_c) as a function of temperature indicate a transition in the carrier transport across the energy barrier from thermionic emission at a high temperature to tunneling at a low temperature. Furthermore, at a low temperature, the nature of the tunneling behavior is ascertained by the current–voltage dependency that helps us feature direct tunneling at a low bias and Fowler–Nordheim tunneling at a high bias for a Pd–MoS₂ contact due to the effective barrier shape modulation by biasing. In contrast, only direct tunneling is observed for a Cr–MoS₂ contact over the entire applied bias range. In addition, simple analytical calculations were carried out to extract R_c at the gating range, and the results are consistent with the experimental data. Our results describe the transition in carrier transport mechanisms across a metal–MoS₂ interface, and this information provides guidance for the design of future flexible, transparent electronic devices based on 2-dimensional materials.