Carrier Transport at the Metal-MoS2 Interface

TL;DR

This paper investigates the transition of carrier transport mechanisms at metal-MoS2 interfaces in FETs, revealing temperature-dependent behaviors and tunneling phenomena that inform future 2D material device design.

Contribution

It provides a detailed analysis of carrier transport transition mechanisms and distinguishes between different tunneling behaviors at metal-MoS2 contacts, supported by experimental and analytical data.

Findings

Transition from thermionic emission to tunneling with decreasing temperature.

Identification of direct and Fowler-Nordheim tunneling regimes.

Consistent analytical and experimental contact resistance measurements.

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 (Rc) as a function of temperature indicate a transition in the carrier transport across the energy barrier from a 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 Rc 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.