Semi-Metal Edge Contact for Barrier-Free Carrier Transport in MoS₂ Field Effect Transistors

Abstract

The high contact resistance (Rc) arising at the interface between a metal and a two-dimensional (2D) material presents a significant challenge to carrier transport in semiconductor devices based on 2D materials. The van der Waals gap and metal-induced gap states formed at the 2D interface give rise to an uncontrollable Schottky barrier, resulting in a high Rc. In this study, we report the achievement of very low Rc and ohmic behavior of molybdenum disulfide (MoS2) field-effect transistors through the implementation of the edge contacts using semimetallic antimony (Sb). Our findings reveal that the edge contacts formed with Sb facilitate barrier-free carrier injection at the interface of MoS2 devices, leading to highly efficient charge transport at room temperature, resulting in an unexpectedly further lowered Rc (600 Ω·μm) at 10 K with a negligible Schottky barrier height. Further support for barrier-free ohmic transport is provided by density functional theory simulations, confirming that semimetallic Sb exhibits a very low density of states (DOS), with the Fermi level aligning well with the DOS of MoS2. Additionally, a comparison of linearity in output I–V characteristics with other metals confirms the superiority of the Sb edge contacts.