Tunable electronic properties and Schottky barrier in Janus Ti3C2FO and TMD heterostructures by interface atomic species and disorder

Abstract

In two-dimensional (2D) Janus MXenes materials, asymmetric disordered surface termination can greatly enhance material functionality. In this work, considering surface termination composition and disorder in 2D Janus MXenes, we designed five models of Janus Ti3C2FO, and then systematically investigated the electronic and contact properties of the corresponding Janus Ti3C2FO and TMD (TMD=WS2, MoS2 and WSe2) heterostructures using the density functional theory method. When the top and bottom surfaces of Janus Ti3C2FO are purely occupied by F and O atoms, respectively, Janus Ti3C2FO shows a pseudogap, which disappears in the presence of the mixed F and O atoms. It was found that the surface termination atomic species and disorder of Janus Ti3C2FO can effectively control the contact nature and Schottky barrier height (SBH) of these Ti3C2FO/TMD heterostructures and lead to a different response of their contact properties to the interlayer distance and external electric field. The presence of pure F atoms at the interface induces in the SBHs a strong dependence on the decrease in interlayer distance, while the pure O atoms causes both ΦB,n and ΦB,p to be almost pinned. Our study provides important new insight into the tuning of contact properties of MXenes/TMD heterostructures.