Schottky Contact in Monolayer WS2 Field‐Effect Transistors

Abstract Monolayer (ML) WS 2 is a promising material to be the channel of nanoscale field‐effect transistors (FETs). In ML WS 2 FETs, the interfacial properties between ML WS 2 and electrodes significantly affect the device performance, due to the possible existence of Schottky barriers at the interface. In this paper, the electronic and transport properties of both the lateral and the vertical interfaces between ML WS 2 and six common metals is calculated (Sc, Ti, Ag, Cu, Au, and Pt) by the density functional theory and the quantum transport simulation. n ‐type Schottky contact exists with the lateral electron Schottky barrier height (SBH) of 0.28, 0.36, 0.25, 0.46, 1.00 eV for Sc, Ti, Ag, Cu, and Au electrode, respectively, while p ‐type Schottky contact exists with the lateral hole SBH of 0.98 eV for Pt electrode. The average pinning factor at the lateral interface obtained from linear fitting to the SBHs and the Schottky–Bardin model is 0.32 and 0.28, respectively, suggestive of a strong Fermi level pinning originating from the metal induced gap states. The work reveals the properties of the lateral interfaces between ML WS 2 channels and electrodes theoretically for the first time, providing an instruction to design ML WS 2 devices.