Enhanced Electrical Transport Properties of Molybdenum Disulfide Field-Effect Transistors by Using Alkali Metal Fluorides as Dielectric Capping Layers.

The electronic properties of 2D materials are highly influenced by the molecular activity at their interfaces. A method was proposed to address this issue by employing passivation techniques using monolayer MoS field-effect transistors (FETs) while preserving high performance. Herein, we have used alkali metal fluorides as dielectric capping layers, including lithium fluoride (LiF), sodium fluoride (NaF), and potassium fluoride (KF) dielectric capping layers, to mitigate the environmental impact of oxygen and water exposure. Among them, the LiF dielectric capping layer significantly improved the transistor performance, specifically in terms of enhanced field effect mobility from 74 to 137 cm/V·s, increased current density from 17 μA/μm to 32.13 μA/μm at a drain voltage of of 1 V, and decreased subthreshold swing to 0.8 V/dec The results have been analytically verified by X-ray photoelectron spectroscopy (XPS) and Raman, and photoluminescence (PL) spectroscopy, and the demonstrated technique can be extended to other transition metal dichalcogenide (TMD)-based FETs, which can become a prospect for cutting-edge electronic applications. These findings highlight certain important trade-offs and provide insight into the significance of interface control and passivation material choice on the electrical stability, performance, and enhancement of the MoS FET.