Atomically controlled ultrathin 2H-VS2: A promising candidate for n-channel FET

Abstract

Two-dimensional transition metal dichalcogenides (2D-TMDs) have emerged as highly promising materials for next-generation ultrathin, flexible, and transparent electronic devices. Among the various members of the 2D-TMD family, VS2 also holds significant promise owing to its tunable electronic properties. However, the thermal instability and tendency to form intermediate stoichiometric phases pose significant challenges for the phase-pure synthesis of VS2. We optimized the growth parameters for large area atomically thin and controlled monolayer VS2 through atmospheric pressure chemical vapor deposition. This is validated through vibrational (Raman) spectroscopy, optical (Photoluminescence) microscopy, and x-ray photoelectron spectroscopy measurements, which substantiate the phase purity of the as-synthesized VS2. This is further verified by density functional theoretical calculations. Raman peaks at 403 and 383 cm−1 correspond to in-plane and out-of-plane atomic vibrations, respectively, while PL shows the bandgap ∼1.80 eV, validating the semiconducting nature. Subsequently, a field effect transistor (FET) device is fabricated using a mask-less photolithography process to explore the feasibility of a 2D-VS2 ultrathin layer as a channel material for a 2D-FET device. The electronic transport characteristics of VS2-FET exhibits an n-type semiconducting nature, with the charge carrier mobility μ ∼ 0.25 cm2 V−1 S−1.