Large-area CVD growth of two-dimensional transition metal dichalcogenides and monolayer MoS₂ and WS₂ metal-oxide-semiconductor field-effect transistors

Abstract

Two-dimensional semiconducting materials such as MoS₂ and WS₂ have been attractive for use in ultra-scaled electronic and optoelectronic devices because of their atomically-thin thickness, direct band gap, and lack of dangling bonds. Methods for large-area growth of 2D semiconducting materials are needed to bring them to practical applications. This thesis aims to develop reliable methods for growing high-quality monolayer MoS₂ and WS₂ by CVD and explore their intrinsic electrical transport properties for electronic and optoelectronic device applications. The as-grown monolayer MoS₂ and WS₂ exhibit n-type semiconducting behavior with excellent optical properties. Various techniques are employed to characterize the CVD-grown materials, including photoluminescence, UV-visible absorption, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. Moreover, the electronic transport characteristics of single-layer CVD-grown MoS₂ and WS₂ field-effect transistors with a back-gated configuration are demonstrated.