| Summary: | Monolayer MoS<sub>2</sub> can be used for various applications such as flexible optoelectronics and electronics due to its exceptional optical and electronic properties. For these applications, large-area synthesis of high-quality monolayer MoS<sub>2</sub> is highly desirable. However, the conventional chemical vapor deposition (CVD) method using MoO<sub>3</sub> and S powder has shown limitations in synthesizing high-quality monolayer MoS<sub>2</sub> over a large area on a substrate. In this study, we present a novel carbon cloth-assisted CVD method for large-area uniform synthesis of high-quality monolayer MoS<sub>2</sub>. While the conventional CVD method produces thick MoS<sub>2</sub> films in the center of the substrate and forms MoS<sub>2</sub> monolayers at the edge of the thick MoS<sub>2</sub> films, our carbon cloth-assisted CVD method uniformly grows high-quality monolayer MoS<sub>2</sub> in the center of the substrate. The as-synthesized monolayer MoS<sub>2</sub> was characterized in detail by Raman/photoluminescence spectroscopy, atomic force microscopy, and transmission electron microscopy. We reveal the growth process of monolayer MoS<sub>2</sub> initiated from MoS<sub>2</sub> seeds by synthesizing monolayer MoS<sub>2</sub> with varying reaction times. In addition, we show that the CVD method employing carbon powder also produces uniform monolayer MoS<sub>2</sub> without forming thick MoS<sub>2</sub> films in the center of the substrate. This confirms that the large-area growth of monolayer MoS<sub>2</sub> using the carbon cloth-assisted CVD method is mainly due to reducing properties of the carbon material, rather than the effect of covering the carbon cloth. Furthermore, we demonstrate that our carbon cloth-assisted CVD method is generally applicable to large-area uniform synthesis of other monolayer transition metal dichalcogenides, including monolayer WS<sub>2</sub>.
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