Modified Spatially Confined Strategy Enabled Mild Growth Kinetics for Facile Growth Management of Atomically-Thin Tungsten Disulfides

Chemical vapor deposition (CVD) has been widely used to produce high quality 2D transitional metal dichalcogenides (2D TMDCs). However, violent evaporation and large diffusivity discrepancy of metal and chalcogen precursors at elevated temperatures often result in poor regulation on X:M molar ratio (M = Mo, W etc.; X = S, Se, and Te), and thus it is rather challenging to achieve the desired products of 2D TMDCs. Here, a modified spatially confined strategy (MSCS) is utilized to suppress the rising S vapor concentration between two aspectant substrates, upon which the lateral/vertical growth of 2D WS2 can be selectively regulated via proper S:W zones correspond to greatly broadened time/growth windows. An S:W-time (SW-T) growth diagram was thus proposed as a mapping guide for the general understanding of CVD growth of 2D WS2 and the design of growth routes for the desired 2D WS2. Consequently, a comprehensive growth management of atomically thin WS2 is achieved, including the versatile controls of domain size, layer number, and lateral/vertical heterostructures (MoS2-WS2). The lateral heterostructures show an enhanced hydrogen evolution reaction performance. This study advances the substantial understanding to the growth kinetics and provides an effective MSCS protocol for growth design and management of 2D TMDCs.

Automated summary

Chemical vapor deposition (CVD) is widely used to produce high quality 2D transitional metal dichalcogenides (2D TMDCs). However, regulation of the X:M molar ratio in CVD growth of 2D TMDCs is challenging due to violent evaporation and large diffusivity discrepancy of metal and chalcogen precursors. In this study, a modified spatially confined strategy (MSCS) is proposed to selectively regulate the growth of 2D WS2. A comprehensive growth management of atomically thin WS2 is achieved, including the versatile controls of domain size, layer number, and lateral/vertical heterostructures.