Effect of WO3 precursor and sulfurization process on WS2 crystals growth by atmospheric pressure CVD.

Atomically thin dichalcogenide layered materials have attracted significant interest owing to their direct-gap property for nanoelectronics and optoelectronics applications. In this prospect, controllable synthesis of high quality WS 2 crystals by a chemical vapor deposition (CVD) process is of great importance. Here, we report the effect of sulfurization process and WO 3 precursor on WS 2 growth in an atmospheric pressure (AP) CVD. The quantity of WO 3 powder spread on SiO 2 /Si substrate significantly affect the nucleation and layer numbers of triangular-shaped WS 2 crystals. Pyramid-like few-layers stacked structure of WS 2 crystals are obtained from densely spread WO 3 powder. Whereas, larger triangular crystals (~70 µm) are obtained by controlling the amount of WO 3 precursor and rate of sulfurization at 750 °C. This finding can be significant to understand WS 2 growth by the AP-CVD process with controlled sulfurization of WO 3 powder and thereby realizing synthesis of larger crystals. [ABSTRACT FROM AUTHOR]