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 WS2 crystals by a chemical vapor deposition (CVD) process is of great importance. Here, we report the effect of sulfurization process and WO3 precursor on WS2 growth in an atmospheric pressure (AP), CVD. The quantity of WO3 powder spread on SiO2/Si substrate significantly affect the nucleation and layer numbers of triangular-shaped WS2 crystals. Pyramid-like few-layers stacked structure of WS2 crystals are obtained from densely spread WO, powder. Whereas, larger triangular crystals (similar to 70 mu m) are obtained by controlling the amount of WO, precursor and rate of sulfurization at 750 degrees C. This finding can be significant to understand WS2 growth by the AP-CVD process with controlled sulfurization of WO3 powder and thereby realizing synthesis of larger crystals. (C) 2015 Elsevier B.V. All rights reserved.