CVD controlled preparation and growth mechanism of 2H-WS2 nanosheets

In this work, tungsten disulfide (WS 2 ) nanosheets with good morphology are prepared by improved chemical vapor deposition (CVD) using a mixture of transition metal oxides and chalcogenide as precursors. By optimizing the growth conditions, the high-quality WS 2 nanosheets with different morphologies, including large triangular, hexagonal, small triangular, terraced and spiral structures are obtained as the growth temperature of 850 °C, Ar gas flow rate of 50 sccm and holding time for 15 min. The detailed structural analyses by XRD , XPS , TEM and Raman measurements suggest that that the deposited WS 2 nanosheets exhibit the 2H phase structure with high crystallization quality and uniform distribution of W and S elements. The formation of large triangular, hexagonal, and small triangular structures is related to the growth rate of different crystal planes of S atoms or W atoms. In addition, the formation of terraced and spiral stacking structures originates from the difference of supersaturation of precursors, which can be explained by the layer-by-layer stacking (LBL) growth and the spiral-dislocation-driven (SDD) mechanisms, respectively.