CVD controlled growth of large-scale WS2 monolayers

Abstract

Monolayer tungsten disulfide (WS2) with a direct band gap of ca. 2.0 eV and stable properties has been a hotspot in two-dimensional (2D) nanoelectronics and optoelectronics. However, it remains challenging to successfully prepare monolayer WS2. In this paper, we report the chemical vapor deposition (CVD) growth behavior of hexagonal WS2 monolayers by using WS2 powders and sodium triosulfate (Na2S2O3) as precursors. We observed the Na2S2O3 has a significant effect on the WS2 triangular and leaf-like shapes. In addition, based on proposed S-termination and W-termination theory, the growth mechanisms for different shapes of WS2 were discussed.