Sulfur‐Mastery: Precise Synthesis of 2D Transition Metal Dichalcogenides

Abstract Chemical vapor deposition (CVD) has been developed as the most promising method for the growth of transition metal dichalcogenides (TMDs). In this work, the key factor determining the growth of TMDs is ascertained. A straightforward method is devised to directly achieve a holistic control of thickness, shape, and size of WS 2 flakes via a single parameter control, namely, the status of the S‐precursor. The thickness‐dependent growth of WS 2 flakes from mono‐ to quad‐layers is achieved by precise control of the feeding rate of elemental S‐precursor. Moreover, the explicit control over amount and exposure time of S‐precursor determines the most optimum combination of these parameters to tune the shape of the crystals from triangular to hexagonal with appropriate size. Hence, the experimental findings provide a promising strategy to engineer the growth evolution of WS 2 atomic layers by fine tuning of the sulfur supply, paving a pathway to scalable electronic and photonic devices.