Controllable CVD Growth of Monolayered WS2 From Triangular Flakes toward Wafer‐Scale Thin Film by Precise Design of Growth Environment

Abstract Here, a large‐area monolayered WS 2 thin film is synthesized via near atmospheric pressure chemical vapor deposition, and the effects of different parameter adjustments on the growth of the monolayered WS 2 thin films are discussed. Unlike previous studies, which focused on the growth of WS 2 flakes, the current study investigated the effect of two experimental configurations, face‐up and face‐down, on the growth of the WS 2 from triangular flakes into large‐area and high‐coverage wafer‐scale thin films. A series of Ar/H 2 gas ratio parameters for the monolayered WS 2 growth and the effect of H 2 addition are discussed when the configuration is face‐up. The following face‐down method is the key strategy for the large‐area growth of monolayered WS 2 films. A large‐area monolayered WS 2 synthesis is successfully realized on half of a two‐inch sapphire substrate by adjusting parameters such as temperature, pressure, carrier gas, and gas flow rate. Finally, a large‐area monolayered WS 2 film is used as the channel material to fabricate back‐gate field‐effect transistor arrays, with which I on /I off ratios of 10 5 to 10 6 and the highest carrier mobility of 0.84 cm 2 V −1 S −1 can be achieved.