| Summary: | The chemical vapor deposition (CVD) method is widely used for synthesizing two-dimensional (2D) materials such as molybdenum disulfide (MoS _2 ) because of the process’ simplicity, relatively low cost, compatibility with other process, and tendency to result in high-quality crystalline materials. However, the growth of films with a uniform large area of several square centimeters with control of the number of layers remains challenging. Here, a MoS _2 synthesis technique that enables thickness and size control of wafer-scale films with high uniformity and continuity is proposed. This CVD technique is a powerful and simple method to control the layer number and size of MoS _2 films without using additive chemicals or a complex process. The thickness of the MoS _2 films can be controlled from one to four layers by adjusting the concentration of MoO _3 . MoS _2 films with dimensions greater than 10 cm can be grown by manipulating the Ar/H _2 S ratio. In addition, a photodetector based on CVD-grown MoS _2 is shown to exhibit a high current on–off ratio of 10 ^5 and gate-tunability. It also shows a high responsibility of 1.2 A W ^−1 , external quantum efficiency of 345%, and a specific detectivity of 1.2 × 10 ^11 Jones. The proposed CVD technique can provide a facile direction for the controllable synthesis of wafer-scale MoS _2 films with diverse applications in future optoelectronic devices.
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