Effect of different precursors on CVD growth of molybdenum disulfide

Control over thickness, size, and area of chemical vapor deposition (CVD) grown molybdenum disulfide (MoS2) flakes is crucial for device application. Herein, we report a quantitative comparison of CVD synthesis of MoS2 on SiO2/Si substrate using three different precursors viz., molybdenum trioxide (MoO3), ammonium heptamolybdate (AHM), and tellurium (Te). A three-step chemical reaction mechanism of evolution of MoS2 from MoO3 micro-crystals is proposed for MoO3 precursor. Furthermore, a strategy based on growth temperature and ratio of amount of precursors is developed to systematically control thickness and area of MoS2 flakes. Our findings show that for large-sized crystalline monolayer MoS2 flakes, MoO3 is a better choice than AHM and Te-assisted synthesis. Moreover, Te as growth promoter, can lower down growth temperature by 250C. This study can be further used to fabricate MoS2 based high-performance electronic devices such as photodetectors, thin film transistors, and sensors.