Study on Growth Parameters for Monolayer MoS2 Synthesized by CVD Using Solution-based Metal Precursors

Two-dimensional (2D) materials have received a considerable amount of attention owing to their unique properties compared with those of bulk materials, such as ultralow thickness with no dangling bonds and direct bandgap for monolayers.Monolayer MoS 2 with a direct bandgap of ~1.8 eV is representative of 2D semiconductors, which can facilitate a high on/off ratio in field-effect transistors and can have various optoelectronic applications in the visible range.Large area MoS 2 monolayers are generally synthesized using chemical vapor deposition (CVD) methods, where various types of metal precursors are utilized.Here, we report the effects of process parameters on the growth mode of MoS 2 monolayers prepared by CVD using solution-based metal precursors.We investigated various growth modes of MoS 2 flakes depending on the growth temperature and time, Mo-precursor concentration in precursor solutions, and carrier gas amount.The synthesized MoS 2 monolayers revealed typical n-type semiconductor behaviors, which were investigated by optical microscopy, confocal photoluminescence and Raman spectroscopy, atomic force microscopy, and I-V characterization of field-effect transistors.The n-doping effect was reduced by removing unreacted precursors after transferring the MoS 2 layer on new SiO 2 /Si substrates.