Bottom-up water-based solution synthesis for a large MoS2 atomic layer for thin-film transistor applications

A bottom-up water-based solution-process method was developed for atomic layered MoS 2 with a one-step annealing process and no sulfurization. The chosen MoS 2 precursor is water soluble and was carefully formulated to obtain good coating properties on a silicon substrate. The coated precursor was annealed in a furnace one time to crystallize it. This method can obtain a large and uniform atomic layer of 2D MoS 2 with 2H lattice structure. The number of atomic layers (4–7) was controlled through the precursor concentrations and showed good uniformity, which was confirmed by STEM and AFM. Four types of thin-film transistors (TFTs) were prepared from the solution-processed MoS 2 on Al 2 O 3 and SiO 2 dielectric with either thermal evaporated Al or printed Ag source and drain electrodes. The best result shows an improved mobility of 8.5 cm 2 V −1 s −1 and a reasonable on–off ratio of about 1.0 × 10 5 with solid output saturation.