Space-confined and uniform growth of 2D MoS2 flakes

As an important next-generation photoelectric material, the controlled synthesis of two-dimensional molybdenum disulfide (2D MoS2) with high uniformity is imperative. Traditional MoS2 growth methods in the open space usually require a large amount of raw materials and have poor uniformity of growth results. In this paper, we report a space-confined method for uniformly growing large MoS2 flakes on the SiO2/Si substrate. As the precursor film coated on the bottom substrate is restricted in a small confined space between the top and bottom substrates separated by a small spacer, it is efficiently utilized, achieving large MoS2 flakes with good uniformity on the top substrate. By further tuning the content of NaCl catalyst in the precursor, single-layer or multi-layer MoS2 flakes can be obtained in a controlled manner, and well characterized by Raman, XPS, PL and AFM. The uniform distribution of Mo-containing species and its high concentration in the confined space, contributing to the efficient growth of uniform large MoS2 flakes. This research will provide guidance for rational synthesis of 2D MoS2 flakes on dielectric substrates.