Large-area growth of molybdenum disulphide monolayers for integrated photonics

Electronic devices based on single/few-layer transition-metal dichacogenide semiconductors heavily rely on mechanically exfoliated micro-flakes. Uncontrollable position and dimension are significant obstacles to integration of electronics and photonics using these layered two-dimensional materials. In this report, we grow continuous few-layer MoS$_2$ film on SiO$_2$/Si wafers using a cost-effective solution process and thermal decomposition. The number of the layers can be controlled by the spin-coating rate of the solution. Multi-layers can be controllably reduced layer-by-layer using an Ar-plasma etch. Compared with chemical vapor depositions which usually require temperature of 600-900 C, the low temperature of 450 C used here offers more flexibility in MoS$_2$ direct growth on other materials such as flexible plastic substrates. The good crystalline quality over area of $50 \times 50$ $\mu$m$^2$ and the controlled layer thickness enable broad applications of 2D semiconductor films to realizing integrated photonic devices.