Large Scale and High-Yield Janus Monolayer Mosse with Controllable Composition By Plasma-Assisted Chemical Vapor Reaction

We report a top-down method for high-yield production of Janus monolayer MoSSe. In particular, we replace the top S atom with Se by controlled plasma-assisted selenization of monolayer MoS2. Based on the Raman Spectroscopy results, all of the characterized monolayer MoS2 triangles are completely transformed to Janus MoSSe. The Janus structure of MoSSe is confirmed directly by means of high-resolution transmission electron microscopy (TEM) and energy-dependent X-ray photoelectron spectroscopy (XPS). Density Functional Theory (DFT) calculations are performed to determine the effect of the Se-concentration on the electronic properties of Janus MoSSe. Our method provides an avenue towards high-yield production and full exploration of Janus Transition Metal Dichalcogenides (TMDs).