Passivation of Transition Metal Dichalcogenides Monolayers with a Surface-Confined Atomically Thick Sulfur Layer

Surface passivation can eliminate the charge doping of monolayer transition metal dichalcogenides (TMDs) during the device fabrication, which is important for the large-scale production of ultra-stable materials and high-performance devices. The uniformity and atomical thickness of the passivating layers with a low dielectric constant (κ) are essentials to preserving the intrinsic properties of monolayer TMDs in harsh environments. Herein, a surface-confined mechanism is developed to encapsulate TMDs monolayers by atomically thin sulfur layers with high spatial homogeneity (named S–MX₂). The bottom bilayer S atoms are strongly confined by the upper S monolayers when the low-κ S reaches three layers on the surface of TMDs, which spontaneously renders the uniform distribution on a large scale. The intrinsic electrical and optical properties of monolayer S–MX₂ are well maintained and show excellent long-term stability under harsh environments. Herein this work, a way to eliminate surface doping of monolayer TMDs for their practical application in large-area-integrated circuits is provided.