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–MX 2 ). 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–MX 2 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.