Interface Defect Engineering of a Large-Scale CVD-Grown MoS₂ Monolayer via Residual Sodium at the SiO₂/Si Substrate

Alkali metal halide-assisted chemical vapor deposition (CVD) methods can produce wafer-scale uniform monolayer transition metal dichalcogenides (TMDs). Further defect engineering is necessary to obtain high-performance functional devices. While defect engineering has focused on the surface of the monolayer TMDs or the contact property, interface defect engineering is rare and non-trivial. Based on a NaCl-assisted CVD-grown large-scale uniform MoS₂ monolayer on SiO₂/Si substrate, a trace amount of Na cations is present, residing at the SiO₂ substrate during the CVD-growth process and contributes to the n-type doping into the supported monolayer MoS₂. Furthermore, the residual Na cations are electrically moved toward the bottom side of monolayer MoS₂ to passivate the interfacial defects.