Highly Reproducible Epitaxial Growth of Wafer-Scale Single-Crystal Monolayer MoS on Sapphire.

2D semiconducting transition-metal dichalcogenides (TMDs) have attracted considerable attention as channel materials for next-generation transistors. To meet the industry needs, large-scale production of single-crystal monolayer TMDs in highly reproducible and energy-efficient manner is critically significant. Herein, it is reported that the high-reproducible, high-efficient epitaxial growth of wafer-scale monolayer MoS single crystals on the industry-compatible sapphire substrates, by virtue of a deliberately designed "face-to-face" metal-foil-based precursor supply route, carbon-cloth-filter based precursor concentration decay strategy, and the precise optimization of the chalcogenides and metal precursor ratio (i.e., S/Mo ratio). This unique growth design can concurrently guarantee the uniform release, short-distance transport, and moderate deposition of metal precursor on a wafer-scale substrate, affording high-efficient and high-reproducible growth of wafer-scale single crystals (over two inches, six times faster than usual). Moreover, the S/Mo precursor ratio is found as a key factor for the epitaxial growth of MoS single crystals with rather high crystal quality, as convinced by the relatively high electronic performances of related devices. This work demonstrates a reliable route for the batch production of wafer-scale single-crystal 2D materials, thus propelling their practical applications in highly integrated high-performance nanoelectronics and optoelectronics.