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[Display omitted] • A carbon-free inorganic precursor, MoO 2 Cl 2 , as the molybdenum source for atomically thin MoS 2 growth was pioneeringly identified. • Uniquely, MoO 2 Cl 2 is available for integration with the standard well-controlled MOCVD system. • Using MoO 2 Cl 2 and H 2 S as the molybdenum and sulfur sources, respectively, in a standard MOCVD set-up ensures a highly reproducible growth process and eliminates the carbon contamination existing in typical MOCVD-grown MoS 2. • Carbon-free monolayer MoS 2 films were successfully grown with decent quality and wafer-scale homogeneity. To bring atomically thin transition metal dichalcogenides (TMDs) to practical application, a highly reproducible process to grow them over a large scale is indispensable. Here, we develop a carbon-free reproducible route for the scalable growth of high-quality monolayer MoS 2 by selecting molybdenum dichloride dioxide (MoO 2 Cl 2) as the Mo source and integrating the precursor with a standard low-pressure cold-wall metalorganic chemical vapor deposition (MOCVD) system. Specifically, combined with H 2 S as the sulfur source and using catalytic Dragontrail glass (DT-glass) as the main substrate, we investigate the effect of MoO 2 Cl 2 flux, temperature, and deposition time on the growth, confirming MoO 2 Cl 2 with reasonably high vapor pressure is well compatible with the MOCVD system that enables precise control of sources for uniform nucleation and growth of MoS 2 over a large area. We successfully demonstrate the growth of carbon-free MoS 2 monolayers on DT-glass with decent crystalline, optical, and electrical properties. Additionally, the initial attempts also manifest that the proposed strategy could be generalized for growing ultrathin MoS 2 on other technologically important substrates, such as SiO 2 /Si and quartz, exhibiting superior optical quality and wafer-scale uniformity. This work provides a new avenue for the large-scale production of high-quality MoS 2 monolayers and facilitates their use in practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exciton-polariton couplings in Raman spectroscopy are investigated with hybrid structure of monolayer MoS 2 and spectrally tunable plasmonic nanogrooves (NGs). • The Raman mapping images demonstrate that the NGs hybridized with atomically thin MoS 2 can contribute to enhanced Raman signals with high uniformity. • The second-order Raman modes are clearly observed at the room temperature in the coupled samples. • The enhancements in Raman spectra are further examined through electromagnetic field enhancements. Surface-enhanced Raman spectroscopy (SERS) has been applied to analyze 2D materials with plasmonic enhancement at hotspots, localized at gaps or junctions. However, the SERS technique strongly demands hotspots at excitation laser wavelengths to achieve energy confinement at the excitation wavelength. In this study, we report the enhancement of Raman signals by the plasmon-exciton coupling between large-area monolayer MoS 2 and plasmonic nanogrooves (NGs). The plasmon-exciton coupling enhances Raman signal instead of SERS enhancement at an excitation wavelength. In addition, spectrally tunable plasmonic NGs are utilized to investigate coupled and de-coupled enhancements. The enhancement performance is further examined through electromagnetic field enhancement. We demonstrate that the proposed nanostructures integrated with atomically thin 2D materials, showing highly uniform Raman signals, are applicable for broad applications in materials science and nanophotonic. [ABSTRACT FROM AUTHOR]