Enhancing Raman spectra by coupling plasmons and excitons for large area MoS2 monolayers.

[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]