Surface enhanced resonant Raman scattering in hybrid MoSe2@Au nanostructures

We report on the surface enhanced resonant Raman scattering (SERRS) in hybrid MoSe 2 @Au plasmonic-excitonic nanostructures, focusing on the situation where the localized surface plasmon resonance of Au nanodisks is finely tuned to the exciton absorption of monolayer MoSe 2 . Using a resonant excitation, we investigate the SERRS in MoSe 2 @Au and the resonant Raman scattering (RRS) in a MoSe 2 @SiO 2 reference. Both optical responses are compared to the non-resonant Raman scattering signal, thus providing an estimate of the relative contributions from the localized surface plasmons and the confined excitons to the Raman scattering enhancement. We determine a SERRS/RRS enhancement factor exceeding one order of magnitude. Furthermore, using numerical simulations, we explore the optical near-field properties of the hybrid MoSe 2 @Au nanostructure and investigate the SERRS efficiency dependence on the nanodisk surface morphology and on the excitation wavelength. We demonstrate that a photothermal effect, due to the resonant plasmonic pumping of electron-hole pairs into the MoSe 2 layer, and the surface roughness of the metallic nanostructures are the main limiting factors of the SERRS efficiency.