Polarization-Dependent Light Emission and Charge Creation in MoS2 Monolayers on Plasmonic Au Nanogratings.

We fabricated plasmonic hybrid nanostructures consisting of MoS2 monolayer flakes and Au nanogratings with a period of 500 nm. The angle-resolved reflectance and photoluminescence spectra of the hybrid nanostructures clearly indicated a coupling between surface plasmon polaritons (SPPs) and incoming photons. The surface photovoltage (SPV) maps could visualize the spatial distribution of net charges while shining light on the sample. Considerable polarization and wavelength dependence of the SPV signals suggested that the SPP mode enhanced the light-matter interaction and resulting exciton generation in the MoS2 monolayer. From the photoluminescence spectra and the morphology of the suspended MoS2 region, it could be noted that light irradiation did not much raise the temperature of the MoS2 monolayers on the nanogratings. Nanoscopic SPV and surface topography measurements could reveal the local optoelectronic and mechanical properties of MoS2 monolayers. This work provided us insights into the proposal of a high-performance MoS2/metal optoelectronic devices, based on the understanding of the SPP-photon and SPP-exciton coupling.