Monolayers for Plasmon-Exciton Coupling*

This study explores the synthesis and properties of hybrid plasmonic/2-dimensional semiconductor nanostructures by combining gold nanotriangle (NT) arrays with mechanically exfoliated MoSe₂ monolayers on a sapphire substrate. The MoSe₂ monolayers exhibit an exciton emission at 786 nm at room temperature. Using nanosphere lithography with polystyrene beads, an array of gold NTs is thermally deposited on top of these transition metal dichalcogenide (TMDC) monolayers. Characterization through Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) determines the shape and height of the gold NTs. Transmission measurements are employed to investigate the shift of the plasmon resonance of the gold NT arrays as a function of the NT height and of the exciton transition in the combined MoSe₂ monolayer/gold NT samples. The experiments are accompanied by COMSOL simulations. This work paves the way for applications of plasmon-coupled TMDC nanostructures.