Plasmon-induced efficient hot carrier generation in graphene on gold ultrathin film with periodic array of holes: Ultrafast pump-probe spectroscopy*

Surface plasmon polaritons (SPPs) due to their inherent property of nanoscale confinement and localization, smaller than the interacting light wavelength, show strong light-matter interaction. Here, using ultrafast transient absorption spectroscopy we show that a high density of hot-electrons can be generated in graphene, through a strong interaction in a hybrid plasmonic structure of graphene with 3D gold hole array. Notably, pump-induced reflectivity shows significant signatures in the spectral window corresponding to extraordinary optical transmission resonances of gold hole array originating from the carrier dynamics in graphene. A comparative study of the graphene on gold film with and without hole array confirms the highly efficient direct plasmon-induced hot carrier generation in graphene.