Hyper-Doped Silicon Nanoantennas And Metasurfaces For Tunable Infrared Plasmonics

We present the experimental realization of ordered arrays of hyper-doped silicon nanodisks, which exhibit a localized surface plasmon resonance. The plasmon is widely tunable in a spectral window between 2 and 5 mu m by adjusting the free carrier concentration between 1020 and 1021 cm(-3). We show that strong infrared light absorption can be achieved with all-silicon plasmonic metasurfaces employing nanostructures with dimensions as low as 100 nm in diameter and 23 nm in height. Our numerical simulations show an excellent agreement with the experimental data and provide physical insights on the impact of the nanostructure shape as well as of near-field effects on the optical properties of the metasurface. Our results open highly promising perspectives for integrated all-silicon-based plasmonic devices for instance for chemical or biological sensing or for thermal imaging.