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 μm 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.

Using localized surface plasmon resonance (LSPR) as an optical probe we demonstrate the presence of free carriers in phosphorus doped silicon nanocrystals (SiNCs) embedded in a silica matrix. In small SiNCs, with radius ranging from 2.6 to 5.5  nm, the infrared spectroscopy study coupled to numerical simulations allows us to determine the number of electrically active phosphorus atoms with a precision of a few atoms. We demonstrate that LSP resonances can be supported with only about 10 free electrons per nanocrystal, confirming theoretical predictions and probing the limit of the collective nature of plasmons. We reveal the appearance of an avoided crossing behavior linked to the hybridization between the localized surface plasmon in the doped nanocrystals and the silica matrix phonon modes. Finally, a careful analysis of the scattering time dependence versus carrier density in the small size regime allows us to detect the appearance of a new scattering process at high dopant concentration, which can be explained by P clustering inside the SiNCs.

In this work, a thorough study of the phosphorus (P) heavy doping of thin Silicon-On-Insulator (SOI) layers by UV nanosecond Laser Thermal Annealing (LTA) is presented. The melting regimes and the regrowth processes as well as the redistribution and activation of P in the top-Si amorphized layer were studied as a function of the implant dose and laser annealing conditions. The results highlight the crucial role of the thin crystalline silicon layer preserved after amorphization of the top-Si layer, which provides nucleation seeds for the liquid phase recrystallization. The impact of the implant dose on the recrystallization process is investigated in detail, in terms of melt energy thresholds, crystallographic nature of the resolidified layer, defect formation, surface roughness and hillocks formation at the silicon surface. For all the implanted doses, optimized laser annealing conditions were identified, corresponding to the laser energies just preceding the onset of the full melt. Such optimized layers exhibit perfect crystallinity, negligible P out-diffusion, an almost perfectly flat P depth profile located below the segregation-induced surface pile-up peak and dopant active concentrations well above 1×10 21 cm -3 , close to the highest reported values reported for phosphorus in bulk Si substrates.