Plasmonic Nanosponges Filled by Silicon for Enhanced White Light Emission
Plasmonic nanosponges is a powerful platform for various nanophotonic applications owing to extremely high local field enhancement in the metallic nanopores. The filling of the nanopores by the high-refractive index semiconductors (e.g. Si, Ge, GaP, etc.) opens up opportunities for enhancement of nonlinear effects in these materials. However, this task remains challenging due to lack of knowledge on the integration process of metal and high-index semiconductor components in such nanoobjects. Here, we investigate metal-dielectric nanoparticles fabricated from bilayered Si/Au films by the laser printing technique via combination of theoretical and experimental methods. We reveal that these hybrid nanoparticles represent the Au sponge-like nanostructure filled with the Si nanocrystallites. We also demonstrate that the Au net provides strong near-field enhancement in the Si grains increasing the white light photoluminescence in the hybrid nanostructures compared to uniform Si nanoparticles. These results pave the way for engineering of the internal structure of the sponge-like hybrid nanoparticles possessing white light luminescent and control their optical properties on demand.