Hybrid Au@Si microspheres produced via laser irradiation in liquid for nonlinear photonics

Abstract Hybrid nanomaterials with chemical composition integrating light-emitting low-loss semiconductors with plasmon-active metals are highly demanded for optoelectronics, nanophotonics and sensors. However, there is a still lack for high-performing and inexpensive methods allowing facile integration of plasmonic and all-dielectric concepts within unified practically relevant nanostructures and ensuring their production at gram-per-hour yield. Here, we report one-step synthesis of hybrid Au@Si nanomaterial with unique composition and morphology via scalable and high-performing pulsed laser irradiation of isopropanol solution containing commercial Si micro-powder and AuCl4- ions. The resulting hybrid nanomaterial represents sub-micron nanocrystalline Si grains embedded into Au surrounding forming micro-spheres (MSs) additionally decorated with Au nanoparticles. Such unique structure and chemical composition of the Au@Si MSs permits to efficiently absorb and enhance incident radiation within rather broad spectral range spanning from visible to near-IR making the nanomaterial promising for plasmon-mediated amplification of linear and nonlinear optical effects. Efficient generation of broadband hot-carrier-induced photoluminescence of nanocrystalline Si grains upon IR femtosecond-laser sub-nJ pump proves the produced nanomaterial as advanced nanophotonic platform for nano-spectroscopy and sensing.