Synthesis of Colloidal Silicon Nanosphere Involving Undergraduate Students at Illinois State University

High Refractive Index dielectric (HRI) nanoparticles have arisen as an alternative in nanophotonics research for their low loss compared to plasmonic (gold and silver) particles, and the possibility to generate Mie resonances of both electric and magnetic character, which can yield highly directional light scattering. Among several HRI materials, silicon (Si) has attracted significant attention as the lowest order Mie resonances, i.e., the electric and magnetic dipole resonances, of a few hundred nanometer Si sphere appear in the optical regime. In Applied Nanomaterials Lab at Illinois State University, we are using a high-temperature fabrication method to obtain perfectly spherical and monodisperse Si nanoparticles with diameter ~ 150-200 nm dimension for various nanophotonic applications. The fabrication process begins with the high temperature (1500 ^oC) annealing of silicon monoxide (SiO) to obtain Si nanoparticles embedded in SiO₂ matrix. At the end, the Si nanoparticles are liberated from SiO₂ using hydrofluoric acid (HF) acid. We have imaged the particles using scanning electron microscopy, and UV-VIS spectroscopy and single particles spectroscopy were performed to characterize the scattering of the particles.