SERS-Active Substrates Based on Embedded Ag Nanoparticles in c-Si: Modeling, Technology, Application

Abstract

A simple method for obtaining SiO₂:Ag:Si and Ag:Si hybrid nanostructures is presented. High-temperature annealing of an Ag island film on the surface of c-Si makes it possible to preserve the plasmonic properties of Ag nanoparticles and protect them from external influences by coating them with a thermally grown layer of SiO₂. The calculation of the electric field strength distribution in the structure with embedded Ag nanoparticles in c-Si demonstrates the presence of intrinsic “hot spots” at the corners of the nanoparticles, which leads to a maximum enhancement factor (~10⁶) of Raman scattering. A numerical calculation of the dependence of the spectral position of a localized plasmon resonance on the geometry of structures can serve as a basis for their design in the future. Surface-enhanced Raman scattering showed reliable detection of the methyl orange from an aqueous solution at a concentration of <10^–5 M.