Scattering of light by plasmonic nanoparticles on a silicon substrate.

We introduce an effective refractive-index model to predict the spectral positions of localized surface plasmon (LSP) modes of a silver nanoparticle on a thin-film silicon substrate using a semi-analytical method. The enhanced scattering into the substrate caused by the nanoparticle dipole and quadrupole modes is verified by comparing theoretical and simulation results. We suggest that the LSP modes can be tuned linearly with the thickness of the silicon substrate and the size of the nanoparticles. These findings provide simple and important physical insights for optimizing the absorption in a thin-film silicon solar cell by tuning the LSP modes of the nanoparticles deployed on the surface.