Surface plasmons for enhanced silicon light-emitting diodes and solar cells

Localized surface plasmons on metallic nanoparticles can be surprisingly efficient at coupling light into or out of a silicon waveguide. In this paper we review our recent work where we have demonstrated a factor of 8 times enhancement in the electroluminescence from a silicon-on-insulator light-emitting diode at 900 nm using silver nanoparticles, in the first report of a surface plasmon-enhanced silicon light-emitting diode. Our theoretical work has shown that the enhancement seen in this system at long wavelengths is mainly a single-particle effect, in contrast to previous suggestions that it is a waveguide-mediated multi-particle effect, and that there is a dramatic enhancement of the scattering cross-section for waveguided light in these devices. We discuss the route towards increasing this enhancement further and provide predictions of the limits on the maximum potential efficiency enhancement, as well as the potential of metal particles for applications in thin film silicon solar cells.