On the Photoluminescence of Si Nanoparticles

Silicon nanoparticles with diameters ranging from 3 to 50 nm were prepared by thermal evaporation. The nanoparticles showed visible light emissions from 5000 Å to 9000 Å, with peak intensity at 8000-8200 Å, when excited with a He-Cd laser. The intensity increased with decreasing particle size. Based on the photoluminescence (PL) characteristics, it is suggested that the PL for particles larger than 9 nm is surface state-induced, while the PL for those smaller than 9 nm is ascribed to quantum confinement effects.