Secondary growth and photoluminescence from erbium implanted silica nanowires

Gold-catalyzed silica nanowires were grown using vapor from the active oxidation of the silicon substrate and then implanted with erbium and annealed. During prolonged annealing at 1100 °C, where the concentration of vapor-phase reactants is sufficient to support nanowire growth, the erbium rich precipitates act as catalysts for the growth of a second generation of nanowires. These secondary nanowires increase in photoluminescence as they grow, suggesting that a fraction of the optically active erbium is incorporated into the growing wire. The resulting luminescent nanostructures have a very large surface-to-volume fraction and are well suited for optical-sensing applications.