Preparation of luminescent Si nanoparticles by tailoring the size, crystallinity and surface composition

The preparation of sizeable quantities of luminescent Si nanoparticles (Si-np) with controlled morphology is a challenging task. Here, we describe two strategies aiming at size reduction of the Si-np produced in a laser-assisted silane pyrolysis reactor without detrimental effects on the process yield and on the nanoparticle structural and compositional properties. The first method is based on the addition of a sensitizer gas to dilute silane and consequently reduce the nucleation centres density without decreasing the reaction temperature. The second consists in the introduction of a collector at a variable distance from the irradiated region to freeze the particle growth and decrease the inter-particle sintering probability. We report on the characterization of the produced Si-np, and we show that by combining the two methods, we are able to prepare 4 nm crystalline core size nanoparticles with a productivity of 1 g per hour. We also describe the enhancement effect of the wet-chemical oxidation processes on the luminescence emission intensity of the Si-np.