Preparation of luminescent silicon nanoparticles by photothermal aerosol synthesis followed by acid etching

CO₂ laser-induced pyrolysis of silane (photothermal aerosol synthesis) was used to produce Si nanoparticles. Particles with an average diameter as small as 5 nm were prepared directly from silane in the gas phase. Etching these particles with mixtures of hydrofluoric acid (HF) and nitric acid (HNO₃) is shown to be an effective method to reduce the size of the particles produced by silane pyrolysis. After etching, silicon particles with controlled visible luminescence at room temperature were produced. The wavelength of maximum photoluminescence (PL) intensity can be controlled from over 780-500 nm by controlling the etching time and conditions.