Web-like Agglomeration and photoluminescence of silica nanoparticles and silicon nanocrystals

摘要

A method which combines laser vaporization of metal targets with controlled condensation in a diffusion colud chamber is used to synthesize nanoscale particles (10-20 nm). The silica nanoparticles and the surface-oxidized silicon nanocrystals aggregate into novel web-like microstructures. These aggregates are very porous and have very large surface areas (460 m~2/g for the silica particles). The emission photoluminescence spectrum from the Si nanocrystals is similar to that observed for porous Si. Bright blue photoluminescence from the nanoparticle silica has been observed upon irradiation with UV light. The photoluminescence is explained by the presence of intrinsic defects of the type Si(II)~o in the amorphous silica.