Nucleation and growth of Si nanowires from silicon oxide

Nucleation and growth of Si nanowires by laser ablation and thermal evaporation of Si powder sources mixed with ${\mathrm{SiO}}_{2}$ have been investigated by means of transmission electron microscopy. At the initial nucleation stage, Si oxide vapor condensed on the substrate and formed Si nanoparticles (the nuclei of nanowires). Each Si nanowire nucleus consisted of a polycrystalline Si core containing a high density of defects and a Si oxide shell. A growth mechanism was proposed based on the microstructure and different morphologies of the Si nanowires observed.