Direct growth of amorphous silica nanowires by solid state transformation of SiO2 films

Amorphous silica nanowires (a-SiONWs) were produced by direct solid state transformation from silica films. The silica nanowires grow on TiN/Ni/SiO2/Si substrates during the annealing in H2 or a H2:CH4 mixture at 1050 °C. Titanium nitride (TiN) films were used to induce a solid state reaction with silica (SiO2) films on silicon wafers to provide silicon atoms into growing nanowires. The TiN layers induce the diffusion of silicon and oxygen to the surface by a stress gradient built inside the films. The nickel diffuses to the surface during the TiN deposition and acts as a nucleation site for the a-SiONWs.