Dependence of Morphology of SiO_x Nanowires on the Supersaturation of Au-Si Alloy Liquid Droplets Formed on the Au Coated Si Substrate

A thermodynamic theory about the dependence of morphology of SiO_x nanowires on the super-saturation of alloy liquid droplets has been proposed on the basis of the vapor-liquid-solid growth mechanism and has been supported experimentally. By changing the Si-concentration in the Au-Si liquid droplets formed on the Au-coated Si substrate, firework-, tulip-, and bud-shaped SiO_x nanowires were synthesized by a thermal evaporation method and distributed concentrically around some void defects in the Si substrate. The voids were formed underneath the surface of the Si substrate during the thermal evaporation at 850°C and resulted in the Si-concentration deficient thus different saturation of Au-Si droplets. Electron microscopy analysis showed that the nanowires had an amorphous structure and were terminated by Au-Si particles.