Size-selected growth of ultrathin SiO2 nanowires on surface and their decoration by Au nanoparticles

We report about a simple, versatile, low-cost and high-throughput methodology for the size-selected growth of SiO2 nanowires (NWs) on surfaces and on their surface decoration by Au nanoparticles (NPs). In contrast to a standard method involving the solid state reaction of thin Au films on Si at high temperature in the presence of trace amount oxygen (resulting in the formation of SiO2 NWs with a very high dispersion in diameters), the proposed method involves the same reaction between sizeselected colloidal Au NPs and the Si substrate. By microscopic analyses we demonstrate that, by such a method: 1) NWs of very low diameter can be grown with respect to those originating by films; 2) the size dispersion of the obtained NWs is much lower with respect to those originating by films; 3) the NWs' diameter can be finely tuned by controlling the colloidal NPs starting size; 4) it is possible to decorate such NWs by Au NPs simply coating them by Au film and inducing, by a thermal process, the dewetting of the film.