RESEARCH PAPER Au nanoparticles decorated SiO 2 nanowires by dewetting on curved surfaces: facile synthesis and nanoparticles–nanowires sizes correlation F. Ruffino • M. G. Grimaldi Received: 17 May 2013 / Accepted: 30 July 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract We report a solid-state synthesis for SiO 2 nanowires (NWs) (up to 20 microns in length and from about 40 to about 150 nm in diameter) coated by Au nanoparticles (NPs) (from about 20 to about 80 nm in diameter). This protocol is based on three steps: (1) large area production of very long SiO 2 NWs on a Si surface exploiting a simple Au/Si solid-state reaction at high temperature; (2) coating of the SiO 2 NWs by a Au film of desired thickness using sputtering deposi- tions; and (3) a thermal process to induce a dewetting process of the Au-film coating the SiO 2 NWs to obtain Au NPs on the curved surface of the NWs. The morphology evolution of the SiO 2 NWs was followed, in each step, by scanning electron microscopy anal- yses. They allowed to correlate the evolution of the NPs size with the NWs sizes for different thicknesses of the starting Au-film coating the NWs and different annealing temperatures of the dewetting process. Some theoretical concepts, related to the dewetting process of a film on a curved surface were used to describe the experimental data. The main advantages of the proposed protocols include: (i) simplicity and low-cost (it is based only on sputtering depositions and thermal processes), and (ii) versatility based on the possibility of tuning Au-film thickness and annealing temperature to tune the NPs–NWs sizes ratio. These advantages can make this technique suitable for the mass production of Au NPs-coated SiO 2 NWs toward applications in electronic devices, biosensors, and nanoscale optical devices. Keywords SiO 2 nanowires  Au nanoparticles  Sputtering deposition  Annealing  Scanning electron microscopy  Dewetting on curved surfaces Introduction Since the discovery of carbon nanotubes in 1991 (Iijimma 1991), the various types of one-dimensional nanostructures such as tubes, wires, rods, and belts have been studied and their application to nanoscale devices has been developed using their unique physical, optical, and electronic properties. Among them, silicon (Si)-based nanostructures will be required in the future applications as the dimensions of the Si-integrated circuit continue to shrink. In particular, among Si-based nanostructures, SiO 2 nanowires (NWs) recently are gaining a great scien- tific and technological interest due to potential applications such as new electronic devices, biosen- sors, nanoscale optical devices, and sensors F. Ruffino  M. G. Grimaldi Dipartimento di Fisica e Astronomia, Universita ` di Catania, via S. Sofia 64, 95123 Catania, Italy F. Ruffino (&)  M. G. Grimaldi Center for Materials and Technologies for Information Communication and Solar Energy (MATIS CNR-IMM), via S. Sofia 64, 95123 Catania, Italy e-mail: francesco.ruffino@ct.infn.it 123 J Nanopart Res (2013) 15:1909 DOI 10.1007/s11051-013-1909-6