Growth of silicon nanowires of controlled diameters by electrodeposition in ionic liquid at room temperature

Silicon nanowires were fabricated for the first time by electrochemical template synthesis at room temperature. This innovative, cheap, and simple process consists of electroreduction of Si ions using a nonaqueous solvent and insulating nanoporous membranes with average pore diameters from 400 to 15 nm which fix the nanowires diameters. Characterization techniques such as scanning and transmission electron microscopies, infrared absorption measurements, X-ray diffraction experiments, energy dispersive X-ray, and Raman spectrometries show that the as-deposited silicon nanowires are amorphous, composed of pure Si and homogeneous in sizes with average diameters and lengths well matching with the nanopores' diameters and the thicknesses of the membranes. Thanks to annealing treatments, it is possible to crystallize the Si nanowires, demonstrating the potentiality for this innovative electrochemical process to obtain a wide range of Si nanowires with well controlled diameters and lengths.