Template-Assisted Electrochemical Liquid-Liquid-Solid Deposition of Crystalline Ge Nanowires

Electrodeposition of crystalline Ge nanowires from GeO₂ aqueous solutions through an electrochemical liquid-liquid-solid (ec-LLS) process using Ga nano/microdroplets of various sizes has been demonstrated. A silica template featuring regularly spaced opening with defined sizes was prepared on Si substrates by a modified nanosphere lithography patterning process. These platforms were used to electrodeposit Ga droplet arrays with defined sizes and pitch. The Ga nano/microdroplets subsequently enabled growth of crystalline Ge nanowires through ec-LLS in aqueous electrolyte as a function of droplet size. Scanning electron micrographs of the as-produced Ge nanowires showed the base size of the Ge nanowires tracks the Ga droplet diameter. All nanowires featured a consistent taper, with a cone angle of approximately 10°. For the Ga droplets larger than 1 µm in diameter, no nanowires were observed under the employed ec-LLS conditions, but a large isotropic Ge deposit was formed. These cumulative results demonstrate effects that liquid metal size(volume) have on electrodeposition by ec-LLS.