Electrodeposition of Cu nanowire arrays with a template

Cu nanowire arrays were electrodeposited with a template of a polycarbonate (PC) filter. Pt-Pd alloy film was sputtered on one side of the PC filter and then used as cathode in 0.6 M CuSO4 aqueous solution (pH 2). Potentiostatic electrodeposition at -400 mV vs. Cu reference electrode was conducted in two kinds of electrolytic cell configurations, cathode over anode (C/A) and anode over cathode (A/C). The transient variation of the cathodic current clearly showed four stages in both cell configurations; (I) nucleation and crystal growth mode of Cu on the Pt-Pd film, (II) filling up with electrodeposited Cu in the nanosized pores, (III) covering of the surface of the template with Cu, and (IV) growth of a Cu thick film. In Stage II, the cathodic current increased in the A/C configuration, while it decreased in the C/A. The duration time of Stage II was shorter in the A/C configuration than that in the C/A. The difference of the cathodic current variation between the two configurations was smaller with smaller sized pores. These phenomena suggest that the ionic mass transfer rate of Cu2+ ion accompanied by electrodeposition is enhanced by a kind of natural convection even in and around such a nanosized pore and that the pores are filled up faster with electrodeposited Cu in the A/C than in the C/A configuration. (C) 2003 Elsevier B.V. All rights reserved.