A systematic study was conducted on the fabrication, structural characterization, and transport properties of Zn nanowires with diameters between 40 and 100 nm. Zinc nanowires were fabricated by electrodepositing Zn into commercially available polycarbonate (PC) or anodic aluminum oxide (AAO) membranes. By controlling the electrodeposition process, we found that the nanowires can be single-crystal, polycrystalline Zn, crystalline Zn/nanocrystalline ZnO composites, or entirely ZnO. The microstructure and chemistry was characterized by using transmission electron microscopy. Transport studies on single-crystal or polycrystalline Zn nanowire arrays embedded inside the membrane showed that the superconducting transition temperature, Tc, is insensitive to the nanowire diameter and morphology. The superconductivity shows a clear crossover from bulklike to quasi-1D behavior, as evidenced by residual low-temperature resistance, when the diameter of the wires is reduced to 70 nm (20 times smaller than the bulk coherence length).

Microstructure and interdiffusion of striped Au/ Sn/Au nanowires grown by sequential electrodeposition of Au and Sn in porous polycarbonate membranes were investigated by X-ray diffraction, HRTEM, STEM, EDS, and electrical transport measurements. The Au/Sn junctions were found to contain two intermetallic phases: AuSn, and AuSn 4 . Mechanisms for the formation of these intermetallic phases and the effect of these phases on the superconductivity of striped nanowires were discussed.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.