IOP PUBLISHING NANOTECHNOLOGY Nanotechnology 18 (2007) 175707 (8pp) doi:10.1088/0957-4484/18/17/175707 Single-step growth and low resistance interconnecting of gold nanowires Birol Ozturk 1 , Bret N Flanders 1,4 , Daniel R Grischkowsky 2 and Tetsuya D Mishima 3 1 Department of Physics, Oklahoma State University, Stillwater, OK 74078, USA 2 School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK 74078, USA 3 Homer L Dodge Department of Physics and Astronomy and Center for Semiconductor Physics in Nanostructures, University of Oklahoma, Norman, OK 73019, USA E-mail: bret.flanders@okstate.edu Received 20 January 2007, in final form 25 February 2007 Published 2 April 2007 Online at stacks.iop.org/Nano/18/175707 Abstract We present a single-step, electrochemical approach to the growth and low contact resistance interconnecting of gold nanowires with targeted points on lithographic electrodes. Electron diffraction studies indicate that these nanowires are composed of face-centred cubic crystalline gold, and that the crystal structure is invariant along the wire lengths. Four-point resistance determinations of these electrode–nanowire–electrode assemblies consistently yield resistances of <50 , and the contributions from the electrode–wire contacts are of the order of 10 . Atomic force microscopy was used to depict the structurally integrated nature of the electrode–wire contacts. This feature underlies the low electrode–wire contact resistances. (Some figures in this article are in colour only in the electronic version) 1. Introduction Nanowire synthesis is one of the most fundamental sub- processes of nanodevice fabrication. Of the many elements and compounds from which nanowires may be made, gold is technologically important for its low resistivity (2.21 μ cm) [23], its inertness to attack by air and its resistance to sulfur-based tarnishing [12]. Additionally, gold is more biocompatible than most metals, rendering it suitable for implantation in [19, 27] or electrical interfacing with [13, 31, 42] cells and tissue in nano-biological applications [4, 33]. It may even prove feasible to perform novel electrophysiological characterizations of live cells by interfacing multiple gold nanowires with a set of targeted sites on a single cell, a challenging and long-standing goal [13, 30]. Finally, the well-established transport properties of bulk gold render the gold nanowire an ideal system in which to determine how metallic transport evolves with diminishing wire diameter [6]. These research areas would benefit from 4 Author to whom any correspondence should be addressed. a gold nanowire fabrication methodology that permits the targeted placement of the wires in surrounding circuitry and that attains low contact resistance interconnecting of the wires with this circuitry. This combination of features will foster predictable nanowire behaviour in the assembled devices and it will enable reliable characterization of the nanowire-transport properties. A variety of fabrication techniques have been developed in the past decade that yield high quality nanowires. Perhaps the most widely used nanowire synthesis is the vapour– liquid–solid method, where metallic nanodroplets catalyze the condensation, nucleation, and axial growth of vaporous growth material [44, 50]. This technique produces pristine arrays of single-crystal nanowires from a wide variety of materials [8, 15, 26, 41, 45, 46, 50, 51], arrangements that have been exploited in various photonic [16] and electronic [11] applications. Recently, this approach was refined to allow for the catalyst-free growth of metal-silicide nanowires [34]. In an alternative approach, porous substrates [48], nanotubes [49]. DNA and other biomolecules [39] have been used as templates in the formation of gold nanowires with very small diameters 0957-4484/07/175707+08$30.00 1 © 2007 IOP Publishing Ltd Printed in the UK