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0921-T01-09

DNA-Templated Assembly of Conducting Gold Nanowires Amro Satti1,2, Damian Aherne1,2, Claire Barrett3, Liam Floyd3, Aidan Quinn3, Gareth Redmond3, and Donald Fitzmaurice1,2 1 School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin, D4, Ireland 2 Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin, Ireland 3 Nanotechnology Group, Tyndall National Institute, Lee Maltings, Cork, Ireland ABSTRACT The use of DNA to template the assembly of gold nanowires from gold nanoparticles is reported. Double-stranded calf thymus DNA, was deposited on a polystyrene-coated silicon wafer substrate. The substrate was then exposed to an aqueous dispersion of positively charged gold nanoparticles (~ 4 nm diameter), which adsorbed at the negatively charged DNA template. The adsorbed nanoparticles were then enlarged and enjoined by electroless deposition leading to formation of continuous nanowires of 85 nm average diameter. Gold electrodes were then overlaid on individual nanowires using conventional lithographic techniques. Two-terminal current-voltage measurements were employed to characterize the electrical characteristics of single nanowires. The nanowires exhibit resistivity values < 6 × 10-7 Ωm. These and related findings have implications for the design and assembly of next generation electronic devices.

INTRODUCTION The demand for integrated circuits that will allow information to be retrieved, processed, and stored at even faster speeds remains undiminished. This is despite the fact that scaling has doubled the density of the wires and switches that comprise such circuits every 18 months giving rise to Moore’s Law [1]. While it is expected that CMOS will continue to be the dominant technology in device fabrication over the next decade, it is expected that alternative fabrication techniques applied to production of novel devices for data processing and storage will emerge [2]. Chemical synthesis and self-assembly in solution have been proposed as potential bottom-up approaches for fabrication and assembly, respectively, of building blocks for future electronics applications. Several research groups have used DNA to template the assembly of nanowires at patterned substrates [3-9]. In this context we report on selective assembly of 4 nm diameter 4(dimethylamino) pyridine (DMAP)-stabilized gold nanoparticles at double-stranded calf thymus DNA. We also report on the use of DNA to template the assembly of gold nanowires through electroless deposition. Following overlay of contact electrodes using conventional top-down lithographic and processing techniques, subsequent structural and electrical characterization of these wires were employed to investigate the nanowire morphology and electrical characteristics.

EXPERIMENTAL DETAILS Preparation of DMAP-stabilized gold nanoparticles A stable aqueous dispersion of DMAP-stabilized gold nanoparticles was prepared as described elsewhere [10]. Briefly, DMAP was transferred from a chloroformic phase to