Semiconducting nanowires and nanotubes are an emerging class of 1D nanostructures that represent attractive building blocks for nanoscale electronic and photonic devices. For example, inorganic semiconductor nanowires [1][2][3] and carbon nanotubes, [4] show great promise for nanoelectronic devices and integrated nanosystems because they can function both as device components for logic, memory, and sensing applications and also as interconnects. Inorganic semiconductor nanowires are also attracting increasing research interest as building blocks for integrated nanophotonic systems, since they can function as subwavelength optical waveguides, emissive devices, and photodetectors. [1][2][3][5][6][7][8][9][10][11][12] With respect to the latter, photoconductance measurements have recently been reported for a range of single inorganic nanowire devices: InP, [5] ZnO, [6] GaN, [7] and Si, [8] as well as for carbon-nanotube devices.[13]While inorganic nanowires and carbon nanotubes have been explored in depth, the challenge of controlled fabrication of 1D nanostructures based on organic molecular materials suitable for integrated (opto)electronic applications has yet to be as comprehensively addressed. In particular, semiconducting polymers are attractive materials due to their chemically tunable optical and electronic properties, as well as their facility for solution processing. [14,15] 1D nanostructures fabricated from such polymers have been the subject of recent research with regard to their physical, chemical, electronic, and photonic properties. [16][17][18][19][20] However, demonstration of viable polymer nanowire technologies will require the development of reliable methods for the production of such structures with good control over critical parameters such as diameter, length, morphology, and chemical composition. Recently, a new method for the formation of organic nanotubes and nanowires through the wetting of porous anodized alumina membranes has been reported. [20] This method of template wetting using solution-based or molten material does not require specialized apparatus and is broadly applicable across a wide range of organic materials, including small molecules, oligomers, polymers, blends, and multicomponent solutions.[20]In this work, we demonstrate that solution-assisted template wetting may be successfully exploited for high-yield controlled synthesis of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(bithiophene)] (F8T2) nanowires. Following liberation from the template and dispersion, our method produces discrete nanowires with average lengths of 15 lm and mean diameters of 200 nm. We report on the electrical characteristics of singlenanowire devices and, further, on the use of single F8T2 nanowires in photoconductivity-based photodetectors. To date, there have been relatively few reports on photoconductivity in 1D polymer nanostructures; for example, Kim and coworkers have reported photoconductance in single bilayer nanotubes comprising poly-(p-phenylenevinylene) (PPV) nanotube cores and carbonized PP...

Single nanopore electrodes and nanopore electrode arrays have been fabricated using a focused ion beam (FIB) method. High aspect ratio pores (approximately 150-400-nm diameter and 500-nm depth) were fabricated using direct-write local ion milling of a silicon nitride layer over a buried platinum electrode. This local milling results in formation of a recessed platinum electrode at the base of each nanopore. The electrochemical properties of these nanopore metal electrodes have been characterized by voltammetry. Steady-state voltammograms were obtained for a range of array sizes as well as for single nanopore electrodes. High-resolution scanning electron microscopy imaging of the arrays showed that the pores had truncated cone, rather than cylindrical, conformations. A mathematical model describing diffusion to an electrode located at the base of a truncated conical pore was developed and applied to the analysis of the electrode geometries. The results imply that diffusion to the pore mouth is the dominant mass transport process rather than diffusion to the electrode surface at the base of the truncated cone. FIB milling thus represents a simple and convenient method for fabrication of prototype nanopore electrode arrays, with scope for applications in sensing and fundamental electrochemical studies.

Here we report on the DNA-templated self-assembly of conducting gold nanowires between gold electrodes lithographically patterned on a silicon oxide substrate. An aqueous dispersion of 4-(dimethylamino)pyridine-stabilized gold nanoparticles was prepared. These nanoparticles recognize and bind selectively double-stranded calf thymus DNA aligned between the gold electrodes to form a linear nanoparticle array. Continuous polycrystalline gold nanowires are obtained by electroless deposition that enlarges and enjoins the individual gold nanoparticles. The above nanowires were structurally characterized using a range of electron and scanning probe microscopies and electrically characterized at room temperature using a standard probe setup. The results of these characterizations show these wires to be 20 nm high and 40 nm wide, to be continuous between interdigitated gold electrodes with an interelectrode spacing of 0.2 or 1.0 μm, and to possess a resistivity of 2 × 10-4 Ωm. These DNA-templated nanowires, the smallest reported to date, exhibit resistivities consistent with reported findings and current theory. The use of DNA as a template for the self-assembly of conducting gold nanowires represents a potentially important approach to the fabrication of nanoscale interconnects.