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Highly-ordered arrays of parallel carbon nanotubes were grown by pyrolysis of acetylene on cobalt within a hexagonal close-packed nanochannel alumina template at 650 °C. The nanotubes are characterized by a narrow size distribution, large scale periodicity, and high densities. Using this method ordered nanotubes with diameters from 10 nm to several hundred nm and lengths up to 100 μm can be produced. The high level of ordering and uniformity in these arrays is useful for applications in data storage, field emission displays and sensors, and offers the prospect of deriving computational functions from the collective behavior of symmetrically coupled nanotubes. The fabrication method used is compatible with standard lithographic processes and thus enables future integration of such periodic carbon nanotube arrays with silicon microelectronics.

A novel way of engineering DNA molecules involves substituting the imino proton of each base pair with a metal ion to obtain M-DNA with altered electronic properties. We report the first direct evidence of metalliclike conduction through 15 microm long M-DNA. In contrast, measurements on B-DNA give evidence of semiconducting behavior with a few hundred meV band gap at room temperature. The drastic change of M-DNA conductivity points to a new degree of freedom in the development of future molecular electronics utilizing DNA, such as creating all-DNA junction devices for use as nanoelectronic building blocks.

In this work we demonstrate the feasibility of electric-field tuning of the plasmonic spectrum of a novel gold nanodot array in a liquid crystal matrix. As opposed to previously reported microscopically observed near-field spectral tuning of individual gold nanoparticles, this system exhibits macroscopic far-field spectral tuning. The nanodot-liquid crystal matrix also displays strong anisotropic absorption characteristics, which can be effectively described as a collective ensemble within a composite matrix in the lateral dimension and a group of noninteracting individual particles in the normal direction. The effective medium model and the Mie theory are employed to describe the experimental results.

The Cooper pairing mechanism that binds single electrons to form pairs in metals allows electrons to circumvent the exclusion principle and condense into a single superconducting or zero-resistance state. We present results from an amorphous bismuth film system patterned with a nanohoneycomb array of holes, which undergoes a thickness-tuned insulator-superconductor transition. The insulating films exhibit activated resistances and magnetoresistance oscillations dictated by the superconducting flux quantum h/2e. This 2e period is direct evidence indicating that Cooper pairing is also responsible for electrically insulating behavior.

Persistent efforts have been made to achieve efficient light emission from silicon in the hope of extending the reach of silicon technology into fully integrated optoelectronic circuits, meeting the needs for high-bandwidth intrachip and interchip connects. Enhanced light emission from silicon is known to be theoretically possible, enabled mostly through quantum-confinement effects. Furthermore, Raman-laser conversion was demonstrated in silicon waveguides. Here we report on optical gain and stimulated emission in uniaxially nanopatterned silicon-on-insulator using a nanopore array as an etching mask. In edge-emission measurements, we observed threshold behaviour, optical gain, longitudinal cavity modes and linewidth narrowing, along with a collimated far-field pattern, all indicative of amplification and stimulated emission. The sub-bandgap 1,278 nm emission peak is attributed to A-centre mediated phononless direct recombination between trapped electrons and free holes. The controlled nanoscale silicon engineering, combined with the low material loss in this sub-bandgap spectral range and the long electron lifetime in such A-type trapping centres, gives rise to the measured optical gain and stimulated emission and provides a new pathway to enhance light emission from silicon.

Electrochemical DNA detection systems are an attractive approach to the development of multiplexed, high-throughput DNA analysis systems for clinical and research applications. We have engineered a new class of nanoelectrode ensembles (NEEs) that constitute a useful platform for biomolecular electrochemical sensing. High-sensitivity DNA detection was achieved at oligonucleotide-functionalized NEEs using a label-free electrocatalytic assay. Attomole levels of DNA were detected using the NEEs, validating the promise of nanoarchitectures for ultrasensitive biosensing.

A nonlithographic second-order self-assembly process for synthesizing uniform and ordered arrays of nanorods and nanodots is presented and applied to the fabrication of ZnO nanorod arrays. Nucleation sites were defined by patterning Au nanodot catalysts with a self-organized array of nanopores formed in anodized aluminum oxide (AAO). The self-assembled vertically aligned ZnO nanorods grown on GaN exhibit hexagonal facets, and have a uniform diameter of 60 nm and a mean length of 400 nm. The growth technique is simple, robust, and offers a direct control over array and single nanorod configurations. The growth temperature is significantly lower than normal, and yet, the resultant defect level is much lower than normal.