Nanostructures are of great interest not only for their basic scientific richness, but also because they have the potential to revolutionize critical technologies. The miniaturization of electronic devices over the past century has profoundly affected human communication, computation, manufacturing and transportation systems. True molecular-scale electronic devices are now emerging that set the stage for future integrated nanoelectronics. Recently, there have been dramatic parallel advances in the miniaturization of mechanical and electromechanical devices. Commercial microelectromechanical systems now reach the submillimetre to micrometre size scale, and there is intense interest in the creation of next-generation synthetic nanometre-scale electromechanical systems. We report on the construction and successful operation of a fully synthetic nanoscale electromechanical actuator incorporating a rotatable metal plate, with a multi-walled carbon nanotube serving as the key motion-enabling element.
We have measured the temperature-dependent thermal conductivity kappa(T) of individual multiwall boron nitride nanotubes using a microfabricated test fixture that allows direct transmission electron microscopy characterization of the tube being measured. kappa(T) is exceptionally sensitive to isotopic substitution, with a 50% enhancement in kappa(T) resulting for boron nitride nanotubes with 99.5% 11B. For isotopically pure boron nitride nanotubes, kappa rivals that of carbon nanotubes of similar diameter.
We report on the precise positioning of a carbon nanotube on an atomic force microscope (AFM) tip. By using a nanomanipulator inside a scanning electron microscope, an individual nanotube was retrieved from a metal foil by the AFM tip. The electron beam allows us to control the nanotube length and to sharpen its end. The performance of these tips for AFM imaging is demonstrated by improved lateral resolution of DNA molecules.
Live imaging of operating multiwall carbon nanotube ͑MWCNT-͒ based electronic devices is performed by high resolution transmission electron microscopy. Our measurements allow us to correlate electronic transport with changes in device structure. Surface contamination, contact annealing, and sequential wall removal are observed. Temperature profiles confirm diffusive conduction in MWCNTs in the high bias limit. This technique provides a general platform for studying nanoscale systems, where geometric configuration and electronic transport are intimately connected.
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