Showing papers by "James Hone published in 2007"
TL;DR: An unusually long mean free path at room temperature has been experimentally confirmed and suggests anomalous localization effects in single-walled carbon nanotube devices with channel lengths that vary 4 orders of magnitude.
Abstract: We present an experimental investigation on the scaling of resistance in individual single-walled carbon nanotube devices with channel lengths that vary 4 orders of magnitude on the same sample. The electron mean free path is obtained from the linear scaling of resistance with length at various temperatures. The low temperature mean free path is determined by impurity scattering, while at high temperature, the mean free path decreases with increasing temperature, indicating that it is limited by electron-phonon scattering. An unusually long mean free path at room temperature has been experimentally confirmed. Exponentially increasing resistance with length at extremely long length scales suggests anomalous localization effects.
301 citations
TL;DR: In this paper, the mechanical properties of nanowires consisting of nanoporous gold are studied experimentally, and the elastic modulus, residual stress, and yield stress are measured by deflective tensile testing and nanoindentation, and are about 9 GPa, 65 MPa, and 110 MPa.
136 citations
TL;DR: In this paper, the existence of broad and weakly asymmetric features in the high energy Raman modes of freely suspended metallic carbon nanotubes of defined chiral index was reported.
Abstract: We report the existence of broad and weakly asymmetric features in the high-energy ($G$) Raman modes of freely suspended metallic carbon nanotubes of defined chiral index. A significant variation in peak width (from $12\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$ to $110\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$) is observed as a function of the nanotube's chiral structure. When the nanotubes are electrostatically gated, the peak widths decrease. The broadness of the Raman features is understood as the consequence of coupling of the phonon to electron-hole pairs, the strength of which varies with the nanotube chiral index and the position of the Fermi energy.
89 citations
TL;DR: In this article, the performance of a redox polymer-mediated glucose anode catalyzed by glucose oxidase and supported on a multiscale carbon material was reported. But the performance was limited by biocatalyst and reactant transport in the micro-and nanoscale pores of the support material.
Abstract: We report the electrochemical performance of a redox polymer-mediated glucose anode catalyzed by glucose oxidase and sup-ported on a multiscale carbon material. The support is composed of carbon paper upon which is grown multiwall nanotubes bychemical vapor deposition combined with ohmic heating of the carbon paper. The material possessed 100-fold higher surface areaand demonstrated tenfold higher electrochemical performance, compared to bare carbon paper. Maximum performance is limitedby biocatalyst and reactant transport in the micro- and nanoscale pores of the support material.© 2007 The Electrochemical Society. DOI: 10.1149/1.2712049 All rights reserved.Manuscript submitted November 8, 2006; revised manuscript received January 4, 2007. Available electronically March 6, 2007.
59 citations
TL;DR: In this paper, the authors measured two-port properties of individual MWNTs using a network analyser from a frequency of 0.5 to 50 GHz and showed the frequency dependence of the equivalent resistance of MWNT, which decreases with increasing frequency.
Abstract: Carbon nanotubes (CNTs) are considered as promising candidates for transmission lines as well as microcircuit interconnects in future nanoscale electronic systems. Owing to the growing interest in the use of microwave signals, understanding the transmission properties at high frequencies is essential to assess the applicability of multi-walled carbon nanotubes (MWNTs). In this work, we measured two-port properties of individual MWNTs using a network analyser from a frequency of 0.5 to 50 GHz. The radio-frequency transmission parameters were obtained from the measured S-parameter data. Our results show the frequency dependence of the equivalent resistance of MWNTs, which decreases with increasing frequency. This confirms that metallic CNTs will be useful for transmitting GHz signals in nanoelectric devices.
43 citations
TL;DR: The results of two sets of experiments to measure the elastic?plastic behavior of gold at the nanometre length scale are reported in this article, and the results of detailed finite element analyses of the specimen suggest that the critical resolved shear stress of the gold single crystal was as high as 135?MPa which would lead to a maximum uniaxial stress of about 500?MPa after several per cent strain.
Abstract: The results of two sets of experiments to measure the elastic?plastic behaviour of gold at the nanometre length scale are reported. One set of experiments was on free-standing nanoscale single crystals of gold, and the other was on free-standing nanoscale specimens of open-celled nanoporous gold. Both types of specimens were fabricated from commercially available leaf which was either pure Au or a Au/Ag alloy following by dealloying of the Ag. Mechanical testing specimens of a 'dog-bone' shape were fabricated from the leaf using standard lithographic procedures after the leaf had been glued onto a silicon wafer. The thickness of the gauge portion of the specimens was about 100?nm, the width between 250?nm and 300?nm and the length 7??m. The specimens were mechanically loaded with a nanoindenter (MTS) at the approximate midpoint of the gauge length. The resulting force?displacement curve of the single crystal gold was serrated and it was evident that slip localization occurred on individual slip systems; however, the early stages of the plastic deformation occurred in a non-localized manner. The results of detailed finite element analyses of the specimen suggest that the critical resolved shear stress of the gold single crystal was as high as 135?MPa which would lead to a maximum uniaxial stress of about 500?MPa after several per cent strain. The behaviour of the nanoporous gold was substantially different. It exhibited an apparent elastic behaviour until the point where it failed in an apparently brittle manner, although it is assumed that plastic deformation occurred in the ligaments prior to failure. The average elastic stiffness of three specimens was measured to be Enp = 8.8?GPa and the stress at ultimate failure averaged 190?MPa for the three specimens tested. Scaling arguments suggest that the stress in the individual ligaments could approach the theoretical shear strength.
40 citations
TL;DR: In this article, the authors presented passive network properties of individual multi-walled carbon nanotubes (MWNTs) up to 110 GHz measured at room temperature and extracted frequency-dependent electric properties of the MWNTs using an equivalent R-L-C circuit model.
Abstract: Metallic carbon nanotubes (CNTs) are promising as transmission lines or interconnects in radio-frequency nanoelectric circuits. This paper presents passive network properties of individual multi-walled carbon nanotubes (MWNTs) up to 110 GHz measured at room temperature. From the S-parameter data, frequency-dependent electric properties of the MWNT were extracted using an equivalent R-L-C circuit model. The ac impedance of the MWNT decreases significantly with increasing frequency, as predicted by earlier theoretical work. In particular, the equivalent resistance decreases a few hundred times. Our findings show that MWNTs can carry high-frequency currents much better than dc.
29 citations
TL;DR: Combinations of up to 6 zone-edge and zone-center optical phonons are observed in the Raman spectra of individual single-walled carbon nanotubes (SWNTs) and provide information on the phonon structure, exciton-phonon coupling, and excitonic transitions in nanot tubes.
Abstract: (Received 25 June 2006; published 23 January 2007)Combinations of up to 6 zone-edge and zone-center optical phonons are observed in the Raman spectraof individual single-walled carbon nanotubes (SWNTs) These multiphonon Raman modes exhibit distinctsignatures of the one-dimensional nature of SWNTs and provide information on the phonon structure,exciton-phonon coupling, and excitonic transitions in nanotubes
26 citations
TL;DR: In this article, a hybrid CNFET/CMOS inverter is presented that combines carbon nanotube field effect transistors (CNFET) with conventional, silicon-based complementary metal oxide semiconductor (CMOS) technology.
Abstract: A hybrid technology is presented that combines carbon nanotube field-effect transistors (CNFET) with conventional, silicon-based complementary metal oxide semiconductor (CMOS) technology. The fabrication involves the chemical vapor deposition growth and optical characterization of carbon nanotubes, which are then transferred with lithographic precision onto a commercially fabricated CMOS substrate. In this manner, CNFET devices are fabricated on top of the interconnection network of the CMOS chip, providing a three-dimensional integration of active devices, “sandwiching” wiring, and passives. As a demonstration of this approach, a simple hybrid CNFET/CMOS inverter is fabricated and tested.
15 citations
TL;DR: Carbon nanotubes have been used to probe the properties of bilayer systems resembling living cell membranes, and could offer new insights into the working of cells.
Abstract: Carbon nanotubes have been used to probe the properties of bilayer systems resembling living cell membranes. Such experiments could offer new insights into the working of cells.
8 citations
Patent•
02 Mar 2007
TL;DR: In this paper, a cell growth substrate and an external force generator associated with the substrate is presented for stimulating growth of a cell in vitro, cell differentiation in vitro and a cellular response in vivo, for treating a wound.
Abstract: The present invention provides for a cell growth substrate, wherein the substrate comprises a growth medium and a cross-linked polymer, wherein increased strain on the polymer does not substantially increase rigidity of the polymer, and wherein the polymer has an elastic modulus (E) of about 0.1 kPa to about 10.0 kPa. An apparatus for applying a perturbation to a cell in vitro is also provided, wherein the apparatus comprises the cell growth substrate and an external force generator associated with the substrate. The invention further provides methods for stimulating growth of a cell in vitro, cell differentiation in vitro, and a cellular response in vitro, for promoting growth of a cell in vivo, for treating a wound.
TL;DR: In this paper, a method of controlling the nonlinearity of nano-resonators without additional complicated systems is presented, where the critical amplitude up to which the resonators display linear harmonic oscillation increases with increasing electrothermal power.
Abstract: A method of controlling the nonlinearity of nano-resonators without additional complicated systems is presented. With increasing electrothermal power, the critical amplitude up to which the resonators display linear harmonic oscillation increases. Using this technique, the resonator driven into the nonlinear regime can be recovered back into the linear range.
06 May 2007
TL;DR: In this paper, the effect of axial strain on individual single-walled carbon nanotubes has been investigated experimentally and changes in the optical transition energies reflect both the nature of the transition being probed and crystallographic structure of the nanotube.
Abstract: The effect of axial strain on individual single-walled carbon nanotubes has been investigated experimentally. Changes in the optical transition energies reflect both the nature of the transition being probed and crystallographic structure of the nanotube.
06 May 2007
TL;DR: In this paper, the Raman spectra of the high energy (G) modes from individual metallic carbon nanotubes were obtained and broadened to widths up to 100 cm, indicating strong phonon damping by electron-hole pairs.
Abstract: We have obtained Raman spectra of the high-energy (G) modes from individual metallic carbon nanotubes. The Raman lines are broadened to widths up to 100 cm?1, indicating strong phonon damping by electron-hole pairs.