Showing papers by "James Hone published in 2006"
TL;DR: This work describes a method to wire molecules into gaps in single-walled carbon nanotubes (SWNTs) and shows how to install functionality in the molecular backbone that allows the conductance of the single-molecule bridges to switch with pH.
Abstract: Molecular electronics is often limited by the poorly defined nature of the contact between the molecules and the metal surface. We describe a method to wire molecules into gaps in single-walled carbon nanotubes (SWNTs). Precise oxidative cutting of a SWNT produces carboxylic acid-terminated electrodes separated by gaps of
467 citations
TL;DR: This work directly verified the systematic changes in transition energies of semiconducting nanotubes as a function of their chirality and observed predicted energy splittings of optical transitions in metallic nanot tubes.
Abstract: We simultaneously determined the physical structure and optical transition energies of individual single-walled carbon nanotubes by combining electron diffraction with Rayleigh scattering spectroscopy These results test fundamental features of the excited electronic states of carbon nanotubes We directly verified the systematic changes in transition energies of semiconducting nanotubes as a function of their chirality and observed predicted energy splittings of optical transitions in metallic nanotubes
228 citations
TL;DR: In this paper, Rayleigh scattering spectroscopy is applied to probe the optical transitions of given individual carbon nanotubes in their isolated and bundled forms, and the transition energies of SWNTs are observed to undergo redshifts of tens of meVs.
Abstract: The electronic properties of single-walled carbon nanotubes (SWNTs) are altered by intertube coupling whenever bundles are formed. These effects are examined experimentally by applying Rayleigh scattering spectroscopy to probe the optical transitions of given individual SWNTs in their isolated and bundled forms. The transition energies of SWNTs are observed to undergo redshifts of tens of meVs upon bundling with other SWNTs. These intertube coupling effects can be understood as arising from the mutual dielectric screening of SWNTs in a bundle.
124 citations
TL;DR: In this paper, a highly effective electrothermal tuning method is demonstrated for Al-SiC nanomechanical resonators, which can be used for effective frequency tuning in deployable SiC-based nanoelectromechanical system devices and systems for applications that would benefit from SiC as the structural material.
Abstract: A highly effective electrothermal tuning method is demonstrated for Al–SiC nanomechanical resonators. Doubly clamped beam devices are actuated and read out using a magnetomotive technique under a moderate vacuum at room temperature. Direct current applied to a beam heats the structure and shifts the resonance frequency downward. Frequency shifts of 10% are easily achievable, and the thermal time constant of these structures is in the submicrosecond range. The initial frequency and frequency tunability are studied for beams of varying Al thickness, and the device performance can be accurately modelled using simple mechanical and thermal models. Because of the different mechanical properties of SiC and Al, both the initial frequency and the frequency tunability can be modified by varying the Al layer thickness. This approach has the potential to become an important tool for effective frequency tuning in deployable SiC-based nanoelectromechanical system devices and systems for applications that would benefit from SiC as the structural material.
106 citations
TL;DR: It is found that tilting the substrates supporting the Co ultrathin film catalysts can grow more, longer carbon nanotubes, and a mechanism is discussed for the growth of long SWNTs.
Abstract: We report a simple and efficient chemical vapor deposition (CVD) process that can grow oriented and long single-walled carbon nanotubes (SWNTs) using a cobalt ultrathin film (∼1 nm) as the catalyst and ethanol as carbon feedstock. In the process, millimeter- to centimeter-long, oriented and high-quality SWNTs can grow horizontally on various flat substrate surfaces, traverse slits as large as hundreds of micrometers wide, or grow over vertical barriers as high as 20 μm. Such observations demonstrate that the carbon nanotubes are suspended in the gas flow during the growth. The trace amount of self-contained water (0.2−5 wt %) in ethanol may act as a mild oxidizer to clean the nanotubes and to elongate the lifetime of the catalysts, but no yield improvement was observed at the CVD temperature of 850 °C. We found that tilting the substrates supporting the Co ultrathin film catalysts can grow more, longer carbon nanotubes. A mechanism is discussed for the growth of long SWNTs.
88 citations
TL;DR: In this paper, a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual single-walled carbon nanotubes as shadow masks during metal deposition, was described.
Abstract: We describe a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual single-walled carbon nanotubes as shadow masks during metal deposition. More than 80% of the devices display current-voltage dependencies characteristic of direct electron tunneling. Fits to the current-voltage data yield gap widths in the 0.8–2.3nm range for these devices, dimensions that are well suited for single-molecule transport measurements.
29 citations
TL;DR: In this paper, a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual single-walled carbon nanotubes as shadow masks during metal deposition, was described.
Abstract: We describe a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual single-walled carbon nanotubes as shadow masks during metal deposition. More than 80% of the devices display current-voltage dependencies characteristic of direct electron tunneling. Fits to the current-voltage data yield gap widths in the 0.8-2.3 nm range for these devices, dimensions that are well suited for single-molecule transport measurements.
21 citations
TL;DR: In this article, a method for producing nanometer-scale gaps, based on metal evaporation through a suspended single-walled carbon nanotube acting as a shadow mask, is presented.
Abstract: The authors present a method for producing nanometer-scale gaps, based on metal evaporation through a suspended single-walled carbon nanotube acting as a shadow mask. 83% of the nanogap devices display current-voltage dependencies characteristic of direct electron tunneling. Fits to the current-voltage data yield gap widths in the 0.8–2.3nm range for these devices, dimensions that are well suited for single-molecule transport measurements.
16 citations
TL;DR: In this article, the authors used a mechanical transfer technique in parallel with optical characterization, achieving the goal of placing "the nanotube we want, where we want it" using long nanotubes grown by CVD across a slit etched through a Si wafer.
Abstract: Because subtle changes in physical structure (chirality) can cause the electronic structure of carbon nanotubes to vary from metallic to semiconducting, the goal of fully controlled nanotube device fabrication has proved elusive. Using a mechanical transfer technique in parallel with optical characterization, we have achieved the goal of placing 'the nanotube we want, where we want it'. Long nanotubes are grown by CVD across a slit etched through a Si wafer and then examined by Rayleigh scattering. By combining this technique with structural characterization by electron diffraction, we are able to map each spectrum to a unique (n, m) structure. After structural characterization, a chosen nanotube can be transferred to a substrate in the desired location, and devices fabricated using standard e-beam lithography techniques. We have fabricated a number of devices in this manner and are beginning to fully explore the detailed relationship between structure and transport.
15 citations
TL;DR: In this paper, the resonance frequency of a nanomechanical silicon carbide resonator was tuned to 10.12 MHz using the magnetomotive transduction technique and the resonance quality was improved by 10% with Joule heating of DC current.
Abstract: Electrothermal tuning of nanomechanical silicon carbide resonators has been demonstrated. The detected mechanical resonance of the untuned resonator was 10.12 MHz and has a quality factor of about 2000 as measured using the magnetomotive transduction technique. Also, the resonance frequency was tuned by 10% with Joule heating of DC current.
14 citations
TL;DR: In this article, single crystal nanowires of gold were fabricated from a single grain of pure gold leaf by standard lithographic techniques, with center section of 7μm in length, 250nm in width, and 100nm in thickness.
Abstract: Freestanding single crystal nanowires of gold were fabricated from a single grain of pure gold leaf by standard lithographic techniques, with center section of 7μm in length, 250nm in width, and 100nm in thickness. The ends remained anchored to a silicon substrate. The specimens were deflected via nanoindenter until plastic deformation was achieved. Nonlocalized and localized plastic deformations were observed. The resulting force-displacement curves were simulated using continuum single crystal plasticity. A set of material parameters which closely reproduce the experimental results suggests that the initial critical resolved shear stress was as high as 135MPa.
Journal Article•
TL;DR: The electronic properties of single-walled carbon nanotubes (SWNTs) are altered by intertube coupling whenever bundles are formed by applying Rayleigh scattering spectroscopy to probe the optical transitions of given individual SWNTs in their isolated and bundled forms.
Abstract: Feng Wang, Matthew Y. Sfeir, Limin Huang, X. M. Henry Huang, Yang Wu, Jaehee Kim, James Hone, Stephen O’Brien, Louis E. Brus, and Tony F. Heinz Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA Department of Chemistry, Columbia University, New York, New York 10027, USA Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA (Received 31 August 2005; published 28 April 2006)
Journal Article•
Journal Article•
20 Oct 2006
TL;DR: In this paper, the optical transitions of individual single-walled carbon nanotubes are measured in their isolated and bundled forms, and the observed inter-tube coupling effects attributed to dielectric screening are discussed.
Abstract: Optical transitions of individual single-walled carbon nanotubes are measured in their isolated and bundled forms. The observed inter-tube coupling effects attributed to dielectric screening.
TL;DR: In this article, the physical displacement of individual single-walled carbon nanotubes is measured by Rayleigh light scattering and each nanotube's Young's modulus is determined by an applied Lorentz force.
Abstract: The physical displacement of individual single-walled carbon nanotubes is measured by Rayleigh light scattering. Each nanotube's Young's modulus is determined by an applied Lorentz force.
21 May 2006
TL;DR: In this paper, the physical structure and optical transition energies of individual single-walled carbon nanotubes were determined by combining electron diffraction with Rayleigh scattering spectroscopy, which permits study of the energy-level structure as a function of nanotube chirality.
Abstract: By combining electron diffraction with Rayleigh scattering spectroscopy, we determine the physical structure and optical transition energies of individual single-walled carbon nanotubes. This permits study of the energy-level structure as a function of nanotube chirality.
01 Jan 2006
TL;DR: In this article, Rayleigh scattering spectroscopy is applied to probe the optical transitions of given individual carbon nanotubes in their isolated and bundled forms, and the transition energies of SWNTs are observed to undergo redshifts of tens of meVs.
Abstract: The electronic properties of single-walled carbon nanotubes (SWNTs) are altered by intertube coupling whenever bundles are formed. These effects are examined experimentally by applying Rayleigh scattering spectroscopy to probe the optical transitions of given individual SWNTs in their isolated and bundled forms. The transition energies of SWNTs are observed to undergo redshifts of tens of meVs upon bundling with other SWNTs. These intertube coupling effects can be understood as arising from the mutual dielectric screening of SWNTs in a bundle.
TL;DR: By combining electron diffraction with Rayleigh scattering spectroscopy, the crystal structure and optical transition energies of individual single-walled carbon nanotubes were determined in this article.
Abstract: By combining electron diffraction with Rayleigh scattering spectroscopy, we simultaneously determine the crystal structure and the optical transition energies of individual single-walled carbon nanotubes.