Showing papers on "Carbon nanotube published in 2001"
TL;DR: A review of recent advances in carbon nanotubes and their composites can be found in this article, where the authors examine the research work reported in the literature on the structure and processing of carbon Nanotubes.
4,709 citations
TL;DR: The assembly of functional nanoscale devices from indium phosphide nanowires, the electrical properties of which are controlled by selective doping are reported, and electric-field-directed assembly can be used to create highly integrated device arrays from nanowire building blocks.
Abstract: Nanowires and nanotubes carry charge and excitons efficiently, and are therefore potentially ideal building blocks for nanoscale electronics and optoelectronics. Carbon nanotubes have already been exploited in devices such as field-effect and single-electron transistors, but the practical utility of nanotube components for building electronic circuits is limited, as it is not yet possible to selectively grow semiconducting or metallic nanotubes. Here we report the assembly of functional nanoscale devices from indium phosphide nanowires, the electrical properties of which are controlled by selective doping. Gate-voltage-dependent transport measurements demonstrate that the nanowires can be predictably synthesized as either n- or p-type. These doped nanowires function as nanoscale field-effect transistors, and can be assembled into crossed-wire p-n junctions that exhibit rectifying behaviour. Significantly, the p-n junctions emit light strongly and are perhaps the smallest light-emitting diodes that have yet been made. Finally, we show that electric-field-directed assembly can be used to create highly integrated device arrays from nanowire building blocks.
3,280 citations
TL;DR: The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device and shows linear temperature dependence with a value of 80 microV/K at room temperature.
Abstract: The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W/K m at room temperature, which is 2 orders of magnitude higher than the estimation from previous experiments that used macroscopic mat samples. The temperature dependence of the thermal conductivity of nanotubes exhibits a peak at 320 K due to the onset of umklapp phonon scattering. The measured thermoelectric power shows linear temperature dependence with a value of 80 microV/K at room temperature.
3,166 citations
TL;DR: Observations suggest that carbon nanotubes, with their rigid nonpolar structures, might be exploited as unique molecular channels for water and protons, with the channel occupancy and conductivity tunable by changes in the local channel polarity and solvent conditions.
Abstract: Confinement of matter on the nanometre scale can induce phase transitions not seen in bulk systems1. In the case of water, so-called drying transitions occur on this scale2,3,4,5 as a result of strong hydrogen-bonding between water molecules, which can cause the liquid to recede from nonpolar surfaces to form a vapour layer separating the bulk phase from the surface6. Here we report molecular dynamics simulations showing spontaneous and continuous filling of a nonpolar carbon nanotube with a one-dimensionally ordered chain of water molecules. Although the molecules forming the chain are in chemical and thermal equilibrium with the surrounding bath, we observe pulse-like transmission of water through the nanotube. These transmission bursts result from the tight hydrogen-bonding network inside the tube, which ensures that density fluctuations in the surrounding bath lead to concerted and rapid motion along the tube axis7,8,9. We also find that a minute reduction in the attraction between the tube wall and water dramatically affects pore hydration, leading to sharp, two-state transitions between empty and filled states on a nanosecond timescale. These observations suggest that carbon nanotubes, with their rigid nonpolar structures10,11, might be exploited as unique molecular channels for water and protons, with the channel occupancy and conductivity tunable by changes in the local channel polarity and solvent conditions.
3,115 citations
TL;DR: In this paper, a self-consistent ab initio technique for modeling quantum transport properties of atomic and molecular scale nanoelectronic devices under external bias potentials was proposed, based on density functional theory using norm conserving nonlocal pseudopotentials to define the atomic core and nonequilibrium Green's functions (NEGF's) to calculate the charge distribution.
Abstract: We report on a self-consistent ab initio technique for modeling quantum transport properties of atomic and molecular scale nanoelectronic devices under external bias potentials. The technique is based on density functional theory using norm conserving nonlocal pseudopotentials to define the atomic core and nonequilibrium Green's functions (NEGF's) to calculate the charge distribution. The modeling of an open device system is reduced to a calculation defined on a finite region of space using a screening approximation. The interaction between the device scattering region and the electrodes is accounted for by self-energies within the NEGF formalism. Our technique overcomes several difficulties of doing first principles modeling of open molecular quantum coherent conductors. We apply this technique to investigate single wall carbon nanotubes in contact with an Al metallic electrode. We have studied the current-voltage characteristics of the nanotube-metal interface from first principles. Our results suggest that there are two transmission eigenvectors contributing to the ballistic conductance of the interface, with a total conductance $G\ensuremath{\approx}{G}_{0}$ where ${G}_{0}{=2e}^{2}/h$ is the conductance quanta. This is about half of the expected value for infinite perfect metallic nanotubes.
2,581 citations
TL;DR: In this paper, the authors have produced nanotube-in-oil suspensions and measured their effective thermal conductivity, which is anomalously greater than theoretical predictions and is nonlinear with nanotubes loadings.
Abstract: We have produced nanotube-in-oil suspensions and measured their effective thermal conductivity. The measured thermal conductivity is anomalously greater than theoretical predictions and is nonlinear with nanotube loadings. The anomalous phenomena show the fundamental limits of conventional heat conduction models for solid/liquid suspensions. We have suggested physical concepts for understanding the anomalous thermal behavior of nanotube suspensions. In comparison with other nanostructured materials dispersed in fluids, the nanotubes provide the highest thermal conductivity enhancement, opening the door to a wide range of nanotube applications.
2,546 citations
TL;DR: Single-walled carbon nanotubes are molecular wires that exhibit interesting structural, mechanical, electrical, and electromechanical properties that make for an ideal miniaturized sensor.
Abstract: Single-walled carbon nanotubes (SWNTs) are molecular wires that exhibit interesting structural, mechanical, electrical, and electromechanical properties. 1-3 A SWNT is unique among solidstate materials in that every atom is on the surface. Surface chemistry could therefore be critical to the physical properties of SWNTs and their applications. 3-10 SWNT sidewall functionalization is important to soluble nanotubes, 4-6 self-assembly on surfaces, and chemical sensors. 8-10 For these purposes, it is imperative to functionalize the sidewalls of SWNTs in noncovalent ways to preserve the sp 2 nanotube structure and thus their electronic characteristics. Immobilization of biomolecules on carbon nanotubes has been pursued in the past, motivated by the prospects of using nanotubes as new types of biosensor materials. 11-15 The electronic properties of nanotubes coupled with the specific recognition properties of the immobilized biosystems would indeed make for an ideal miniaturized sensor. A prerequisite for research in this area is the development of chemical methods to immobilize biological molecules onto carbon nanotubes in a reliable manner. Thus far, only limited work has been carried out with multiwalled carbon nanotubes (MWNTs). 11-15 Metallothionein proteins were trapped inside and placed onto the outer surfaces of open-ended MWNTs.11-14 Streptavidin was found to adsorb on MWNTs presumably via hydrophobic interactions between the nanotubes and hydrophobic domains of the proteins. 15 DNA molecules adsorbed on MWNTs via nonspecific interactions were also observed. 12-14
2,516 citations
Book•
01 Jan 2001
TL;DR: In this article, the relationship of carbon nanotubes to other carbon materials has been discussed, and the properties of single-wall and multi-wall carbon Nanotubes have been investigated.
Abstract: Introduction to Carbon Materials Research (M.S. Dresselhaus, Ph. Avouris).- Relation of Carbon Nanotubes to Other Carbon Materials (M.S. Dresselhaus, M. Endo).- Nanotube Growth and Characterization (Dai).- Growth Mechanisms (J.-C. Charlier, S. Iijima).- Nanotubes from Inorganic Materials (R. Tenne, A.K. Zettl).- Electronic Properties and Defects (S.G. Louie).- Electrical Transport in Single-Wall Carbon Nanotubes (Z. Yao, C. Dekker, Ph. Avouris).- Scanning Probe Microscopy Studies (T.W. Odom, J.H. Hafner, C.M. Lieber).- Optical Properties and Raman Spectroscopy (R. Saito, H. Kataura).- Electron Spectroscopy Studies (J.H. Fink, P. Lambin).- Phonons and Thermal Properties of Carbon Nanotubes (J. Hone).- Mechanical Properties (B.I. Yakobson, Ph. Avouris).- Physical Properties of Multi-Wall Nanotubes (L. Forro, C. Schonenberger).- Applications of Carbon Nanotubes (P.M. Ajayan, O.Z. Zhou).- Subject Index.
2,444 citations
IBM1
TL;DR: A simple and reliable method for selectively removing single carbon shells from MWNTs and SWNT ropes to tailor the properties of these composite nanotubes and to directly address the issue of multiple-shell transport.
Abstract: Carbon nanotubes display either metallic or semiconducting properties. Both large, multiwalled nanotubes (MWNTs), with many concentric carbon shells, and bundles or “ropes” of aligned single-walled nanotubes (SWNTs), are complex composite conductors that incorporate many weakly coupled nanotubes that each have a different electronic structure. Here we demonstrate a simple and reliable method for selectively removing single carbon shells from MWNTs and SWNT ropes to tailor the properties of these composite nanotubes. We can remove shells of MWNTs stepwise and individually characterize the different shells. By choosing among the shells, we can convert a MWNT into either a metallic or a semiconducting conductor, as well as directly address the issue of multiple-shell transport. With SWNT ropes, similar selectivity allows us to generate entire arrays of nanoscale field-effect transistors based solely on the fraction of semiconducting SWNTs.
1,838 citations
TL;DR: In this article, the theoretical external specific surface area of single and multi-walled carbon nanotubes and of carbon-nanotube bundles is calculated as a function of their characteristics.
1,836 citations
TL;DR: In this paper, a general thermodynamic drive for this wrapping is discussed, wherein the polymer disrupts both the hydrophobic interface with water and the smooth tube-tube interactions in aggregates.
TL;DR: Nanotubes derivatized with a 4-tert-butylbenzene moiety were found to possess significantly improved solubility in organic solvents and represents the marriage of wire-like nanotubes with molecular electronic devices.
Abstract: Small-diameter (ca. 0.7 nm) single-wall carbon nanotubes are predicted to display enhanced reactivity relative to larger-diameter nanotubes due to increased curvature strain. The derivatization of these small-diameter nanotubes via electrochemical reduction of a variety of aryl diazonium salts is described. The estimated degree of functionalization is as high as one out of every 20 carbons in the nanotubes bearing a functionalized moiety. The functionalizing moieties can be removed by heating in an argon atmosphere. Nanotubes derivatized with a 4-tert-butylbenzene moiety were found to possess significantly improved solubility in organic solvents. Functionalization of the nanotubes with a molecular system that has exhibited switching and memory behavior is shown. This represents the marriage of wire-like nanotubes with molecular electronic devices.
TL;DR: It is shown that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes, by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions.
Abstract: We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an (n,m) individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t). For example, the strong RBM intensity observed at 156 cm(-1) for 785 nm laser excitation is assigned to the (13,10) metallic chiral nanotube on a Si/SiO2 surface.
TL;DR: In this article, the current carrying capacity and reliability of multiwalled carbon nanotubes under high current densities (>109 A/cm2) were investigated and shown that no observable failure in the nanotube structure and no measurable change in the resistance are detected at temperatures up to 250 ˚C and for time scales up to 2 weeks.
Abstract: The current-carrying capacity and reliability studies of multiwalled carbon nanotubes under high current densities (>109 A/cm2) show that no observable failure in the nanotube structure and no measurable change in the resistance are detected at temperatures up to 250 °C and for time scales up to 2 weeks. Our results suggest that nanotubes are potential candidates as interconnects in future large-scale integrated nanoelectronic devices.
IBM1
TL;DR: In this paper, the authors showed that n-type carbon nanotubes can be prepared not only by doping but also by simple annealing of SWNT-based p-FETs in a vacuum.
Abstract: Single wall carbon nanotubes (SWCNTs) have been used as the active channels of field effect transistors (FET). The next development step involves the integration of CNTFETs to form logic gates; the basic units of computers. For this we need to have both p- and n-type CNTFETs. However, without special treatment, the obtained CNTFETs are always p-type: the current carriers are holes and the devices are ON for negative gate bias. Here we show that n-type CNTFETs can be prepared not only by doping but also by a simple annealing of SWNT-based p-FETs in a vacuum. We use our ability to prepare both p- and n-type nanotube transistors to build the first nanotube-based logic gates: voltage inverters. Using spatially resolved doping we implemented this logic function on a single nanotube bundle.
01 Mar 2001
TL;DR: In this paper, a unique chirality assignment was made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t).
Abstract: We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an (n,m) individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t). For example, the strong RBM intensity observed at 156 cm(-1) for 785 nm laser excitation is assigned to the (13,10) metallic chiral nanotube on a Si/SiO2 surface.
TL;DR: In this paper, the growth of vertically aligned carbon nanotubes using a direct current plasma enhanced chemical vapor deposition system was reported, and the growth properties were studied as a function of the Ni catalyst layer thickness, bias voltage, deposition temperature, C2H2:NH3 ratio, and pressure.
Abstract: The growth of vertically aligned carbon nanotubes using a direct current plasma enhanced chemical vapor deposition system is reported. The growth properties are studied as a function of the Ni catalyst layer thickness, bias voltage, deposition temperature, C2H2:NH3 ratio, and pressure. It was found that the diameter, growth rate, and areal density of the nanotubes are controlled by the initial thickness of the catalyst layer. The alignment of the nanotubes depends on the electric field. Our results indicate that the growth occurs by diffusion of carbon through the Ni catalyst particle, which rides on the top of the growing tube.
TL;DR: Simulations of the behaviour of water encapsulated in carbon nanotubes suggest the existence of a variety of new ice phases not seen in bulk ice, and of a solid–liquid critical point beyond which the distinction between solid and liquid phases disappears.
Abstract: Following their discovery1, carbon nanotubes have attracted interest not only for their unusual electrical and mechanical properties, but also because their hollow interior can serve as a nanometre-sized capillary2,3,4,5,6,7, mould8,9,10,11 or template12,13,14 in material fabrication. The ability to encapsulate a material in a nanotube also offers new possibilities for investigating dimensionally confined phase transitions15. Particularly intriguing is the conjecture16 that matter within the narrow confines of a carbon nanotube might exhibit a solid–liquid critical point17 beyond which the distinction between solid and liquid phases disappears. This unusual feature, which cannot occur in bulk material, would allow for the direct and continuous transformation of liquid matter into a solid. Here we report simulations of the behaviour of water encapsulated in carbon nanotubes that suggest the existence of a variety of new ice phases not seen in bulk ice, and of a solid–liquid critical point. Using carbon nanotubes with diameters ranging from 1.1 nm to 1.4 nm and applied axial pressures of 50 MPa to 500 MPa, we find that water can exhibit a first-order freezing transition to hexagonal and heptagonal ice nanotubes, and a continuous phase transformation into solid-like square or pentagonal ice nanotubes.
TL;DR: Room-temperature single-electron transistors are realized within individual metallic single-wall carbon nanotube molecules, and unconventional power-law dependencies in the measured transport properties are observed for which a resonant tunneling Luttinger-liquid mechanism is suggested.
Abstract: Room-temperature single-electron transistors are realized within individual metallic single-wall carbon nanotube molecules. The devices feature a short (down to ∼20 nanometers) nanotube section that is created by inducing local barriers into the tube with an atomic force microscope. Coulomb charging is observed at room temperature, with an addition energy of 120 millielectron volts, which substantially exceeds the thermal energy. At low temperatures, we resolve the quantum energy levels corresponding to the small island. We observe unconventional power-law dependencies in the measured transport properties for which we suggest a resonant tunneling Luttinger-liquid mechanism.
TL;DR: This work describes an example of a coherent molecular electronic device whose behaviour is explicitly dependent on quantum interference between propagating electron waves—a Fabry–Perot electron resonator based on individual single-walled carbon nanotubes with near-perfect ohmic contacts to electrodes.
Abstract: The behaviour of traditional electronic devices can be understood in terms of the classical diffusive motion of electrons. As the size of a device becomes comparable to the electron coherence length, however, quantum interference between electron waves becomes increasingly important, leading to dramatic changes in device properties. This classical-to-quantum transition in device behaviour suggests the possibility for nanometer-sized electronic elements that make use of quantum coherence. Molecular electronic devices are promising candidates for realizing such device elements because the electronic motion in molecules is inherently quantum mechanical and it can be modified by well defined chemistry. Here we describe an example of a coherent molecular electronic device whose behaviour is explicitly dependent on quantum interference between propagating electron waves-a Fabry-Perot electron resonator based on individual single-walled carbon nanotubes with near-perfect ohmic contacts to electrodes. In these devices, the nanotubes act as coherent electron waveguides, with the resonant cavity formed between the two nanotube-electrode interfaces. We use a theoretical model based on the multichannel Landauer-Buttiker formalism to analyse the device characteristics and find that coupling between the two propagating modes of the nanotubes caused by electron scattering at the nanotube-electrode interfaces is important.
01 Jan 2001
TL;DR: Carbon nanotubes have attracted the fancy of many scientists worldwide as discussed by the authors, and the small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications.
Abstract: Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications. In this review we describe some of the important materials science applications of carbon nanotubes. Specifically we discuss the electronic and electrochemical applications of nanotubes, nanotubes as mechanical reinforcements in high performance composites, nanotube-based field emitters, and their use as nanoprobes in metrology and biological and chemical investigations, and as templates for the creation of other nanostructures. Electronic properties and device applications of nanotubes are treated elsewhere in the book. The challenges that ensue in realizing some of these applications are also discussed from the point of view of manufacturing, processing, and cost considerations.
TL;DR: In this paper, a multistage purification method has been investigated for extracting the Fe metal catalyst and non-SWNT carbon from nanotubes produced by the HiPco process.
Abstract: A purification method is given for extracting the Fe metal catalyst and non-SWNT carbon from nanotubes produced by the HiPco process.1,2 A multistage purification method has been investigated. Sample purity is documented by ESEM, TEM, TGA, Raman and UV-vis−near-IR spectroscopy. Metal catalyzed oxidation at low temperature has been shown to selectively remove non-SWNT carbon and permit extraction of iron with concentrated HCl. Prolonged catalyzed oxidation has been found to preferentially remove smaller diameter tubes. The onset of oxidation of purified smaller diameter HiPco SWNTs is also found to be approximately 100 °C lower than for purified larger diameter tubes produced in the laser-oven process.
TL;DR: In this article, the diameters of single-walled carbon nanotubes are determined by their diameters in the cores of catalytic nanoparticles with diameters between 1−2 nm and 3−5 nm.
Abstract: Discrete catalytic nanoparticles with diameters in the range of 1−2 nm and 3−5 nm respectively are obtained by placing controllable numbers of metal atoms into the cores of apoferritin, and used for growth of single-walled carbon nanotube (SWNTs) on substrates by chemical vapor deposition (CVD). Atomic force microscopy (AFM), transmission electron microscopy (TEM), and micro-Raman spectroscopy are used to characterize isolated nanotubes grown from the discrete nanoparticles. The characterizations, carried out at single-tube and single-particle level, obtain clear evidence that the diameters of nanotubes are determined by the diameters of catalytic nanoparticles. With nanoparticles placed on ultrathin alumina membranes, isolated SWNTs are grown and directly examined by transmission electron microscopy. For the first time, both ends of an as-grown single-walled nanotube are imaged by TEM, leading to a microscopic picture of nanotube growth mechanism. It is shown that controlling the structures of catalytic ...
IBM1
TL;DR: Single-wall carbon nanotube (SWNT) field-effect transistors offer the novel possibility of ambipolar Ohmic contacts and the properties of SWNT junctions to TiC are discussed in detail.
Abstract: Ambipolar electrical transport is reported in single-wall carbon nanotube (SWNT) field-effect transistors. In particular, the properties of SWNT junctions to TiC are discussed in detail. The carbide-nanotube junctions are abrupt and robust. In contrast to planar junctions, these contacts present low resistance for the injection of both $p$- and $n$-type carriers---the apparent barrier height of the junction is modified by the gate field. Thus SWNTs offer the novel possibility of ambipolar Ohmic contacts.
TL;DR: The electrochemical behavior of a film of single-wall carbon nanotubes functionalized with carboxylic acid groups was studied extensively on a glassy carbon (GC) electrode and showed favorable electrocatalytic behavior toward the oxidation of biomolecules such as dopamine, epinephrine, and ascorbic acid.
Abstract: The electrochemical behavior of a film of single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups was studied extensively on a glassy carbon (GC) electrode. One stable couple corresponding to the redox of the carboxylic acid group, which was supported by XPS and IR experiments, was observed. The electrode process involved four electrons, while the rate-determining step was a one-electron reduction. The SWNT film-modified electrode showed favorable electrocatalytic behavior toward the oxidation of biomolecules such as dopamine, epinephrine, and ascorbic acid.
01 Jan 2001
TL;DR: An overview of the mechanical properties of carbon nanotubes, starting from the linear elastic parameters, nonlinear elastic instabilities and buckling, and the inelastic relaxation, yield strength and fracture mechanisms is presented in this paper.
Abstract: This paper presents an overview of the mechanical properties of carbon nanotubes, starting from the linear elastic parameters, nonlinear elastic instabilities and buckling, and the inelastic relaxation, yield strength and fracture mechanisms. A summary of experimental findings is followed by more detailed discussion of theoretical and computational models for the entire range of the deformation amplitudes. Non-covalent forces (supra-molecular interactions) between the nanotubes and with the substrates are also discussed, due to their significance in potential applications.
TL;DR: In this paper, pyridine-like N structures are observed to be responsible for the metallic behavior and prominent features near the Fermi level, which could pave the way to real molecular heterojunction devices.
Abstract: Nitrogen-doped carbon nanotubes have been synthesized using pyrolysis and characterized by scanning tunneling spectroscopy and transmission electron microscopy. The doped nanotubes are all metallic and exhibit strong electron donor states near the Fermi level. Using tight-binding and ab initio calculations, we observe that pyridine-like N structures are responsible for the metallic behavior and the prominent features near the Fermi level. These electron rich structures are the first example of n-type nanotubes, which could pave the way to real molecular heterojunction devices.