Meyya Meyyappan

Carbon Nanotubes : Science and Applications

STRUCTURES AND PROPERTIES OF CARBON NANOTUBES, Jie Han Bonding of Carbon Atoms Defect-Free Nanotube Defective Nanotubes Electrical Properties Optical and Optoelectronic Properties Mechanical and Electromechanical Properties Magnetic and Electromagnetic Properties Chemical and Electrochemical Properties Thermal and Thermoelectric Properties COMPUTATIONAL NANOTECHNOLOGY OF CARBON NANOTUBES, Deepak Srivastava Multiscale Simulation Techniques for Computational Nanotechnology Structure and Symmetry Nanomechanics and Thermal Properties Chemical Functionalization, Physisorption, and Diffusion in Carbon Nanotubes Nanoelectronics and Sensors Summary and Outlook GROWTH OF CARBON NANOTUBES BY ARC DISCHARGE AND LASER ABLATION, Alexander P. Moravsky, Eugene M. Wexler, and Raouf O. Loutfy Arc Discharge Production of MWNTs MWNT Production by Laser Ablation of Graphite Arc Discharge Production of SWNTs Arc Discharge Production of DWNTs SWNT Production by Laser Ablation of Carbon-Metal Target Conclusions GROWTH: CVD AND PECVD, M. Meyyappan Growth Apparatus Catalyst Preparation Growth Results Growth Mechanisms Modeling and Diagnostics Challenges and Future Directions CHARACTERIZATION TECHNIQUES IN CARBON NANOTUBE RESEARCH, K. McGuire and A.M. Rao Electron Microscopy Atomic Force and Scanning Tunneling Microscopy Properties Characterization Electrical Conductivity Measurements Thermoelectric Measurements Raman Spectroscopy X-Ray Diffraction Summary APPLICATIONS IN SCANNING PROBE MICROSCOPY, Cattien V. Nguyen Development of the Atomic Force Microscope and the Role of the Scanning Probe Mechanical Properties of Carbon Nanotubes in the Context of SPM Applications Fabrication of Carbon Nanotube Scanning Probes Applications of Carbon Nanotube Probes Summary NANOELECTRONICS APPLICATIONS, Toshishige Yamada Carrier Characterization Doping Methods SWNT FETs Intermolecular Metal-Semiconductor SWNT Heterojunctions SWNT pn Junction as Esaki Diode Single-Electron Tunneling Devices Using SWNTs Other Semiconducting SWNT Devices Transport in Metallic SWNTs General Remarks on NanoFETs FIELD EMISSION, Philippe Sarrazin Structure and Microstructure of CNT Emitters Applications of CNT Emitters Conclusions CARBON NANOTUBE APPLICATIONS: CHEMICAL AND PHYSICAL SENSORS, Jing Li Carbon Nanotube Chemical Sensors Carbon Nanotube Physical Sensors and Actuators Summary and Outlook APPLICATIONS: BIOSENSORS, Jun Li Fabrication of Carbon Nanotube Biosensors Biosensing Applications Summary and Future Directions APPLICATIONS: COMPOSITES, E.V. Barrera, M.L. Shofner, and E.L. Corral Nanotube Superiority Polymer Nanocomposites Nanotube-Metal Composites Ceramic Matrix Composites Summary and Outlook OTHER APPLICATIONS, M. Meyyappan Applications in Integrated Circuit Manufacturing Catalyst Support and Absorbents Storage/Intercalation of Metals Membranes and Separation

Functionalization of Carbon Nanotubes

The functionalization of single wall carbon nanotubes (SWCNTs) is a very actively discussed topic in contemporary nanotube literature because the planned modification of SWCNT properties is believed to open the road towards real nanotechnology applications. In this contribution, some recent results are reported on the subject. Covalent attachment of functional groups, their influence on tube-tube stacking, detachment of functional groups, selective nand p-type intercalation as well as special reactions carried out in the interior of SWCNTs are discussed. Clean room conditions for interior of single wall carbon nanotubes is demonstrated.

Optical properties of single-crystalline ZnO nanowires on m-sapphire

ZnO nanowires have been synthesized using a catalyst-assisted heteroepitaxial carbothermal reduction approach on a m-sapphire substrate. Intricate and uniform arrays have been obtained with each nanowire forming an angle ∼30° with the substrate normal. Photoluminescence studies at room temperature for wavelengths between 335 and 620 nm reveal a strong single exciton peak at ∼380u2009nm (3.26 eV) with accompanying deep-level blueshifted emission peaks at ∼486, 490, and 510 nm. UV resonant Raman spectroscopy has been used to characterize the nanowires at room temperature with multiphonon scattering exhibiting phonon quantum confinement.

Ultrasensitive label-free DNA analysis using an electronic chip based on carbon nanotube nanoelectrode arrays

We report the detection of DNA PCR amplicons using an ultrasensitive label-free electronic technique based on multiwalled carbon nanotube (MWNT) nanoelectrode arrays embedded in an SiO(2) matrix. Specific PCR amplicons are reliably detected using electrochemical (EC) methods through allele-specific oligonucleotide hybridization. The inherent guanine bases in the DNA amplicon target of [Formula: see text] bases serve as signal moieties with the aid of Ru(bpy)(3)(2+) mediators, providing an amplified anodic current associated with the oxidation of guanine groups at the nanoelectrode surface. The reduced size and density of the nanoelectrode array provided by MWNTs dramatically improves the sensitivity of EC detection. In addition, the abundant guanine bases in target DNA produce a large signal. Less than [Formula: see text] target amplicons can be detected on a microspot, approaching the sensitivity limit of conventional laser-based fluorescence techniques. This method also eliminates the labelling requirement and makes the measurements much simpler. This platform can be employed for developing highly automated electronic chips with multiplex nanoelectrode arrays for quick DNA analysis.

Electronic properties of multiwalled carbon nanotubes in an embedded vertical array

We demonstrate integration of carbon nanotubes into large scale vertically aligned electrode arrays, by filling the as-grown samples with conformal SiO2 using chemical vapor deposition. Subsequent mechanical polishing yields a flat surface with only the very ends of the nanotube array exposed. The electronic properties of individual carbon nanotubes in the array are measured using current-sensing atomic force microscopy. These vertical nanotube arrays are suitable for fabricating various electronic devices and sensors.

Fabrication approach for molecular memory arrays

We present an approach to tackle long-standing problems in contacts, thermal damage, pinhole induced short circuits and interconnects in molecular electronic device fabrication and integration. Our approach uses metallic nanowires as top electrodes to connect and interconnect molecular wires assembled on electrode arrays in crossbar architectures. Using this simple and reliable approach, we have revealed intriguing memory effects for several different molecular wires, and demonstrated their applications in molecular memory arrays. Our approach has great potential to be used for fast screening of molecular wire candidates and construction of molecular devices.

Effects of gamma radiation on poly(methyl methacrylate)/single-wall nanotube composites

Single-wall carbon nanotube (SWNT)/poly(methyl methacrylate) (PMMA) composites were fabricated and exposed to ionizing radiation for a total dose of 5.9 Mrads. Neat nanotube paper and pure PMMA were also exposed for comparison, and nonirradiated samples served as controls. A concentration of 0.26 wt% SWNT increased the glass transition temperature ( T g ), the Vickers hardness number, and modulus of the matrix. Irradiation of the composite did not significantly change the T g , the Vickers hardness number, or the modulus; however, the real and imaginary parts of the complex permittivity increased after irradiation. The dielectric properties were found to be more labile to radiation effects than mechanical properties.

A glow-discharge approach for functionalization of carbon nanotubes

We demonstrate the functionalization of single-walled carbon nanotubes (SWNTs) using a glow discharge for generating atomic or molecular radicals. A 30-s exposure to a cold plasma of H2 results in near-saturation coverage of SWNT with atomic hydrogen. Functionalization of SWNTs with atomic hydrogen is confirmed by an infrared band at 2924u2009cm−1, characteristic of C–H stretching mode. A corresponding decrease in the ultraviolet absorption is also observed, which is due to a loss of some conjugated C–C π bonds in hydrogen covered SWNTs.

Effect of metastable oxygen molecules in high density power-modulated oxygen discharges

A spatially averaged (well mixed) reactor model was used to simulate a power-modulated (pulsed) high density oxygen discharge. Chemistry involving the high energy oxygen metastable molecules O2M(Au200a3Σu++Cu200a3Δu+cu200a1Σu−) was included in the simulation. This chemistry was necessary to capture the experimentally observed increase in the O− negative ion density in the afterglow of the pulsed discharge. As the electron temperature drops in the afterglow, the rate coefficient of electron attachment with O2M increases several fold. The wall recombination probability of oxygen atoms affected the O− density drastically. For the conditions studied, the maximum O− density in the afterglow increased with pressure, decreased with power, and showed a maximum with pulse period. The time in the afterglow at which the peak O− density occurred decreased with pressure and power, and was independent of the pulse period. Knowing the temporal evolution of O− in the afterglow may be important for applications requiring extraction o...

Carbon nanotube networks by chemical vapor deposition

We have demonstrated assembly of two- and three-dimensional networks of single-walled carbon nanotubes (SWNTs) using a microsphere assembly approach. The catalyst microcapsules are made from the solution based impregnation of uniform diameter, porous polystyrene microspheres. Chemical vapor deposition on the microcapsule arrays produces highly interconnected SWNT networks. Varying the microsphere diameter and catalyst solution composition allows varying the pattern spacing, catalyst yield, and network interconnectivity.