This PDF file contains the front matter associated with SPIE Proceedings Volume 7037, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

We investigate high frequency electrical and mechanical performances of carbon nanotube based devices. Using configurations with multiple single-wall nanotubes in parallel, we show that HF nanotube transistors with intrinsic cut-off frequencies as high as 30 GHz can be obtained on rigid substrates. Adapting our process to plastic substrates, we also obtained highly flexible HF transistors showing constant transconductances up to at least 6 GHz, as-measured cut-off frequencies as high as 1 GHz (5-8 GHz after de-embedding) and stable DC performances upon bending. We probed electromechanical properties of individual suspended carbon multiwall nanotubes by using a modified AFM. DC deflection measurements on different devices are in agreement with a continuum model prediction and consistent with a Young's modulus of 0.4 TPa. Preliminary HF measurements on a doubly clamped device showed a resonant frequency of 200MHz consistent with a Young's modulus of 0.43 TPa. This implies that built-in mechanical stress in the case of MWNTs is negligeable.

The electrical properties of carbon nanotube FETs (CNTFETs) have been studied in detail. The conduction type of the CNTFETs was dependent on the work function of the contact metal, which suggests that Fermi level pinning at the metal/nanotube interface is not strong. Based on the two-probe and four-probe resistance measurements, it has been shown that the carrier transport at the contact is explained by the edge contact model even in the diffusive regime. The chemical doping using F₄TCNQ was effective in reducing not only the channel resistance but also the contact resistance. In the CNTFETs fabricated using plasma-enhanced (PE) CVD-grown nanotubes, the drain current of the most of the devices could be modulated by the gate voltage with small OFF current suggesting the preferential growth of the nanotubes with semiconducting behavior. Multichannel top-gate CNTFETs with horizontally-aligned nanotubes as channels have been successfully fabricated using CNT growth on the ST-cut quartz substrate, arc-discharge plasma deposition of the catalyst metal, and ALD gate insulator deposition. The devices show normally-on and n-type conduction property with a relatively-high ON current of 13 mA/mm. CNTFETs with nanotube network have also been fabricated by direct growth on the SiO₂/Si substrate using grid-inserted PECVD and using catalyst formed on the channel area of the FETs. The uniformity of the electrical properties of the network channel CNTFETs were very good. Finally, it has been shown that the surface potential profile measurement based on the electrostatic force detection in the scanning probe microscopy was effective in studying the behavior of the CNTFETs such as the transient behavior and the effect of the defects.

Breaking of the symmetry of a single-wall carbon nanotube in the field of a helical wrap of ionized single-stranded DNA is investigated. For a non-chiral tube, the helical perturbation generates "natural" optical activity in the DNA-nanotube complex. The one-electron absorption spectrum for light polarized across the tube is sensitive to the band structure modulation due to the wrapping. Lifting of optical selection rules results in new optical transitions and circular dichroism of the complex. These optical effects are predicted to serve as qualitative tools to directly identify the DNA wrapping.

Ultra-thin single wall carbon nanotubes (SWNTs) with a diameter of only 0.3 nm were synthesized in the nano-channels of AlPO4-11 porous single crystals. Raman spectra, with excitation wavelengths in the range from 457.9 to 647.1 nm, show excellent agreement with the density functional calculations of the Raman-active vibration modes of the armchair (2,2) SWCNTs. Calculated imaginary part of the dielectric function also displays qualitative agreement with the resonant Raman data. Interestingly, the (2,2) nanotube has two metastable ground state corresponding two slightly different lattice constants in axial direction, one state is metallic and the other is semiconducting. The polarizibility of the Raman modes agrees well with the calculated intensities for non-resonant Raman scattering, although the resonant Raman scattering plays a key role in the process. Both theory and experiment show the free-standing (2,2) SWNTs to be unstable. Confinement of the SWNTs in the nano-channels stablilizes the structure.

Carbon nanotubes have been extensively studied due to their unique property and potential application like field emission. For successful implementation, it is essential to know the properties of carbon nanotubes. In this work, we propose a simple method to estimate the electric property of multi walled carbon nanotubes (MWCNTs) by ac dielectrophoresis. Dielectrophoresis is a phenomenon resulted from the inhomogeneous electric field and has been used to sort out colloids with different dielectric properties. When applied ac dielectrophoresis, the movement of the colloids depends on the polarizability of the colloids relative to the medium as well as the applied frequency. In certain frequency, the direction of dielectrophoresis force will change and this crossover frequency is related to the electric property of colloids. Since the crossover frequency is a function of the particle's dielectric property, as a result, if the crossover frequency can be obtained, then the electric property of MWCNTs can be estimated. In a preliminary experiment, NanoAmor MWCNTs (95+%, core diameter: 5-10 nm, outside diameter 20-40 nm, length 5-15 μm) mixed with alcohol, DI water and the surfactant was injected onto a dielectrophoresis microfluidic chip to measure the crossover frequency. These MWCNTs were under negative dielectrophoresis (repelled from high electric field) for frequencies over 12 KHz, and were under positive dielectrophoresis (attracted to the high electric field) for frequencies under 1 KHz. These results were compared with the CM factor frequency spectrum with known electric properties. The results show that for positive dielectrophoresis in low frequency and negative dielectrophoresis in high frequency is a characteristic of conducting materials which indicates that these MWCNTs are conducting in nature. One application of this technique is the characterization of electric property of SWCNT which is currently under investigation.

Flexible transparent conducting films (TCFs) were fabricated on a PET substrate by various methods using carbon nanotubes dispersed in organic or water-based solution. Thin multi-walled carbon nanotubes, double-walled carbon nanotubes, and single-walled carbon nanotubes were used to compare the performance for TCFs. Optimal design rules for types of nanotubes, surfactants, the degree of dispersion, and film preparation methods were discussed. The TCFs were characterized by scanning electron microscopy, TGA, Raman, optical absorption spectra, and sheet resistance. The dispersion of CNTs in water and in bisolvent has been tried. A simple acid treatment on the TCF film increased the conductivity by about four times. Doping and functionalization techniques will be further introduced to improve the conductivity of the film.

Integrated circuits fabrication is soon reaching strong limitations. Help could come from using carbon nanotubes as conducting wires for interconnects. Although this solution was proposed six years ago, researchers still come up with many obstacles such as localization, low temperature growth on copper, contacting and reproducibility. The integration processes exposed here intend to meet the industrial requirements. Two approaches are then possibly followed. Either using densely packed single wall (SWCNT) (or very tiny multiwall) nanotubes, or filling up the whole interconnect diameter with a single large multiwall (MWCNT) nanotube. In this work, we focus on the integration of multiwall vertical interconnects. Densely packed MWCNTs are grown in via holes by CVD. Alternatively, we have developed a method to obtain a single large nanofibre grown by PECVD (MWCNF) in each via hole. Electrical measurements are performed on CVD and PECVD grown carbon nanotubes. The role of electron-phonon interaction in these devices is also briefly discussed.

Carbon Nanotubes are intensively studied as a new functional material for nanoelectronics and nano electromechanical systems, including nanosensor devices. Single-walled carbon nanotubes (SWNTs) show unique mechanical and electromechanical properties and they change electronic properties by interacting with the environment (this can be e.g. used for chemical and biochemical sensing). Therefore nanotubes are very promising candidates for active elements in future nanoscaled transducers. Concepts for carbon nanotube sensors for mechanical and chemical detection schemes are presented. We focus on single-walled carbon nanotubes as natural macro molecular functional structures with an option for low scale integration in micro and nano electromechanical systems (MEMS and NEMS).

This publication deals with the design of carbon nanotubes (CNT) based nano-electromechanical system (NEMS) consisting in a variable capacitor working at microwave frequencies. This device is based on an array of moveable CNT cantilever electrostatically actuated over a ground plane (figure 1 and 2). To design this component, a time-efficient numerical algorithm for the prediction of CNT electromechanical behavior has been developed. This numerical tool permits to calculate the pull-in voltage and flexion of the CNT's tip for various devices' parameters like CNT's diameter and length, initial air gap (g) ... Our software also takes into account the Van der Waals (VdW) forces and the fringing field effects. The results demonstrate that, unlike for RF-MEMS, fringing field effects are preponderant for CNT-based NEMS. This paper also discusses on the accuracy of the developed software. In order to validate our prediction, we used finite element simulation software : COMSOL® and experimental results found in literature and compare them to our prediction. Results prove that we obtain, for a decrease of the simulation time by two orders of magnitude, a maximum error on the pull-in voltage of 7% for various kinds of structures and dimensions. These results were finally used for the design of NEMS demonstrators. The microwave behavior of the varactors, over a large range of frequency, is presented. Simulations with 3D finite-element-method electromagnetic software were performed to optimize the structure and predict its microwave performances, which conclude the design of our microwave carbon nanotubes (CNT) based nano-electromechanical system (NEMS) variable capacitor.

This work reports the elongation and subsequent dispersion of carbon nano tube (CNT) aggregates driven by the electric field in a liquid crystal (LC) medium. Longitudinal and cross sectional views of CNT aggregates were investigated in homogeneously aligned cell driven by in-plane field and homeotropic aligned cell, respectively. CNT aggregates firstly were aligned toward field line by dielectrophoretic torque and secondly they were elongated above a certain threshold field due to interaction between induced dipole moment and electric field. The CNTs aggregates elongated linearly with varying electric fields. The original morphology of the CNT aggregates was restored after the removal of the field. The evidence of a complete restoration indicated that the elasticity of CNT aggregates obeyed Hooke's Law. The elongation was fully reversible only below a certain breakdown field. Above breakdown electric field, CNT aggregates were ruptured and fragmented into small pieces and consequently CNTs got dispersed in LC medium.

We present a new photonic micro-optical device based on an array of electrodes made from vertically aligned multiwall carbon nanotubes used to address a liquid crystal cell. The electrodes create a Gaussian electric field profile which is used to reorient a planar aligned nematic liquid crystal. The variation in refractive index within the liquid crystal layer acts like a graded index optical element which can be varied by changing the applied electric field to the carbon nanotube. Results are presented from a device fabricated with a 10um pitch between the micro-optical elements.

Carbon nanotubes (CNTs) have been researched as a possible important new component in various devices because they have a promising potential in applications such as microelectronic devices, sensors, actuators and optoelectronic devices. For the use of CNTs in such applications, especially in mass fabrication, a pattering process for CNT layers that is compatible with CMOS (Complementary Metal Oxide Semiconductor) processes is necessary. There have been some reports in the literature on the patterning of CNTs, but either the reported methods were not compatible with CMOS processes or the capability for precise control of the pattern geometry was not good. In this paper we describe a new patterning method that can be used in the fabrication of devices and other applications which use carbon nanotubes as a component material. This method also can be used in the patterning of other highly porous materials. Further, the process is compatible with conventional microelectronic fabrication processes and it is high-speed. Single walled carbon nanotube (SWNT) films were patterned by an excimer laser projection photoablation process at low incident energy conditions. The CNTs were deposited on a quartz substrate, and then a conventional photoresist was coated on it as a photoablation assistor. The photoresist and the CNTs were patterned simultaneously by the photoablation process, and then the photoresist was removed. Due to the physical force of the ablation-dissociated photoresist fragments, the CNTs were patterned cleanly even though the incident fluence on them was significantly lower than the threshold energy otherwise needed for their direct ablation.

We present some early results on the controlled growth of carbon nanotubes inside lateral porous alumina templates. Such lateral templates provide an easy way of organizing nano-objects in the plane of their supporting substrate, with potential densities of more than 100/μm, thus paving the way for the realization of dense circuits. Here we discuss the growth conditions inside the lateral pores of the templates, with the aim of avoiding the parasitic deposition of amorphous carbon. Our organization method should also apply to other nanostructures such as semiconductor nanowires.

We present evidence that, when laser light was tightly focused into aqueous suspension of mono-dispersed single-wall carbon nanotubes (SWCNTs), density of nanotubes was locally increased at the focus spot of light. We prepared mono-dispersed HiPco SWCNTs in an aqueous surfactant solution by sonication and following ultracentrifugation. We built a confocal Raman microscope system equipped with a 633 nm He-Ne laser, and launched the laser light into SWCNTs suspension filled in a glass micro-cell by a high numerical aperture objective lens (N.A.=1.35). We monitored temporal change in Raman spectrum of SWCNTs excited by the laser light. We clearly observed significant intensity increase of a particular radial breathing mode, however the increase of the Raman signal did not last permanently, rather showed transient response. This result implies that SWCNTs with particular chirality were selectively accumulated by optical gradient force of Raman-probing laser light. We discuss the independent behavior of the radial breathing modes, with respect to the wavelength of the laser light and the chirality of corresponding SWCNTs.

The promising field emission properties of carbon nanotubes, or CNTs, have resulted in them being identified as desirable sources for electron microscopes and other electron beam equipment. A new process to grow single CNTs aligned to the electron-optical axis inside electron source modules has been developed. The process involves putting the entire source-suppressor module inside a plasma-enhanced chemical vapour deposition reaction chamber. This is a process which can be scaled up to mass production. The resultant CNT electron sources were inserted into an electron microscope for imaging. Though current stability was found to be comparable to the tungsten cold-field emitter (with a maximum-minimum variation of 3-7% of the mean current over one hour), the reduced brightness was found to be an order of magnitude greater than a typical Schottky source (at 3×10⁹ Acm²sr^-1) with a kinetic energy spread of 0.28 eV. Imaging with a CNT source has produced a marked improvement in resolution when compared to a Schottky source using the same electron-optics. The properties measured show that the CNT source compares favourably with and in some cases improves upon other sources available today. In particular, the CNT source would be of most benefit to low-voltage, high-resolution microscopy.

We present the first steps for the validation of the concept of a new optically driven field emission cathode. The approach relies on the interaction of surface plasmons with vertically aligned multi-wall carbon nanotubes or metallic nanowire arrays. The objective is to modulate the field emission current by using the optical field component at the emitter apex through antenna coupling. Thanks to metallic surface gratings, surface plasmons will be generated and localized in the vicinity of nanoemitters to increase the interaction. First simulations and preliminary experimental measurements are presented jointly with perspectives for the wideband modulation of electronic beams up to THz.

Carbon nanotubes (CNTs) arrays were prepared by microwave plasma-enhanced chemical vapor deposition (MPCVD) method. Nickel layer of 7 nm in thickness on 100-nm thickness titanium nitride film was transformed into discrete islands after hydrogen plasma pretreatment. CNTs were then grown up on Ni-coated areas by MPCVD. Their field emission properties were studied and evaluated. From formulism analysis, superior CNT films with very low emission onset electric field, about 0.425 V/micron (at J =10 micro-A/cm²), are attained without post-deposition treatment. The large field amplification factor arising from small curvature radius of nanotube tips is responsible for good emission characteristics.

Single-walled carbon nanotubes (SWNTs) have been investigated as a key potential candidate for high performance electronic devices. Two representative device forms are carbon nanotube based field effect transisotors (FETs) and diodes. In contrast of high popularity of FET devices for the fundamental studies as well as applications, carbon nanotube based diodes have been rarely studied. Recently, we developed a facile chemical route to realize the SWNT Schottky diode via mass transport of lithium ions by applying bias voltages on 1-pyrenemethylamine(1-PMA) functionalized SWNTs in which lithium ions were intercalated. The intercalated Li ions were transported and reduced on the drain electrode, of which work function was then significantly modulated. Because the modulated work function induces large Schottky barrier between the drain electrode and SWNT, the current of reversed direction is effectively blocked while the forward direction current flows through the relatively small Schottky barrier. The migration of lithium ions was characterized by scanning photoelectron microscopy (SPEM) and space resolved x-ray photoelectron spectroscopy. To measure the intensity of Li 1s XPS peak, the population of lithium ions was observed along the nanotube axis from the source to drain electrodes. As a result, the highest population of lithium was observed at near the drain electrode. This approach using the concept of mass transport of lithium ions to modulate the metal contact characteristics is a simple and promising process that can be further applied not only to SWNT-based electronics but also to various nanomaterial-based electronic devices.

Zinc oxide nanowire networks are attractive as alternatives to organic and amorphous semiconductors due to their wide bandgap, flexibility and transparency. We demonstrate the fabrication of thin film transistors (TFT)s which utilize ZnO nanowires as the semiconducting channel. These thin film transistors can be transparent and flexible and processed at low temperatures on to a variety of substrates. The nanowire networks are created using a simple contact transfer method that is easily scalable. Apparent nanowire network mobility values can be as high as 3.8 cm²/Vs (effective thin film mobility: 0.03 cm²/Vs) in devices with 20μm channel lengths and ON/OFF ratios of up to 10⁴.

We present theoretical study of the atomic, electronic and transport properties of silicon nanowires and single-walled carbon nanotubes using atomistic simulation. For silicon nanowires, we present investigation of the atomic structure and electronic properties of ultrathin nanowires with different surface structures and growth directions and the trend of such property variations with increasing nanowire diameters using density functional theory with both local atomic basis and plane waves. For single-walled carbon nanotubes, we present self-consistent tight-binding study of the electronic and transport properties of semiconducting carbon nanotubes in contact with metal electrodes. We discuss insights obtained from such atomistic study on the contact, and diameter dependence of junction conductance. Finally, we examine the application of single-walled carbon nanotubes as novel nanofluidic channels by analyzing the structure and kinetics of water molecules confined and transported through the nanotube channels using molecular dynamics simulation.

Thin films of functionalized single-wall carbon nanotubes were deposited on silicon chips by drop-coating and inkjet printing. These sensors were subjected to 1-100 ppm NOx, CO, H₂S and H₂O vapor in synthetic air. We have found that besides the expected changes in the electrical resistance of the film, there are also characterteristic differences in the noise pattern of the resistance vs. time function. This phenomenon is called fluctuation enhanced sensing and it can be used to increase the amount of information gathered from a carbon nanotube sensor device. The main advantage of fluctuation enhanced sensing is the improved selectivity of the sensor even if changes in electical resistance are rather low. Combined with differentiation based on modifying the adsorption characterstics of the nanotubes (e.g. by covalent functionalization), fluctuation enhanced sensing appears to be a very useful method for bringing cheap and reliable carbon nanotube based chemical sensors to the market.

This paper will evaluate the usefulness of two nanostructuring techniques in order to grow low turn-on voltage electrodes for use in micro-discharge plasma applications such as the ST+D Ltd e-nose device. These devices are based on micro-plasma technology and currently operate at around 150V (at 10^-2 Torr) or 3KV at atmosphere utilising a propriety power source. The application of such technology is the qualitative and qualitative detection of NOx with detection capabilities as low as 5 parts per billion. The e-nose patented device has undergone basic trials in a clinical environment and it is currently demonstrating 50ppb sensitivities, with an ultimate aim of moving this to parts per trillion.

In previous papers, we reported the first dry actuator that can be fabricated simply by layer-by-layer casting, using 'bucky gel', a gelatinous room-temperature ionic liquid containing single-walled carbon nanotubes (SWNTs). The actuator has a bimorph configuration with a polymer-supported internal ionic liquid electrolyte layer sandwiched by polymer-supported bucky-gel electrode layers, which allow quick and long-lived operation in air at low applied voltages. In this paper, some of the recent developments of the actuator performance are reported.

We report here recent progress in nanophotonics with single-wall carbon nanotubes (SWNTs). A photonic model structure, the planar λ/2-microcavity, modifies the photonic density of modes at the location of the embedded SWNTs. As a result, the radiative properties of the SWNTs are modified due to the enhancement or inhibition of the microcavity-controlled spontaneous emission (scattering) rate. We use single-molecule optical microscopy and spectroscopy to investigate individual SWNTs (bundles), spatially isolated and immobilized in the photonic structure, and to measure the microcavity-controlled emission (Raman and photoluminescence) characteristics. Ultimately, we demonstrate experimentally that the integration of a field-effect transistor (FET) based on a single, semiconducting SWNT with a λ/2-microcavity results in a strong spectral and angular narrowing of the electrically excited and cavity-enhanced infrared radiation emitted by the nano-light source. Integrated nanophotonic devices based on carbon nanotubes hold great promise for application in quantum optics and optical communication.

The present work highlights the prospects of application of the nanocomposite, polyaniline (PANI) - polyvinylchloride(PVC)- Multi Walled Carbon Nanotube (MWNT), in pressure sensing devices. The above nanocomposite sample in the form of pressed pellet shows orders of change in electrical conductivity with applied pressure in the range 10E5 Pa to 10E9 Pa, even for very small applied bias of a few milli-volts. The percentage variation of electrical conductivity with applied pressure is strikingly large for this composite. There is ample scope for further investigations in this direction especially if the samples can be cast in the form of free-standing films.

We report on the fabrication of a buckypaper from thin multiwalled carbon nanotubes modified with hydroxyl groups (t-MWCNTs-OH), which was achieved by hydrogen-bond driven assembly of t-MWCNTs-OH. Although the carboxyl-containing t-MWNTs exist in a typical entangled state within the film, it was found that hydroxyl-containing t-MWCNTs can assemble into bundle structures induced by the intermolecular hydrogen bonds upon densification of the carbon nanotube (CNT) suspension. The upshift of the G band in the Raman spectra and the enhanced hydrogen bonds in FTIR spectra of the spray coated nanotube films illustrate the assembly of hydroxyl-containing t-MWCNTs through hydrogen bonding. The assembled structure was also visualized by electron microscopy analysis. This is the first report in which a flexible buckypaper was fabricated with the t-MWCNTs using a conventional filtration method without a special mechanical trick.

This paper deals with the development of a micro-interconnection technology suitable for the elaboration of RF-NEMS (Nano-ElectroMechanical Systems) varactors. It aims to present an extension of RF MEMS concept into nano-scale domain by using multi-walled carbon nanotubes (MWCNT) as movable part instead of micrometric membranes into reconfigurable passive circuits for microwave applications. For such a study, horizontal configuration of the NEMS varactors has been chosen and is commented. The technology is established to fulfill several constraints, technological and microwave ones. As far as technological requirements are concerned, specific attentions and tests have been carried out to satisfy: • Possible and later industrialization. No e-beam technique has been selected for RF NEMS varactor elaboration. Lateral MWCNT growth performed on a Ni catalyst layer, sandwiched between two SiO₂ layers, showed feasibility of suspended MWCNT beam. • High thermal budget, induced by the MWCNT growth by CVD (Chemical Vapor Deposition), at least to 600°C. All the dielectric and metallic layers, required to interlink the nano world with the micrometric measurements one, have been studied accordingly. Consequently, the order of the technological steps has been identified. About microwave and actuation specifications (targeted close to 25V), the minimization of losses and actuation voltage implies large layer's thicknesses compared to the CNT diameter. Several specific technological issues are presented in this paper, taking care of both technological and microwave compatibility to go toward RF NEMS varactor's elaboration.

We investigated a linear carbon nanotube motor serving as the key building block for nanoscale motion control by using molecular dynamics simulations. This linear nanomotor, is based on the electrostatically telescoping multi-walled carbon-nanotube with ultralow intershell sliding friction, is controlled by the gate potential with the capacitance feedback sensing. The resonant harmonic peaks are induced by the interference between the driving frequencies and its self-frequency. The temperature is very important factor to operate this nanomotor.

The unique properties of graphene have recently attracted major attention leading to proposals in electronic, optoelectronic, and detector applications. Micro-Raman spectroscopy has been utilized as a convenient tool for identifying graphene layers. Most Raman studies were limited to layers on silicon substrates with an oxide layer thickness of 300 nm, rendering graphene visible under an optical microscope. The development of graphene technology requires its integration with different materials and strict control of the number of layers and defects. Thus it is important to extend the nanometrology capabilities of Raman spectroscopy to arbitrary substrates and temperatures. Here we report that the deconvolution of the 2D band allows one to count graphene layers even when placed on "inconvenient" substrates such as glass or sapphire. We also show that even small excitation laser power typically used for Raman spectroscopy may lead to strong heating in graphene. The determined temperature coefficients for graphene allowed us to evaluate the temperature rise and decouple the temperature effects from those due to variations in the graphene edges or substrates.

We investigated a carbon nanotube (CNT) oscillator controlled by the thermal gas expansion using classical molecular dynamics simulations. When the temperature rapidly increased, the force on the CNT oscillator induced by the thermal gas expansion rapidly increased and pushed out the CNT oscillator. As the CNT oscillator extruded from the outer nanotube, the suction force on the CNT oscillator increased by the excess van der Waals vdW energy. When the CNT oscillator reached at the maximum extrusion point, the CNT oscillator was encapsulated into the outer nanotube by the suction force. Therefore, the CNT oscillator could be oscillated by both the gas expansion and the excess vdW interaction. As the temperature increased, the amplitude of the CNT oscillator increased. At the high temperatures, the CNT oscillator escaped from the outer nanotube, because the force on the CNT oscillator due to the thermal gas expansion was higher than the suction force due to the excess vdW energy. By the appropriate temperature controls, such as the maximum temperature, the heating rate, and the cooling rate, the CNT oscillator could be operated.

We propose a novel carbon-nanotube (CNT)-based nonvolatile memory, which can serve as a key building block for molecular-scale computers and perform molecular dynamics simulations to investigate the dynamic operation of a double-walled CNT memory. We find that the most important physical characteristics of the proposed nanometer-scale memory device are the bi-stability achieved by using the CNT inter-wall van der Waals interaction, the CNT-metal binding energies and the reversibility caused by the electrostatic attractive forces. Since the CNT shuttle can have a high kinetic energy during the transition, the dynamical collisions between the CNT and the metal electrodes are very important factors to be considered for design of an electrostatically telescoping CNT memory. The long collision time and the several rebounds cause a delay in the state transition.

The coupled oscillation of multi-walled CNT oscillators consisting of (5n,5n) CNTs was investigated by molecular dynamics simulations. The oscillation feature of the CNT oscillators can not be described by a continuum theory. All walls of the multi-walled CNT are oscillated due to the interwall coupling. The frequencies of the multi-walled CNT oscillators are higher than those of the double-walled CNT oscillators. In spire of the different core CNT, the frequency peaks due to the interwall coupling are similar to each other as the number of walls increases. This reason is that the interwall coupling effects increase as the number of walls increases.

The properties of liquid crystal (LCs) can be altered by incorporating guest materials. The physical properties of carbon nano tubes doped liquid crystal (CNTs/LC) and pristine LC have been investigated. The rotational viscosity of CNTs/LC was lower whereas dielectric anisotropy was almost the same as compared to pristine LC. Also the twisted nematic LC cell driven by vertical field and homogeneously aligned nematic LC cells doped with carbon nanotubes (CNTs) driven by an in-plane field were fabricated and their electro-optic characteristics were investigated. The response time of CNTs doped LC was found to be improved due to the decrease in rotational viscosity.