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Sample records for carbon nanotube transistors

  1. Carbon nanotube electrodes in organic transistors.

    PubMed

    Valitova, Irina; Amato, Michele; Mahvash, Farzaneh; Cantele, Giovanni; Maffucci, Antonio; Santato, Clara; Martel, Richard; Cicoira, Fabio

    2013-06-01

    The scope of this Minireview is to provide an overview of the recent progress on carbon nanotube electrodes applied to organic thin film transistors. After an introduction on the general aspects of the charge injection processes at various electrode-semiconductor interfaces, we discuss the great potential of carbon nanotube electrodes for organic thin film transistors and the recent achievements in the field. PMID:23639944

  2. Stretchable transistors with buckled carbon nanotube films as conducting channels

    DOEpatents

    Arnold, Michael S; Xu, Feng

    2015-03-24

    Thin-film transistors comprising buckled films comprising carbon nanotubes as the conductive channel are provided. Also provided are methods of fabricating the transistors. The transistors, which are highly stretchable and bendable, exhibit stable performance even when operated under high tensile strains.

  3. Noise characteristics of single-walled carbon nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-01

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors.

  4. Noise characteristics of single-walled carbon nanotube network transistors.

    PubMed

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-16

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors. PMID:21828739

  5. Carbon nanotube transistors, sensors, and beyond

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian

    Carbon nanotubes are tiny hollow cylinders, made from a single graphene sheet, that possess many amazing properties. Another reason why nanotubes have generated intense research activities from scientists of various disciplines is they represent a new class of materials for the study of one-dimensional physics. In this thesis we investigate the electrical transport of semiconducting single-walled carbon nanotubes and their potential applications as biological sensors. Electrons have been predicted, by theoretical physicists, to go through nanotubes without much resistance. But this has not been properly quantified experimentally, and the origin of the routinely observed large resistance in nanotubes is not clear. In this thesis we show that in moderate long high quality nanotubes the electrical transport is limited by electron-phonon scattering. Systematic studies are carried out using many devices of different diameters at various temperatures. The resistance and inverse of peak mobility are observed to decrease linearly with temperature, indicating the influence of phonons. The conductance and peak mobility scales with nanotube diameters also, in a linear fashion and quadratic fashion respectively. Based on electron-phonon scattering, a theory model is developed that can not only predict how the resistance changes with gate voltage but also explain the observed temperature and diameter dependence. This work clarifies the nature of electrical transport in nanotubes and sets a performance limit of nanotube devices in diffusive regime. The electrical transport in nanotubes is extremely sensitive to local electrostatic environment due to their small size, large surface to volume ratio and high mobility, making nanotubes ideal key elements in biological sensors. In the second part of this thesis, we integrate nanotubes with supported lipid bilayers, mimic structures of cell membranes, and use this platform as a way to introduce biomolecules into the vicinity of

  6. Hysteresis free carbon nanotube thin film transistors comprising hydrophobic dielectrics

    NASA Astrophysics Data System (ADS)

    Lefebvre, J.; Ding, J.; Li, Z.; Cheng, F.; Du, N.; Malenfant, P. R. L.

    2015-12-01

    We present two examples of carbon nanotube network thin film transistors with strongly hydrophobic dielectrics comprising either Teflon-AF or a poly(vinylphenol)/poly(methyl silsesquioxane) (PVP/pMSSQ) blend. In the absence of encapsulation, bottom gated transistors in air ambient show no hysteresis between forward and reverse gate sweep direction. Device threshold gate voltage and On-current present excellent time dependent stability even under dielectric stress. Furthermore, threshold gate voltage for hole conduction is negative upon device encapsulation with PVP/pMSSQ enabling much improved current On/Off ratio at 0 V. This work addresses two major challenges impeding solution based fabrication of relevant thin film transistors with printable single-walled carbon nanotube channels.

  7. Hysteresis modeling in ballistic carbon nanotube field-effect transistors.

    PubMed

    Liu, Yian; Moura, Mateus S; Costa, Ademir J; de Almeida, Luiz Alberto L; Paranjape, Makarand; Fontana, Marcio

    2014-01-01

    Theoretical models are adapted to describe the hysteresis effects seen in the electrical characteristics of carbon nanotube field-effect transistors. The ballistic transport model describes the contributions of conduction energy sub-bands over carbon nanotube field-effect transistor drain current as a function of drain-source and gate-source voltages as well as other physical parameters of the device. The limiting-loop proximity model, originally developed to understand magnetic hysteresis, is also utilized in this work. The curves obtained from our developed model corroborate well with the experimentally derived hysteretic behavior of the transistors. Modeling the hysteresis behavior will enable designers to reliably use these effects in both analog and memory applications. PMID:25187698

  8. Hysteresis modeling in ballistic carbon nanotube field-effect transistors

    PubMed Central

    Liu, Yian; Moura, Mateus S; Costa, Ademir J; de Almeida, Luiz Alberto L; Paranjape, Makarand; Fontana, Marcio

    2014-01-01

    Theoretical models are adapted to describe the hysteresis effects seen in the electrical characteristics of carbon nanotube field-effect transistors. The ballistic transport model describes the contributions of conduction energy sub-bands over carbon nanotube field-effect transistor drain current as a function of drain-source and gate-source voltages as well as other physical parameters of the device. The limiting-loop proximity model, originally developed to understand magnetic hysteresis, is also utilized in this work. The curves obtained from our developed model corroborate well with the experimentally derived hysteretic behavior of the transistors. Modeling the hysteresis behavior will enable designers to reliably use these effects in both analog and memory applications. PMID:25187698

  9. A spiking neuron circuit based on a carbon nanotube transistor.

    PubMed

    Chen, C-L; Kim, K; Truong, Q; Shen, A; Li, Z; Chen, Y

    2012-07-11

    A spiking neuron circuit based on a carbon nanotube (CNT) transistor is presented in this paper. The spiking neuron circuit has a crossbar architecture in which the transistor gates are connected to its row electrodes and the transistor sources are connected to its column electrodes. An electrochemical cell is incorporated in the gate of the transistor by sandwiching a hydrogen-doped poly(ethylene glycol)methyl ether (PEG) electrolyte between the CNT channel and the top gate electrode. An input spike applied to the gate triggers a dynamic drift of the hydrogen ions in the PEG electrolyte, resulting in a post-synaptic current (PSC) through the CNT channel. Spikes input into the rows trigger PSCs through multiple CNT transistors, and PSCs cumulate in the columns and integrate into a 'soma' circuit to trigger output spikes based on an integrate-and-fire mechanism. The spiking neuron circuit can potentially emulate biological neuron networks and their intelligent functions. PMID:22710137

  10. Fabrication of Carbon Nanotube Field Effect Transistors Using Plasma-Enhanced Chemical Vapor Deposition Grown Nanotubes

    NASA Astrophysics Data System (ADS)

    Ohnaka, Hirofumi; Kojima, Yoshihiro; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2006-06-01

    Single-walled carbon nanotubes are grown using grid-inserted plasma-enhanced chemical vapor deposition (PECVD). The field effect transistor operation was confirmed using the PECVD grown carbon nanotubes (CNTs). The preferential growth of the semiconducting nanotubes was confirmed in the grid-inserted PECVD by measuring current-voltage (I-V) characteristics of the devices. Based on the measurement of the electrical breakdown of the metallic CNTs, the probability of growing the semiconducting nanotubes has been estimated to be more than 90%.

  11. Imaging dissipation and hot spots in carbon nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Estrada, David; Pop, Eric

    2011-02-01

    We use infrared thermometry of carbon nanotube network (CNN) transistors and find the formation of distinct hot spots during operation. However, the average CNN temperature at breakdown is significantly lower than expected from the breakdown of individual nanotubes, suggesting extremely high regions of power dissipation at the CNN junctions. Statistical analysis and comparison with a thermal model allow the estimate of an upper limit for the average tube-tube junction thermal resistance, ˜4.4×1011 K/W (thermal conductance of ˜2.27 pW/K). These results indicate that nanotube junctions have a much greater impact on CNN transport, dissipation, and reliability than extrinsic factors such as low substrate thermal conductivity.

  12. Enhanced shot noise in carbon nanotube field-effect transistors

    SciTech Connect

    Betti, A.; Fiori, G.; Iannaccone, G.

    2009-12-21

    We predict shot noise enhancement in defect-free carbon nanotube field-effect transistors through a numerical investigation based on the self-consistent solution of the Poisson and Schroedinger equations within the nonequilibrium Green's functions formalism, and on a Monte Carlo approach to reproduce injection statistics. Noise enhancement is due to the correlation between trapping of holes from the drain into quasibound states in the channel and thermionic injection of electrons from the source, and can lead to an appreciable Fano factor of 1.22 at room temperature.

  13. Carbon Nanotube Synaptic Transistor Network for Pattern Recognition.

    PubMed

    Kim, Sungho; Yoon, Jinsu; Kim, Hee-Dong; Choi, Sung-Jin

    2015-11-18

    Inspired by the human brain, a neuromorphic system combining complementary metal-oxide semiconductor (CMOS) and adjustable synaptic devices may offer new computing paradigms by enabling massive neural-network parallelism. In particular, synaptic devices, which are capable of emulating the functions of biological synapses, are used as the essential building blocks for an information storage and processing system. However, previous synaptic devices based on two-terminal resistive devices remain challenging because of their variability and specific physical mechanisms of resistance change, which lead to a bottleneck in the implementation of a high-density synaptic device network. Here we report that a three-terminal synaptic transistor based on carbon nanotubes can provide reliable synaptic functions that encode relative timing and regulate weight change. In addition, using system-level simulations, the developed synaptic transistor network associated with CMOS circuits can perform unsupervised learning for pattern recognition using a simplified spike-timing-dependent plasticity scheme. PMID:26512729

  14. Thin film transistors using PECVD-grown carbon nanotubes.

    PubMed

    Ono, Yuki; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2010-05-21

    Thin film transistors with a carbon nanotube (CNT) network as a channel have been fabricated using grid-inserted plasma-enhanced chemical vapor deposition (PECVD) which has the advantage of preferential growth of the CNTs with semiconducting behavior in the I-V characteristics of CNT field effect transistors (CNT-FETs). Taking advantage of the preferential growth and suppression of bundle formation, a large ON current of 170 microA mm(-1), which is among the largest in these kinds of devices with a large ON/OFF current ratio of about 10(5), has been realized in the relatively short channel length of 10 microm. The field effect mobility of the device was 5.8 cm(2) V(-1) s(-1). PMID:20418603

  15. Thin film transistors using PECVD-grown carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ono, Yuki; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2010-05-01

    Thin film transistors with a carbon nanotube (CNT) network as a channel have been fabricated using grid-inserted plasma-enhanced chemical vapor deposition (PECVD) which has the advantage of preferential growth of the CNTs with semiconducting behavior in the I-V characteristics of CNT field effect transistors (CNT-FETs). Taking advantage of the preferential growth and suppression of bundle formation, a large ON current of 170 µA mm - 1, which is among the largest in these kinds of devices with a large ON/OFF current ratio of about 105, has been realized in the relatively short channel length of 10 µm. The field effect mobility of the device was 5.8 cm2 V - 1 s - 1.

  16. Radio frequency analog electronics based on carbon nanotube transistors.

    PubMed

    Kocabas, Coskun; Kim, Hoon-Sik; Banks, Tony; Rogers, John A; Pesetski, Aaron A; Baumgardner, James E; Krishnaswamy, S V; Zhang, Hong

    2008-02-01

    The potential to exploit single-walled carbon nanotubes (SWNTs) in advanced electronics represents a continuing, major source of interest in these materials. However, scalable integration of SWNTs into circuits is challenging because of difficulties in controlling the geometries, spatial positions, and electronic properties of individual tubes. We have implemented solutions to some of these challenges to yield radio frequency (RF) SWNT analog electronic devices, such as narrow band amplifiers operating in the VHF frequency band with power gains as high as 14 dB. As a demonstration, we fabricated nanotube transistor radios, in which SWNT devices provide all of the key functions, including resonant antennas, fixed RF amplifiers, RF mixers, and audio amplifiers. These results represent important first steps to practical implementation of SWNTs in high-speed analog circuits. Comparison studies indicate certain performance advantages over silicon and capabilities that complement those in existing compound semiconductor technologies. PMID:18227509

  17. Radio frequency analog electronics based on carbon nanotube transistors

    PubMed Central

    Kocabas, Coskun; Kim, Hoon-sik; Banks, Tony; Rogers, John A.; Pesetski, Aaron A.; Baumgardner, James E.; Krishnaswamy, S. V.; Zhang, Hong

    2008-01-01

    The potential to exploit single-walled carbon nanotubes (SWNTs) in advanced electronics represents a continuing, major source of interest in these materials. However, scalable integration of SWNTs into circuits is challenging because of difficulties in controlling the geometries, spatial positions, and electronic properties of individual tubes. We have implemented solutions to some of these challenges to yield radio frequency (RF) SWNT analog electronic devices, such as narrow band amplifiers operating in the VHF frequency band with power gains as high as 14 dB. As a demonstration, we fabricated nanotube transistor radios, in which SWNT devices provide all of the key functions, including resonant antennas, fixed RF amplifiers, RF mixers, and audio amplifiers. These results represent important first steps to practical implementation of SWNTs in high-speed analog circuits. Comparison studies indicate certain performance advantages over silicon and capabilities that complement those in existing compound semiconductor technologies. PMID:18227509

  18. Carbon nanotube transistor based high-frequency electronics

    NASA Astrophysics Data System (ADS)

    Schroter, Michael

    At the nanoscale carbon nanotubes (CNTs) have higher carrier mobility and carrier velocity than most incumbent semiconductors. Thus CNT based field-effect transistors (FETs) are being considered as strong candidates for replacing existing MOSFETs in digital applications. In addition, the predicted high intrinsic transit frequency and the more recent finding of ways to achieve highly linear transfer characteristics have inspired investigations on analog high-frequency (HF) applications. High linearity is extremely valuable for an energy efficient usage of the frequency spectrum, particularly in mobile communications. Compared to digital applications, the much more relaxed constraints for CNT placement and lithography combined with already achieved operating frequencies of at least 10 GHz for fabricated devices make an early entry in the low GHz HF market more feasible than in large-scale digital circuits. Such a market entry would be extremely beneficial for funding the development of production CNTFET based process technology. This talk will provide an overview on the present status and feasibility of HF CNTFET technology will be given from an engineering point of view, including device modeling, experimental results, and existing roadblocks. Carbon nanotube transistor based high-frequency electronics.

  19. High-performance radio frequency transistors based on diameter-separated semiconducting carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cao, Yu; Che, Yuchi; Seo, Jung-Woo T.; Gui, Hui; Hersam, Mark C.; Zhou, Chongwu

    2016-06-01

    In this paper, we report the high-performance radio-frequency transistors based on the single-walled semiconducting carbon nanotubes with a refined average diameter of ˜1.6 nm. These diameter-separated carbon nanotube transistors show excellent transconductance of 55 μS/μm and desirable drain current saturation with an output resistance of ˜100 KΩ μm. An exceptional radio-frequency performance is also achieved with current gain and power gain cut-off frequencies of 23 GHz and 20 GHz (extrinsic) and 65 GHz and 35 GHz (intrinsic), respectively. These radio-frequency metrics are among the highest reported for the carbon nanotube thin-film transistors. This study provides demonstration of radio frequency transistors based on carbon nanotubes with tailored diameter distributions, which will guide the future application of carbon nanotubes in radio-frequency electronics.

  20. Phonon populations and electrical power dissipation in carbon nanotube transistors.

    PubMed

    Steiner, Mathias; Freitag, Marcus; Perebeinos, Vasili; Tsang, James C; Small, Joshua P; Kinoshita, Megumi; Yuan, Dongning; Liu, Jie; Avouris, Phaedon

    2009-05-01

    Carbon nanotubes and graphene are candidate materials for nanoscale electronic devices. Both materials show weak acoustic phonon scattering and long mean free paths for low-energy charge carriers. However, high-energy carriers couple strongly to optical phonons, which leads to current saturation and the generation of hot phonons. A non-equilibrium phonon distribution has been invoked to explain the negative differential conductance observed in suspended metallic nanotubes, while Raman studies have shown the electrical generation of hot G-phonons in metallic nanotubes. Here, we present a complete picture of the phonon distribution in a functioning nanotube transistor including the G and the radial breathing modes, the Raman-inactive zone boundary K mode and the intermediate-frequency mode populated by anharmonic decay. The effective temperatures of the high- and intermediate-frequency phonons are considerably higher than those of acoustic phonons, indicating a phonon-decay bottleneck. Most importantly, inclusion of scattering by substrate polar phonons is needed to fully account for the observed electronic transport behaviour. PMID:19421219

  1. Directed Assembly of Single Wall Carbon Nanotube Field Effect Transistors.

    PubMed

    Penzo, Erika; Palma, Matteo; Chenet, Daniel A; Ao, Geyou; Zheng, Ming; Hone, James C; Wind, Shalom J

    2016-02-23

    The outstanding electronic properties of single wall carbon nanotubes (SWCNTs) have made them prime candidates for future nanoelectronics technologies. One of the main obstacles to the implementation of advanced SWCNT electronics to date is the inability to arrange them in a manner suitable for complex circuits. Directed assembly of SWCNT segments onto lithographically patterned and chemically functionalized substrates is a promising way to organize SWCNTs in topologies that are amenable to integration for advanced applications, but the placement and orientational control required have not yet been demonstrated. We have developed a technique for assembling length sorted and chirality monodisperse DNA-wrapped SWCNT segments on hydrophilic lines patterned on a passivated oxidized silicon substrate. Placement of individual SWCNT segments at predetermined locations was achieved with nanometer accuracy. Three terminal electronic devices, consisting of a single SWCNT segment placed either beneath or on top of metallic source/drain electrodes were fabricated. Devices made with semiconducting nanotubes behaved as typical p-type field effect transistors (FETs), whereas devices made with metallic nanotubes had a finite resistance with little or no gate modulation. This scalable, high resolution approach represents an important step forward toward the potential implementation of complex SWCNT devices and circuits. PMID:26807948

  2. Wafer-level hysteresis-free resonant carbon nanotube transistors.

    PubMed

    Cao, Ji; Bartsch, Sebastian T; Ionescu, Adrian M

    2015-03-24

    We report wafer-level fabrication of resonant-body carbon nanotube (CNT) field-effect transistors (FETs) in a dual-gate configuration. An integration density of >10(6) CNTFETs/cm(2), an assembly yield of >80%, and nanoprecision have been simultaneously obtained. Through combined chemical and thermal treatments, hysteresis-free (in vacuum) suspended-body CNTFETs have been demonstrated. Electrostatic actuation by lateral gate and FET-based readout of mechanical resonance have been achieved at room temperature. Both upward and downward in situ frequency tuning has been experimentally demonstrated in the dual-gate architecture. The minuscule mass, high resonance frequency, and in situ tunability of the resonant CNTFETs offer promising features for applications in radio frequency signal processing and ultrasensitive sensing. PMID:25752991

  3. Exploration of vertical scaling limit in carbon nanotube transistors

    NASA Astrophysics Data System (ADS)

    Qiu, Chenguang; Zhang, Zhiyong; Yang, Yingjun; Xiao, Mengmeng; Ding, Li; Peng, Lian-Mao

    2016-05-01

    Top-gated carbon nanotube field-effect transistors (CNT FETs) were fabricated by using ultra-thin (4.5 nm or thinner) atomic-layer-deposition grown HfO2 as gate insulator, and shown to exhibit high gate efficiency, i.e., all examined (totally 76) devices present very low room temperature subthreshold swing with an averaged value of 64 mV/Dec, without observable carrier mobility degradation. The gate leakage of the CNT FET under fixed gate voltage is dependent not only on the thickness of HfO2 insulator, but also on the diameter of the CNT. The vertical scaling limit of CNT FETs is determined by gate leakage standard in ultra large scale integrated circuits. HfO2 film with effective oxide thickness of 1.2 nm can provide both excellent gate electrostatic controllability and small gate leakage for sub-5 nm FETs based on CNT with small diameter.

  4. Monoclonal Antibodies Attached to Carbon Nanotube Transistors for Paclitaxel Detection

    NASA Astrophysics Data System (ADS)

    Lee, Wonbae; Lau, Calvin; Richardson, Mark; Rajapakse, Arith; Weiss, Gregory; Collins, Philip; UCI, Molecular Biology; Biochemistry Collaboration; UCI, Departments of Physics; Astronomy Collaboration

    Paclitaxel is a naturally-occurring pharmaceutical used in numerous cancer treatments, despite its toxic side effects. Partial inhibition of this toxicity has been demonstrated using weakly interacting monoclonal antibodies (3C6 and 8A10), but accurate monitoring of antibody and paclitaxel concentrations remains challenging. Here, single-molecule studies of the kinetics of antibody-paclitaxel interactions have been performed using single-walled carbon nanotube field-effect transistors. The devices were sensitized with single antibody attachments to record the single-molecule binding dynamics of paclitaxel. This label-free technique recorded a range of dynamic interactions between the antibody and paclitaxel, and it provided sensitive paclitaxel detection for pM to nM concentrations. Measurements with two different antibodies suggest ways of extending this working range and uncovering the mechanistic differences among different antibodies.

  5. Towards parallel fabrication of single electron transistors using carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Islam, Muhammad R.; Joung, Daeha; Khondaker, Saiful I.

    2015-05-01

    Single electron transistors (SETs) are considered to be promising building blocks for post CMOS era electronic devices, however, a major bottleneck for practical realization of SET based devices is a lack of a parallel fabrication approach. Here, we have demonstrated a technique for the scalable fabrication of SETs using single-walled carbon nanotubes (SWNTs). The approach is based on the integration of solution processed individual SWNTs via dielectrophoresis (DEP) at the selected position of the circuit with a 100 nm channel length, where the metal-SWNT Schottky contact works as a tunnel barrier. Measurements carried out at a low temperature (4.2 K) show that the majority of the devices with a contact resistance (RT) > 100 kΩ display SET behavior. For the devices with 100 kΩ < RT < 1 MΩ, periodic, well-defined Coulomb diamonds with a charging energy of ~14 meV, corresponding to the transport through a single quantum dot (QD) was observed. For devices with high RT (>1 MΩ) multiple QD behavior was observed. From the transport study of 50 SWNT devices, a total of 38 devices show SET behavior giving a yield of 76%. The results presented here are a significant step forward for the practical realization of SET based devices.Single electron transistors (SETs) are considered to be promising building blocks for post CMOS era electronic devices, however, a major bottleneck for practical realization of SET based devices is a lack of a parallel fabrication approach. Here, we have demonstrated a technique for the scalable fabrication of SETs using single-walled carbon nanotubes (SWNTs). The approach is based on the integration of solution processed individual SWNTs via dielectrophoresis (DEP) at the selected position of the circuit with a 100 nm channel length, where the metal-SWNT Schottky contact works as a tunnel barrier. Measurements carried out at a low temperature (4.2 K) show that the majority of the devices with a contact resistance (RT) > 100 kΩ display SET

  6. High performance transistors via aligned polyfluorene-sorted carbon nanotubes

    SciTech Connect

    Brady, Gerald J.; Joo, Yongho; Singha Roy, Susmit; Gopalan, Padma; Arnold, Michael S.

    2014-02-24

    We evaluate the performance of exceptionally electronic-type sorted, semiconducting, aligned single-walled carbon nanotubes (s-SWCNTs) in field effect transistors (FETs). High on-conductance and high on/off conductance modulation are simultaneously achieved at channel lengths which are both shorter and longer than individual s-SWCNTs. The s-SWCNTs are isolated from heterogeneous mixtures using a polyfluorene-derivative as a selective agent and aligned on substrates via dose-controlled, floating evaporative self-assembly at densities of ∼50 s-SWCNTs μm{sup −1}. At a channel length of 9 μm the s-SWCNTs percolate to span the FET channel, and the on/off ratio and charge transport mobility are 2.2 × 10{sup 7} and 46 cm{sup 2} V{sup −1} s{sup −1}, respectively. At a channel length of 400 nm, a large fraction of the s-SWCNTs directly span the channel, and the on-conductance per width is 61 μS μm{sup −1} and the on/off ratio is 4 × 10{sup 5}. These results are considerably better than previous solution-processed FETs, which have suffered from poor on/off ratio due to spurious metallic nanotubes that bridge the channel. 4071 individual and small bundles of s-SWCNTs are tested in 400 nm channel length FETs, and all show semiconducting behavior, demonstrating the high fidelity of polyfluorenes as selective agents and the promise of assembling s-SWCNTs from solution to create high performance semiconductor electronic devices.

  7. Self aligned hysteresis free carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Shlafman, M.; Tabachnik, T.; Shtempluk, O.; Razin, A.; Kochetkov, V.; Yaish, Y. E.

    2016-04-01

    Hysteresis phenomenon in the transfer characteristics of carbon nanotube field effect transistor (CNT FET) is being considered as the main obstacle for successful realization of electronic devices based on CNTs. In this study, we prepare four kinds of CNTFETs and explore their hysteretic behavior. Two kinds of devices comprise on-surface CNTs (type I) and suspended CNTs (type II) with thin insulating layer underneath and a single global gate which modulates the CNT conductance. The third and fourth types (types III and IV) consist of suspended CNT over a metallic local gate underneath, where for type IV the local gate was patterned self aligned with the source and drain electrodes. The first two types of devices, i.e., type I and II, exhibit substantial hysteresis which increases with scanning range and sweeping time. Under high vacuum conditions and moderate electric fields ( |E |>4 ×106 V /cm ), the hysteresis for on-surface devices cannot be eliminated, as opposed to suspended devices. Interestingly, type IV devices exhibit no hysteresis at all at ambient conditions, and from the different roles which the global and local gates play for the four types of devices, we could learn about the hysteresis mechanism of this system. We believe that these self aligned hysteresis free FETs will enable the realization of different electronic devices and sensors based on CNTs.

  8. High field breakdown characteristics of carbon nanotube thin film transistors.

    PubMed

    Gupta, Man Prakash; Behnam, Ashkan; Lian, Feifei; Estrada, David; Pop, Eric; Kumar, Satish

    2013-10-11

    The high field properties of carbon nanotube (CNT) network thin film transistors (CN-TFTs) are important for their practical operation, and for understanding their reliability. Using a combination of experimental and computational techniques we show how the channel geometry (length L(C) and width W(C)) and network morphology (average CNT length L(t) and alignment angle distribution θ) affect heat dissipation and high field breakdown in such devices. The results suggest that when WC ≥ L(t), the breakdown voltage remains independent of W(C) but varies linearly with L(C). The breakdown power varies almost linearly with both W(C) and L(C) when WC > L(t). We also find that the breakdown power is more susceptible to the variability in the network morphology compared to the breakdown voltage. The analysis offers new insight into the tunable heat dissipation and thermal reliability of CN-TFTs, which can be significantly improved through optimization of the network morphology and device geometry. PMID:24029606

  9. Towards parallel fabrication of single electron transistors using carbon nanotubes.

    PubMed

    Islam, Muhammad R; Joung, Daeha; Khondaker, Saiful I

    2015-06-01

    Single electron transistors (SETs) are considered to be promising building blocks for post CMOS era electronic devices, however, a major bottleneck for practical realization of SET based devices is a lack of a parallel fabrication approach. Here, we have demonstrated a technique for the scalable fabrication of SETs using single-walled carbon nanotubes (SWNTs). The approach is based on the integration of solution processed individual SWNTs via dielectrophoresis (DEP) at the selected position of the circuit with a 100 nm channel length, where the metal-SWNT Schottky contact works as a tunnel barrier. Measurements carried out at a low temperature (4.2 K) show that the majority of the devices with a contact resistance (RT) > 100 kΩ display SET behavior. For the devices with 100 kΩ < RT < 1 MΩ, periodic, well-defined Coulomb diamonds with a charging energy of ∼14 meV, corresponding to the transport through a single quantum dot (QD) was observed. For devices with high RT (>1 MΩ) multiple QD behavior was observed. From the transport study of 50 SWNT devices, a total of 38 devices show SET behavior giving a yield of 76%. The results presented here are a significant step forward for the practical realization of SET based devices. PMID:25962565

  10. Carbon nanotube transistor based high-frequency electronics

    NASA Astrophysics Data System (ADS)

    Schroter, Michael

    At the nanoscale carbon nanotubes (CNTs) have higher carrier mobility and carrier velocity than most incumbent semiconductors. Thus CNT based field-effect transistors (FETs) are being considered as strong candidates for replacing existing MOSFETs in digital applications. In addition, the predicted high intrinsic transit frequency and the more recent finding of ways to achieve highly linear transfer characteristics have inspired investigations on analog high-frequency (HF) applications. High linearity is extremely valuable for an energy efficient usage of the frequency spectrum, particularly in mobile communications. Compared to digital applications, the much more relaxed constraints for CNT placement and lithography combined with already achieved operating frequencies of at least 10 GHz for fabricated devices make an early entry in the low GHz HF market more feasible than in large-scale digital circuits. Such a market entry would be extremely beneficial for funding the development of production CNTFET based process technology. This talk will provide an overview on the present status and feasibility of HF CNTFET technology will be given from an engineering point of view, including device modeling, experimental results, and existing roadblocks.

  11. Imperceptible and Ultraflexible p-Type Transistors and Macroelectronics Based on Carbon Nanotubes.

    PubMed

    Cao, Xuan; Cao, Yu; Zhou, Chongwu

    2016-01-26

    Flexible thin-film transistors based on semiconducting single-wall carbon nanotubes are promising for flexible digital circuits, artificial skins, radio frequency devices, active-matrix-based displays, and sensors due to the outstanding electrical properties and intrinsic mechanical strength of carbon nanotubes. Nevertheless, previous research effort only led to nanotube thin-film transistors with the smallest bending radius down to 1 mm. In this paper, we have realized the full potential of carbon nanotubes by making ultraflexible and imperceptible p-type transistors and circuits with a bending radius down to 40 μm. In addition, the resulted transistors show mobility up to 12.04 cm(2) V(-1) S(-1), high on-off ratio (∼10(6)), ultralight weight (<3 g/m(2)), and good mechanical robustness (accommodating severe crumpling and 67% compressive strain). Furthermore, the nanotube circuits can operate properly with 33% compressive strain. On the basis of the aforementioned features, our ultraflexible p-type nanotube transistors and circuits have great potential to work as indispensable components for ultraflexible complementary electronics. PMID:26624921

  12. High-performance carbon nanotube thin-film transistors on flexible paper substrates

    SciTech Connect

    Liu, Na; Yun, Ki Nam; Yu, Hyun-Yong; Lee, Cheol Jin; Shim, Joon Hyung

    2015-03-09

    Single-walled carbon nanotubes (SWCNTs) are promising materials as active channels for flexible transistors owing to their excellent electrical and mechanical properties. However, flexible SWCNT transistors have never been realized on paper substrates, which are widely used, inexpensive, and recyclable. In this study, we fabricated SWCNT thin-film transistors on photo paper substrates. The devices exhibited a high on/off current ratio of more than 10{sup 6} and a field-effect mobility of approximately 3 cm{sup 2}/V·s. The proof-of-concept demonstration indicates that SWCNT transistors on flexible paper substrates could be applied as low-cost and recyclable flexible electronics.

  13. Carbon nanotube network thin-film transistors on flexible/stretchable substrates

    DOEpatents

    Takei, Kuniharu; Takahashi, Toshitake; Javey, Ali

    2016-03-29

    This disclosure provides systems, methods, and apparatus for flexible thin-film transistors. In one aspect, a device includes a polymer substrate, a gate electrode disposed on the polymer substrate, a dielectric layer disposed on the gate electrode and on exposed portions of the polymer substrate, a carbon nanotube network disposed on the dielectric layer, and a source electrode and a drain electrode disposed on the carbon nanotube network.

  14. Hysteresis in Carbon Nanotube Transistors: Measurement and Analysis of Trap Density, Energy Level, and Spatial Distribution.

    PubMed

    Park, Rebecca Sejung; Shulaker, Max Marcel; Hills, Gage; Suriyasena Liyanage, Luckshitha; Lee, Seunghyun; Tang, Alvin; Mitra, Subhasish; Wong, H-S Philip

    2016-04-26

    We present a measurement technique, which we call the Pulsed Time-Domain Measurement, for characterizing hysteresis in carbon nanotube field-effect transistors, and demonstrate its applicability for a broad range of 1D and 2D nanomaterials beyond carbon nanotubes. The Pulsed Time-Domain Measurement enables the quantification (density, energy level, and spatial distribution) of charged traps responsible for hysteresis. A physics-based model of the charge trapping process for a carbon nanotube field-effect transistor is presented and experimentally validated using the Pulsed Time-Domain Measurement. Leveraging this model, we discover a source of traps (surface traps) unique to devices with low-dimensional channels such as carbon nanotubes and nanowires (beyond interface traps which exist in today's silicon field-effect transistors). The different charge trapping mechanisms for interface traps and surface traps are studied based on their temperature dependencies. Through these advances, we are able to quantify the interface trap density for carbon nanotube field-effect transistors (∼3 × 10(13) cm(-2) eV(-1) near midgap), and compare this against a range of previously studied dielectric/semiconductor interfaces. PMID:27002483

  15. Advances in NO2 sensing with individual single-walled carbon nanotube transistors

    PubMed Central

    Muoth, Matthias; Roman, Cosmin; Haluska, Miroslav; Hierold, Christofer

    2014-01-01

    Summary The charge carrier transport in carbon nanotubes is highly sensitive to certain molecules attached to their surface. This property has generated interest for their application in sensing gases, chemicals and biomolecules. With over a decade of research, a clearer picture of the interactions between the carbon nanotube and its surroundings has been achieved. In this review, we intend to summarize the current knowledge on this topic, focusing not only on the effect of adsorbates but also the effect of dielectric charge traps on the electrical transport in single-walled carbon nanotube transistors that are to be used in sensing applications. Recently, contact-passivated, open-channel individual single-walled carbon nanotube field-effect transistors have been shown to be operational at room temperature with ultra-low power consumption. Sensor recovery within minutes through UV illumination or self-heating has been shown. Improvements in fabrication processes aimed at reducing the impact of charge traps have reduced the hysteresis, drift and low-frequency noise in carbon nanotube transistors. While open challenges such as large-scale fabrication, selectivity tuning and noise reduction still remain, these results demonstrate considerable progress in transforming the promise of carbon nanotube properties into functional ultra-low power, highly sensitive gas sensors. PMID:25551046

  16. End-bonded contacts for carbon nanotube transistors with low, size-independent resistance.

    PubMed

    Cao, Qing; Han, Shu-Jen; Tersoff, Jerry; Franklin, Aaron D; Zhu, Yu; Zhang, Zhen; Tulevski, George S; Tang, Jianshi; Haensch, Wilfried

    2015-10-01

    Moving beyond the limits of silicon transistors requires both a high-performance channel and high-quality electrical contacts. Carbon nanotubes provide high-performance channels below 10 nanometers, but as with silicon, the increase in contact resistance with decreasing size becomes a major performance roadblock. We report a single-walled carbon nanotube (SWNT) transistor technology with an end-bonded contact scheme that leads to size-independent contact resistance to overcome the scaling limits of conventional side-bonded or planar contact schemes. A high-performance SWNT transistor was fabricated with a sub-10-nanometer contact length, showing a device resistance below 36 kilohms and on-current above 15 microampere per tube. The p-type end-bonded contact, formed through the reaction of molybdenum with the SWNT to form carbide, also exhibited no Schottky barrier. This strategy promises high-performance SWNT transistors, enabling future ultimately scaled device technologies. PMID:26430114

  17. End-bonded contacts for carbon nanotube transistors with low, size-independent resistance

    NASA Astrophysics Data System (ADS)

    Cao, Qing; Han, Shu-Jen; Tersoff, Jerry; Franklin, Aaron D.; Zhu, Yu; Zhang, Zhen; Tulevski, George S.; Tang, Jianshi; Haensch, Wilfried

    2015-10-01

    Moving beyond the limits of silicon transistors requires both a high-performance channel and high-quality electrical contacts. Carbon nanotubes provide high-performance channels below 10 nanometers, but as with silicon, the increase in contact resistance with decreasing size becomes a major performance roadblock. We report a single-walled carbon nanotube (SWNT) transistor technology with an end-bonded contact scheme that leads to size-independent contact resistance to overcome the scaling limits of conventional side-bonded or planar contact schemes. A high-performance SWNT transistor was fabricated with a sub-10-nanometer contact length, showing a device resistance below 36 kilohms and on-current above 15 microampere per tube. The p-type end-bonded contact, formed through the reaction of molybdenum with the SWNT to form carbide, also exhibited no Schottky barrier. This strategy promises high-performance SWNT transistors, enabling future ultimately scaled device technologies.

  18. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

    SciTech Connect

    Seo, M.; Kim, H.; Kim, Y. H.; Yun, H.; McAllister, K.; Lee, S. W.; Na, J.; Kim, G. T.; Lee, B. J.; Kim, J. J.; Jeong, G. H.; Lee, I.; Kim, K. S.

    2015-07-20

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems.

  19. A review of carbon nanotube- and graphene-based flexible thin-film transistors.

    PubMed

    Sun, Dong-Ming; Liu, Chang; Ren, Wen-Cai; Cheng, Hui-Ming

    2013-04-22

    Carbon nanotubes (CNTs) and graphene have attracted great attention for numerous applications for future flexible electronics, owing to their supreme properties including exceptionally high electronic conductivity and mechanical strength. Here, the progress of CNT- and graphene-based flexible thin-film transistors from material preparation, device fabrication techniques to transistor performance control is reviewed. State-of-the-art fabrication techniques of thin-film transistors are divided into three categories: solid-phase, liquid-phase, and gas-phase techniques, and possible scale-up approaches to achieve realistic production of flexible nanocarbon-based transistors are discussed. In particular, the recent progress in flexible all-carbon nanomaterial transistor research is highlighted, and this all-carbon strategy opens up a perspective to realize extremely flexible, stretchable, and transparent electronics with a relatively low-cost and fast fabrication technique, compared to traditional rigid silicon, metal and metal oxide electronics. PMID:23519953

  20. Electric Characteristics of the Carbon Nanotube Network Transistor with Directly Grown ZnO Nanoparticles.

    PubMed

    Kim, Un Jeong; Bae, Gi Yoon; Suh, Dong Ik; Park, Wanjun

    2016-03-01

    We report on the electrical characteristics of field effect transistors fabricated with random networks of single-walled carbon nanotubes with surfaces modified by ZnO nanoparticles. ZnO nanoparticles are directly grown on single-walled carbon nanotubes by atomic layer deposition using diethylzinc (DEZ) and water. Electrical observations show that ZnO nanoparticles act as charge transfer sources that provide electrons to the nanotube channel. The valley position in ambipolar transport of nanotube transistors is negatively shifted for 3V due to the electronic n-typed property of ZnO nanoparticles. However, the Raman resonance remains invariant despite the charge transfer effect produced by ZnO nanoparticles. PMID:27455727

  1. Electrostatic Simulation of Charge Trapping in Carbon Nanotube Vertical Organic Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Crawford, Jennifer; Rinzler, Andrew; Hershfield, Selman

    The carbon nanotube vertical organic field effect transistor is a vertical sequence consisting of a gate electrode, gate dielectric, thin nanotube network source electrode, organic semiconducting channel and finally the drain electrode. The drain current is modulated by the gate voltage which varies a Schottky barrier between source and channel layers. Hysteresis in the current-voltage characteristic has been observed when a electret charge trapping layer is placed between the nanotube source and the gate dielectric. We provide a model for charge injection into a trapping layer placed in contact with the carbon nanotube film and solve self-consistently for the electrostatics and the occupancy of the traps. For a range of applied gate voltages the simulations demonstrate hysteresis of the carbon nanotubes' charge as a result of the electric field produced by the trapped charge. This affects the current by modulating the Schottky barrier. This work was supported by the NSF Grant DMR-1461019.

  2. Short Channel Field-Effect-Transistors with Inkjet-Printed Semiconducting Carbon Nanotubes.

    PubMed

    Jang, Seonpil; Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2015-11-01

    Short channel field-effect-transistors with inkjet-printed semiconducting carbon nanotubes are fabricated using a novel strategy to minimize material consumption, confining the inkjet droplet into the active channel area. This fabrication approach is compatible with roll-to-roll processing and enables the formation of high-performance short channel device arrays based on inkjet printing. PMID:26312458

  3. Mechanically Durable and Highly Stretchable Transistors Employing Carbon Nanotube Semiconductor and Electrodes.

    PubMed

    Chortos, Alex; Koleilat, Ghada I; Pfattner, Raphael; Kong, Desheng; Lin, Pei; Nur, Roda; Lei, Ting; Wang, Huiliang; Liu, Nan; Lai, Ying-Chih; Kim, Myung-Gil; Chung, Jong Won; Lee, Sangyoon; Bao, Zhenan

    2016-06-01

    Mechanically durable stretchable trans-istors are fabricated using carbon nanotube electrical components and tough thermoplastic elastomers. After an initial conditioning step, the electrical characteristics remain constant with strain. The strain-dependent characteristics are similar in orthogonal stretching directions. Devices can be impacted with a hammer and punctured with a needle while remaining functional and stretchable. PMID:26179120

  4. Room-temperature single charge sensitivity in carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Peng, H. B.; Hughes, M. E.; Golovchenko, J. A.

    2006-12-01

    Electrical current fluctuation studies are reported for coaxial p-type and n-type single-wall carbon nanotube field-effect transistors (FETs). Abrupt discrete switching of the source-drain current is observed at room temperature. The authors attribute these random telegraph signals to charge fluctuating electron traps near the FET conduction channels. Evolution of the current-switching behavior associated with the occupancy of individual electron traps is demonstrated and analyzed statistically. The result strongly indicates room temperature single charge sensitivity in carbon nanotube FETs, which may offer potential applications for single molecule sensors based on suitably prepared FET devices.

  5. Controlled n-Type Doping of Carbon Nanotube Transistors by an Organorhodium Dimer.

    PubMed

    Geier, Michael L; Moudgil, Karttikay; Barlow, Stephen; Marder, Seth R; Hersam, Mark C

    2016-07-13

    Single-walled carbon nanotube (SWCNT) transistors are among the most developed nanoelectronic devices for high-performance computing applications. While p-type SWCNT transistors are easily achieved through adventitious adsorption of atmospheric oxygen, n-type SWCNT transistors require extrinsic doping schemes. Existing n-type doping strategies for SWCNT transistors suffer from one or more issues including environmental instability, limited carrier concentration modulation, undesirable threshold voltage control, and/or poor morphology. In particular, commonly employed benzyl viologen n-type doping layers possess large thicknesses, which preclude top-gate transistor designs that underlie high-density integrated circuit layouts. To overcome these limitations, we report here the controlled n-type doping of SWCNT thin-film transistors with a solution-processed pentamethylrhodocene dimer. The charge transport properties of organorhodium-treated SWCNT thin films show consistent n-type behavior when characterized in both Hall effect and thin-film transistor geometries. Due to the molecular-scale thickness of the organorhodium adlayer, large-area arrays of top-gated, n-type SWCNT transistors are fabricated with high yield. This work will thus facilitate ongoing efforts to realize high-density SWCNT integrated circuits. PMID:27253896

  6. In vitro detection of biological molecules using carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Briman, Mikhail Borisovich

    The operation and the stability of different types of carbon nanotube field-effect transistors in the liquid buffer are investigated. The effects of environmental parameters of aqueous solutions such as pH and the ionic-strength on the device parameters are also reported. Another set of experiments carried out in the electrolyte showed that number fluctuations are the most likely source of low frequency electrical noise found in the devices. Finally, charge transfer was found to be the dominant effect in the mechanism of nanotube-protein interactions.

  7. High-performance air-stable n-type carbon nanotube transistors with erbium contacts.

    PubMed

    Shahrjerdi, Davood; Franklin, Aaron D; Oida, Satoshi; Ott, John A; Tulevski, George S; Haensch, Wilfried

    2013-09-24

    So far, realization of reproducible n-type carbon nanotube (CNT) transistors suitable for integrated digital applications has been a difficult task. In this work, hundreds of n-type CNT transistors from three different low work function metals-erbium, lanthanum, and yttrium-are studied and benchmarked against p-type devices with palladium contacts. The crucial role of metal type and deposition conditions is elucidated with respect to overall yield and performance of the n-type devices. It is found that high oxidation rates and sensitivity to deposition conditions are the major causes for the lower yield and large variation in performance of n-type CNT devices with low work function metal contacts. Considerable improvement in device yield is attained using erbium contacts evaporated at high deposition rates. Furthermore, the air-stability of our n-type transistors is studied in light of the extreme sensitivity of these metals to oxidation. PMID:24006886

  8. Analytical ballistic theory of carbon nanotube transistors: Experimental validation, device physics, parameter extraction, and performance projection

    NASA Astrophysics Data System (ADS)

    Akinwande, Deji; Liang, Jiale; Chong, Soogine; Nishi, Yoshio; Wong, H.-S. Philip

    2008-12-01

    We developed a fully analytical ballistic theory of carbon nanotube field effect transistors enabled by the development of an analytical surface potential capturing the temperature dependence and gate and quantum capacitance electrostatics. The analytical ballistic theory is compared to the experimental results of a ballistic transistor with good agreement. The validated analytical theory enables intuitive circuit design, provides techniques for parameter extraction of the bandgap and surface potential, and elucidates on the device physics of drain optical phonon scattering and its role in reducing the linear conductance and intrinsic gain of the transistor. Furthermore, a threshold voltage definition is proposed reflecting the bandgap-diameter dependence. Projections for key analog and digital performances are discussed.

  9. Enhancement of minority carrier injection in ambipolar carbon nanotube transistors using double-gate structures

    NASA Astrophysics Data System (ADS)

    Kim, Bongjun; Liang, Kelly; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2016-07-01

    We show that double-gate ambipolar thin-film transistors can be operated to enhance minority carrier injection. The two gate potentials need to be significantly different for enhanced injection to be observed. This enhancement is highly beneficial in devices such as light-emitting transistors where balanced electron and hole injections lead to optimal performance. With ambipolar single-walled carbon nanotube semiconductors, we demonstrate that higher ambipolar currents are attained at lower source-drain voltages, which is desired for portable electronic applications, by employing double-gate structures. In addition, when the two gates are held at the same potential, the expected advantages of the double-gate transistors such as enhanced on-current are also observed.

  10. Light-emitting polymer/carbon nanotube hybrid transistors: below and above the percolation limit

    NASA Astrophysics Data System (ADS)

    Wang, Ming; Jakubka, Florian; Gannott, Florentina; Zaumseil, Jana

    2013-09-01

    Hybrids of semiconducting polymers and single-walled carbon nanotubes (SWNT) are interesting for organic electronic devices such as solar cells, light-emitting diodes and field-effect transistors (FETs). They are easily produced by selective dispersion of SWNTs in polymer solutions by ultrasonication followed by centrifugation. We demonstrate that nanotubes at concentration levels well below the percolation limit significantly improve charge injection of both holes and electrons into semiconducting polymers in top-gate FETs. This leads to lower contact resistances and reduced threshold voltages, thus the maximum ambipolar currents and visible light emission due to electron-hole recombination are considerably enhanced. The improved injection of holes and electrons allows for a much wider range of accessible polymers for ambipolar and light-emitting transistors. The same conjugated polymers can also be used to enrich specific semiconducting SWNT and to produce high-performance ambipolar nanotube network FETs. These show efficient nearinfrared electroluminescence. Mapping the emission from these networks during a gate voltage sweep allows us to visualize preferential current paths and investigate percolation models for purely semiconducting nanotube networks.

  11. Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors.

    PubMed

    Chen, Haitian; Cao, Yu; Zhang, Jialu; Zhou, Chongwu

    2014-01-01

    Carbon nanotubes and metal oxide semiconductors have emerged as important materials for p-type and n-type thin-film transistors, respectively; however, realizing sophisticated macroelectronics operating in complementary mode has been challenging due to the difficulty in making n-type carbon nanotube transistors and p-type metal oxide transistors. Here we report a hybrid integration of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors to achieve large-scale (>1,000 transistors for 501-stage ring oscillators) complementary macroelectronic circuits on both rigid and flexible substrates. This approach of hybrid integration allows us to combine the strength of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors, and offers high device yield and low device variation. Based on this approach, we report the successful demonstration of various logic gates (inverter, NAND and NOR gates), ring oscillators (from 51 stages to 501 stages) and dynamic logic circuits (dynamic inverter, NAND and NOR gates). PMID:24923382

  12. Ultrasensitive Detection of DNA Hybridization Using Carbon Nanotube Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Maehashi, Kenzo; Matsumoto, Kazuhiko; Kerman, Kagan; Takamura, Yuzuru; Tamiya, Eiichi

    2004-12-01

    We have sensitively detected DNA hybridization using carbon nanotube field-effect transistors (CNTFETs) in real time. Amino modified peptide nucleic acid (PNA) oligonucleotides at 5' end were covalently immobilized onto the Au surface of the back gate. For 11-mer PNA oligonucletide probe, full-complementary DNA with concentration as low as 6.8 fM solution could be effectively detected. Our CNTFET-based biochip is a promising candidate for the development of an integrated, high-throughput, multiplexed DNA biosensor for medical, forensic and environmental diagnostics.

  13. Fabrication process of carbon nanotube field effect transistors using atomic layer deposition passivation for biosensors.

    PubMed

    Nakashima, Yasuhiro; Ohno, Yutaka; Kishimoto, Shigeru; Okochi, Mina; Honda, Hiroyuki; Mizutani, Takashi

    2010-06-01

    Fabrication process of the carbon nanotube (CNT) field effect transistors (FETs) for biosensors was studied. Atomic layer deposition (ALD) of HfO2 was applied to the deposition of the passivation/gate insulator film. The CNT-FETs did not show the drain current degradation after ALD passivation even though the passivation by Si3N4 deposited by plasma-enhanced chemical vapor deposition (PECVD) resulted in a significant drain current decrease. This indicates the advantage of the present ALD technique in terms of the damage suppression. The biosensing operation was confirmed using thus fabricated CNT-FETs. PMID:20355371

  14. Recent Progress in Obtaining Semiconducting Single-Walled Carbon Nanotubes for Transistor Applications.

    PubMed

    Islam, Ahmad E; Rogers, John A; Alam, Muhammad A

    2015-12-22

    High purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with a narrow diameter distribution are required for high-performance transistors. Achieving this goal is extremely challenging because the as-grown material contains mixtures of s-SWCNTs and metallic- (m-) SWCNTs with wide diameter distributions, typically inadequate for integrated circuits. Since 2000, numerous ex situ methods have been proposed to improve the purity of the s-SWCNTs. The majority of these techniques fail to maintain the quality and integrity of the s-SWCNTs with a few notable exceptions. Here, the progress in realizing high purity s-SWCNTs in as-grown and post-processed materials is highlighted. A comparison of transistor parameters (such as on/off ratio and field-effect mobility) obtained from test structures establishes the effectiveness of various methods and suggests opportunities for future improvements. PMID:26540144

  15. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    SciTech Connect

    Aïssa, B.; Nedil, M.; Kroeger, J.; Haddad, T.; Rosei, F.

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  16. Highly stretchable carbon nanotube transistors enabled by buckled ion gel gate dielectrics

    SciTech Connect

    Wu, Meng-Yin; Chang, Tzu-Hsuan; Ma, Zhenqiang; Zhao, Juan; Xu, Feng; Jacobberger, Robert M.; Arnold, Michael S.

    2015-08-03

    Deformable field-effect transistors (FETs) are expected to facilitate new technologies like stretchable displays, conformal devices, and electronic skins. We previously demonstrated stretchable FETs based on buckled thin films of polyfluorene-wrapped semiconducting single-walled carbon nanotubes as the channel, buckled metal films as electrodes, and unbuckled flexible ion gel films as the dielectric. The FETs were stretchable up to 50% without appreciable degradation in performance before failure of the ion gel film. Here, we show that by buckling the ion gel, the integrity and performance of the nanotube FETs are extended to nearly 90% elongation, limited by the stretchability of the elastomer substrate. The FETs maintain an on/off ratio of >10{sup 4} and a field-effect mobility of 5 cm{sup 2} V{sup −1} s{sup −1} under elongation and demonstrate invariant performance over 1000 stretching cycles.

  17. Metal contact effect on the performance and scaling behavior of carbon nanotube thin film transistors.

    PubMed

    Xia, Jiye; Dong, Guodong; Tian, Boyuan; Yan, Qiuping; Zhang, Han; Liang, Xuelei; Peng, Lianmao

    2016-05-21

    Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact resistivity was found to increase with channel length, which is a consequence of the percolating nature of the transport in CNT films, and this behavior does not exist in CNT-FETs and normal 2D Ohmic conductors. Electrical transport in CNT-TFTs has been predicted to scale with channel length by stick percolation theory. However, the scaling behavior is also impacted, or even covered up by the effect of Rc. Once the contact effect is excluded, the covered scaling behavior can be revealed correctly. A possible way of reducing Rc in CNT-TFTs was proposed. We believe the findings in this paper will strengthen our understanding of CNT-TFTs, and even accelerate the commercialization of CNT-TFT technology. PMID:27121370

  18. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors; Toward all carbon electronics

    NASA Astrophysics Data System (ADS)

    Lee, Sang Wook; Seo, Miri; Na, Junhong; Kim, Yong Hyeon; Lee, Byeong-Joo; Kim, Jin-Ju; Yun, Hoyeol; Kim, Hakseong; Yoon, Ho-Ang; Kim, Keun Soo; Jeong, Goo-Hwan; Kim, Gyu Tae

    2014-03-01

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode array on top of the pre-deposited SWNTs which were aligned along one direction. Aligned arrays of SWNTs were synthesized by thermal chemical vapor deposition (CVD) method on quartz substrate. The micro scale contact electrodes and following circuit structures were defined by photo lithography on the large area graphene produced by CVD. Both of the single and multi layer graphene were used for the electrode materials. In this presentation, the device fabrication procedure, the contact properties, and the transistor performances of the device structures were discussed. This work was supported by NRF.

  19. Vacuum filtration based formation of liquid crystal films of semiconducting carbon nanotubes and high performance transistor devices

    NASA Astrophysics Data System (ADS)

    King, Benjamin; Panchapakesan, Balaji

    2014-05-01

    In this paper, we report ultra-thin liquid crystal films of semiconducting carbon nanotubes using a simple vacuum filtration process. Vacuum filtration of nanotubes in aqueous surfactant solution formed nematic domains on the filter membrane surface and exhibited local ordering. A 2D fast Fourier transform was used to calculate the order parameters from scanning electron microscopy images. The order parameter was observed to be sensitive to the filtration time demonstrating different regions of transformation namely nucleation of nematic domains, nanotube accumulation and large domain growth.Transmittance versus sheet resistance measurements of such films resulted in optical to dc conductivity of σ opt/σ dc = 9.01 indicative of purely semiconducting nanotube liquid crystal network.Thin films of nanotube liquid crystals with order parameters ranging from S = 0.1-0.5 were patterned into conducting channels of transistor devices which showed high I on/I off ratios from 10-19 800 and electron mobility values μ e = 0.3-78.8 cm2 (V-s)-1, hole mobility values μ h = 0.4-287 cm2 (V-s)-1. High I on/I off ratios were observed at low order parameters and film mass. A Schottky barrier transistor model is consistent with the observed transistor characteristics. Electron and hole mobilities were seen to increase with order parameters and carbon nanotube mass fractions. A fundamental tradeoff between decreasing on/off ratio and increasing mobility with increasing nanotube film mass and order parameter is therefore concluded. Increase in order parameters of nanotubes liquid crystals improved the electronic transport properties as witnessed by the increase in σ dc/σ opt values on macroscopic films and high mobilities in microscopic transistors. Liquid crystal networks of semiconducting nanotubes as demonstrated here are simple to fabricate, transparent, scalable and could find wide ranging device applications.

  20. Polymer-Sorted Semiconducting Carbon Nanotube Networks for High-Performance Ambipolar Field-Effect Transistors

    PubMed Central

    2014-01-01

    Efficient selection of semiconducting single-walled carbon nanotubes (SWNTs) from as-grown nanotube samples is crucial for their application as printable and flexible semiconductors in field-effect transistors (FETs). In this study, we use atactic poly(9-dodecyl-9-methyl-fluorene) (a-PF-1-12), a polyfluorene derivative with asymmetric side-chains, for the selective dispersion of semiconducting SWNTs with large diameters (>1 nm) from plasma torch-grown SWNTs. Lowering the molecular weight of the dispersing polymer leads to a significant improvement of selectivity. Combining dense semiconducting SWNT networks deposited from an enriched SWNT dispersion with a polymer/metal-oxide hybrid dielectric enables transistors with balanced ambipolar, contact resistance-corrected mobilities of up to 50 cm2·V–1·s–1, low ohmic contact resistance, steep subthreshold swings (0.12–0.14 V/dec) and high on/off ratios (106) even for short channel lengths (<10 μm). These FETs operate at low voltages (<3 V) and show almost no current hysteresis. The resulting ambipolar complementary-like inverters exhibit gains up to 61. PMID:25493421

  1. Defect Screening Effects of Fluoropolymer Capping in Single Walled Carbon Nanotube Transistors

    NASA Astrophysics Data System (ADS)

    Jang, Seonpil; Kim, Bongjun; Geier, Michael; Hersam, Mark; Dodabalapur, Ananth

    2015-03-01

    One of the most promising uses of single walled carbon nanotubes (SWCNTs) is as active channel semiconductor materials in field-effect transistors (FETs). Recent advances in the availability of highly sorted semiconducting SWCNT source material and in printing such nanotubes to realize high-performance thin-film transistors make them very promising candidates for printed electronics. In this presentation, we report on the substantial improvements in the characteristics of SWCNT FET devices and circuits comprised of these devices by the use of coatings of the fluoropolymer containing copolymer, PVDF-TrFE. The origins of these improvements may be attributed to the polar nature of C-F bonds and the local organization of the fluoropolymer at the interfaces with the SWCNTs so as to partially neutralize charged defects. This hypothesis was tested by the experiments using a number of vapor phase polar molecules which produce similar effects on the FET characteristics. The polar vapor experiments show that dipoles can partially neutralize residual charges arising from defects/impurities. The dipole present in polar molecules adopts an orientation that tends to cancel the effects of the charged defect/impurity from the perspective of mobile charges in the SWCNTs.

  2. Polymer-sorted semiconducting carbon nanotube networks for high-performance ambipolar field-effect transistors.

    PubMed

    Schiessl, Stefan P; Fröhlich, Nils; Held, Martin; Gannott, Florentina; Schweiger, Manuel; Forster, Michael; Scherf, Ullrich; Zaumseil, Jana

    2015-01-14

    Efficient selection of semiconducting single-walled carbon nanotubes (SWNTs) from as-grown nanotube samples is crucial for their application as printable and flexible semiconductors in field-effect transistors (FETs). In this study, we use atactic poly(9-dodecyl-9-methyl-fluorene) (a-PF-1-12), a polyfluorene derivative with asymmetric side-chains, for the selective dispersion of semiconducting SWNTs with large diameters (>1 nm) from plasma torch-grown SWNTs. Lowering the molecular weight of the dispersing polymer leads to a significant improvement of selectivity. Combining dense semiconducting SWNT networks deposited from an enriched SWNT dispersion with a polymer/metal-oxide hybrid dielectric enables transistors with balanced ambipolar, contact resistance-corrected mobilities of up to 50 cm(2)·V(-1)·s(-1), low ohmic contact resistance, steep subthreshold swings (0.12-0.14 V/dec) and high on/off ratios (10(6)) even for short channel lengths (<10 μm). These FETs operate at low voltages (<3 V) and show almost no current hysteresis. The resulting ambipolar complementary-like inverters exhibit gains up to 61. PMID:25493421

  3. Device and circuit-level performance of carbon nanotube field-effect transistor with benchmarking against a nano-MOSFET

    PubMed Central

    2012-01-01

    The performance of a semiconducting carbon nanotube (CNT) is assessed and tabulated for parameters against those of a metal-oxide-semiconductor field-effect transistor (MOSFET). Both CNT and MOSFET models considered agree well with the trends in the available experimental data. The results obtained show that nanotubes can significantly reduce the drain-induced barrier lowering effect and subthreshold swing in silicon channel replacement while sustaining smaller channel area at higher current density. Performance metrics of both devices such as current drive strength, current on-off ratio (Ion/Ioff), energy-delay product, and power-delay product for logic gates, namely NAND and NOR, are presented. Design rules used for carbon nanotube field-effect transistors (CNTFETs) are compatible with the 45-nm MOSFET technology. The parasitics associated with interconnects are also incorporated in the model. Interconnects can affect the propagation delay in a CNTFET. Smaller length interconnects result in higher cutoff frequency. PMID:22901374

  4. Device and circuit-level performance of carbon nanotube field-effect transistor with benchmarking against a nano-MOSFET.

    PubMed

    Tan, Michael Loong Peng; Lentaris, Georgios; Amaratunga Aj, Gehan

    2012-01-01

    The performance of a semiconducting carbon nanotube (CNT) is assessed and tabulated for parameters against those of a metal-oxide-semiconductor field-effect transistor (MOSFET). Both CNT and MOSFET models considered agree well with the trends in the available experimental data. The results obtained show that nanotubes can significantly reduce the drain-induced barrier lowering effect and subthreshold swing in silicon channel replacement while sustaining smaller channel area at higher current density. Performance metrics of both devices such as current drive strength, current on-off ratio (Ion/Ioff), energy-delay product, and power-delay product for logic gates, namely NAND and NOR, are presented. Design rules used for carbon nanotube field-effect transistors (CNTFETs) are compatible with the 45-nm MOSFET technology. The parasitics associated with interconnects are also incorporated in the model. Interconnects can affect the propagation delay in a CNTFET. Smaller length interconnects result in higher cutoff frequency. PMID:22901374

  5. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-01

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10-5 of on/off ratio and ~8 cm2 V-1 s-1 of field effect mobility.

  6. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition.

    PubMed

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-22

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10(-5) of on/off ratio and approximately 8 cm2 V(-1) s(-1) of field effect mobility. PMID:19567966

  7. Intrinsic memory function of carbon nanotube-based ferroelectric field-effect transistor.

    PubMed

    Fu, Wangyang; Xu, Zhi; Bai, Xuedong; Gu, Changzhi; Wang, Enge

    2009-03-01

    We demonstrate the intrinsic memory function of ferroelectric field-effect transistors (FeFETs) based on an integration of individual single-walled carbon nanotubes (SWCNTs) and epitaxial ferroelectric films. In contrast to the previously reported "charge-storage" CNT-FET memories, whose operations are haunted by a lack of control over the "charge traps", the present CNT-FeFETs exhibit a well-defined memory hysteresis loop induced by the reversible remnant polarization of the ferroelectric films. Large memory windows approximately 4 V, data retention time up to 1 week, and ultralow power consumption (energy per bit) of femto-joule, are highlighted in this report. Further simulations and experimental results show that the memory device is valid under operation voltage less than 1 V due to an electric-field enhancement effect induced by the ultrathin SWCNTs. PMID:19206218

  8. Modeling of Gate Bias Modulation in Carbon Nanotube Field-Effect-Transistor

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    The threshold voltages of a carbon-nanotube (CNT) field-effect transistor (FET) are studied. The CNT channel is so thin that there is no voltage drop perpendicular to the gate electrode plane, and this makes the device characteristics quite unique. The relation between the voltage and the electrochemical potentials, and the mass action law for electrons and holes are examined in the context of CNTs, and inversion and accumulation threshold voltages (V(sub Ti), and V(sub Ta)) are derived. V(sub Ti) of the CNTFETs has a much stronger doping dependence than that of the metal-oxide- semiconductor FETs, while V(sub Ta) of both devices depends weakly on doping with the same functional form.

  9. Carbon nanotube based field-effect transistors: merits and fundamental limits

    NASA Astrophysics Data System (ADS)

    Peng, Lian-Mao

    The development of even more powerful computer systems are made possible by scaling of CMOS transistors, and this simple process has afforded continuous improvement in both the device switch time and integration density. However, CMOS scaling has become very difficult at the 22-nm node and unlikely to be rewarding beyond the 14-nm node. Among other new approaches, carbon nanotube devices are emerging as the most promising technique with unique properties that are ideal for nanoelectronics. In particular, perfect n-type and p-type contacts are now available for controlled injection of electrons into the conduction band and holes into the valence band of the CNT, paving the way for a doping free fabrication of CNT based ballistic CMOS, high performance optoelectronic devices, and integrated circuits. These results will be compared with data projected for Si CMOS toward the end of the roadmap at 2026, as well as with those thermodynamic and quantum limits.

  10. Floating-gated memory based on carbon nanotube field-effect transistors with Si floating dots

    NASA Astrophysics Data System (ADS)

    Seike, Kohei; Fujii, Yusuke; Ohno, Yasuhide; Maehashi, Kenzo; Inoue, Koichi; Matsumoto, Kazuhiko

    2014-01-01

    We have fabricated a carbon nanotube field-effect transistor (CNTFET)-based nonvolatile memory device with Si floating dots. The electrical characteristics of this memory device were compared with those of devices with a HfO2 charge storage layer or Au floating dots. For a sweep width of 6 V, the memory window of the devices with the Si floating dots increased twofold as compared with that of the devices with the HfO2 layer. Moreover, the retention characteristics revealed that, for the device with the Au floating dots, the off-state had almost the same current as the on-state at the 400th s. However, the devices with the Si floating dots had longer-retention characteristics. The results indicate that CNTFET-based devices with Si floating dots are promising candidates for low-power consumption nonvolatile memory devices.

  11. Performance analysis of junctionless carbon nanotube field effect transistors using NEGF formalism

    NASA Astrophysics Data System (ADS)

    Barbastegan, Saber; Shahhoseini, Ali

    2016-04-01

    This paper presents the simulation study of a junctionless carbon nanotube field effect transistor (JL-CNTFET) and a comparison is made with the conventional CNTFET using the atomistic scale simulation, within the non-equilibrium Green’s function (NEGF) formalism. In order to have a comprehensive analysis, both analog and digital parameters of the device are studied. Results have shown that JL-CNTFET with respect to C-CNTFET shows slightly higher ION/IOFF ratio about two times larger than that of C-CNTFET, smaller electric field along channel more than three order of magnitude and reduced tunneling current about 100 times. In addition, the investigation of analog properties of both devices has exhibited that junctionless structure has a transconductance about two times and an intrinsic gain of 15 dB larger than C-CNTFET in same bias condition which makes JL-CNTFET a promising candidate for low voltage analog applications.

  12. Detection of α-fetoprotein in human serum using carbon nanotube transistor

    NASA Astrophysics Data System (ADS)

    So, Hye-Mi; Park, Dong-Won; Lee, Seong-Kyu; Kim, Beom Soo; Chang, Hyunju; Lee, Jeong-O.

    2009-03-01

    We have fabricated antibody-coated carbon nanotube field effect transistor (CNT-FET) sensor for the detection of α-fetoprotein (AFP), single chain glycoprotein of 70 kDa that is normally expressed in the fetal liver, in human serum. The AFP-specific antibodies were immobilized on CNT with linker molecule such as pyrenebutyric acid N-hydroxysuccinimide ester. To prevent nonspecific adsorption of antigen, we performed blocking procedure using bovine serum albumin (BSA). Antibody-antigen binding was determined by measuring electrical conductance change of FET and took an average of thereshold voltage change before and after binding. Also we checked concentration-dependent conductance change in human serum using both p-type SWNT-FETs and n-type SWNT-FETs.

  13. Metal contact effect on the performance and scaling behavior of carbon nanotube thin film transistors

    NASA Astrophysics Data System (ADS)

    Xia, Jiye; Dong, Guodong; Tian, Boyuan; Yan, Qiuping; Zhang, Han; Liang, Xuelei; Peng, Lianmao

    2016-05-01

    Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact resistivity was found to increase with channel length, which is a consequence of the percolating nature of the transport in CNT films, and this behavior does not exist in CNT-FETs and normal 2D Ohmic conductors. Electrical transport in CNT-TFTs has been predicted to scale with channel length by stick percolation theory. However, the scaling behavior is also impacted, or even covered up by the effect of Rc. Once the contact effect is excluded, the covered scaling behavior can be revealed correctly. A possible way of reducing Rc in CNT-TFTs was proposed. We believe the findings in this paper will strengthen our understanding of CNT-TFTs, and even accelerate the commercialization of CNT-TFT technology.Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact

  14. Suspended single-walled carbon-nanotube field-effect transistor for gas sensing application

    NASA Astrophysics Data System (ADS)

    Wada, Yukiko; Fujita, Yoshihiro; Takei, Kuniharu; Arie, Takayuki; Akita, Seiji

    2015-06-01

    We investigate the pressure dependence of transfer characteristics of suspended single-walled carbon-nanotube field-effect transistors. We find that the gate bias around the charge neutral point with low drain current is appropriate for gas sensing application, while the high gate bias condition with high drain current that induces Joule heating in the suspended region for the desorption of the adsorbed molecules is preferable for the vacuum gauge application based on the heat exchange surrounding gas molecules, where the temperature at the suspended channel is investigated based on the simple one-dimensional heat transport model. We also revealed that the pressure dependence of the channel conductance at the gate bias around the charge neutral point can be explained by the Langmuir isotherm.

  15. All-printed and transparent single walled carbon nanotube thin film transistor devices

    NASA Astrophysics Data System (ADS)

    Sajed, Farzam; Rutherglen, Christopher

    2013-09-01

    We present fully transparent single-walled all-carbon nanotube thin film transistors (SWCNT TFT) fabricated using low-cost inkjet printing methods. Such a demonstration provides a platform towards low cost fully printed transparent electronics. The SWCNT TFTs were printed with metallic and semiconducting SWCNT using a room temperature printing process, without the requirement of expensive cleanroom facilities. The unoptimized SWCNT TFTs fabricated exhibited an Ion/off ratio of 92 and mobility of 2.27 cm2V-1s-1 and transmissivity of 82%. The combination of both high electrical performance and high transparency make all-SWCNT TFTs desirable for next generation transparent display backplanes and products such as Google Glass.

  16. A measurement technique for circumventing hysteresis and conductance drift in carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Tunnell, Andrew; Ballarotto, Vincent; Cumings, John

    2014-01-01

    We present a measurement protocol that effectively eliminates both the hysteresis and the temporal drift typically observed in the channel conductance of single-walled carbon nanotube field-effect transistors (SWNT FETs) during the application of gate voltages. Before each resistance measurement, the gate is first stepped through a series of alternating positive and negative voltages to produce a neutral charge distribution within the device. This process is highly effective at removing the hysteresis in the channel conductance, and time-dependent measurements further demonstrate that the drain current is stable and single-valued, independent of the prior measurement history. The effectiveness of this method can be understood within the Preisach hysteresis model, which we demonstrate as a useful framework to predict the observed results.

  17. A measurement technique for circumventing hysteresis and conductance drift in carbon nanotube field-effect transistors.

    PubMed

    Tunnell, Andrew; Ballarotto, Vincent; Cumings, John

    2014-01-31

    We present a measurement protocol that effectively eliminates both the hysteresis and the temporal drift typically observed in the channel conductance of single-walled carbon nanotube field-effect transistors (SWNT FETs) during the application of gate voltages. Before each resistance measurement, the gate is first stepped through a series of alternating positive and negative voltages to produce a neutral charge distribution within the device. This process is highly effective at removing the hysteresis in the channel conductance, and time-dependent measurements further demonstrate that the drain current is stable and single-valued, independent of the prior measurement history. The effectiveness of this method can be understood within the Preisach hysteresis model, which we demonstrate as a useful framework to predict the observed results. PMID:24394672

  18. Sensing Reversible Protein–Ligand Interactions with Single-Walled Carbon Nanotube Field-Effect Transistors

    PubMed Central

    2015-01-01

    We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker. Binding affinities at different pH values were quantified, and the sensor’s response at various ionic strengths was analyzed. Furthermore, protein “fingerprints” of NeutrAvidin and streptavidin were obtained by monitoring their adsorption at several pH values. Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS). PMID:25126155

  19. Single-molecule measurements of proteins using carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Sims, Patrick Craig

    Single-walled carbon nanotube (SWCNT) field-effect transistors (FETs) provide a promising platform for investigating proteins at the single-molecule level. Recently, we have demonstrated that SWCNT FETs have sufficient sensitivity and bandwidth to monitor the conformational motions and processivity of an individual T4 lysozyme molecule. This is accomplished by functionalizing a SWCNT FET device with a single protein and measuring the conductance versus time through the device as it is submerged in an electrolyte solution. To generalize this approach for the study of a wide variety of proteins at the single-molecule level, this dissertation investigates the conjugation process to determine and isolate the key parameters involved in functionalizing a SWCNT with a single protein, the physical basis for transducing conformational motion of a protein into an electrical signal, and finally, the general application of the technique to monitor the binary and ternary complex formation of cAMP-dependent protein kinase (PKA).

  20. Inkjet printed ambipolar transistors and inverters based on carbon nanotube/zinc tin oxide heterostructures

    SciTech Connect

    Kim, Bongjun; Jang, Seonpil; Dodabalapur, Ananth; Geier, Michael L.; Prabhumirashi, Pradyumna L.; Hersam, Mark C.

    2014-02-10

    We report ambipolar field-effect transistors (FETs) consisting of inkjet printed semiconductor bilayer heterostructures utilizing semiconducting single-walled carbon nanotubes (SWCNTs) and amorphous zinc tin oxide (ZTO). The bilayer structure allows for electron transport to occur principally in the amorphous oxide layer and hole transport to occur exclusively in the SWCNT layer. This results in balanced electron and hole mobilities exceeding 2 cm{sup 2} V{sup −1} s{sup −1} at low operating voltages (<5 V) in air. We further show that the SWCNT-ZTO hybrid ambipolar FETs can be integrated into functional inverter circuits that display high peak gain (>10). This work provides a pathway for realizing solution processable, inkjet printable, large area electronic devices, and systems based on SWCNT-amorphous oxide heterostructures.

  1. Modeling and simulation of carbon nanotube field effect transistor and its circuit application

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Saini, Dinesh Kumar; Agarwal, Dinesh; Aggarwal, Sajal; Khosla, Mamta; Raj, Balwinder

    2016-07-01

    The carbon nanotube field effect transistor (CNTFET) is modelled for circuit application. The model is based on the transport mechanism and it directly relates the transport mechanism with the chirality. Also, it does not consider self consistent equations and thus is used to develop the HSPICE compatible circuit model. For validation of the model, it is applied to the top gate CNTFET structure and the MATLAB simulation results are compared with the simulations of a similar structure created in NanoTCAD ViDES. For demonstrating the circuit compatibility of the model, two circuits viz. inverter and SRAM are designed and simulated in HSPICE. Finally, SRAM performance metrics are compared with those of device simulations from Nano TCAD ViDES.

  2. Demonstration of high current carbon nanotube enabled vertical organic field effect transistors at industrially relevant voltages

    NASA Astrophysics Data System (ADS)

    McCarthy, Mitchell

    The display market is presently dominated by the active matrix liquid crystal display (LCD). However, the active matrix organic light emitting diode (AMOLED) display is argued to become the successor to the LCD, and is already beginning its way into the market, mainly in small size displays. But, for AMOLED technology to become comparable in market share to LCD, larger size displays must become available at a competitive price with their LCD counterparts. A major issue preventing low-cost large AMOLED displays is the thin-film transistor (TFT) technology. Unlike the voltage driven LCD, the OLEDs in the AMOLED display are current driven. Because of this, the mature amorphous silicon TFT backplane technology used in the LCD must be upgraded to a material possessing a higher mobility. Polycrystalline silicon and transparent oxide TFT technologies are being considered to fill this need. But these technologies bring with them significant manufacturing complexity and cost concerns. Carbon nanotube enabled vertical organic field effect transistors (CN-VFETs) offer a unique solution to this problem (now known as the AMOLED backplane problem). The CN-VFET allows the use of organic semiconductors to be used for the semiconductor layer. Organics are known for their low-cost large area processing compatibility. Although the mobility of the best organics is only comparable to that of amorphous silicon, the CN-VFET makes up for this by orienting the channel vertically, as opposed to horizontally (like in conventional TFTs). This allows the CN-VFET to achieve sub-micron channel lengths without expensive high resolution patterning. Additionally, because the CN-VFET can be easily converted into a light emitting transistor (called the carbon nanotube enabled vertical organic light emitting transistor---CN-VOLET) by essentially stacking an OLED on top of the CN-VFET, more potential benefits can be realized. These potential benefits include, increased aperture ratio, increased OLED

  3. The Effect of Hydrophobin Protein on Conductive Properties of Carbon Nanotube Field-Effect Transistors: First Study on Sensing Mechanism.

    PubMed

    Yotprayoonsakl, Peerapong; Szilvay, Géza R; Laaksonen, Päivi; Linder, Markus B; Ahlskog, Markus

    2015-03-01

    Hydrophobin is a surface active protein having both hydrophobic and hydrophilic functional domains which has previously been used for functionalization and solubilization of graphene and carbon nanotubes. In this work, field-effect transistors based on single nanotubes have been employed for electronic detection of hydrophobin protein in phosphate buffer solution. Individual nanotubes, single- and multiwalled, are characterized by atomic force microscopy after being immersed in protein solution, showing a relatively dense coverage with hydrophobin. We have studied aspects such as nanotube length (0.3-1.2 µm) and the hysteresis effect in the gate voltage dependent conduction. When measured in ambient condition after the exposure to hydrophobin, the resistance increase has a strong dependence on the nanotube length, which we ascribe to mobility degradation and localization effects. The change could be exceptionally large when measured in-situ in solution and at suitable gate voltage conditions, which is shown to relate to the different mechanism behind the hysteresis effect. PMID:26413623

  4. Micropatterned single-walled carbon nanotube electrodes for use in high-performance transistors and inverters.

    PubMed

    Kang, Woonggi; Kim, Nam Hee; Lee, Dong Yun; Chang, Suk Tai; Cho, Jeong Ho

    2014-06-25

    We demonstrated the solution-processed single-walled carbon nanotube (SWNT) source-drain electrodes patterned using a plasma-enhanced detachment patterning method for high-performance organic transistors and inverters. The high-resolution SWNT electrode patterning began with the formation of highly uniform SWNT thin films on a hydrophobic silanized substrate. The SWNT source-drain patterns were then formed by modulating the interfacial energies of the prepatterned elastomeric mold and the SWNT thin film using oxygen plasma. The SWNT films were subsequently selectively delaminated using a rubber mold. The patterned SWNTs could be used as the source-drain electrodes for both n-type PTCDI-C8 and p-type pentacene field-effect transistors (FETs). The n- and p-type devices exhibited good and exactly matched electrical performances, with a field-effect mobility of around 0.15 cm(2) V(-1) s(-1) and an ON/OFF current ratio exceeding 10(6). The single electrode material was used for both the n and p channels, permitting the successful fabrication of a high-performance complementary inverter by connecting a p-type pentacene FET to an n-type PTCDI-C8 FET. This patterning technique was simple, inexpensive, and easily scaled for the preparation of large-area electrode micropatterns for flexible microelectronic device fabrication. PMID:24915751

  5. Solution-Processed Carbon Nanotube and Chemically Synthesized Graphene Nanoribbon Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Bennett, Patrick Bryce

    Carbon nanotubes (CNTs) possess great potential as high performance semiconducting channels due to their one-dimensional nature, extremely high mobility, and their demonstrated ability to transport electrons ballistically in transistors. However, the presence of metallic CNTs in CNT films and arrays represents a major impediment towards large-scale integration. Methods of solution purification have demonstrated partial success in metallic CNT removal, although their effects on device performance are unknown. While this problem may be solvable, new synthesis techniques have recently resulted in the creation of high-density films of graphene nanoribbons (GNRs) with atomically smooth edges, uniform widths, and uniform band structure. These may ultimately supplant CNTs in device applications due to their theoretically similar, but uniform electronic properties. This work aims to study the effects of purification of semiconducting CNTs in thin film transistors (TFTs) and to develop methods to increase device performance when metallic CNTs are present. Devices consisting of large networks of CNTs as well as short channel, single CNT devices are characterized to determine the effects of solution processing on CNTs themselves. Short channel, bottom-up GNR devices are fabricated to compare their performance to CNT transistors. The first half of this dissertation describes the methods of integrating CNTs from various sources into transistors. Growth and transfer are described, as well as methods of creating aqueous suspensions for solution processing. Development of novel surfactant materials based on biomimetic polymers used to suspend CNTs in solution are reported and characterized. Methods of deposition out of solution and onto insulating substrates are covered. Device fabrication from start to finish is detailed, with the subtleties of processing required to produce sub 10-nm channel length devices explained. The second half reports devices produced via these techniques

  6. Functionalized carbon nanotube field effect transistors for chemical and biological sensing

    NASA Astrophysics Data System (ADS)

    Chen, Michelle Hsiu-Yu

    Specific, sensitive, reproducible, and rapid detection of chemical and biological species is crucial for the environment, disease diagnosis, and even homeland security. Owing to the miniature size, large surface to volume ratio, high electrical conductivity, and compatibility with dense array fabrication, carbon nanotubes are excellent candidates for sensing application. In this thesis we present nanosealed chemical and biological sensors based on functionalized single-walled carbon nanotube field effect transistors (SWNT-FETs). For chemical sensors, single stranded DNA/RNA serve as the chemical recognition sites and SWNT-FETs as the electronic readout components. Non-covalent functionalization of SWNT-FETs with DNA/RNA resulted in current changes when exposed to gaseous analytes, whereas the bare nanotube devices show no detectable change. The sensor responses differ in sign and magnitude depending both on the type of gaseous analyte and the sequence of DNA/RNA being used. DNA/RNA functionalized SWNT-FET gas sensors possess rapid recovery and self-regenerating ability, which could lead to realization of large arrays for sensitive electronic olfaction and disease diagnosis. For biological sensors, we present proof-of-concept experiments for developing highly sensitive and last-response miniaturized SWNT-FET biosensors for electrically detecting adenovirus using ligand-receptor-protein specificity. SWNTs are mildly oxidized to form carboxylic groups on the surfaces without compromising the electronic integrity of the nanotubes. Then the human coxsackievirus and adenovirus receptor (CAR) is covalently functionalized onto the nanotube surface via diimide-activated amidation process. Upon exposure of the device to adenovirus protein, Ad12 Knob (Knob), specific binding of Knob to CAR decreases the current that flows through the SWNT-FET device. For control experiment, the CAR-SWNT device is exposed to YieF, which is a virus protein that does not bind specifically to CAR

  7. High-yield sorting of small-diameter carbon nanotubes for solar cells and transistors.

    PubMed

    Wang, Huiliang; Koleilat, Ghada I; Liu, Peng; Jiménez-Osés, Gonzalo; Lai, Ying-Chih; Vosgueritchian, Michael; Fang, Ya; Park, Steve; Houk, Kendall N; Bao, Zhenan

    2014-03-25

    We describe herein a high-yield method to selectively disperse semiconducting CoMoCAT (CO disproportionation on Co-Mo catalysts) single-walled carbon nanotubes (SWNTs) with regioregular poly(3-alkylthiophenes) polymers. We observed that the dispersion yield was directly related to the length of the polymer's alkyl side chains. Molecular dynamics simulations in explicit toluene (real toluene molecules) indicate that polythiophenes with longer alkyl side chains bind strongly to SWNTs, due to the increased overall surface contact area with the nanotube. Furthermore, the sorting process selectively enriches smaller-diameter CoMoCAT SWNTs with larger bandgaps, which is ideal for solar cell applications. Compared to the larger diameter sorted HiPco (High-Pressure CO) SWNTs, solar cells fabricated using our sorted CoMoCAT SWNTs demonstrated higher open-circuit voltage (Voc) and infrared external quantum efficiency (EQE). The Voc achieved is the highest reported for solar cells based on SWNT absorbers under simulated AM1.5 solar illumination. Additionally, we employed the sorted CoMoCAT SWNTs to fabricate thin film transistors with excellent uniformity and device performance. PMID:24484388

  8. Low Power, Red, Green and Blue Carbon Nanotube Enabled Vertical Organic Light Emitting Transistors for Active Matrix OLED Displays

    SciTech Connect

    McCarthy, M. A.; Liu, B.; Donoghue, E. P.; Kravchenko, Ivan I; Kim, D. Y.; So, Franky; Rinzler, A. G.

    2011-01-01

    Organic semiconductors are potential alternatives to polycrystalline silicon as the semiconductor used in the backplane of active matrix organic light emitting diode displays. Demonstrated here is a light-emitting transistor with an organic channel, operating with low power dissipation at low voltage, and high aperture ratio, in three colors: red, green and blue. The single-wall carbon nanotube network source electrode is responsible for the high level of performance demonstrated. A major benefit enabled by this architecture is the integration of the drive transistor, storage capacitor and light emitter into a single device. Performance comparable to commercialized polycrystalline-silicon TFT driven OLEDs is demonstrated.

  9. Fabrication of air-stable n-type carbon nanotube thin-film transistors on flexible substrates using bilayer dielectrics.

    PubMed

    Li, Guanhong; Li, Qunqing; Jin, Yuanhao; Zhao, Yudan; Xiao, Xiaoyang; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan

    2015-11-14

    Single-walled carbon nanotube (SWNT) thin-film transistors hold great potential for flexible electronics. However, fabrication of air-stable n-type devices by methods compatible with standard photolithography on flexible substrates is challenging. Here, we demonstrated that by using a bilayer dielectric structure of MgO and atomic layer deposited (ALD) Al2O3 or HfO2, air-stable n-type devices can be obtained. The mechanism for conduction type conversion was elucidated and attributed to the hole depletion in SWNT, the decrease of the trap state density by MgO assimilating adsorbed water molecules in the vicinity of SWNT, and the energy band bending because of the positive fixed charges in the ALD layer. The key advantage of the method is the relatively low temperature (120 or 90 °C) required here for the ALD process because we need not employ this step to totally remove the absorbates on the SWNTs. This advantage facilitates the integration of both p-type and n-type transistors through a simple lift off process and compact CMOS inverters were demonstrated. We also demonstrated that the doping of SWNTs in the channel plays a more important role than the Schottky barriers at the metal contacts in carbon nanotube thin-film transistors, unlike the situation in individual SWNT-based transistors. PMID:26451806

  10. Strain effects on the performance of zero-Schottky-barrier double-walled carbon nanotube transistors

    NASA Astrophysics Data System (ADS)

    Wahab, Md. Abdul; Khosru, Quazi D. M.

    2010-08-01

    Schrodinger's equation is solved using recursive Green's function algorithm self-consistently with Poisson's equation to study the transport physics of uniaxial and torsional strained double-walled (DW) carbon nanotube (CNT) field-effect transistors (FETs) and to analyze their performance. The characteristics and performance of proposed DW CNTFET are compared with existing single-walled (SW) CNTFET. The strain has great impact on the I-V characteristics of both SW and DW CNT devices. Tensile and torsional strains improve greatly the off-state current and on/off current ratio of both devices. Compressive strain improves on-state current, but this improvement is comparatively small. The effect of strain on off-state current, on-state current, and on/off current ratio is higher in SW CNTFET. The inverse subthreshold slope of DW CNTFET is better than SW CNTFET. But the variation in inverse subthreshold slope with strain is smaller in DW CNTFET. Unlike SW CNTFET the on-state transconductance of DW CNTFET improves with tensile and torsional strains, and degrades with compressive strain. The on-state cut-off frequency of DW CNTFET also shows opposite behavior to SW CNTFET with strain following on-state transconductance. Concrete Physical description is provided to explain all above changes with strain.

  11. Enzyme assays using sensor arrays based on ion-selective carbon nanotube field-effect transistors.

    PubMed

    Melzer, K; Bhatt, V Deep; Jaworska, E; Mittermeier, R; Maksymiuk, K; Michalska, A; Lugli, P

    2016-10-15

    In the fields of clinical diagnostics and point-of-care diagnosis as well as food and environmental monitoring there is a high demand for reliable high-throughput, rapid and highly sensitive assays for a simultaneous detection of several analytes in complex and low-volume samples. Sensor platforms based on solution-processable electrolyte-gated carbon nanotube field-effect transistors (CNT-FETs) are a simple and cost-effective alternative for conventional assays. In this work we demonstrate a selective as well as direct detection of the products of an enzyme-substrate interaction, here the for metabolic processes important urea-urease system, with sensors based on spray-coated CNT-FETs. The selective and direct detection is achieved by immobilizing the enzyme urease via certain surface functionalization techniques on the sensor surface and further modifying the active interfaces with polymeric ion-selective membranes as well as pH-sensitive layers. Thereby, we can avoid the generally applied approach for a field-effect based detection of enzyme reactions via detecting changes in the pH value due to an on-going enzymatic reaction and directly detect selectively the products of the enzymatic conversion. Thus, we can realize a buffering-capacity independent monitoring of changes in the substrate concentration. PMID:27140308

  12. Modeling of Gate Bias Modulation in Carbon Nanotube Field-Effect-Transistors

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryan (Technical Monitor)

    2002-01-01

    The threshold voltages of a carbon nanotube (CNT) field-effect transistor (FET) are derived and compared with those of the metal oxide-semiconductor (MOS) FETs. The CNT channel is so thin that there is no voltage drop perpendicular to the gate electrode plane, which is the CNT diameter direction, and this makes the CNTFET characteristics quite different from those in MOSFETs. The relation between the voltage and the electrochemical potentials, and the mass action law for electrons and holes are examined in the context of CNTs, and it is shown that the familiar relations are still valid because of the macroscopic number of states available in the CNTs. This is in sharp contrast to the cases of quantum dots. Using these relations, we derive an inversion threshold voltage V(sub Ti) and an accumulation threshold voltage V(sub Ta) as a function of the Fermi level E(sub F) in the channel, where E(sub F) is a measure of channel doping. V(sub Ti) of the CNTFETs has a much stronger dependence than that of MOSFETs, while V(sub Ta)s of both CNTFETs and MOSFETs depend quite weakly on E(sub F) with the same functional form. This means the transition from normally-off mode to normally-on mode is much sharper in CNTFETs as the doping increases, and this property has to be taken into account in circuit design.

  13. Compact model for ballistic MOSFET-like carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Abdolkader, Tarek M.; Fikry, Wael

    2016-01-01

    In this work, a compact model for MOSFET-like ballistic carbon nanotube field-effect transistors (CNFETs) is presented. The model is based on calculating the charge and surface potential on the top of the barrier between source and drain using closed-form analytical formulae. The formula for the surface potential is obtained by merging two simplified expressions obtained in two extreme cases (very low and very high gate bias). Two fitting parameters are introduced whose values are extracted by best fitting model results with numerically calculated ones. The model has a continuous derivative and thus it is SPICE-compatible. Accuracy of the model is compared to previous analytical model presented in the literature with numerical results taken as a reference. Proposed model proves to give less relative error over a wide range of gate biases, and for a drain bias up to 0.5 V. In addition, the model enables the calculation of quantum and gate capacitance analytically reproducing the negative capacitance behaviour known in CNFETs.

  14. Fabrication and characterization of junctionless carbon nanotube field effect transistor for cholesterol detection

    SciTech Connect

    Barik, Md. Abdul Dutta, Jiten Ch.

    2014-08-04

    We have reported fabrication and characterization of polyaniline (PANI)/zinc oxide (ZnO) membrane-based junctionless carbon nanotube field effect transistor deposited on indium tin oxide glass plate for the detection of cholesterol (0.5–22.2 mM). Cholesterol oxidase (ChOx) has been immobilized on the PANI/ZnO membrane by physical adsorption technique. Electrical response has been recorded using digital multimeter (Agilent 3458A) in the presence of phosphate buffer saline of 50 mM, pH 7.0, and 0.9% NaCl contained in a glass pot. The results of response studies for cholesterol reveal linearity as 0.5–16.6 mM and improved sensitivity of 60 mV/decade in good agreement with Nernstian limit ∼59.2 mV/decade. The life time of this sensor has been found up to 5 months and response time of 1 s. The limit of detection with regression coefficient (r) ∼ 0.998 and Michaelis-Menten constant (K{sub m}) were found to be ∼0.25 and 1.4 mM, respectively, indicating high affinity of ChOx to cholesterol. The results obtained in this work show negligible interference with glucose and urea.

  15. Strain on field effect transistors with single–walled–carbon nanotube network on flexible substrate

    SciTech Connect

    Kim, T. G.; Kim, U. J.; Lee, E. H.; Hwang, J. S.; Hwang, S. W. E-mail: sangsig@korea.ac.kr; Kim, S. E-mail: sangsig@korea.ac.kr

    2013-12-07

    We have systematically analyzed the effect of strain on the electrical properties of flexible field effect transistors with a single-walled carbon nanotube (SWCNT) network on a polyethersulfone substrate. The strain was applied and estimated at the microscopic scale (<1 μm) by using scanning electron microscope (SEM) equipped with indigenously designed special bending jig. Interestingly, the strain estimated at the microscopic scale was found to be significantly different from the strain calculated at the macroscopic scale (centimeter-scale), by a factor of up to 4. Further in-depth analysis using SEM indicated that the significant difference in strain, obtained from two different measurement scales (microscale and macroscale), could be attributed to the formation of cracks and tears in the SWCNT network, or at the junction of SWCNT network and electrode during the strain process. Due to this irreversible morphological change, the electrical properties, such as on current level and field effect mobility, lowered by 14.3% and 4.6%, respectively.

  16. Evaluation of interface trap densities and quantum capacitance in carbon nanotube network thin-film transistors.

    PubMed

    Yoon, J; Choi, B; Choi, S; Lee, J; Lee, J; Jeon, M; Lee, Y; Han, J; Lee, J; Kim, D M; Kim, D H; Kim, S; Choi, S-J

    2016-07-22

    The interface trap density in single-walled carbon nanotube (SWNT) network thin-film transistors (TFTs) is a fundamental and important parameter for assessing the electronic performance of TFTs. However, the number of studies on the extraction of interface trap densities, particularly in SWNT TFTs, has been insufficient. In this work, we propose an efficient technique for extracting the energy-dependent interface traps in SWNT TFTs. From the measured dispersive, frequency-dependent capacitance-voltage (C-V) characteristics, the dispersive-free, frequency-independent C-V curve was obtained, thus enabling the extraction and analysis of the interface trap density, which was found to be approximately 8.2 × 10(11) eV(-1) cm(-2) at the valence band edge. The frequency-independent C-V curve also allows further extraction of the quantum capacitance in the SWNT network without introducing any additional fitting process or parameters. We found that the extracted value of the quantum capacitance in SWNT networks is lower than the theoretical value in aligned SWNTs due to the cross point of SWNTs on the SWNT network. Therefore, the method proposed in this work indicates that the C-V measurement is a powerful tool for obtaining deep physical insights regarding the electrical performance of SWNT TFTs. PMID:27285674

  17. Single-Wall Carbon Nanotube Field Effect Transistors with Non-Volatile Memory Operation

    NASA Astrophysics Data System (ADS)

    Sakurai, Tatsuya; Yoshimura, Takeshi; Akita, Seiji; Fujimura, Norifumi; Nakayama, Yoshikazu

    2006-10-01

    We describe the fabrication and electrical characteristics of single-wall carbon-nanotubes field-effect transistors (CNT-FETs) with a non-volatile memory function using ferroelectric thin films as gate insulators. The ferroelectric-gate CNT-FETs were fabricated using single-wall CNTs synthesized from alcohol by catalytic chemical vapor deposition and sol-gel derived PbZr0.5Ti0.5O3 thin films. The ferroelectric-gate CNT-FETs showed modulation of the drain current with the gate voltage and the threshold voltage shift (memory window) on the drain current-gate voltage characteristics. Moreover, the memory window was saturated around 1.1 V as the gate voltage sweeping range increased. These results indicate that carriers in CNTs are controlled by spontaneous polarization of the ferroelectric films. Because ferroelectrics exhibit complex couplings between their electrical, structural, mechanical, thermal, and optical properties, and because CNTs have unique mechanical and electrical properties, ferroelectric-gate CNT-FETs offer promise as potentially useful nanoelectronics devices not only for non-volatile memory elements but also for high-sensitivity sensors.

  18. Evaluation of interface trap densities and quantum capacitance in carbon nanotube network thin-film transistors

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Choi, B.; Choi, S.; Lee, J.; Lee, J.; Jeon, M.; Lee, Y.; Han, J.; Lee, J.; Kim, D. M.; Kim, D. H.; Kim, S.; Choi, S.-J.

    2016-07-01

    The interface trap density in single-walled carbon nanotube (SWNT) network thin-film transistors (TFTs) is a fundamental and important parameter for assessing the electronic performance of TFTs. However, the number of studies on the extraction of interface trap densities, particularly in SWNT TFTs, has been insufficient. In this work, we propose an efficient technique for extracting the energy-dependent interface traps in SWNT TFTs. From the measured dispersive, frequency-dependent capacitance–voltage (C–V) characteristics, the dispersive-free, frequency-independent C–V curve was obtained, thus enabling the extraction and analysis of the interface trap density, which was found to be approximately 8.2 × 1011 eV‑1 cm‑2 at the valence band edge. The frequency-independent C–V curve also allows further extraction of the quantum capacitance in the SWNT network without introducing any additional fitting process or parameters. We found that the extracted value of the quantum capacitance in SWNT networks is lower than the theoretical value in aligned SWNTs due to the cross point of SWNTs on the SWNT network. Therefore, the method proposed in this work indicates that the C–V measurement is a powerful tool for obtaining deep physical insights regarding the electrical performance of SWNT TFTs.

  19. Advantages of flattened electrode in bottom contact single-walled carbon nanotube field-effect transistor

    SciTech Connect

    Setiadi, Agung; Akai-Kasaya, Megumi Saito, Akira; Kuwahara, Yuji

    2014-09-01

    We fabricated single-walled carbon nanotube (SWNT) field-effect transistor (FET) devices on flattened electrodes, in which there are no height difference between metal electrodes and the substrate. SWNT-FET fabricated using bottom contact technique have some advantages, such that the SWNTs are free from electron irradiation, have direct contact with the desired metal electrodes, and can be functionalized before or after deposition. However, the SWNTs can be bent at the contact point with the metal electrodes leading to a different electrical characteristic of the devices. The number of SWNT direct junctions in short channel length devices is drastically increased by the use of flattened electrodes due to strong attractive interaction between SWNT and the substrate. The flattened electrodes show a better balance between their hole and electron mobility compared to that of the non-flattened electrodes, that is, ambipolar FET characteristic. It is considered that bending of the SWNTs in the non-flattened electrode devices results in a higher Schottky barrier for the electrons.

  20. Wafer scale fabrication of carbon nanotube thin film transistors with high yield

    NASA Astrophysics Data System (ADS)

    Tian, Boyuan; Liang, Xuelei; Yan, Qiuping; Zhang, Han; Xia, Jiye; Dong, Guodong; Peng, Lianmao; Xie, Sishen

    2016-07-01

    Carbon nanotube thin film transistors (CNT-TFTs) are promising candidates for future high performance and low cost macro-electronics. However, most of the reported CNT-TFTs are fabricated in small quantities on a relatively small size substrate. The yield of large scale fabrication and the performance uniformity of devices on large size substrates should be improved before the CNT-TFTs reach real products. In this paper, 25 200 devices, with various geometries (channel width and channel length), were fabricated on 4-in. size ridged and flexible substrates. Almost 100% device yield were obtained on a rigid substrate with high out-put current (>8 μA/μm), high on/off current ratio (>105), and high mobility (>30 cm2/V.s). More importantly, uniform performance in 4-in. area was achieved, and the fabrication process can be scaled up. The results give us more confidence for the real application of the CNT-TFT technology in the near future.

  1. Fluoropolymer coatings for improved carbon nanotube transistor device and circuit performance

    NASA Astrophysics Data System (ADS)

    Jang, Seonpil; Kim, Bongjun; Geier, Michael L.; Prabhumirashi, Pradyumna L.; Hersam, Mark C.; Dodabalapur, Ananth

    2014-09-01

    We report on the marked improvements in key device characteristics of single walled carbon nanotube (SWCNT) field-effect transistors (FETs) by coating the active semiconductor with a fluoropolymer layer such as poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE). The observed improvements include: (i) A reduction in off-current by about an order of magnitude, (ii) a significant reduction in the variation of threshold voltage, and (iii) a reduction in bias stress-related instability and hysteresis present in device characteristics. These favorable changes in device characteristics also enhance circuit performance and the oscillation amplitude, oscillation frequency, and increase the yield of printed complementary 5-stage ring oscillators. The origins of these improvements are explored by exposing SWCNT FETs to a number of vapor phase polar molecules which produce similar effects on the FET characteristics as the PVDF-TrFE. Coating of the active SWCNT semiconductor layer with a fluoropolymer will be advantageous for the adoption of SWCNT FETs in a variety of printed electronics applications.

  2. Fabrication and characterization of junctionless carbon nanotube field effect transistor for cholesterol detection

    NASA Astrophysics Data System (ADS)

    Barik, Md. Abdul; Dutta, Jiten Ch.

    2014-08-01

    We have reported fabrication and characterization of polyaniline (PANI)/zinc oxide (ZnO) membrane-based junctionless carbon nanotube field effect transistor deposited on indium tin oxide glass plate for the detection of cholesterol (0.5-22.2 mM). Cholesterol oxidase (ChOx) has been immobilized on the PANI/ZnO membrane by physical adsorption technique. Electrical response has been recorded using digital multimeter (Agilent 3458A) in the presence of phosphate buffer saline of 50 mM, pH 7.0, and 0.9% NaCl contained in a glass pot. The results of response studies for cholesterol reveal linearity as 0.5-16.6 mM and improved sensitivity of 60 mV/decade in good agreement with Nernstian limit ˜59.2 mV/decade. The life time of this sensor has been found up to 5 months and response time of 1 s. The limit of detection with regression coefficient (r) ˜ 0.998 and Michaelis-Menten constant (Km) were found to be ˜0.25 and 1.4 mM, respectively, indicating high affinity of ChOx to cholesterol. The results obtained in this work show negligible interference with glucose and urea.

  3. Highly Uniform Carbon Nanotube Field-Effect Transistors and Medium Scale Integrated Circuits.

    PubMed

    Chen, Bingyan; Zhang, Panpan; Ding, Li; Han, Jie; Qiu, Song; Li, Qingwen; Zhang, Zhiyong; Peng, Lian-Mao

    2016-08-10

    Top-gated p-type field-effect transistors (FETs) have been fabricated in batch based on carbon nanotube (CNT) network thin films prepared from CNT solution and present high yield and highly uniform performance with small threshold voltage distribution with standard deviation of 34 mV. According to the property of FETs, various logical and arithmetical gates, shifters, and d-latch circuits were designed and demonstrated with rail-to-rail output. In particular, a 4-bit adder consisting of 140 p-type CNT FETs was demonstrated with higher packing density and lower supply voltage than other published integrated circuits based on CNT films, which indicates that CNT based integrated circuits can reach to medium scale. In addition, a 2-bit multiplier has been realized for the first time. Benefitted from the high uniformity and suitable threshold voltage of CNT FETs, all of the fabricated circuits based on CNT FETs can be driven by a single voltage as small as 2 V. PMID:27459084

  4. Detection of the Odor Signature of Ovarian Cancer using DNA-Decorated Carbon Nanotube Field Effect Transistor Arrays

    NASA Astrophysics Data System (ADS)

    Kehayias, Christopher; Kybert, Nicholas; Yodh, Jeremy; Johnson, A. T. Charlie

    Carbon nanotubes are low-dimensional materials that exhibit remarkable chemical and bio-sensing properties and have excellent compatibility with electronic systems. Here, we present a study that uses an electronic olfaction system based on a large array of DNA-carbon nanotube field effect transistors vapor sensors to analyze the VOCs of blood plasma samples collected from patients with malignant ovarian cancer, patients with benign ovarian lesions, and age-matched healthy subjects. Initial investigations involved coating each CNT sensor with single-stranded DNA of a particular base sequence. 10 distinct DNA oligomers were used to functionalize the carbon nanotube field effect transistors, providing a 10-dimensional sensor array output response. Upon performing a statistical analysis of the 10-dimensional sensor array responses, we showed that blood samples from patients with malignant cancer can be reliably differentiated from those of healthy control subjects with a p-value of 3 x 10-5. The results provide preliminary evidence that the blood of ovarian cancer patients contains a discernable volatile chemical signature that can be detected using DNA-CNT nanoelectronic vapor sensors, a first step towards a minimally invasive electronic diagnostic technology for ovarian cancer.

  5. Electronic transport properties of inner and outer shells in near ohmic-contacted double-walled carbon nanotube transistors

    SciTech Connect

    Zhang, Yuchun; Zhou, Liyan; Zhao, Shangqian; Wang, Wenlong; Liang, Wenjie; Wang, Enge

    2014-06-14

    We investigate electronic transport properties of field-effect transistors based on double-walled carbon nanotubes, of which inner shells are metallic and outer shells are semiconducting. When both shells are turned on, electron-phonon scattering is found to be the dominant phenomenon. On the other hand, when outer semiconducting shells are turned off, a zero-bias anomaly emerges in the dependence of differential conductance on the bias voltage, which is characterized according to the Tomonaga-Luttinger liquid model describing tunneling into one-dimensional materials. We attribute these behaviors to different contact conditions for outer and inner shells of the double-walled carbon nanotubes. A simple model combining Luttinger liquid model for inner metallic shells and electron-phonon scattering in outer semiconducting shells is given here to explain our transport data at different temperatures.

  6. Carbon nanotube macroelectronics

    NASA Astrophysics Data System (ADS)

    Zhang, Jialu

    In this dissertation, I discuss the application of carbon nanotubes in macroelectronis. Due to the extraordinary electrical properties such as high intrinsic carrier mobility and current-carrying capacity, single wall carbon nanotubes are very desirable for thin-film transistor (TFT) applications such as flat panel display, transparent electronics, as well as flexible and stretchable electronics. Compared with other popular channel material for TFTs, namely amorphous silicon, polycrystalline silicon and organic materials, nanotube thin-films have the advantages of low-temperature processing compatibility, transparency, and flexibility, as well as high device performance. In order to demonstrate scalable, practical carbon nanotube macroelectroncis, I have developed a platform to fabricate high-density, uniform separated nanotube based thin-film transistors. In addition, many other essential analysis as well as technology components, such as nanotube film density control, purity and diameter dependent semiconducting nanotube electrical performance study, air-stable n-type transistor fabrication, and CMOS integration platform have also been demonstrated. On the basis of the above achievement, I have further demonstrated various kinds of applications including AMOLED display electronics, PMOS and CMOS logic circuits, flexible and transparent electronics. The dissertation is structured as follows. First, chapter 1 gives a brief introduction to the electronic properties of carbon nanotubes, which serves as the background knowledge for the following chapters. In chapter 2, I will present our approach of fabricating wafer-scale uniform semiconducting carbon nanotube thin-film transistors and demonstrate their application in display electronics and logic circuits. Following that, more detailed information about carbon nanotube thin-film transistor based active matrix organic light-emitting diode (AMOLED) displays is discussed in chapter 3. And in chapter 4, a technology to

  7. Improving Contact Interfaces in Fully Printed Carbon Nanotube Thin-Film Transistors.

    PubMed

    Cao, Changyong; Andrews, Joseph B; Kumar, Abhinay; Franklin, Aaron D

    2016-05-24

    Single-walled carbon nanotubes (CNTs) printed into thin films have been shown to yield high mobility, thermal conductivity, mechanical flexibility, and chemical stability as semiconducting channels in field-effect, thin-film transistors (TFTs). Printed CNT-TFTs of many varieties have been studied; however, there has been limited effort toward improving overall CNT-TFT performance. In particular, contact resistance plays a dominant role in determining the performance and degree of variability in the TFTs, especially in fully printed devices where the contacts and channel are both printed. In this work, we have systematically investigated the contact resistance and overall performance of fully printed CNT-TFTs employing three different printed contact materials-Ag nanoparticles, Au nanoparticles, and metallic CNTs-each in the following distinct contact geometries: top, bottom, and double. The active channel for each device was printed from the dispersion of high-purity (>99%) semiconducting CNTs, and all printing was carried out using an aerosol jet printer. Hundreds of devices with different channel lengths (from 20 to 500 μm) were fabricated for extracting contact resistance and determining related contact effects. Printed bottom contacts are shown to be advantageous compared to the more common top contacts, regardless of contact material. Further, compared to single (top or bottom) contacts, double contacts offer a significant decrease (>35%) in contact resistance for all types of contact materials, with the metallic CNTs yielding the best overall performance. These findings underscore the impact of printed contact materials and structures when interfacing with CNT thin films, providing key guidance for the further development of printed nanomaterial electronics. PMID:27097302

  8. Quasi-ballistic carbon nanotube array transistors with current density exceeding Si and GaAs

    PubMed Central

    Brady, Gerald J.; Way, Austin J.; Safron, Nathaniel S.; Evensen, Harold T.; Gopalan, Padma; Arnold, Michael S.

    2016-01-01

    Carbon nanotubes (CNTs) are tantalizing candidates for semiconductor electronics because of their exceptional charge transport properties and one-dimensional electrostatics. Ballistic transport approaching the quantum conductance limit of 2G0 = 4e2/h has been achieved in field-effect transistors (FETs) containing one CNT. However, constraints in CNT sorting, processing, alignment, and contacts give rise to nonidealities when CNTs are implemented in densely packed parallel arrays such as those needed for technology, resulting in a conductance per CNT far from 2G0. The consequence has been that, whereas CNTs are ultimately expected to yield FETs that are more conductive than conventional semiconductors, CNTs, instead, have underperformed channel materials, such as Si, by sixfold or more. We report quasi-ballistic CNT array FETs at a density of 47 CNTs μm−1, fabricated through a combination of CNT purification, solution-based assembly, and CNT treatment. The conductance is as high as 0.46 G0 per CNT. In parallel, the conductance of the arrays reaches 1.7 mS μm−1, which is seven times higher than the previous state-of-the-art CNT array FETs made by other methods. The saturated on-state current density is as high as 900 μA μm−1 and is similar to or exceeds that of Si FETs when compared at and equivalent gate oxide thickness and at the same off-state current density. The on-state current density exceeds that of GaAs FETs as well. This breakthrough in CNT array performance is a critical advance toward the exploitation of CNTs in logic, high-speed communications, and other semiconductor electronics technologies. PMID:27617293

  9. Quasi-ballistic carbon nanotube array transistors with current density exceeding Si and GaAs.

    PubMed

    Brady, Gerald J; Way, Austin J; Safron, Nathaniel S; Evensen, Harold T; Gopalan, Padma; Arnold, Michael S

    2016-09-01

    Carbon nanotubes (CNTs) are tantalizing candidates for semiconductor electronics because of their exceptional charge transport properties and one-dimensional electrostatics. Ballistic transport approaching the quantum conductance limit of 2G 0 = 4e (2)/h has been achieved in field-effect transistors (FETs) containing one CNT. However, constraints in CNT sorting, processing, alignment, and contacts give rise to nonidealities when CNTs are implemented in densely packed parallel arrays such as those needed for technology, resulting in a conductance per CNT far from 2G 0. The consequence has been that, whereas CNTs are ultimately expected to yield FETs that are more conductive than conventional semiconductors, CNTs, instead, have underperformed channel materials, such as Si, by sixfold or more. We report quasi-ballistic CNT array FETs at a density of 47 CNTs μm(-1), fabricated through a combination of CNT purification, solution-based assembly, and CNT treatment. The conductance is as high as 0.46 G 0 per CNT. In parallel, the conductance of the arrays reaches 1.7 mS μm(-1), which is seven times higher than the previous state-of-the-art CNT array FETs made by other methods. The saturated on-state current density is as high as 900 μA μm(-1) and is similar to or exceeds that of Si FETs when compared at and equivalent gate oxide thickness and at the same off-state current density. The on-state current density exceeds that of GaAs FETs as well. This breakthrough in CNT array performance is a critical advance toward the exploitation of CNTs in logic, high-speed communications, and other semiconductor electronics technologies. PMID:27617293

  10. Fabrication of air-stable n-type carbon nanotube thin-film transistors on flexible substrates using bilayer dielectrics

    NASA Astrophysics Data System (ADS)

    Li, Guanhong; Li, Qunqing; Jin, Yuanhao; Zhao, Yudan; Xiao, Xiaoyang; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan

    2015-10-01

    Single-walled carbon nanotube (SWNT) thin-film transistors hold great potential for flexible electronics. However, fabrication of air-stable n-type devices by methods compatible with standard photolithography on flexible substrates is challenging. Here, we demonstrated that by using a bilayer dielectric structure of MgO and atomic layer deposited (ALD) Al2O3 or HfO2, air-stable n-type devices can be obtained. The mechanism for conduction type conversion was elucidated and attributed to the hole depletion in SWNT, the decrease of the trap state density by MgO assimilating adsorbed water molecules in the vicinity of SWNT, and the energy band bending because of the positive fixed charges in the ALD layer. The key advantage of the method is the relatively low temperature (120 or 90 °C) required here for the ALD process because we need not employ this step to totally remove the absorbates on the SWNTs. This advantage facilitates the integration of both p-type and n-type transistors through a simple lift off process and compact CMOS inverters were demonstrated. We also demonstrated that the doping of SWNTs in the channel plays a more important role than the Schottky barriers at the metal contacts in carbon nanotube thin-film transistors, unlike the situation in individual SWNT-based transistors.Single-walled carbon nanotube (SWNT) thin-film transistors hold great potential for flexible electronics. However, fabrication of air-stable n-type devices by methods compatible with standard photolithography on flexible substrates is challenging. Here, we demonstrated that by using a bilayer dielectric structure of MgO and atomic layer deposited (ALD) Al2O3 or HfO2, air-stable n-type devices can be obtained. The mechanism for conduction type conversion was elucidated and attributed to the hole depletion in SWNT, the decrease of the trap state density by MgO assimilating adsorbed water molecules in the vicinity of SWNT, and the energy band bending because of the positive fixed

  11. Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer

    NASA Astrophysics Data System (ADS)

    Xu, Wenya; Dou, Junyan; Zhao, Jianwen; Tan, Hongwei; Ye, Jun; Tange, Masayoshi; Gao, Wei; Xu, Weiwei; Zhang, Xiang; Guo, Wenrui; Ma, Changqi; Okazaki, Toshiya; Zhang, Kai; Cui, Zheng

    2016-02-01

    Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (+/-2 V) and subthreshold swing (SS) (122-161 mV dec-1), high effective mobility (up to 17.6-37.7 cm2 V-1 s-1) and high on/off ratio (104-107). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption.Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge

  12. High-performance carbon-nanotube-based complementary field-effect-transistors and integrated circuits with yttrium oxide

    SciTech Connect

    Liang, Shibo; Zhang, Zhiyong Si, Jia; Zhong, Donglai; Peng, Lian-Mao

    2014-08-11

    High-performance p-type carbon nanotube (CNT) transistors utilizing yttrium oxide as gate dielectric are presented by optimizing oxidization and annealing processes. Complementary metal-oxide-semiconductor (CMOS) field-effect-transistors (FETs) are then fabricated on CNTs, and the p- and n-type devices exhibit symmetrical high performances, especially with low threshold voltage near to zero. The corresponding CMOS CNT inverter is demonstrated to operate at an ultra-low supply voltage down to 0.2 V, while displaying sufficient voltage gain, high noise margin, and low power consumption. Yttrium oxide is proven to be a competitive gate dielectric for constructing high-performance CNT CMOS FETs and integrated circuits.

  13. Radio Frequency Transistors Using Aligned Semiconducting Carbon Nanotubes with Current-Gain Cutoff Frequency and Maximum Oscillation Frequency Simultaneously Greater than 70 GHz.

    PubMed

    Cao, Yu; Brady, Gerald J; Gui, Hui; Rutherglen, Chris; Arnold, Michael S; Zhou, Chongwu

    2016-07-26

    In this paper, we report record radio frequency (RF) performance of carbon nanotube transistors based on combined use of a self-aligned T-shape gate structure, and well-aligned, high-semiconducting-purity, high-density polyfluorene-sorted semiconducting carbon nanotubes, which were deposited using dose-controlled, floating evaporative self-assembly method. These transistors show outstanding direct current (DC) performance with on-current density of 350 μA/μm, transconductance as high as 310 μS/μm, and superior current saturation with normalized output resistance greater than 100 kΩ·μm. These transistors create a record as carbon nanotube RF transistors that demonstrate both the current-gain cutoff frequency (ft) and the maximum oscillation frequency (fmax) greater than 70 GHz. Furthermore, these transistors exhibit good linearity performance with 1 dB gain compression point (P1dB) of 14 dBm and input third-order intercept point (IIP3) of 22 dBm. Our study advances state-of-the-art of carbon nanotube RF electronics, which have the potential to be made flexible and may find broad applications for signal amplification, wireless communication, and wearable/flexible electronics. PMID:27327074

  14. Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer.

    PubMed

    Xu, Wenya; Dou, Junyan; Zhao, Jianwen; Tan, Hongwei; Ye, Jun; Tange, Masayoshi; Gao, Wei; Xu, Weiwei; Zhang, Xiang; Guo, Wenrui; Ma, Changqi; Okazaki, Toshiya; Zhang, Kai; Cui, Zheng

    2016-02-28

    Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (±2 V) and subthreshold swing (SS) (122-161 mV dec(-1)), high effective mobility (up to 17.6-37.7 cm(2) V(-1) s(-1)) and high on/off ratio (10(4)-10(7)). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption. PMID:26847814

  15. Enhanced ambipolar charge injection with semiconducting polymer/carbon nanotube thin films for light-emitting transistors.

    PubMed

    Gwinner, Michael C; Jakubka, Florian; Gannott, Florentina; Sirringhaus, Henning; Zaumseil, Jana

    2012-01-24

    We investigate the influence of small amounts of semiconducting single-walled carbon nanotubes (SWNTs) dispersed in polyfluorenes such as poly(9,9-di-n-octylfluorene-alt-benzothiadiazole (F8BT) and poly(9,9-dioctylfluorene) (F8) on device characteristics of bottom contact/top gate ambipolar light-emitting field-effect transistors (LEFETs) based on these conjugated polymers. We find that the presence of SWNTs within the semiconducting layer at concentrations below the percolation limit significantly increases both hole and electron injection, even for a large band gap semiconductor like F8, without leading to significant luminescence quenching of the conjugated polymer. As a result of the reduced contact resistance and lower threshold voltages, larger ambipolar currents and thus brighter light emission are observed. We examine possible mechanisms of this effect such as energy level alignment, reduced bulk resistance above the contacts, and field-enhanced injection at the nanotube tips. The observed ambipolar injection improvement is applicable to most conjugated polymers in staggered transistor configurations or similar organic electronic devices where injection barriers are an issue. PMID:22142143

  16. Unipolar p-type single-walled carbon nanotube field-effect transistors using TTF-TCNQ as the contact material.

    PubMed

    Xian, Xiaojun; Yan, Kai; Zhou, Wei; Jiao, Liying; Wu, Zhongyun; Liu, Zhongfan

    2009-12-16

    We demonstrate herein that organic metal tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) can serve as an ideal material for source and drain electrodes to build unipolar p-type single-walled carbon nanotube (SWNTs) field-effect transistors (FETs). SWNTs were synthesized by the chemical vapor deposition (CVD) method on silicon wafer and then TTF-TCNQ was deposited by thermal evaporation through a shadow mask to form the source and drain contacts. An SiO2 layer served as the gate dielectric and Si was used as the backgate. Transfer characteristics show that these TTF-TCNQ contacted devices are Schottky barrier transistors just like conventional metal contacted SWNT-FETs. The most interesting characteristic of these SWNT transistors is that all devices demonstrate the unipolar p-type transport behavior. This behavior originates from the unique crystal structure and physical properties of TTF-TCNQ and this device may have potential applications in carbon nanotube electronics. PMID:19923654

  17. Unipolar p-type single-walled carbon nanotube field-effect transistors using TTF-TCNQ as the contact material

    NASA Astrophysics Data System (ADS)

    Xian, Xiaojun; Yan, Kai; Zhou, Wei; Jiao, Liying; Wu, Zhongyun; Liu, Zhongfan

    2009-12-01

    We demonstrate herein that organic metal tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) can serve as an ideal material for source and drain electrodes to build unipolar p-type single-walled carbon nanotube (SWNTs) field-effect transistors (FETs). SWNTs were synthesized by the chemical vapor deposition (CVD) method on silicon wafer and then TTF-TCNQ was deposited by thermal evaporation through a shadow mask to form the source and drain contacts. An SiO2 layer served as the gate dielectric and Si was used as the backgate. Transfer characteristics show that these TTF-TCNQ contacted devices are Schottky barrier transistors just like conventional metal contacted SWNT-FETs. The most interesting characteristic of these SWNT transistors is that all devices demonstrate the unipolar p-type transport behavior. This behavior originates from the unique crystal structure and physical properties of TTF-TCNQ and this device may have potential applications in carbon nanotube electronics.

  18. Low voltage, high performance inkjet printed carbon nanotube transistors with solution processed ZrO2 gate insulator

    NASA Astrophysics Data System (ADS)

    Kim, Bongjun; Jang, Seonpil; Prabhumirashi, Pradyumna L.; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2013-08-01

    High-performance single-walled carbon nanotube (SWCNT) thin-film transistors are fabricated by single-pass inkjet printing of SWCNTs on high-κ solution-processed ZrO2 gate dielectric. We demonstrate that an ultraviolet ozone treatment of the ZrO2 substrate is critical in achieving a uniform dispersion of sorted SWCNTs in the semiconducting channel. The resulting devices exhibit excellent performance with mobility and on/off current ratio exceeding 30 cm2 V-1 s-1 and 105, respectively, at low operating voltages (<5 V). The single-pass inkjet printing process demonstrated in this letter shows great promise as a reliable and scalable method for SWCNT based high performance electronics.

  19. Accurate extraction of mobility in carbon nanotube network transistors using C-V and I-V measurements

    NASA Astrophysics Data System (ADS)

    Yoon, Jinsu; Lee, Dongil; Kim, Chaewon; Lee, Jieun; Choi, Bongsik; Kim, Dong Myong; Kim, Dae Hwan; Lee, Mijung; Choi, Yang-Kyu; Choi, Sung-Jin

    2014-11-01

    The mobility of single-walled carbon nanotube (SWNT) network thin-film transistors (TFTs) is an essential parameter. Previous extraction methods for mobility encountered problems in extracting accurate intrinsic mobility due to the uncertainty of the SWNT density in the network channel and the existence of contact resistance at the source/drain electrodes. As a result, efficient and accurate extraction of the mobility in SWNT TFTs is challenging using previous methods. We propose a direct method of extracting accurate intrinsic mobility in SWNT TFTs by employing capacitance-voltage and current-voltage measurements. Consequently, we simply obtain accurate intrinsic mobility within the ink-jet printed SWNT TFTs without any complicated calculations.

  20. Single charge detection in capacitively coupled integrated single electron transistors based on single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Ishibashi, Koji

    2012-09-01

    Single charge detection is demonstrated in the capacitively coupled integrated single electron transistors (SETs) in single-walled carbon nanotubes (SWCNTs) quantum dots. Two SETs are fabricated based on two different SWCNTs aligned in parallel, by taking advantage of the aligned growth of SWCNTs and subsequent transfer-printed techniques. In order to make both two SETs be capacitively coupled, a metal finger is fabricated on the top of them. The charge sensing is proved by the response of a detector current in one SWCNT-SET when the number of electrons in the other SWCNT-SET is changed by sweeping the corresponding gate voltages. In this integrated device, shifts of Coulomb oscillation peaks due to the single electron event are also observed.

  1. Thin-film transistors using DNA-wrapped semiconducting single-wall carbon nanotubes with selected chiralities

    NASA Astrophysics Data System (ADS)

    Kuwahara, Yuki; Nihey, Fumiyuki; Ohmori, Shigekazu; Saito, Takeshi

    2015-10-01

    Selected semiconducting chiralities, (7,5), (7,6), and (8,4), of DNA-wrapped single-wall carbon nanotubes (DNA-SWCNTs) were used for thin-film transistors (TFTs). Chirality separation was carried out by ion exchange chromatography (IEX) with the ssDNA of the (TAT)4 sequence. An on/off ratio of 3.8 × 106 with a carrier mobility of 11 cm2/(V·s) was successfully achieved in the fabricated SWCNT-TFTs. The comparison between the on/off ratios obtained before (101-102) and after IEX (104-107) indicated that the IEX separation process sufficiently improves the performance of SWCNT-TFTs because of the reducing metallic SWCNT pathways in the TFT channel.

  2. Probing Biological Processes on Supported Lipid Bilayers with Single-Walled Carbon Nanotube Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose Manuel; Craighead, Harold; McEuen, Paul

    2006-03-01

    We have formed supported lipid bilayers (SLBs) by small unilamellar vesicle fusion on substrates containing single-walled carbon nanotube field-effect transistors (SWNT-FETs). We are able to detect the self-assembly of SLBs electrically with SWNT-FETs since their threshold voltages are shifted by this event. The SLB fully covers the NT surface and lipid molecules can diffuse freely in the bilayer surface across the NT. To study the interactions of important biological entities with receptors imbedded within the membrane, we have also integrated a membrane protein, GT1b ganglioside, in the bilayer. While bare gangliosides can diffuse freely across the NT, interestingly the NT acts as a diffusion barrier for the gangliosides when they are bound with tetanus toxin. This experiment opens the possibility of using SWNT-FETs as biosensors for label-free detection.

  3. Attachment of a Genetically Engineered Antibody to a Carbon Nanotube Transistor for Detection of Prostate Cancer Biomarkers

    NASA Astrophysics Data System (ADS)

    Lerner, Mitchell; Dailey, Jennifer; Goldsmith, Brett; Robinson, Matthew; Johnson, A. T. Charlie

    2011-03-01

    We have developed a novel detection method for osteopontin (OPN) by attaching an engineered single chain variable fragment (scFv) protein with high binding affinity for OPN to a carbon nanotube transistor. Osteopontin is a potential new biomarker for prostate cancer; its presence in humans is already associated with several forms of cancer, arthritis, osteoporosis and stress. Prostate cancer is the most commonly diagnosed cancer and second leading cause of cancer deaths among American men and as such represents a major public health issue. Detection of early-stage cancer often results in successful treatment, with long term disease-free survival in 60-90% of patients. Electronic transport measurements are used to detect the presence of OPN in solution at clinically relevant concentrations.

  4. Role of hybridization on the Schottky barrier height of carbon nanotube field effect transistors

    NASA Astrophysics Data System (ADS)

    Casterman, D.; de Souza, M. M.; Tahraoui, A.; Durkan, C.; Milne, W. I.

    2009-03-01

    The impact of hybridization on the Schottky barrier height (SBH) for holes at a metal/nanotube contact is investigated using ab initio density-functional theory. For small diameters, the impact of hybridization is a deviation of the SBH in comparison to that calculated using the “ 1/d ” rule, where d is the diameter of the carbon nanotube (CNT). In the hybridization region, the SBH reduces with chiral angle, suggesting that CNTs in this region may well be suited to microelectronic applications due to small SBH and large band gaps. Hybridization also causes a difference between the effective mass of electrons and holes, supposed to be identical within the tight-binding approximation. A strongly patterned behavior of the effective mass dependent on chirality and diameter is also reported here.

  5. A facile and low-cost length sorting of single-wall carbon nanotubes by precipitation and applications for thin-film transistors

    NASA Astrophysics Data System (ADS)

    Gui, Hui; Chen, Haitian; Khripin, Constantine Y.; Liu, Bilu; Fagan, Jeffrey A.; Zhou, Chongwu; Zheng, Ming

    2016-02-01

    Semiconducting single-wall carbon nanotubes (SWCNTs) with long lengths are highly desirable for many applications such as thin-film transistors and circuits. Previously reported length sorting techniques usually require sophisticated instrumentation and are hard to scale up. In this paper, we report for the first time a general phenomenon of a length-dependent precipitation of surfactant-dispersed carbon nanotubes by polymers, salts, and their combinations. Polyelectrolytes such as polymethacrylate (PMAA) and polystyrene sulfonate (PSS) are found to be especially effective on cholate and deoxycholate dispersed SWCNTs. By adding PMAA to these nanotube dispersions in a stepwise fashion, we have achieved nanotube precipitation in a length-dependent order: first nanotubes with an average length of 650 nm, and then successively of 450 nm, 350 nm, and 250 nm. A similar effect of nanotube length sorting has also been observed for PSS. To demonstrate the utility of the length fractionation, the 650 nm-long nanotube fraction was subjected to an aqueous two-phase separation to obtain semiconducting enriched nanotubes. Thin-film transistors fabricated with the resulting semiconducting SWCNTs showed a carrier mobility up to 18 cm2 (V s)-1 and an on/off ratio up to 107. Our result sheds new light on the phase behavior of aqueous nanotube dispersions under high concentrations of polymers and salts, and offers a facile, low-cost, and scalable method to produce length sorted semiconducting nanotubes for macroelectronics applications.Semiconducting single-wall carbon nanotubes (SWCNTs) with long lengths are highly desirable for many applications such as thin-film transistors and circuits. Previously reported length sorting techniques usually require sophisticated instrumentation and are hard to scale up. In this paper, we report for the first time a general phenomenon of a length-dependent precipitation of surfactant-dispersed carbon nanotubes by polymers, salts, and their

  6. Contact and channel resistances of ballistic and non-ballistic carbon-nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Park, Jong-Myeon; Hong, Shin-Nam

    2016-01-01

    Recently, many research has been conducted on the carbon-nanotube field-effect transistors (CNFETs) in expectation that the CNFETs could replace metal-oxide-semiconductor field-effect transistors (MOSFETs) in the sub-10-nm era. In consideration of both ballistic conduction and nonballistic conduction, including elastic scattering, optical phonon scattering, and acoustic phonon scattering, this paper presents the simulated dependence of the coaxially-gated single-walled semiconducting CNFET characteristics on the contact and the channel lengths. When the contact length was longer than 100 nm, the CNFETs showed a constant minimal value of the contact resistance. In this case, the saturated drain current was higher than that of CNFETs with a shorter contact length. When the channel was longer than 600 nm, the channel resistance was significantly increased due to acoustic phonon scattering. When the channel was shorter than 200 - 250 nm with optical scattering, acoustic scattering or all three scattering mechanisms taken into account, the contact resistance began to become larger than channel resistance.

  7. Transistors: Chemically Functionalized, Well-Dispersed Carbon Nanotubes in Lithium-Doped Zinc Oxide for Low-Cost, High-Performance Thin-Film Transistors (Small 14/2016).

    PubMed

    Son, Gi-Cheol; Chee, Sang-Soo; Jun, Ji-Hyun; Son, Myungwoo; Lee, Sun Sook; Choi, Youngmin; Jeong, Sunho; Ham, Moon-Ho

    2016-04-01

    A simple, wet-chemical method for the surface functionalization of carbon nanotubes with hydrophilic groups is introduced in Li-doped ZnO by S. Jeong, M. H. Ham, and co-workers, on page 1859. This results in the uniform spatial distribution of single-walled carbon nanotubes in ultrathin ZnO-based matrix oxides, and facilitates high-mobility, low-cost metal-oxide-based thin-film transistors. This approach is compatible with various film formation processes, even printing processes, and enables the realization of high-performance, cost-effective, large-area electronics and displays based on metal oxides. PMID:27061455

  8. Supported lipid bilayer/carbon nanotube hybrids

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose M.; Craighead, Harold G.; McEuen, Paul L.

    2007-03-01

    Carbon nanotube transistors combine molecular-scale dimensions with excellent electronic properties, offering unique opportunities for chemical and biological sensing. Here, we form supported lipid bilayers over single-walled carbon nanotube transistors. We first study the physical properties of the nanotube/supported lipid bilayer structure using fluorescence techniques. Whereas lipid molecules can diffuse freely across the nanotube, a membrane-bound protein (tetanus toxin) sees the nanotube as a barrier. Moreover, the size of the barrier depends on the diameter of the nanotube-with larger nanotubes presenting bigger obstacles to diffusion. We then demonstrate detection of protein binding (streptavidin) to the supported lipid bilayer using the nanotube transistor as a charge sensor. This system can be used as a platform to examine the interactions of single molecules with carbon nanotubes and has many potential applications for the study of molecular recognition and other biological processes occurring at cell membranes.

  9. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  10. From transistor to nanotube

    NASA Astrophysics Data System (ADS)

    Boudenot, Jean-Claude

    2008-01-01

    We present here the main steps in the evolution of the transistor, since the tremendous invention of such a device and the introduction of the integrated circuit. We will then recall the main steps of Moore's law development. Nanotechnology began at the very beginning of the 21st century. Two aspects are presented in this article: the first, called 'More Moore', consists in continuing the laws of scale up to the physical limits; the second aspect, called 'beyond CMOS' explores new concepts such as spintronics, moletronics, nanotronics and other types of molecular electronics. To cite this article: J.-C. Boudenot, C. R. Physique 9 (2008).

  11. Direct growth of horizontally aligned carbon nanotubes between electrodes and its application to field-effect transistors.

    PubMed

    Hayashi, Yasuhiko; Jang, B; Iijima, T; Tokunaga, T; Hayashi, A; Tanemura, M; Amaratunga, G A J

    2011-12-01

    This paper presents direct growth of horizontally-aligned carbon nanotubes (CNTs) between two predefined various inter-spacing up to tens of microns of electrodes (pads) and its use as CNT field-effect transistors (CNT-FETs). Using the conventional photolithography technique followed by thin film evaporation and lift off, the catalytic electrodes (pads) were prepared, consisting of Pt, Al and Fe triple layers on SiO2/Si substrate. The grown CNTs were horizontally-aligned across the catalytic electrodes on the modified gold image furnace hot stage (thermal CVD) at 800 degrees C by using an alcohol vapor as the carbon source. Scanning and transmission electron microcopies (SEM/TEM) were used to observe the structure, growth direction and density of CNTs, while Raman spectrum analysis was used to indicate the degree of amorphous impurity and diameter of CNTs. Both single- and multi-wall CNTs with diameters of 1.1-2.2 nm were obtained and the CNT density was controlled by thickness of Fe catalytic layer. Following horizontally-aligned growth of CNTs, the electrical properties of back-gate CNT-FETs were measured and showd p-type conduction behaviors of FET. PMID:22409045

  12. Transport in Carbon Nanotube Junctions

    NASA Astrophysics Data System (ADS)

    Khoo, K. H.; Chelikowsky, James R.

    2008-03-01

    There is growing interest in the use of carbon nanotube thin films as transparent electrical conductors and thin-film transistors owing to their high optical transmittance, low sheet resistivity, and ease of fabrication. [1,2] A major contribution to the sheet resistivity originates at nanotube junctions, as electrical contact is typically poor between adjacent nanotubes. It is thus important to characterize carbon nanotube junctions in order to understand the conduction properties of nanotube thin films. To this end, we have performed ab initio density functional theory calculations to investigate the structural, electronic and transport properties of carbon nanotube junctions as a function of nanotube chirality and contact geometry [1] Z. Wu et al., Science 305, 1273 (2004) [2] E. S. Snow, J. P. Novak, P. M. Campbell, and D. Park, Appl. Phys. Lett. 82, 2145 (2003).

  13. Carbon nanotube feedback-gate field-effect transistor: suppressing current leakage and increasing on/off ratio.

    PubMed

    Qiu, Chenguang; Zhang, Zhiyong; Zhong, Donglai; Si, Jia; Yang, Yingjun; Peng, Lian-Mao

    2015-01-27

    Field-effect transistors (FETs) based on moderate or large diameter carbon nanotubes (CNTs) usually suffer from ambipolar behavior, large off-state current and small current on/off ratio, which are highly undesirable for digital electronics. To overcome these problems, a feedback-gate (FBG) FET structure is designed and tested. This FBG FET differs from normal top-gate FET by an extra feedback-gate, which is connected directly to the drain electrode of the FET. It is demonstrated that a FBG FET based on a semiconducting CNT with a diameter of 1.5 nm may exhibit low off-state current of about 1 × 10(-13) A, high current on/off ratio of larger than 1 × 10(8), negligible drain-induced off-state leakage current, and good subthreshold swing of 75 mV/DEC even at large source-drain bias and room temperature. The FBG structure is promising for CNT FETs to meet the standard for low-static-power logic electronics applications, and could also be utilized for building FETs using other small band gap semiconductors to suppress leakage current. PMID:25545108

  14. Selective Dispersion of Highly Pure Large-Diameter Semiconducting Carbon Nanotubes by a Flavin for Thin-Film Transistors.

    PubMed

    Park, Minsuk; Kim, Somin; Kwon, Hyeokjae; Hong, Sukhyun; Im, Seongil; Ju, Sang-Yong

    2016-09-01

    Scalable and simple methods for selective extraction of pure, semiconducting (s) single-walled carbon nanotubes (SWNTs) is of profound importance for electronic and photovoltaic applications. We report a new, one-step procedure to obtain respective large-diameter s- and metallic (m)-SWNT enrichment purity in excess of 99% and 78%, respectively, via interaction between the aromatic dispersing agent and SWNTs. The approach utilizes N-dodecyl isoalloxazine (FC12) as a surfactant in conjunction with sonication and benchtop centrifugation methods. After centrifugation, the supernatant is enriched in s-SWNTs with less carbonaceous impurities, whereas precipitate is enhanced in m-SWNTs. In addition, the use of an increased centrifugal force enhances both the purity and population of larger diameter s-SWNTs. Photoinduced energy transfer from FC12 to SWNTs is facilitated by respective electronic level alignment. Owing to its peculiar photoreduction capability, FC12 can be employed to precipitate SWNTs upon UV irradiation and observe absorption of higher optical transitions of SWNTs. A thin-film transistor prepared from a dispersion of enriched s-SWNTs was fabricated to verify electrical performance of the sorted sample and was observed to display p-type conductance with an average on/off ratio over 10(6) and an average mobility over 10 cm(2)/V·s. PMID:27538495

  15. Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric

    NASA Astrophysics Data System (ADS)

    Lee, Dongil; Yoon, Jinsu; Lee, Juhee; Lee, Byung-Hyun; Seol, Myeong-Lok; Bae, Hagyoul; Jeon, Seung-Bae; Seong, Hyejeong; Im, Sung Gap; Choi, Sung-Jin; Choi, Yang-Kyu

    2016-05-01

    Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm2 V‑1 sec‑1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 104), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process.

  16. Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric.

    PubMed

    Lee, Dongil; Yoon, Jinsu; Lee, Juhee; Lee, Byung-Hyun; Seol, Myeong-Lok; Bae, Hagyoul; Jeon, Seung-Bae; Seong, Hyejeong; Im, Sung Gap; Choi, Sung-Jin; Choi, Yang-Kyu

    2016-01-01

    Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm(2) V(-1) sec(-)1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 10(4)), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process. PMID:27184121

  17. Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric

    PubMed Central

    Lee, Dongil; Yoon, Jinsu; Lee, Juhee; Lee, Byung-Hyun; Seol, Myeong-Lok; Bae, Hagyoul; Jeon, Seung-Bae; Seong, Hyejeong; Im, Sung Gap; Choi, Sung-Jin; Choi, Yang-Kyu

    2016-01-01

    Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm2 V−1 sec−1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 104), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process. PMID:27184121

  18. Carbon nanotube intramolecular junctions

    NASA Astrophysics Data System (ADS)

    Yao, Zhen; Postma, Henk W. Ch.; Balents, Leon; Dekker, Cees

    1999-11-01

    The ultimate device miniaturization would be to use individual molecules as functional devices. Single-wall carbon nanotubes (SWNTs) are promising candidates for achieving this: depending on their diameter and chirality, they are either one-dimensional metals or semiconductors. Single-electron transistors employing metallic nanotubes and field-effect transistors employing semiconducting nanotubes have been demonstrated. Intramolecular devices have also been proposed which should display a range of other device functions. For example, by introducing a pentagon and a heptagon into the hexagonal carbon lattice, two tube segments with different atomic and electronic structures can be seamlessly fused together to create intramolecular metal-metal, metal-semiconductor, or semiconductor-semiconductor junctions. Here we report electrical transport measurements on SWNTs with intramolecular junctions. We find that a metal-semiconductor junction behaves like a rectifying diode with nonlinear transport characteristics that are strongly asymmetric with respect to bias polarity. In the case of a metal-metal junction, the conductance appears to be strongly suppressed and it displays a power-law dependence on temperatures and applied voltage, consistent with tunnelling between the ends of two Luttinger liquids. Our results emphasize the need to consider screening and electron interactions when designing and modelling molecular devices. Realization of carbon-based molecular electronics will require future efforts in the controlled production of these intramolecular nanotube junctions.

  19. Solution-processed single-walled carbon nanotube field effect transistors and bootstrapped inverters for disintegratable, transient electronics

    SciTech Connect

    Jin, Sung Hun E-mail: jhl@snu.ac.kr Shin, Jongmin; Cho, In-Tak; Lee, Jong-Ho E-mail: jhl@snu.ac.kr; Han, Sang Youn; Lee, Dong Joon; Lee, Chi Hwan; Rogers, John A. E-mail: jhl@snu.ac.kr

    2014-07-07

    This paper presents materials, device designs, and physical/electrical characteristics of a form of nanotube electronics that is physically transient, in the sense that all constituent elements dissolve and/or disperse upon immersion into water. Studies of contact effects illustrate the ability to use water soluble metals such as magnesium for source/drain contacts in nanotube based field effect transistors. High mobilities and on/off ratios in transistors that use molybdenum, silicon nitride, and silicon oxide enable full swing characteristics for inverters at low voltages (∼5 V) and with high gains (∼30). Dissolution/disintegration tests of such systems on water soluble sheets of polyvinyl alcohol demonstrate physical transience within 30 min.

  20. Mobilities in ambipolar field effect transistors based on single-walled carbon nanotube network and formed on a gold nanoparticle template

    SciTech Connect

    Wongsaeng, Chalao; Singjai, Pisith

    2014-04-07

    Ambipolar field effect transistors based on a single-walled carbon nanotube (SWNT) network formed on a gold nanoparticle (AuNP) template with polyvinyl alcohol as a gate insulator were studied by measuring the current–gate voltage characteristics. It was found that the mobilities of holes and electrons increased with increasing AuNP number density. The disturbances in the flow pattern of the carbon feedstock in the chemical vapor deposition growth that were produced by the AuNP geometry, resulted in the differences in the crystallinity and the diameter, as well as the changes in the degree of the semiconductor behavior of the SWNTs.

  1. Highly sensitive potassium-doped polypyrrole/carbon nanotube-based enzyme field effect transistor (ENFET) for cholesterol detection.

    PubMed

    Barik, Md Abdul; Sarma, Manoj Kumar; Sarkar, C R; Dutta, Jiten Ch

    2014-10-01

    Highly sensitive potassium (K)-doped carbon nanotube (CNT) and polypyrrole (PPy) nanocomposite membrane-based enzyme field effect transistor (ENFET) has been fabricated on indium tin oxide (ITO) for detection of cholesterol. P-type graphene has been deposited as substrate on ITO glass electrochemically. N-type graphene has been deposited in source and drain regions. Zirconium dioxide (ZrO2) has been deposited on the channel region as gate insulator. K/PPy/CNT composite has been deposited as sensing membrane on the top of ZrO2 layer; 1 μl of cholesterol oxidase (ChOx) has been immobilized on K/PPy/CNT membrane via physical adsorption technique. The response of K/PPy/CNT/FET has been studied using Agilent 3458A digital multimeter in presence of phosphate buffer saline (PBS) of 50 mM, pH 7.0 and 0.9 % NaCl contained in a glass pot. During measurement, 20 μl cholesterol solutions (0.5 to 25 mM) were poured into the pot through micropipette each time. It has been found that K/PPy/CNT/FET has linearly varied from 0.5 to 20 mM. The sensitivity of this FET has been found to be ~400 μA/mM/mm(2) with regression coefficient (r) ~ 0.998. The proposed ENFET has response time of 1 s and stability up to 6 months. The experiment has been repeated 10 times, and only 2.0 % output variation has been observed. The limit of detection (LoD) and Michaelis-Menten constant (K m) were found to be ~1.4 and 2.5 mM, respectively. The results obtained in this work show negligible interference (3.7 %) with uric acid, glucose and urea. PMID:25005579

  2. Scalable and selective dispersion of semiconducting arc-discharged carbon nanotubes by dithiafulvalene/thiophene copolymers for thin film transistors.

    PubMed

    Wang, Huiliang; Mei, Jianguo; Liu, Peng; Schmidt, Kristin; Jiménez-Osés, Gonzalo; Osuna, Sílvia; Fang, Lei; Tassone, Christopher J; Zoombelt, Arjan Pieter; Sokolov, Anatoliy N; Houk, Kendall N; Toney, Michael F; Bao, Zhenan

    2013-03-26

    We report a simple and scalable method to enrich large quantities of semiconducting arc-discharged single-walled carbon nanotubes (SWNTs) with diameters of 1.1-1.8 nm using dithiafulvalene/thiophene copolymers. Stable solutions of highly individualized and highly enriched semiconducting SWNTs were obtained after a simple sonication and centrifuge process. Molecular dynamics (MD) simulations of polymer backbone interactions with and without side chains indicated that the presence of long alkyl side chains gave rise to the selectivity toward semiconducting tubes, indicating the importance of the roles of the side chains to both solubilize and confer selectivity to the polymers. We found that, by increasing the ratio of thiophene to dithiafulvalene units in the polymer backbone (from pDTFF-1T to pDTFF-3T), we can slightly improve the selectivity toward semiconducting SWNTs. This is likely due to the more flexible backbone of pDTFF-3T that allows the favorable wrapping of SWNTs with certain chirality as characterized by small-angle X-ray scattering. However, the dispersion yield was reduced from pDTFF-1T to pDTFF-3T. MD simulations showed that the reduction is due to the smaller polymer/SWNT contact area, which reduces the dispersion ability of pDTFF-3T. These experimental and modeling results provide a better understanding for future rational design of polymers for sorting SWNTs. Finally, high on/off ratio solution-processed thin film transistors were fabricated from the sorted SWNTs to confirm the selective dispersion of semiconducting arc-discharge SWNTs. PMID:23402644

  3. Polyfluorene-sorted, carbon nanotube array field-effect transistors with increased current density and high on/off ratio.

    PubMed

    Brady, Gerald J; Joo, Yongho; Wu, Meng-Yin; Shea, Matthew J; Gopalan, Padma; Arnold, Michael S

    2014-11-25

    Challenges in eliminating metallic from semiconducting single-walled carbon nanotubes (SWCNTs) and in controlling their alignment have limited the development of high-performance SWCNT-based field-effect transistors (FETs). We recently pioneered an approach for depositing aligned arrays of ultra-high-purity semiconducting SWCNTs, isolated using polyfluorene derivatives, called dose-controlled floating evaporative self-assembly. Here, we tailor FETs fabricated from these arrays to achieve on-conductance (G(on)) per width and an on-off ratio (G(on)/G(off)) of 261 μS/μm and 2 × 10(5), respectively, for a channel length (L(ch)) of 240 nm and 116 μS/μm and 1 × 10(6), respectively, for an L(ch) of 1 μm. We demonstrate 1400× greater G(on)/G(off) than SWCNT FETs fabricated by other methods, at comparable G(on) per width of ∼250 μS/μm and 30-100× greater G(on) per width at comparable G(on)/G(off) of 10(5)-10(7). The average G(on) per tube reaches 5.7 ± 1.4 μS at a packing density of 35 tubes/μm for L(ch) in the range 160-240 nm, limited by contact resistance. These gains highlight the promise of using ultra-high-purity semiconducting SWCNTs with controlled alignment for next-generation semiconductor electronics. PMID:25383880

  4. Chemically Functionalized, Well-Dispersed Carbon Nanotubes in Lithium-Doped Zinc Oxide for Low-Cost, High-Performance Thin-Film Transistors.

    PubMed

    Son, Gi-Cheol; Chee, Sang-Soo; Jun, Ji-Hyun; Son, Myungwoo; Lee, Sun Sook; Choi, Youngmin; Jeong, Sunho; Ham, Moon-Ho

    2016-04-13

    Surface-functionalized carbon nanotubes (CNTs) are introduced into lithium-doped ZnO thin-film transistors (TFTs) as an alternative to the conventional incorporation of an expensive element, indium. The crucial role of surface functionalization of CNTs is clarified with the demonstration of indium-free ZnO-based TFTs with a field-effect mobility of 28.6 cm(2) V(-1) s(-1) and an on/off current ratio of 9 × 10(6) for low-cost, high-performance electronics. PMID:26856958

  5. Band-to-band tunneling in a carbon nanotube metal-oxide-semiconductor field-effect transistor is dominated by phonon-assisted tunneling.

    PubMed

    Koswatta, Siyuranga O; Lundstrom, Mark S; Nikonov, Dmitri E

    2007-05-01

    Band-to-band tunneling (BTBT) devices have recently gained a lot of interest due to their potential for reducing power dissipation in integrated circuits. We have performed extensive simulations for the BTBT operation of carbon nanotube metal-oxide-semiconductor field-effect transistors (CNT-MOSFETs) using the nonequilibrium Green's function formalism for both ballistic and dissipative quantum transport. In comparison with recently reported experimental data (J. Am. Chem. Soc. 2006, 128, 3518-3519), we have obtained strong evidence that BTBT in CNT-MOSFETs is dominated by optical phonon assisted inelastic transport, which can have important implications on the transistor characteristics. It is shown that, under large biasing conditions, two-phonon scattering may also become important. PMID:17388638

  6. A study of junction effect transistors and their roles in carbon nanotube field emission cathodes in compact pulsed power applications

    NASA Astrophysics Data System (ADS)

    Shui, Qiong

    This thesis is focusing on a study of junction effect transistors (JFETs) in compact pulsed power applications. Pulsed power usually requires switches with high hold-off voltage, high current, low forward voltage drop, and fast switching speed. 4H-SiC, with a bandgap of 3.26 eV (The bandgap of Si is 1.12eV) and other physical and electrical superior properties, has gained much attention in high power, high temperature and high frequency applications. One topic of this thesis is to evaluate if 4H-SiC JFETs have a potential to replace gas phase switches to make pulsed power system compact and portable. Some other pulsed power applications require cathodes of providing stable, uniform, high electron-beam current. So the other topic of this research is to evaluate if Si JFET-controlled carbon nanotube field emitter cold cathode will provide the necessary e-beam source. In the topic of "4H-SiC JFETs", it focuses on the design and simulation of a novel 4H-SiC normally-off VJFET with high breakdown voltage using the 2-D simulator ATLAS. To ensure realistic simulations, we utilized reasonable physical models and the established parameters as the input into these models. The influence of key design parameters were investigated which would extend pulsed power limitations. After optimizing the key design parameters, with a 50-mum drift region, the predicted breakdown voltage for the VJFET is above 8kV at a leakage current of 1x10-5A/cm2 . The specific on-state resistance is 35 mO·cm 2 at VGS = 2.7 V, and the switching speed is several ns. The simulation results suggest that the 4H-SiC VJFET is a potential candidate for improving switching performance in repetitive pulsed power applications. To evaluate the 4H-SiC VJFETs in pulsed power circuits, we extracted some circuit model parameters from the simulated I-V curves. Those parameters are necessary for circuit simulation program such as SPICE. This method could be used as a test bench without fabricating the devices to

  7. Carbon nanotube composite materials

    DOEpatents

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  8. The effect of local polarized domains of ferroelectric P(VDF/TrFE) copolymer thin film on a carbon nanotube field-effect transistor.

    PubMed

    Nishio, Taichi; Miyato, Yuji; Kobayashi, Kei; Ishida, Kenji; Matsushige, Kazumi; Yamada, Hirofumi

    2008-01-23

    We produced local polarized domains of ferroelectric P(VDF/TrFE) copolymer thin films on a carbon nanotube field-effect transistor (CN-FET) channel by atomic force microscopy (AFM). The drain current versus gate voltage (I(d)-V(g)) curves measured after forming the local polarized domains showed a shift in the threshold voltages. We also found that the amount of the shifts in the threshold voltages gradually decreased during the measurement of this characteristic over 100 h after forming the polarized domains. The mechanisms of the shifts in the threshold voltages and their decreasing behaviour were explained in terms of the excessive charges that were induced upon the formation of the polarized domains. PMID:21817562

  9. Carbon Based Transistors and Nanoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Rouhi, Nima

    Carbon based materials (carbon nanotube and graphene) has been extensively researched during the past decade as one of the promising materials to be used in high performance device technology. In long term it is thought that they may replace digital and/or analog electronic devices, due to their size, near-ballistic transport, and high stability. However, a more realistic point of insertion into market may be the printed nanoelectronic circuits and sensors. These applications include printed circuits for flexible electronics and displays, large-scale bendable electrical contacts, bio-membranes and bio sensors, RFID tags, etc. In order to obtain high performance thin film transistors (as the basic building block of electronic circuits) one should be able to manufacture dense arrays of all semiconducting nanotubes. Besides, graphene synthesize and transfer technology is in its infancy and there is plenty of room to improve the current techniques. To realize the performance of nanotube and graphene films in such systems, we need to economically fabricate large-scale devices based on these materials. Following that the performance control over such devices should also be considered for future design variations for broad range of applications. Here we have first investigated carbon nanotube ink as the base material for our devices. The primary ink used consisted of both metallic and semiconducting nanotubes which resulted in networks suitable for moderate-resistivity electrical connections (such as interconnects) and rfmatching circuits. Next, purified all-semiconducting nanotube ink was used to fabricate waferscale, high performance (high mobility, and high on/off ratio) thin film transistors for printed electronic applications. The parameters affecting device performance were studied in detail to establish a roadmap for the future of purified nanotube ink printed thin film transistors. The trade of between mobility and on/off ratio of such devices was studied and the

  10. Carbon nanotube nanoelectrode arrays

    DOEpatents

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  11. Supported Lipid Bilayer/Carbon Nanotube Hybrids

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose; Craighead, Harold; McEuen, Paul

    2007-03-01

    We form supported lipid bilayers on single-walled carbon nanotubes and use this hybrid structure to probe the properties of lipid membranes and their functional constituents. We first demonstrate membrane continuity and lipid diffusion over the nanotube. A membrane-bound tetanus toxin protein, on the other hand, sees the nanotube as a diffusion barrier whose strength depends on the diameter of the nanotube. Finally, we present results on the electrical detection of specific binding of streptavidin to biotinylated lipids with nanotube field effect transistors. Possible techniques to extract dynamic information about the protein binding events will also be discussed.

  12. Optoelectronics with Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kinoshita, Megumi

    2011-12-01

    The carbon nanotube is a promising material for future micro- and nano-scale electronics because of its unique electronic properties, high carrier mobility and extraordinary capacity for high current density. In particular, semiconducting carbon nanotubes are direct bandgap materials with a typical energy gap in the order of 1 eV, which means they emit light in the near-infrared range, making them an attractive option in telecommunications applications. However, there have been few systematic investigations of electrically-induced light emission (i.e. electroluminescence) from carbon nanotubes, and their emission properties are not well understood. In this dissertation, we explore the characteristics of electroluminescence in three different types of carbon-nanotube devices. The first is a single-tube field-effect transistor (CNTFET), whose emission has previously been found to have a very broad spectral shape and low emission efficiency. We analyze the spectral shape in detail, which reveals that a high electric field near metal contacts contributes most to the bias-dependent component of broadening, in addition to smaller contributions from tube nonuniformity, inelastic scattering of phonons, high temperature, etc. In the second part of the study, single-tube light-emitting diodes are constructed by employing a split top-gate scheme. The split gate creates p- and n-doped regions electrostatically, so that electrons and holes combine between the two sections and can decay radiatively. This configuration creates electron-hole pairs under much lower electric fields and gives us a greater control over carrier distribution in the device channel, resulting in much narrower spectral linewidths and an emission intensity several orders of magnitude larger than that of CNTFETs. The much better signal-to-noise also leads to the observation of emission from defect-induced states. Finally, we extend the idea of the single-tube p-n diode and fabricate CNT film diodes from many

  13. Simultaneous Improvement of Hole and Electron Injection in Organic Field-effect Transistors by Conjugated Polymer-wrapped Carbon Nanotube Interlayers.

    PubMed

    Lee, Seung-Hoon; Khim, Dongyoon; Xu, Yong; Kim, Juhwan; Park, Won-Tae; Kim, Dong-Yu; Noh, Yong-Young

    2015-01-01

    Efficient charge injection is critical for flexible organic electronic devices such as organic light-emitting diodes (OLEDs) and field-effect transistors (OFETs). Here, we investigated conjugated polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWNTs) as solution-processable charge-injection layers in ambipolar organic field-effect transistors with poly(thienylenevinylene-co-phthalimide)s. The interlayers were prepared using poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) or poly(9,9-dioctylfluorene) (PFO) to wrap s-SWNTs. In the contact-limited ambipolar OFETs, the interlayer led to significantly lower contact resistance (Rc) and increased mobilities for both holes and electrons. The resulting PTVPhI-Eh OFETs with PFO-wrapped s-SWNT interlayers showed very well-balanced ambipolar transport properties with a hole mobility of 0.5 cm(2)V(-1)S(-1) and an electron mobility of 0.5 cm(2)V(-1)S(-1) in linear regime. In addition, the chirality of s-SWNTs and kind of wrapping of conjugated polymers are not critical to improving charge-injection properties. We found that the improvements caused by the interlayer were due to the better charge injection at the metal/organic semiconductor contact interface and the increase in the charge concentration through a detailed examination of charge transport with low-temperature measurements. Finally, we successfully demonstrated complementary ambipolar inverters incorporating the interlayers without excessive patterning. PMID:26001198

  14. Simultaneous Improvement of Hole and Electron Injection in Organic Field-effect Transistors by Conjugated Polymer-wrapped Carbon Nanotube Interlayers

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Hoon; Khim, Dongyoon; Xu, Yong; Kim, Juhwan; Park, Won-Tae; Kim, Dong-Yu; Noh, Yong-Young

    2015-05-01

    Efficient charge injection is critical for flexible organic electronic devices such as organic light-emitting diodes (OLEDs) and field-effect transistors (OFETs). Here, we investigated conjugated polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWNTs) as solution-processable charge-injection layers in ambipolar organic field-effect transistors with poly(thienylenevinylene-co-phthalimide)s. The interlayers were prepared using poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) or poly(9,9-dioctylfluorene) (PFO) to wrap s-SWNTs. In the contact-limited ambipolar OFETs, the interlayer led to significantly lower contact resistance (Rc) and increased mobilities for both holes and electrons. The resulting PTVPhI-Eh OFETs with PFO-wrapped s-SWNT interlayers showed very well-balanced ambipolar transport properties with a hole mobility of 0.5 cm2V-1S-1 and an electron mobility of 0.5 cm2V-1S-1 in linear regime. In addition, the chirality of s-SWNTs and kind of wrapping of conjugated polymers are not critical to improving charge-injection properties. We found that the improvements caused by the interlayer were due to the better charge injection at the metal/organic semiconductor contact interface and the increase in the charge concentration through a detailed examination of charge transport with low-temperature measurements. Finally, we successfully demonstrated complementary ambipolar inverters incorporating the interlayers without excessive patterning.

  15. Plumbing carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jin, Chuanhong; Suenaga, Kazu; Iijima, Sumio

    2008-01-01

    Since their discovery, the possibility of connecting carbon nanotubes together like water pipes has been an intriguing prospect for these hollow nanostructures. The serial joining of carbon nanotubes in a controlled manner offers a promising approach for the bottom-up engineering of nanotube structures-from simply increasing their aspect ratio to making integrated carbon nanotube devices. To date, however, there have been few reports of the joining of two different carbon nanotubes. Here we demonstrate that a Joule heating process, and associated electro-migration effects, can be used to connect two carbon nanotubes that have the same (or similar) diameters. More generally, with the assistance of a tungsten metal particle, this technique can be used to seamlessly join any two carbon nanotubes-regardless of their diameters-to form new nanotube structures.

  16. Carbon nanotube devices: Sorting, Assembling, Characterizing

    NASA Astrophysics Data System (ADS)

    Krupke, Ralph

    2009-03-01

    Carbon nanotubes have been studied extensively over the last decade. Various exceptional properties have been revealed which still drive the vision about using carbon nanotube in future electronics, for instance as molecular nanoscale transistors or electromigration resistant interconnects. For many years a major obstacle was the inability to grow nanotubes with defined dimensions (length, diameter) and electronic properties (metallic,semiconducting). Recently those problems have been solved to a large extent by advanced sorting techniques. Today the challenge is to assemble nanotubes devices with defined properties to form a complex circuitry. As progress is made in making highly-integrated nanotube device arrays new characterization techniques have to be developed which allow testing large number of devices within an acceptable time. Along this line I will report on the state-of-the-art of sorting of carbon nanotube, as a base for nanotube device fabrication [1]. I will then explain our strategy to assemble high-density arrays of nanotube devices [2] and discuss a new characterization technique for nanotube devices [3]. Finally I will introduce a novel device engineering tool [4]. [4pt] [1] R. Krupke et al., ``Separation techniques for carbon nanotubes'' in Chemistry of Carbon Nanotubes, p.129-139, American Scientific Publishers 2008[0pt] [2] A. Vijayaraghavan et al., ``Ultra-Large-Scale Directed Assembly of Single-Walled Carbon Nanotube Devices'', Nano Lett. 7 (2007) 1556-1560[0pt] [3] A. Vijayaraghavan et al., ``Imaging Electronic Structure of Carbon Nanotubes by Voltage-Contrast Scanning Electron Microscopy'', Nano Resarch 1 (2008) 321-332[0pt] [4] C. W. Marquardt et al., ``Reversible metal-insulator transitions in metallic single-walled carbon nanotubes'', Nano Lett. 9 (2008) 2767-2772

  17. Reinforced Carbon Nanotubes.

    DOEpatents

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2005-06-28

    The present invention relates generally to reinforced carbon nanotubes, and more particularly to reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  18. Influence of redox molecules on the electronic conductance of single-walled carbon nanotube field-effect transistors: application to chemical and biological sensing.

    PubMed

    Boussaad, Salah; Diner, Bruce A; Fan, Janine

    2008-03-26

    In an effort to develop sensitive nanoscale devices for chemical and biological sensing, we have examined, using liquid gating, the conductance of semiconducting single-walled carbon nanotube-based field-effect transistors (SWCNT-FETs) in the presence of redox mediators. As examples, redox couples K3Fe(CN)6/K4Fe(CN)6 and K2IrCl6/K3IrCl6 are shown to modulate the SWCNT-FET conductance in part through their influence via the electrolyte gate on the electrostatic potential of the solution, as described by Larrimore et al. (Nano Lett. 2006, 6, 3129-1333) and in part through electron transfer between the redox mediators and the nanotubes. In the latter case, the rate of electron transfer is determined by the difference in chemical potential between the redox mediator and the SWCNTs and by the concentrations of the oxidized and reduced forms of the redox couple. Furthermore, these devices can detect the activity of redox enzymes through their sensitivity to the change in oxidation state of the enzyme substrate. An example is given for the blue copper oxidase, Trametes versicolor laccase, in which the rate of change of the SWCNT device conductance is linearly proportional to the rate of oxidation of the substrate 10-(2-hydroxyethyl)phenoxazine, varied over 2 orders of magnitude by the laccase concentration in the picomolar range. The behavior described in this work provides a highly sensitive means with which to do chemical and biological sensing using SWCNTs that is different from the amperometric, capacitive, and field-effect type sensing methods previously described in the literature for this material. PMID:18321094

  19. Scalability of carbon-nanotube-based thin film transistors for flexible electronic devices manufactured using an all roll-to-roll gravure printing system

    PubMed Central

    Koo, Hyunmo; Lee, Wookyu; Choi, Younchang; Sun, Junfeng; Bak, Jina; Noh, Jinsoo; Subramanian, Vivek; Azuma, Yasuo; Majima, Yutaka; Cho, Gyoujin

    2015-01-01

    To demonstrate that roll-to-roll (R2R) gravure printing is a suitable advanced manufacturing method for flexible thin film transistor (TFT)-based electronic circuits, three different nanomaterial-based inks (silver nanoparticles, BaTiO3 nanoparticles and single-walled carbon nanotubes (SWNTs)) were selected and optimized to enable the realization of fully printed SWNT-based TFTs (SWNT-TFTs) on 150-m-long rolls of 0.25-m-wide poly(ethylene terephthalate) (PET). SWNT-TFTs with 5 different channel lengths, namely, 30, 80, 130, 180, and 230 μm, were fabricated using a printing speed of 8 m/min. These SWNT-TFTs were characterized, and the obtained electrical parameters were related to major mechanical factors such as web tension, registration accuracy, impression roll pressure and printing speed to determine whether these mechanical factors were the sources of the observed device-to-device variations. By utilizing the electrical parameters from the SWNT-TFTs, a Monte Carlo simulation for a 1-bit adder circuit, as a reference, was conducted to demonstrate that functional circuits with reasonable complexity can indeed be manufactured using R2R gravure printing. The simulation results suggest that circuits with complexity, similar to the full adder circuit, can be printed with a 76% circuit yield if threshold voltage (Vth) variations of less than 30% can be maintained. PMID:26411839

  20. Scalability of carbon-nanotube-based thin film transistors for flexible electronic devices manufactured using an all roll-to-roll gravure printing system

    NASA Astrophysics Data System (ADS)

    Koo, Hyunmo; Lee, Wookyu; Choi, Younchang; Sun, Junfeng; Bak, Jina; Noh, Jinsoo; Subramanian, Vivek; Azuma, Yasuo; Majima, Yutaka; Cho, Gyoujin

    2015-09-01

    To demonstrate that roll-to-roll (R2R) gravure printing is a suitable advanced manufacturing method for flexible thin film transistor (TFT)-based electronic circuits, three different nanomaterial-based inks (silver nanoparticles, BaTiO3 nanoparticles and single-walled carbon nanotubes (SWNTs)) were selected and optimized to enable the realization of fully printed SWNT-based TFTs (SWNT-TFTs) on 150-m-long rolls of 0.25-m-wide poly(ethylene terephthalate) (PET). SWNT-TFTs with 5 different channel lengths, namely, 30, 80, 130, 180, and 230 μm, were fabricated using a printing speed of 8 m/min. These SWNT-TFTs were characterized, and the obtained electrical parameters were related to major mechanical factors such as web tension, registration accuracy, impression roll pressure and printing speed to determine whether these mechanical factors were the sources of the observed device-to-device variations. By utilizing the electrical parameters from the SWNT-TFTs, a Monte Carlo simulation for a 1-bit adder circuit, as a reference, was conducted to demonstrate that functional circuits with reasonable complexity can indeed be manufactured using R2R gravure printing. The simulation results suggest that circuits with complexity, similar to the full adder circuit, can be printed with a 76% circuit yield if threshold voltage (Vth) variations of less than 30% can be maintained.

  1. Scalability of carbon-nanotube-based thin film transistors for flexible electronic devices manufactured using an all roll-to-roll gravure printing system.

    PubMed

    Koo, Hyunmo; Lee, Wookyu; Choi, Younchang; Sun, Junfeng; Bak, Jina; Noh, Jinsoo; Subramanian, Vivek; Azuma, Yasuo; Majima, Yutaka; Cho, Gyoujin

    2015-01-01

    To demonstrate that roll-to-roll (R2R) gravure printing is a suitable advanced manufacturing method for flexible thin film transistor (TFT)-based electronic circuits, three different nanomaterial-based inks (silver nanoparticles, BaTiO3 nanoparticles and single-walled carbon nanotubes (SWNTs)) were selected and optimized to enable the realization of fully printed SWNT-based TFTs (SWNT-TFTs) on 150-m-long rolls of 0.25-m-wide poly(ethylene terephthalate) (PET). SWNT-TFTs with 5 different channel lengths, namely, 30, 80, 130, 180, and 230 μm, were fabricated using a printing speed of 8 m/min. These SWNT-TFTs were characterized, and the obtained electrical parameters were related to major mechanical factors such as web tension, registration accuracy, impression roll pressure and printing speed to determine whether these mechanical factors were the sources of the observed device-to-device variations. By utilizing the electrical parameters from the SWNT-TFTs, a Monte Carlo simulation for a 1-bit adder circuit, as a reference, was conducted to demonstrate that functional circuits with reasonable complexity can indeed be manufactured using R2R gravure printing. The simulation results suggest that circuits with complexity, similar to the full adder circuit, can be printed with a 76% circuit yield if threshold voltage (Vth) variations of less than 30% can be maintained. PMID:26411839

  2. Highly enhanced gas sensing in single-walled carbon nanotube-based thin-film transistor sensors by ultraviolet light irradiation

    NASA Astrophysics Data System (ADS)

    Chen, Tingting; Wei, Liangming; Zhou, Zhihua; Shi, Diwen; Wang, Jian; Zhao, Jiang; Yu, Yuan; Wang, Ying; Zhang, Yafei

    2012-11-01

    Single-walled carbon nanotube (SWCNT) random networks are easily fabricated on a wafer scale, which provides an attractive path to large-scale SWCNT-based thin-film transistor (TFT) manufacturing. However, the mixture of semiconducting SWCNTs and metallic SWCNTs (m-SWCNTs) in the networks significantly limits the TFT performance due to the m-SWCNTs dominating the charge transport. In this paper, we have achieved a uniform and high-density SWCNT network throughout a complete 3-in. Si/SiO2 wafer using a solution-based assembly method. We further utilized UV radiation to etch m-SWCNTs from the networks, and a remarkable increase in the channel current on/off ratio ( I on/ I off) from 11 to 5.6 × 103 was observed. Furthermore, we used the SWCNT-TFTs as gas sensors to detect methyl methylphosphonate, a stimulant of benchmark threats. It was found that the SWCNT-TFT sensors treated with UV radiation show a much higher sensitivity and faster response to the analytes than those without treatment with UV radiation.

  3. Intrinsically stretchable and transparent thin-film transistors based on printable silver nanowires, carbon nanotubes and an elastomeric dielectric

    PubMed Central

    Liang, Jiajie; Li, Lu; Chen, Dustin; Hajagos, Tibor; Ren, Zhi; Chou, Shu-Yu; Hu, Wei; Pei, Qibing

    2015-01-01

    Thin-film field-effect transistor is a fundamental component behind various mordern electronics. The development of stretchable electronics poses fundamental challenges in developing new electronic materials for stretchable thin-film transistors that are mechanically compliant and solution processable. Here we report the fabrication of transparent thin-film transistors that behave like an elastomer film. The entire fabrication is carried out by solution-based techniques, and the resulting devices exhibit a mobility of ∼30 cm2 V−1 s−1, on/off ratio of 103–104, switching current >100 μA, transconductance >50 μS and relative low operating voltages. The devices can be stretched by up to 50% strain and subjected to 500 cycles of repeated stretching to 20% strain without significant loss in electrical property. The thin-film transistors are also used to drive organic light-emitting diodes. The approach and results represent an important progress toward the development of stretchable active-matrix displays. PMID:26173436

  4. Intrinsically stretchable and transparent thin-film transistors based on printable silver nanowires, carbon nanotubes and an elastomeric dielectric

    NASA Astrophysics Data System (ADS)

    Liang, Jiajie; Li, Lu; Chen, Dustin; Hajagos, Tibor; Ren, Zhi; Chou, Shu-Yu; Hu, Wei; Pei, Qibing

    2015-07-01

    Thin-film field-effect transistor is a fundamental component behind various mordern electronics. The development of stretchable electronics poses fundamental challenges in developing new electronic materials for stretchable thin-film transistors that are mechanically compliant and solution processable. Here we report the fabrication of transparent thin-film transistors that behave like an elastomer film. The entire fabrication is carried out by solution-based techniques, and the resulting devices exhibit a mobility of ~30 cm2 V-1 s-1, on/off ratio of 103-104, switching current >100 μA, transconductance >50 μS and relative low operating voltages. The devices can be stretched by up to 50% strain and subjected to 500 cycles of repeated stretching to 20% strain without significant loss in electrical property. The thin-film transistors are also used to drive organic light-emitting diodes. The approach and results represent an important progress toward the development of stretchable active-matrix displays.

  5. Applications of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ajayan, Pulickel M.; Zhou, Otto Z.

    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.

  6. Investigation of light doping and hetero gate dielectric carbon nanotube tunneling field-effect transistor for improved device and circuit-level performance

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Sun, Yuan; Wang, Huan; Xu, Hongsong; Xu, Min; Jiang, Sitao; Yue, Gongshu

    2016-03-01

    We perform a comparative study (both for device and circuit simulations) of three carbon nanotube tunneling field-effect transistor (CNT-TFET) designs: high-K gate dielectric TFETs (HK-TFETs), hetero gate dielectric TFETs (HTFETs) and a novel CNT-TFET-based combination of light doping and hetero gate dielectric TFETs (LD-HTFETs). At device level, the effects of channel and gate dielectric engineering on the switching and high-frequency characteristics for CNT-TFET have been theoretically investigated using a quantum kinetic model. This model is based on two-dimensional non-equilibrium Green’s functions solved self-consistently with Poisson’s equations. It is revealed that the proposed LD-HTFET structure can significantly reduce leakage current, enhance control ability of the gate on the channel, improve the switching speed, and is more suitable for use in low-power, high-frequency circuits. At circuit level, using HSPICE with look-up table-based Verilog-A models, the performance and reliability of CNT-TFET logic gate circuits is evaluated on the basis of power consumption, average delay, stability, energy consumption and power-delay product (PDP). Simulation results indicate that, compared to a traditional CNT-TFET-based circuit, the one based on LD-HTFET has a significantly better performance (static noise margin, energy, delay, PDP). It is also observed that our proposed design exhibits better robustness under different operational conditions by considering power supply voltage and temperature variations. Our results may be useful for designing and optimizing CNTFET devices and circuits.

  7. Conducting carbonized polyaniline nanotubes

    NASA Astrophysics Data System (ADS)

    Mentus, Slavko; Ćirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 °C min-1 up to a maximum temperature of 800 °C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 µm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 µm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm-1, increased to 0.7 S cm-1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  8. Conducting carbonized polyaniline nanotubes.

    PubMed

    Mentus, Slavko; Cirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 degrees C min(-1) up to a maximum temperature of 800 degrees C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 microm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 microm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm(-1), increased to 0.7 S cm(-1) upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy. PMID:19471087

  9. Carbon nanomaterials: controlled growth and field-effect transistor biosensors

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Na; Hu, Ping-An

    2012-03-01

    Carbon nanostructures, including carbon nanotubes (CNTs) and graphene, have been studied extensively due to their special structures, excellent electrical properties and high chemical stability. With the development of nanotechnology and nanoscience, various methods have been developed to synthesize CNTs/graphene and to assemble them into microelectronic/sensor devices. In this review, we mainly demonstrate the latest progress in synthesis of CNTs and graphene and their applications in field-effect transistors (FETs) for biological sensors.

  10. Transport in Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, S.; Xue, Yong-Qinag; Anantram, M. P.; Saini, Subhash (Technical Monitor)

    1999-01-01

    This presentation discusses coupling between carbon nanotubes (CNT), simple metals (FEG) and a graphene sheet. The graphene sheet did not couple well with FEG, but the combination of a graphene strip and CNT did couple well with most simple metals.

  11. Carbon nanotubes: Fibrillar pharmacology

    NASA Astrophysics Data System (ADS)

    Kostarelos, Kostas

    2010-10-01

    The mechanisms by which chemically functionalized carbon nanotubes flow in blood and are excreted through the kidneys illustrate the unconventional behaviour of these fibrillar nanostructures, and the opportunities they offer as components for the design of advanced delivery vehicles.

  12. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Webber, Stephen E.

    2003-01-01

    These project will explore the functionalization of carbon nanotubes via the formation of molecular complexes with perylene diimide based systems. It is anticipated that these complexes would be soluble in organic solvent and enable the homogenous dispersion of carbon nanotubes in polymer films. Molecular complexes will be prepared and characterized using standard spectroscopic and thermal analytical techniques. Polymer films will be prepared with these complexes and their properties (electrical and thermal conductivity, mechanical properties, stability) evaluated.

  13. Nanotube composite carbon fibers

    NASA Astrophysics Data System (ADS)

    Andrews, R.; Jacques, D.; Rao, A. M.; Rantell, T.; Derbyshire, F.; Chen, Y.; Chen, J.; Haddon, R. C.

    1999-08-01

    Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ˜90%, ˜150%, and 340% respectively, as compared to the corresponding values in unmodified isotropic pitch fibers. These results serve to highlight the potential that exits for developing a spectrum of material properties through the selection of the matrix, nanotube dispersion, alignment, and interfacial bonding.

  14. Carbon Nanotube Solar Cells

    PubMed Central

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement. PMID:22655070

  15. Automated circuit fabrication and direct characterization of carbon nanotube vibrations.

    PubMed

    Zeevi, G; Shlafman, M; Tabachnik, T; Rogachevsky, Z; Rechnitz, S; Goldshtein, I; Shlafman, S; Gordon, N; Alchanati, G; Itzhak, M; Moshe, Y; Hajaj, E M; Nir, H; Milyutin, Y; Izraeli, T Y; Razin, A; Shtempluck, O; Kotchtakov, V; Yaish, Y E

    2016-01-01

    Since their discovery, carbon nanotubes have fascinated many researchers due to their unprecedented properties. However, a major drawback in utilizing carbon nanotubes for practical applications is the difficulty in positioning or growing them at specific locations. Here we present a simple, rapid, non-invasive and scalable technique that enables optical imaging of carbon nanotubes. The carbon nanotube scaffold serves as a seed for nucleation and growth of small size, optically visible nanocrystals. After imaging the molecules can be removed completely, leaving the surface intact, and thus the carbon nanotube electrical and mechanical properties are preserved. The successful and robust optical imaging allowed us to develop a dedicated image processing algorithm through which we are able to demonstrate a fully automated circuit design resulting in field effect transistors and inverters. Moreover, we demonstrate that this imaging method allows not only to locate carbon nanotubes but also, as in the case of suspended ones, to study their dynamic mechanical motion. PMID:27396506

  16. Automated circuit fabrication and direct characterization of carbon nanotube vibrations

    NASA Astrophysics Data System (ADS)

    Zeevi, G.; Shlafman, M.; Tabachnik, T.; Rogachevsky, Z.; Rechnitz, S.; Goldshtein, I.; Shlafman, S.; Gordon, N.; Alchanati, G.; Itzhak, M.; Moshe, Y.; Hajaj, E. M.; Nir, H.; Milyutin, Y.; Izraeli, T. Y.; Razin, A.; Shtempluck, O.; Kotchtakov, V.; Yaish, Y. E.

    2016-07-01

    Since their discovery, carbon nanotubes have fascinated many researchers due to their unprecedented properties. However, a major drawback in utilizing carbon nanotubes for practical applications is the difficulty in positioning or growing them at specific locations. Here we present a simple, rapid, non-invasive and scalable technique that enables optical imaging of carbon nanotubes. The carbon nanotube scaffold serves as a seed for nucleation and growth of small size, optically visible nanocrystals. After imaging the molecules can be removed completely, leaving the surface intact, and thus the carbon nanotube electrical and mechanical properties are preserved. The successful and robust optical imaging allowed us to develop a dedicated image processing algorithm through which we are able to demonstrate a fully automated circuit design resulting in field effect transistors and inverters. Moreover, we demonstrate that this imaging method allows not only to locate carbon nanotubes but also, as in the case of suspended ones, to study their dynamic mechanical motion.

  17. Ambipolar transistors based on random networks of WS2 nanotubes

    NASA Astrophysics Data System (ADS)

    Sugahara, Mitsunari; Kawai, Hideki; Yomogida, Yohei; Maniwa, Yutaka; Okada, Susumu; Yanagi, Kazuhiro

    2016-07-01

    WS2 nanotubes are rolled multiwalled nanotubes made of a layered material, tungsten disulfide. Their fibril structures enable the fabrication of random network films; however, these films are nonconducting, and thus have not been used for electronic applications. Here, we demonstrate that carrier injection into WS2 networks using an electrolyte gating approach could cause these networks to act as semiconducting channels. We clarify the Raman characteristics of WS2 nanotubes under electrolyte gating and confirm the feasibility of the injection of electrons and holes. We reveal ambipolar behaviors of the WS2 nanotube networks in field-effect transistor setups with electrolyte gating.

  18. Carbon Nanotube Flexible and Stretchable Electronics

    NASA Astrophysics Data System (ADS)

    Cai, Le; Wang, Chuan

    2015-08-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail.

  19. Carbon Nanotube Flexible and Stretchable Electronics.

    PubMed

    Cai, Le; Wang, Chuan

    2015-12-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail. PMID:26264684

  20. Fabrication and Characterization of Suspended Carbon Nanotube Devices in Liquid

    SciTech Connect

    Artyukhin, A; Stadermann, M; Stroeve, P; Bakajin, O; Noy, A

    2006-10-30

    Suspended carbon nanotube devices are a promising platform for future bio-electronic applications. Suspended carbon nanotube transistors have been previously fabricated in air; however all previous attempts to bring them into liquid failed. We analyze forces acting on the suspended nanotube devices during immersion into liquids and during device operation and show that surface tension forces acting on the suspended nanotubes during transfer into the liquid phase are responsible for the nanotube damage. We have developed a new strategy that circumvents these limitations by coating suspended nanotubes with a rigid inorganic shell in the gas phase. The coating reinforces the nanotubes and allows them to survive transfer through the interface. Subsequent removal of the coating in the solution phase restores pristine suspended nanotubes. We demonstrate that devices fabricated using this technique preserve their original electrical characteristics.

  1. Templated Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  2. Carbon nanotube array based sensor

    DOEpatents

    Lee, Christopher L.; Noy, Aleksandr; Swierkowski, Stephan P.; Fisher, Karl A.; Woods, Bruce W.

    2005-09-20

    A sensor system comprising a first electrode with an array of carbon nanotubes and a second electrode. The first electrode with an array of carbon nanotubes and the second electrode are positioned to produce an air gap between the first electrode with an array of carbon nanotubes and the second electrode. A measuring device is provided for sensing changes in electrical capacitance between the first electrode with an array of carbon nanotubes and the second electrode.

  3. Electrical properties and applications of carbon nanotube structures.

    PubMed

    Bandaru, Prabhakar R

    2007-01-01

    The experimentally verified electrical properties of carbon nanotube structures and manifestations in related phenomena such as thermoelectricity, superconductivity, electroluminescence, and photoconductivity are reviewed. The possibility of using naturally formed complex nanotube morphologies, such as Y-junctions, for new device architectures are then considered. Technological applications of the electrical properties of nanotube derived structures in transistor applications, high frequency nanoelectronics, field emission, and biological sensing are then outlined. The review concludes with an outlook on the technological potential of nanotubes and the need for new device architectures for nanotube systems integration. PMID:17450889

  4. Carbon Nanotubes for Supercapacitor

    PubMed Central

    2010-01-01

    As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs) and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage. PMID:20672061

  5. Carbon nanotube based pressure sensor for flexible electronics

    SciTech Connect

    So, Hye-Mi; Sim, Jin Woo; Kwon, Jinhyeong; Yun, Jongju; Baik, Seunghyun; Chang, Won Seok

    2013-12-15

    Highlights: • The electromechanical change of vertically aligned carbon nanotubes. • Fabrication of CNT field-effect transistor on flexible substrate. • CNT based FET integrated active pressure sensor. • The integrated device yields an increase in the source-drain current under pressure. - Abstract: A pressure sensor was developed based on an arrangement of vertically aligned carbon nanotubes (VACNTs) supported by a polydimethylsiloxane (PDMS) matrix. The VACNTs embedded in the PDMS matrix were structurally flexible and provided repeated sensing operation due to the high elasticities of both the polymer and the carbon nanotubes (CNTs). The conductance increased in the presence of a loading pressure, which compressed the material and induced contact between neighboring CNTs, thereby producing a dense current path and better CNT/metal contacts. To achieve flexible functional electronics, VACNTs based pressure sensor was integrated with field-effect transistor, which is fabricated using sprayed semiconducting carbon nanotubes on plastic substrate.

  6. Different Technical Applications of Carbon Nanotubes.

    PubMed

    Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

    2015-12-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact. PMID:26377211

  7. Different Technical Applications of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Abdalla, S.; Al-Marzouki, F.; Al-Ghamdi, Ahmed A.; Abdel-Daiem, A.

    2015-09-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  8. Copper-philic carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Belgamwar, Sachin U.; Sharma, Niti Nipun

    2016-04-01

    Carbon nanotube is having poor wet-ability with copper metal. Wet-ability of carbon nanotube was improved by exposing and creating more active sites on the surface of carbon nanotube. Carbon nanotubes were subjected to the prolong ultrasonication treatment of 20×103 Hz and 500W, which helped in disentanglement of carbon nanotube agglomerates and in breaking the weak bonds like pentagonal or heptagonal structure on the surface and on the CNT cap. Disentanglement of the carbon nanotube, resulted in exposing the defective sites on the surface and breaking of weak bonds, which assisted in creating the new defects on the surface. This process results in generates more active sites on the surface and it helps in improving the wet-ability of the carbon nanotube in copper.

  9. A carbon nanotube immunosensor for Salmonella

    NASA Astrophysics Data System (ADS)

    Lerner, Mitchell B.; Goldsmith, Brett R.; McMillon, Ronald; Dailey, Jennifer; Pillai, Shreekumar; Singh, Shree R.; Johnson, A. T. Charlie

    2011-12-01

    Antibody-functionalized carbon nanotube devices have been suggested for use as bacterial detectors for monitoring of food purity in transit from the farm to the kitchen. Here we report progress towards that goal by demonstrating specific detection of Salmonella in complex nutrient broth solutions using nanotube transistors functionalized with covalently-bound anti-Salmonella antibodies. The small size of the active device region makes them compatible with integration in large-scale arrays. We find that the on-state current of the transistor is sensitive specifically to the Salmonella concentration and saturates at low concentration (<1000 cfu/ml). In contrast, the carrier mobility is affected comparably by Salmonella and other bacteria types, with no sign of saturation even at much larger concentrations (108 cfu/ml).

  10. Transport Through Carbon Nanotube Wires

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

  11. The Toxicology of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Donaldson, Ken; Poland, Craig; Duffin, Rodger; Bonner, James

    2012-06-01

    1. Carbon nanotube structure, synthesis and applications C. Singh and W. Song; 2. The aerodynamic behaviour and pulmonary deposition of carbon nanotubes A. Buckley, R. Smith and R Maynard; 3. Utilising the concept of the biologically effective dose to define the particle and fibre hazards of carbon nanotubes K. Donaldson, R. Duffin, F. Murphy and C. Poland; 4. CNT, biopersistence and the fibre paradigm D. Warheit and M. DeLorme; 5. Length-dependent retention of fibres in the pleural space C. Poland, F. Murphy and K. Donaldson; 6. Experimental carcinogenicity of carbon nanotubes in the context of other fibres K. Unfried; 7. Fate and effects of carbon nanotubes following inhalation J. Ryman-Rasmussen, M. Andersen and J. Bonner; 8. Responses to pulmonary exposure to carbon nanotubes V. Castranova and R. Mercer; 9. Genotoxicity of carbon nanotubes R. Schins, C. Albrecht, K. Gerloff and D. van Berlo; 10. Carbon nanotube-cellular interactions; macrophages, epithelial and mesothelial cells V. Stone, M. Boyles, A. Kermanizadeh, J. Varet and H. Johnston; 11. Systemic health effects of carbon nanotubes following inhalation J. McDonald; 12. Dosimetry and metrology of carbon nanotubes L. Tran, L. MacCalman and R. Aitken; Index.

  12. Carbon Nanotube Purification and Functionalization

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Mintz, Eric; Smalley, Richard E.; Meador, Michael A.

    2003-01-01

    Carbon nanotubes have the potential to significantly enhance the mechanical, thermal, and electrical properties of polymers. However, dispersion of carbon nanotubes in a polymer matrix is hindered by the electrostatic forces that cause them to agglomerate. Chemical modification of the nanotubes is necessary to minimize these electrostatic forces and promote adhesion between the nanotubes and the polymer matrix. In a collaborative research program between Clark Atlanta University, Rice University, and NASA Glenn Research Center several approaches are being explored to chemically modify carbon nanotubes. The results of this research will be presented.

  13. Superhydrophobic amorphous carbon/carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Han, Z. J.; Tay, B. K.; Shakerzadeh, M.; Ostrikov, K.

    2009-06-01

    Superhydrophobic amorphous carbon/carbon nanotube nanocomposites are fabricated by plasma immersion ion implantation with carbon nanotube forests as a template. The microstructure of the fabricated nanocomposites shows arrays of carbon nanotubes capped with amorphous carbon nanoparticles. Contact angle measurements show that both advancing and receding angles close to 180° can be achieved on the nanocomposites. The fabrication here does not require patterning of carbon nanotubes or deposition of conformal coatings with low surface energy, which are usually involved in conventional approaches for superhydrophobic surfaces. The relationship between the observed superhydrophobicity and the unique microstructure of the nanocomposites is discussed.

  14. Spin-based optomechanics with carbon nanotubes.

    PubMed

    Li, Jin-Jin; Zhu, Ka-Di

    2012-01-01

    A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing. PMID:23198093

  15. Spin-based Optomechanics with Carbon Nanotubes

    PubMed Central

    Li, Jin-Jin; Zhu, Ka-Di

    2012-01-01

    A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing. PMID:23198093

  16. Multiscale simulation of carbon nanotube devices

    NASA Astrophysics Data System (ADS)

    Adessi, C.; Avriller, R.; Blase, X.; Bournel, A.; Cazin d'Honincthun, H.; Dollfus, P.; Frégonèse, S.; Galdin-Retailleau, S.; López-Bezanilla, A.; Maneux, C.; Nha Nguyen, H.; Querlioz, D.; Roche, S.; Triozon, F.; Zimmer, T.

    2009-05-01

    In recent years, the understanding and accurate simulation of carbon nanotube-based devices has become very challenging. Conventional simulation tools of microelectronics are necessary to envision the performance and use of nanotube transistors and circuits, but the models need to be refined to properly describe the full complexity of such novel type of devices at the nanoscale. Indeed, many issues such as contact resistance, low dimensional electrostatics and screening effects, as well as nanotube doping or functionalization, demand for more accurate quantum approaches. In this article, we review our recent progress on multiscale simulations which aim at bridging first principles calculations with compact modelling, including the comparison between semi-classical Monte Carlo and quantum transport approaches. To cite this article: C. Adessi et al., C. R. Physique 10 (2009).

  17. Carbon nanotubes on a substrate

    DOEpatents

    Gao, Yufei [Kennewick, WA; Liu, Jun [West Richland, WA

    2002-03-26

    The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

  18. Method of manufacturing carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Benavides, Jeanette M. (Inventor); Leidecker, Henning W. (Inventor); Frazier, Jeffrey (Inventor)

    2004-01-01

    A process for manufacturing carbon nanotubes, including a step of inducing electrical current through a carbon anode and a carbon cathode under conditions effective to produce the carbon nanotubes, wherein the carbon cathode is larger than the carbon anode. Preferably, a welder is used to induce the electrical current via an arc welding process. Preferably, an exhaust hood is placed on the anode, and the process does not require a closed or pressurized chamber. The process provides high-quality, single-walled carbon nanotubes, while eliminating the need for a metal catalyst.

  19. Carbon nanotube network varactor.

    PubMed

    Generalov, A A; Anoshkin, I V; Erdmanis, M; Lioubtchenko, D V; Ovchinnikov, V; Nasibulin, A G; Räisänen, A V

    2015-01-30

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. PMID:25556375

  20. Carbon nanotube network varactor

    NASA Astrophysics Data System (ADS)

    Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

  1. Carbon nanotube IR detectors (SV)

    SciTech Connect

    Leonard, F. L.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

  2. Flexible high-performance carbon nanotube integrated circuits.

    PubMed

    Sun, Dong-ming; Timmermans, Marina Y; Tian, Ying; Nasibulin, Albert G; Kauppinen, Esko I; Kishimoto, Shigeru; Mizutani, Takashi; Ohno, Yutaka

    2011-03-01

    Carbon nanotube thin-film transistors are expected to enable the fabrication of high-performance, flexible and transparent devices using relatively simple techniques. However, as-grown nanotube networks usually contain both metallic and semiconducting nanotubes, which leads to a trade-off between charge-carrier mobility (which increases with greater metallic tube content) and on/off ratio (which decreases). Many approaches to separating metallic nanotubes from semiconducting nanotubes have been investigated, but most lead to contamination and shortening of the nanotubes, thus reducing performance. Here, we report the fabrication of high-performance thin-film transistors and integrated circuits on flexible and transparent substrates using floating-catalyst chemical vapour deposition followed by a simple gas-phase filtration and transfer process. The resulting nanotube network has a well-controlled density and a unique morphology, consisting of long (~10 µm) nanotubes connected by low-resistance Y-shaped junctions. The transistors simultaneously demonstrate a mobility of 35 cm(2) V(-1) s(-1) and an on/off ratio of 6 × 10(6). We also demonstrate flexible integrated circuits, including a 21-stage ring oscillator and master-slave delay flip-flops that are capable of sequential logic. Our fabrication procedure should prove to be scalable, for example, by using high-throughput printing techniques. PMID:21297625

  3. Gate-voltage induced trions in suspended carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; Popert, A.; Kato, Y. K.

    2016-01-01

    We observe trion emission from suspended carbon nanotubes where carriers are introduced electrostatically using field-effect transistor structures. The trion peak emerges below the E11 emission energy at gate voltages that coincide with the onset of bright exciton quenching. By investigating nanotubes with various chiralities, we verify that the energy separation between the bright exciton peak and the trion peak becomes smaller for larger diameter tubes. Trion binding energies that are significantly larger compared to surfactant-wrapped carbon nanotubes are obtained, and the difference is attributed to the reduced dielectric screening in suspended tubes.

  4. Carbon Nanotubes Based Quantum Devices

    NASA Technical Reports Server (NTRS)

    Lu, Jian-Ping

    1999-01-01

    This document represents the final report for the NASA cooperative agreement which studied the application of carbon nanotubes. The accomplishments are reviewed: (1) Wrote a review article on carbon nanotubes and its potentials for applications in nanoscale quantum devices. (2) Extensive studies on the effects of structure deformation on nanotube electronic structure and energy band gaps. (3) Calculated the vibrational spectrum of nanotube rope and the effect of pressure. and (4) Investigate the properties of Li intercalated nanotube ropes and explore their potential for energy storage materials and battery applications. These studies have lead to four publications and seven abstracts in international conferences.

  5. Carbon nanotube core graphitic shell hybrid fibers.

    PubMed

    Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

    2013-12-23

    A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

  6. Thermoelectric power in carbon nanotubes

    SciTech Connect

    Mavrinskiy, A. V. Baitinger, E. M.

    2009-04-15

    The theoretical results for the temperature dependence of the thermoelectric power of graphite and semimetal carbon nanotubes are reported. In the calculations, the cylindrical superatomic range structure of nanotubes is taken into account. The Boltzmann equation and the {pi}-electron model of semimetal carbon nanotubes are used. The basic parameters of the calculation are the concentration of electrons, the Fermi energy, and the energy of the local level associated with the cylindrical structure of carbon nanotubes. The theoretical results are compared with the available experimental data.

  7. Synthesis, assembly, and applications of single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Ryu, Koungmin

    This dissertation presents the synthesis and assembly of aligned carbon nanotubes, and their applications in both nano-electronics such as transistor and integrated circuits and macro-electronics in energy conversion devices as transparent conducting electrodes. Also, the high performance chemical sensor using metal oxide nanowire has been demonstrated. Chapter 1 presents a brief introduction of carbon nanotube, followed by discussion of a new synthesis technique using nanosphere lithography to grow highly aligned single-walled carbon nanotubes atop quartz and sapphire substrates. This method offers great potential to produce carbon nanotube arrays with simultaneous control over the nanotube orientation, position, density, diameter and even chirality. Chapter 3 introduces the wafer-scale integration and assembly of aligned carbon nanotubes, including full-wafer scale synthesis and transfer of massively aligned carbon nanotube arrays, and nanotube device fabrication on 4 inch Si/SiO2 wafer to yield submicron channel transistors with high on-current density ˜ 20 muA/mum and good on/off ratio and CMOS integrated circuits. In addition, various chemical doping methods for n-type nanotube transistors are studied to fabricate CMOS integrated nanotube circuits such as inverter, NAND and NOR logic devices. Furthermore, defect-tolerant circuit design for NAND and NOR is proposed and demonstrated to guarantee the correct operation of logic circuit, regardless of the presence of mis-aligned or mis-positioned nanotubes. Carbon nanotube flexible electronics and smart textiles for ubiquitous computing and sensing are demonstrated in chapter 4. A facile transfer printing technique has been introduced to transfer massively aligned single-walled carbon nanotubes from the original sapphire/quartz substrates to virtually any other substrates, including glass, silicon, polymer sheets, and even fabrics. The characterization of transferred nanotubes reveals that the transferred

  8. CARBON NANOTUBES AS MULTIPOLLUTANT SORBENTS

    EPA Science Inventory

    Exploratory Research Program Project - Carbon nanotubes (CNTs) are formed from graphite (or graphene) sheets rolled into tubes, typically with diameters of 1 - 10 nm and lengths of 200 - 500 nm. Carbon nanotubes have unique electrical properties that have led to interest in thei...

  9. Conduction in Carbon Nanotube Networks

    NASA Astrophysics Data System (ADS)

    Kaiser, A. B.; Rogers, S. A.

    2003-10-01

    Recent measurements of the resistivity of single-wall carbon nanotube (SWNT) networks are consistent with our model of metallic conduction interrupted by barriers. We extend our model of thermopower nonlinearities due to peaks in the density of electronic states and apply it to recent thermopower data for carbon nanotube networks.

  10. Studies of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  11. Teslaphoresis of Carbon Nanotubes.

    PubMed

    Bornhoeft, Lindsey R; Castillo, Aida C; Smalley, Preston R; Kittrell, Carter; James, Dustin K; Brinson, Bruce E; Rybolt, Thomas R; Johnson, Bruce R; Cherukuri, Tonya K; Cherukuri, Paul

    2016-04-26

    This paper introduces Teslaphoresis, the directed motion and self-assembly of matter by a Tesla coil, and studies this electrokinetic phenomenon using single-walled carbon nanotubes (CNTs). Conventional directed self-assembly of matter using electric fields has been restricted to small scale structures, but with Teslaphoresis, we exceed this limitation by using the Tesla coil's antenna to create a gradient high-voltage force field that projects into free space. CNTs placed within the Teslaphoretic (TEP) field polarize and self-assemble into wires that span from the nanoscale to the macroscale, the longest thus far being 15 cm. We show that the TEP field not only directs the self-assembly of long nanotube wires at remote distances (>30 cm) but can also wirelessly power nanotube-based LED circuits. Furthermore, individualized CNTs self-organize to form long parallel arrays with high fidelity alignment to the TEP field. Thus, Teslaphoresis is effective for directed self-assembly from the bottom-up to the macroscale. PMID:27074626

  12. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2007-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2, or F2, or CnHm) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

  13. Functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2007-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H.sub.2 or F.sub.2 or C.sub.nH.sub.m) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

  14. Carbon Nanotube Interconnect

    NASA Technical Reports Server (NTRS)

    Li, Jun (Inventor); Meyyappan, Meyya (Inventor)

    2006-01-01

    Method and system for fabricating an electrical interconnect capable of supporting very high current densities ( 10(exp 6)-10(exp 10) Amps/sq cm), using an array of one or more carbon nanotubes (CNTs). The CNT array is grown in a selected spaced apart pattern, preferably with multi-wall CNTs, and a selected insulating material, such as SiOw, or SiuNv is deposited using CVD to encapsulate each CNT in the array. An exposed surface of the insulating material is planarized to provide one or more exposed electrical contacts for one or more CNTs.

  15. MoS{sub 2} nanotube field effect transistors

    SciTech Connect

    Strojnik, M. E-mail: dragan.mihailovic@ijs.si; Mrzel, A.; Buh, J.; Strle, J.; Kovic, A.; Mihailovic, D. E-mail: dragan.mihailovic@ijs.si

    2014-09-15

    We report on electric field effects on electron transport in multi-walled MoS{sub 2} nanotubes (NTs), fabricated using a two-step synthesis method from Mo{sub 6}S{sub x}I{sub 9-x} nanowire bundle precursors. Transport properties were measured on 20 single nanotube field effect transistor (FET) devices, and compared with MoS{sub 2} layered crystal devices prepared using identical fabrication techniques. The NTs exhibited mobilities of up to 0.014 cm{sup 2}V{sup −1}s{sup −1} and an on/off ratio of up to 60. As such they are comparable with previously reported WS{sub 2} nanotube FETs, but materials defects and imperfections apparently limit their performance compared with multilayer MoS{sub 2} FETs with similar number of layers.

  16. Carbon Nanotubes for Space Applications

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya

    2000-01-01

    The potential of nanotube technology for NASA missions is significant and is properly recognized by NASA management. Ames has done much pioneering research in the last five years on carbon nanotube growth, characterization, atomic force microscopy, sensor development and computational nanotechnology. NASA Johnson Space Center has focused on laser ablation production of nanotubes and composites development. These in-house efforts, along with strategic collaboration with academia and industry, are geared towards meeting the agency's mission requirements. This viewgraph presentation (including an explanation for each slide) outlines the research focus for Ames nanotechnology, including details on carbon nanotubes' properties, applications, and synthesis.

  17. Gas detection mechanism for single-walled carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Boyd, Anthony; Dube, Isha; Fedorov, Georgy; Paranjape, Makarand; Barbara, Paola; Georgetown/RRC Kurchatov Collaboration

    2011-03-01

    We study field-effect transistors fabricated with carbon nanotube (CNT) networks to determine whether the gas sensing mechanism is due to molecules adsorbed on the nanotubes, or changes at the interface between the nanotubes and the contacts. Our previous work showed that in devices made with isolated CNT, the response to nitrogen dioxide was mainly due to the contact interfaces. Here, we focus on CNT networks and use SU-8 layers patterned with e-beam lithography to passivate the contact interfaces, while leaving the network exposed. We look to investigate possible differences in sensing mechanism for devices made with isolated tubes versus networks. Work funded by NSF, DMR 1008242.

  18. Analysis of long-channel nanotube field-effect-transistors (NT FETs)

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation provides an analysis of long-channel nanotube (NT) field effect transistors (FET) from NASA's Ames Research Center. The structure of such a transistor including the electrode contact, 1D junction, and the planar junction is outlined. Also mentioned are various characteristics of a nanotube tip-equipped scanning tunnel microscope (STM).

  19. Carbon nanotube based photocathodes

    NASA Astrophysics Data System (ADS)

    Hudanski, Ludovic; Minoux, Eric; Gangloff, Laurent; Teo, Kenneth B. K.; Schnell, Jean-Philippe; Xavier, Stephane; Robertson, John; Milne, William I.; Pribat, Didier; Legagneux, Pierre

    2008-03-01

    This paper describes a novel photocathode which is an array of vertically aligned multi-walled carbon nanotubes (MWCNTs), each MWCNT being associated with one p-i-n photodiode. Unlike conventional photocathodes, the functions of photon-electron conversion and subsequent electron emission are physically separated. Photon-electron conversion is achieved with p-i-n photodiodes and the electron emission occurs from the MWCNTs. The current modulation is highly efficient as it uses an optically controlled reconfiguration of the electric field at the MWCNT locations. Such devices are compatible with high frequency and very large bandwidth operation and could lead to their application in compact, light and efficient microwave amplifiers for satellite telecommunication. To demonstrate this new photocathode concept, we have fabricated the first carbon nanotube based photocathode using silicon p-i-n photodiodes and MWCNT bunches. Using a green laser, this photocathode delivers 0.5 mA with an internal quantum efficiency of 10% and an ION/IOFF ratio of 30.

  20. Carbon nanotube array actuators

    NASA Astrophysics Data System (ADS)

    Geier, S.; Mahrholz, T.; Wierach, P.; Sinapius, M.

    2013-09-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750-2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs.

  1. Carbon nanotube biosensors

    PubMed Central

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  2. Carbon Nanotube Biosensors

    NASA Astrophysics Data System (ADS)

    Tilmaciu, Carmen-Mihaela; Morris, May

    2015-10-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  3. Method for synthesizing carbon nanotubes

    DOEpatents

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  4. Bolometric-Effect-Based Wavelength-Selective Photodetectors Using Sorted Single Chirality Carbon Nanotubes

    PubMed Central

    Zhang, Suoming; Cai, Le; Wang, Tongyu; Shi, Rongmei; Miao, Jinshui; Wei, Li; Chen, Yuan; Sepúlveda, Nelson; Wang, Chuan

    2015-01-01

    This paper exploits the chirality-dependent optical properties of single-wall carbon nanotubes for applications in wavelength-selective photodetectors. We demonstrate that thin-film transistors made with networks of carbon nanotubes work effectively as light sensors under laser illumination. Such photoresponse was attributed to photothermal effect instead of photogenerated carriers and the conclusion is further supported by temperature measurements. Additionally, by using different types of carbon nanotubes, including a single chirality (9,8) nanotube, the devices exhibit wavelength-selective response, which coincides well with the absorption spectra of the corresponding carbon nanotubes. This is one of the first reports of controllable and wavelength-selective bolometric photoresponse in macroscale assemblies of chirality-sorted carbon nanotubes. The results presented here provide a viable route for achieving bolometric-effect-based photodetectors with programmable response spanning from visible to near-infrared by using carbon nanotubes with pre-selected chiralities. PMID:26643777

  5. Carbon nanotubes in hyperthermia therapy

    PubMed Central

    Singh, Ravi; Torti, Suzy V.

    2013-01-01

    Thermal tumor ablation therapies are being developed with a variety of nanomaterials, including single-and multiwalled carbon nanotubes. Carbon nanotubes (CNTs) have attracted interest due to their potential for simultaneous imaging and therapy. In this review, we highlight in vivo applications of carbon nanotube-mediated thermal therapy (CNMTT) and examine the rationale for use of this treatment in recurrent tumors or those resistant to conventional cancer therapies. Additionally, we discuss strategies to localize and enhance the cancer selectivity of this treatment and briefly examine issues relating the toxicity and long term fate of CNTs. PMID:23933617

  6. High performance organic transistors: Percolating arrays of nanotubes functionalized with an electron deficient olefin

    NASA Astrophysics Data System (ADS)

    Kanungo, Mandakini; Malliaras, George G.; Blanchet, Graciela B.

    2010-08-01

    Precise control over the electronic properties of carbon nanotubes is key to their application in plastic electronics. In the present work, we have functionalized carbon nanotubes with an electron withdrawing nonfluorinated olefins via a 2-2 cycloaddition reaction. Our results suggest that the formation of cyclobutanelike four-member ring at the functionalization site is a fairly general approach, independent of specifics of the addend, to converting the grown mixture of metal and semiconductor tubes into high mobility semiconducting tubes without tedious separation requirements. Thin film transistors fabricated from such functionalized tubes exhibit mobilities of ˜30 cm2/V s and on/off ratios in excess of 106. This simple functionalization represents a low cost path to high performance semiconducting inks for printable electronics.

  7. Method for producing carbon nanotubes

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Chen, Chun-Ku

    2006-02-14

    Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

  8. Electronic and Ionic Transport in Carbon Nanotubes and Other Nanostructures

    NASA Astrophysics Data System (ADS)

    Cao, Di

    This thesis describes several experiments based on carbon nanotube nanofludic devices and field-effect transistors. The first experiment detected ion and molecule translocation through one single-walled carbon nanotube (SWCNT) that spans a barrier between two fluid reservoirs. The electrical ionic current is measured. Translocation of small single stranded DNA oligomers is marked by large transient increases in current through the tube and confirmed by a PCR (polymerase chain reaction) analysis. Carbon nanotubes simplify the construction of nanopores, permit new types of electrical measurement, and open new avenues for control of DNA translocation. The second experiment constructed devices in which the interior of a single-walled carbon nanotube field-effect transistor (CNT-FET) acts as a nanofluidic channel that connects two fluid reservoirs, permitting measurement of the electronic properties of the SWCNT as it is wetted by an analyte. Wetting of the inside of the SWCNT by water turns the transistor on, while wetting of the outside has little effect. This finding may provide a new method to investigate water behavior at nanoscale. This also opens a new avenue for building sensors in which the SWCNT functions as an electronic detector. This thesis also presents some experiments that related to nanofabrication, such as construction of FET with tin sulfide (SnS) quantum ribbon. This work demonstrates the application of solution processed IV-VI semiconductor nanostructures in nanoscale devices.

  9. Trion electroluminescence from semiconducting carbon nanotubes.

    PubMed

    Jakubka, Florian; Grimm, Stefan B; Zakharko, Yuriy; Gannott, Florentina; Zaumseil, Jana

    2014-08-26

    Near-infrared emission from semiconducting single-walled carbon nanotubes (SWNTs) usually results from radiative relaxation of excitons. By binding an additional electron or hole through chemical or electrochemical doping, charged three-body excitons, so-called trions, are created that emit light at lower energies. The energy difference is large enough to observe weak trion photoluminescence from doped SWNTs even at room temperature. Here, we demonstrate strong trion electroluminescence from electrolyte-gated, light-emitting SWNT transistors with three different polymer-sorted carbon nanotube species, namely, (6,5), (7,5) and (10,5). The red-shifted trion emission is equal to or even stronger than the exciton emission, which is attributed to the high charge carrier density in the transistor channel. The possibility of trions as a radiative relaxation pathway for triplets and dark excitons that are formed in large numbers by electron-hole recombination is discussed. The ratio of trion to exciton emission can be tuned by the applied voltages, enabling voltage-controlled near-infrared light sources with narrow line widths that are solution-processable and operate at low voltages (<3 V). PMID:25029479

  10. Cantilevered carbon nanotube hygrometer

    NASA Astrophysics Data System (ADS)

    Kuroyanagi, Toshinori; Terada, Yuki; Takei, Kuniharu; Akita, Seiji; Arie, Takayuki

    2014-05-01

    We investigate the effects of humidity on the vibrations of carbon nanotubes (CNTs) using two types of CNT cantilevers: open-ended and close-ended CNT cantilevers. As the humidity increases, the resonant frequency of the open-ended CNT cantilever decreases due to the adsorption of water molecules onto the CNT tip, whereas that of the close-ended CNT cantilever increases probably due to the change in the viscosity of the air surrounding the CNT cantilever, which is negatively correlated with the humidity of air. Our findings suggest that a close-ended CNT cantilever is more suitable for a quick-response and ultrasensitive hygrometer because it continuously reads the viscosity change of moist air in the vicinity of the CNT.

  11. On carbon nanotube resonators

    NASA Astrophysics Data System (ADS)

    Caruntu, Dumitru I.; Salinas Trevino, Cone S.

    2011-04-01

    This paper deals with electrostatically actuated Carbon NanoTubes (CNT) cantilevers for sensor applications. There are three kinds of forces acting on the CNT cantilever: electrostatic, elastostatic, and van der Waals. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forces, electrostatic and van der Waals, are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT dynamics is nonlinear parametric. The method of multiple scales is used to investigate the system under soft excitations and/or weakly nonlinearities. The frequency-amplitude and frequency-phase behavior are found in the case of primary resonance.

  12. Carbon nanotube biconvex microcavities

    SciTech Connect

    Butt, Haider Ahmed, Rajib; Yetisen, Ali K.; Yun, Seok Hyun; Dai, Qing

    2015-03-23

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  13. Carbon nanotube optical mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Rabin, Douglas

    2015-01-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes (CNT) embedded in an epoxy matrix. CNT/epoxy is a multifunctional composite material that has sensing capabilities and can be made to incorporate self-actuation. Moreover, as the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and three-dimensional printing. Therefore, the technology holds promise for the development of a new generation of lightweight, compact "smart" telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics, active optics experiments, and numerical modeling. We discuss possible paths for future development.

  14. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  15. Carbon Nanotube Electron Gun

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  16. Carbon nanotube electron gun

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2010-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  17. Carbon Nanotubes as Thermionic Emitters

    NASA Astrophysics Data System (ADS)

    Loutfy, R. O.; Samandi, M.; Moravsky, A.; Strange, S.

    2004-02-01

    Thermionic converters are an interesting option for lightweight and long-life power generators due to a number of compelling advantages, including all solid construction, no moving parts, and waste heat rejection at high temperature. An experimental set up has been built that allows the screening of thermionic coatings and new nanomaterials from room temperature to 2000 K in high vacuum and at gap sizes as small as 1 μm. A new class of very high temperature compatible materials, carbon nanotubes, has been investigated for their performance as cathodes. Seven different types of carbon nanotubes have been screened as thermionic emitter cathodes and compared to tungsten and nitrogen doped diamond. It has been found that some carbon nanotubes combine excellent temperature stability with good thermal emission performance. Yet, other carbon nanotubes exhibited exceptional combined thermal and field enhanced emission performance.

  18. Carbon Nanotube-Nanocrystal Heterostructures

    SciTech Connect

    Peng, X.; Wong, S.

    2009-04-01

    The importance of generating carbon nanotube-nanoparticle heterostructures is that these composites ought to take advantage of and combine the unique physical and chemical properties of both carbon nanotubes and nanoparticles in one discrete structure. These materials have potential applicability in a range of diverse fields spanning heterogeneous catalysis to optoelectronic device development, of importance to chemists, physicists, materials scientists, and engineers. In this critical review, we present a host of diverse, complementary strategies for the reliable synthesis of carbon nanotube-nanoparticle heterostructures using both covalent as well as non-covalent protocols, incorporating not only single-walled and multi-walled carbon nanotubes but also diverse classes of metallic and semiconducting nanoparticles.

  19. Selective functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  20. PECVD Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    McAninch, Ian; Arnold, James O. (Technical Monitor)

    2001-01-01

    Plasma enhanced chemical vapor deposition (PECVD), using inductively coupled plasma, has been used to grow carbon nanotubes (CNTs) and graphitic carbon fibers (GCF) on substrates sputtered with aluminum and iron catalyst. The capacitive plasma's power has been shown to cause a transition from nanotubes to nanofibers, depending on the strength of the plasma. The temperature, placement, and other factors have been shown to affect the height and density of the tube and fiber growth.

  1. Nanotechnology with Carbon Nanotubes: Mechanics, Chemistry, and Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak

    2003-01-01

    This viewgraph presentation reviews the Nanotechnology of carbon nanotubes. The contents include: 1) Nanomechanics examples; 2) Experimental validation of nanotubes in composites; 3) Anisotropic plastic collapse; 4) Spatio-temporal scales, yielding single-wall nanotubes; 5) Side-wall functionalization of nanotubes; 6) multi-wall Y junction carbon nanotubes; 7) Molecular electronics with Nanotube junctions; 8) Single-wall carbon nanotube junctions; welding; 9) biomimetic dendritic neurons: Carbon nanotube, nanotube electronics (basics), and nanotube junctions for Devices,

  2. Connecting carbon nanotubes using Sn.

    PubMed

    Mittal, Jagjiwan; Lin, Kwang Lung

    2013-08-01

    Process of Sn coating on mutiwalled carbon nanotubes (MWCNT) and formation of interconnections among nanotubes are studied using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX). Surface oxidation of nanotubes during heating with HNO3 prior to the SnCl2 treatment and the bonding between functional groups and Sn are found to be responsible for the coating and its stability. Open nanotubes are filled as well as coated during tin chloride treatment. Coating and filling are converted into the coatings on the inner as well as outer walls of the nanotubes during reduction with H2/N2. EDX studies show the formation of intermetallic compounds e.g., Cu6Sn5 and Cu3Sn at the joints between nanotubes. Formation of intermetallic compounds is supposed to be responsible for providing the required strength for bending and twisting of nanotubes joining of nanotubes. Paper presents a detailed mechanism of coating and filling processes, and interconnections among nanotubes. PMID:23882800

  3. Electrical and optical characterization of carbon nanotube diodes

    NASA Astrophysics Data System (ADS)

    Malapanis, Argyrios

    Carbon nanotubes are good candidates for future applications, including nanoelectronic and nanophotonic devices. Their quasi-one dimensional (1D) character offers appealing device properties. These include reduced carrier scattering, carrier mobility up to two orders of magnitude higher than that of materials used in state-of-the-art computer chips today, current densities rivaling those of the best semiconductors, enhanced optical absorption, and band gaps tunable with tube diameter and doping. Recent breakthroughs in research point to the possibility of placing nanotubes precisely on substrates with densities approaching that of transistors on today's computer chips in a way that's integratable with existing Si-based technology. Such advances may accelerate the day when high-speed and power-efficient applications using carbon nanotubes as the transistor channel can become a reality. Thus the need to explore the fundamental properties of carbon nanotubes becomes more pressing. Using single-walled carbon nanotube (SWNT) p-n diodes as the medium, the purpose of this work is to examine SWNT fundamental properties that little experimental work has dealt with measuring. These properties include the band-gap of a SWNT, band-gap renormalization (shrinkage) as a function of doping, and optical absorption in the infrared region of the spectrum. This dissertation also shows the extreme sensitivity of carbon nanotubes to their environment (i.e. exposure to air). In addition, it demonstrates a new technique---current annealing---that can reverse the degradation of the electrical and optical properties of carbon nanotube diodes due to ambient exposure

  4. Carbon Nanotube Purification

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Delzeit, Clement J. (Inventor)

    2005-01-01

    A method for cleaning or otherwise removing amorphous carbon and other residues that arise in growth of a carbon nanotube (CNT) array. The CNT array is exposed to a plurality of hydroxyls or hydrogen, produced from a selected vapor or liquid source such as H2O or H2O2. and the hydroxyls or hydrogen (neutral or electrically charged) react with the residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. The hydroxyls or hydrogen can be produced by heating the CNT array, residue and selected vapor or liquid source or by application of an electromagnetic excitation signal with a selected frequency or range of frequencies to dissociate the selected vapor or liquid. The excitation frequency can be chirped to cover a selected range of frequencies corresponding to dissociation of the selected vapor or liquid. Sonication may be uscd to supplement dissociation of the H2O and/or H2O2.

  5. Carbon Nanotubes for Polymer Photovoltaics

    NASA Astrophysics Data System (ADS)

    Anctil, Annick; Dileo, Roberta; Schauerman, Chris; Landi, Brian; Raffaelle, Ryne

    2007-03-01

    Carbon nanotubes are being investigated for optical absorption, exciton dissociation, and carrier transport in polymer photovoltaic devices. In the present work, single wall carbon nanotubes (SWNTs) were synthesized by an Alexandrite pulsed laser vaporization reactor at standard conditions and purified based upon our previously reported TOP procedure. The SWNTs were dispersed in polymer composites for pure MEH-PPV, pure P3HT, and [C60]-PCBM-P3HT (1:1 by weight) as a function of nanotube weight loading (0.1 -- 5% w/w). The AM0 current-voltage measurements for structures sandwiched between PEDOT/PSS coated ITO substrates and an evaporated aluminum contact demonstrate the dramatic effect of SWNT content on the short circuit current density, with conversions efficiencies consistently greater than 1%. The temperature coefficient for nanotube-containing polymer photovoltaics has been compared to conventional PCBM-P3HT devices, and the general relationship of increasing efficiency with increasing temperature is observed. However, the necessity to control nanotube percolation to prevent device shunting has led to recent developments which focus on controlling nanotube length through oxidative cutting, the deposition of intrinsic polymer layers, and the use of aligned carbon nanotube arrays for preferential charge transport.

  6. Group IV nanotube transistors for next generation ubiquitous computing

    NASA Astrophysics Data System (ADS)

    Fahad, Hossain M.; Hussain, Aftab M.; Sevilla Torres, Galo A.; Banerjee, Sanjay K.; Hussain, Muhammad M.

    2014-06-01

    Evolution in transistor technology from increasingly large power consuming single gate planar devices to energy efficient multiple gate non-planar ultra-narrow (< 20 nm) fins has enhanced the scaling trend to facilitate doubling performance. However, this performance gain happens at the expense of arraying multiple devices (fins) per operation bit, due to their ultra-narrow dimensions (width) originated limited number of charges to induce appreciable amount of drive current. Additionally arraying degrades device off-state leakage and increases short channel characteristics, resulting in reduced chip level energy-efficiency. In this paper, a novel nanotube device (NTFET) topology based on conventional group IV (Si, SiGe) channel materials is discussed. This device utilizes a core/shell dual gate strategy to capitalize on the volume-inversion properties of an ultra-thin (< 10 nm) group IV nanotube channel to minimize leakage and short channel effects while maximizing performance in an area-efficient manner. It is also shown that the NTFET is capable of providing a higher output drive performance per unit chip area than an array of gate-all-around nanowires, while maintaining the leakage and short channel characteristics similar to that of a single gate-all-around nanowire, the latter being the most superior in terms of electrostatic gate control. In the age of big data and the multitude of devices contributing to the internet of things, the NTFET offers a new transistor topology alternative with maximum benefits from performance-energy efficiency-functionality perspective.

  7. Carbon nanotube network embroidered graphene films for monolithic all-carbon electronics.

    PubMed

    Shi, Enzheng; Li, Hongbian; Yang, Long; Hou, Junfeng; Li, Yuanchang; Li, Li; Cao, Anyuan; Fang, Ying

    2015-01-27

    A unique cage growth of graphene is developed by using carbon nanotube (CNT) spider webs as porous templates, resulting in CNT/graphene hybrids with high conductivity and mechanical flexibility. Furthermore, monolithic all-carbon transistors with graphene as active elements and CNT/graphene hybrids as contacts and interconnects are directly formed by chemical synthesis, and flexible all-carbon bioelectronics are subsequently demonstrated for in vivo mapping of cardiac signals. PMID:25607917

  8. Length-Sorted, Large-Diameter, Polyfluorene-Wrapped Semiconducting Single-Walled Carbon Nanotubes for High-Density, Short-Channel Transistors.

    PubMed

    Hennrich, Frank; Li, Wenshan; Fischer, Regina; Lebedkin, Sergei; Krupke, Ralph; Kappes, Manfred M

    2016-02-23

    Samples of highly enriched semiconducting SWCNTs with average diameters of 1.35 nm have been prepared by combining PODOF polymer wrapping with size-exclusion chromatography. The purity of the material was determined to be >99.7% from the transfer characteristics of short-channel transistors comprising densely aligned sc-SWCNTs. The transistors have a hole mobility of up to 297 cm(2)V(-1) s(-1) and an On/Off ratio as high as 2 × 10(8). PMID:26792404

  9. Electronic Sensitivity of Carbon Nanotubes to Internal Water Wetting

    SciTech Connect

    Cao, Di; Pang, Pei; He, Jin; Luo, Tao; Park, Jae Hyun nmn; Krstic, Predrag S; Nuckolls, Colin; Tang, Jinyao; Lindsay, Stuart

    2011-01-01

    We have constructed devices in which the interior of a single-walled carbon nanotube (SWCNT) field-effect transistor acts as a nanofluidic channel that connects two fluid reservoirs, permitting measurement of the electronic properties of the SWCNT as it is wetted by an analyte. Wetting of the inside of the SWCNT by water turns the transistor on, while wetting of the outside has little effect. These observations are consistent with theoretical simulations that show that internal water both generates a large dipole electric field, causing charge polarization of the tube and metal electrodes, and shifts the valance band of the SWCNT, while external water has little effect.

  10. Occupational Exposure to Carbon Nanotubes and Nanofibers

    MedlinePlus

    ... Current Intelligence Bulletin 65: Occupational Exposure to Carbon Nanotubes and Nanofibers Recommend on Facebook Tweet Share Compartir ... composed of engineered nanoparticles, such as metal oxides, nanotubes, nanowires, quantum dots, and carbon fullerenes (buckyballs), among ...

  11. Probing Photosensitization by Functionalized Carbon Nanotubes

    EPA Science Inventory

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  12. Carbon Nanotube Based Molecular Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  13. Multiscale Modeling with Carbon Nanotubes

    SciTech Connect

    Maiti, A

    2006-02-21

    Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

  14. Directed Growth of Carbon Nanotubes Across Gaps

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance; Meyyapan, Meyya

    2008-01-01

    An experiment has shown that when single-walled carbon nanotubes (SWNTs) are grown by chemical vapor deposition in the presence of an electric field of suitable strength, the nanotubes become aligned along the electric field. In an important class of contemplated applications, one would exploit this finding in fabricating nanotube transistors; one would grow SWNTs across gaps between electrodes that would serve, subsequently, as source and drain contacts during operation of the transistors. In preparation for the experiment, a multilayer catalyst comprising a 20-nmthick underlayer of iridium (platinum group), a 1-nm-thick middle layer of iron, and a 0.2-nm-thick outer layer of molybdenum was ion-beam sputtered onto a quartz substrate. A 25 micrometers-diameter iron wire was used as a shadow mask during the sputtering to create a 25 micrometers gap in the catalyst. Then electrical leads were connected to the catalyst areas separated by the gap so that these catalyst areas would also serve as electrodes. The substrate as thus prepared was placed in a growth chamber that consisted of a quartz tube of 1-in. (2.54-cm) diameter enclosed in a furnace. SWNTs of acceptably high quantity and quality were grown in 10 minutes with methane at atmospheric pressure flowing through the chamber at a rate of 1,000 standard cubic centimeters per minute at a temperature of 900 C. To prevent oxidation of the SWNTs, the chamber was purged with 99.999-percent pure argon before and after growth, and the chamber was cooled to less than 300 C before opening it to the atmosphere after growth. When no voltage was applied across the gap, the SWNTs grew in random directions extending out from the edges of the catalyst at the gap. When a potential of 10 V was applied between the catalyst/electrode areas to create an electric field across the gap, the SWNTs grew across the gap, as shown in the figure.

  15. Large-Scale Processing of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Finn, John; Sridhar, K. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Scale-up difficulties and high energy costs are two of the more important factors that limit the availability of various types of nanotube carbon. While several approaches are known for producing nanotube carbon, the high-powered reactors typically produce nanotubes at rates measured in only grams per hour and operate at temperatures in excess of 1000 C. These scale-up and energy challenges must be overcome before nanotube carbon can become practical for high-consumption structural and mechanical applications. This presentation examines the issues associated with using various nanotube production methods at larger scales, and discusses research being performed at NASA Ames Research Center on carbon nanotube reactor technology.

  16. Electronic structures of carbon nanotube peopods

    NASA Astrophysics Data System (ADS)

    Kuk, Young

    2003-03-01

    Carbon nanotubes have been successfully used for nanometer-sized devices such as diodes and transistors. These discrete devices utilize the spatially varying electronic structures of processed nanotubes by creating defect junctions or introducing substitutional or interstitial dopants. It was recently found that adsorption or insertion of molecules inside or outside of a nanotube modifies the electronic structure as observed with a low-temperature scanning tunneling microscope (LTSTM). We report a method to form spatial variation of the electronic structure by inserting various molecules such as fullerenes, metallo-fullerenes, metals or insulators. The results suggest that one can synthesize this band gap-engineered 1-dimensional wire by self-assembly instead of epitaxial growth. We propose a new type of device structure made by this processing technology. 1. J. Lee, H.J. Kim, G. Kim, Y.-W. Son, J. Ihm, S.J. Kahng, H. Kato, Z.W. Wang, T. Okazaki, H. Shinohara, and Y. Kuk, Nature, 415, 1005 (2002)

  17. Dispersions of Carbon nanotubes in Polymer Matrices

    NASA Technical Reports Server (NTRS)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2010-01-01

    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  18. Controllable Hysteresis and Threshold Voltage of Single-Walled Carbon Nano-tube Transistors with Ferroelectric Polymer Top-Gate Insulators

    NASA Astrophysics Data System (ADS)

    Sun, Yi-Lin; Xie, Dan; Xu, Jian-Long; Zhang, Cheng; Dai, Rui-Xuan; Li, Xian; Meng, Xiang-Jian; Zhu, Hong-Wei

    2016-03-01

    Double-gated field effect transistors have been fabricated using the SWCNT networks as channel layer and the organic ferroelectric P(VDF-TrFE) film spin-coated as top gate insulators. Standard photolithography process has been adopted to achieve the patterning of organic P(VDF-TrFE) films and top-gate electrodes, which is compatible with conventional CMOS process technology. An effective way for modulating the threshold voltage in the channel of P(VDF-TrFE) top-gate transistors under polarization has been reported. The introduction of functional P(VDF-TrFE) gate dielectric also provides us an alternative method to suppress the initial hysteresis of SWCNT networks and obtain a controllable ferroelectric hysteresis behavior. Applied bottom gate voltage has been found to be another effective way to highly control the threshold voltage of the networked SWCNTs based FETs by electrostatic doping effect.

  19. Controllable Hysteresis and Threshold Voltage of Single-Walled Carbon Nano-tube Transistors with Ferroelectric Polymer Top-Gate Insulators.

    PubMed

    Sun, Yi-Lin; Xie, Dan; Xu, Jian-Long; Zhang, Cheng; Dai, Rui-Xuan; Li, Xian; Meng, Xiang-Jian; Zhu, Hong-Wei

    2016-01-01

    Double-gated field effect transistors have been fabricated using the SWCNT networks as channel layer and the organic ferroelectric P(VDF-TrFE) film spin-coated as top gate insulators. Standard photolithography process has been adopted to achieve the patterning of organic P(VDF-TrFE) films and top-gate electrodes, which is compatible with conventional CMOS process technology. An effective way for modulating the threshold voltage in the channel of P(VDF-TrFE) top-gate transistors under polarization has been reported. The introduction of functional P(VDF-TrFE) gate dielectric also provides us an alternative method to suppress the initial hysteresis of SWCNT networks and obtain a controllable ferroelectric hysteresis behavior. Applied bottom gate voltage has been found to be another effective way to highly control the threshold voltage of the networked SWCNTs based FETs by electrostatic doping effect. PMID:26980284

  20. Controllable Hysteresis and Threshold Voltage of Single-Walled Carbon Nano-tube Transistors with Ferroelectric Polymer Top-Gate Insulators

    PubMed Central

    Sun, Yi-Lin; Xie, Dan; Xu, Jian-Long; Zhang, Cheng; Dai, Rui-Xuan; Li, Xian; Meng, Xiang-Jian; Zhu, Hong-Wei

    2016-01-01

    Double-gated field effect transistors have been fabricated using the SWCNT networks as channel layer and the organic ferroelectric P(VDF-TrFE) film spin-coated as top gate insulators. Standard photolithography process has been adopted to achieve the patterning of organic P(VDF-TrFE) films and top-gate electrodes, which is compatible with conventional CMOS process technology. An effective way for modulating the threshold voltage in the channel of P(VDF-TrFE) top-gate transistors under polarization has been reported. The introduction of functional P(VDF-TrFE) gate dielectric also provides us an alternative method to suppress the initial hysteresis of SWCNT networks and obtain a controllable ferroelectric hysteresis behavior. Applied bottom gate voltage has been found to be another effective way to highly control the threshold voltage of the networked SWCNTs based FETs by electrostatic doping effect. PMID:26980284

  1. Carbon nanotube-polymer composite actuators

    DOEpatents

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  2. Gears Based on Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard; Han, Jie; Globus, Al; Deardorff, Glenn

    2005-01-01

    Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by

  3. CMOS Integrated Carbon Nanotube Sensor

    SciTech Connect

    Perez, M. S.; Lerner, B.; Boselli, A.; Lamagna, A.; Obregon, P. D. Pareja; Julian, P. M.; Mandolesi, P. S.; Buffa, F. A.

    2009-05-23

    Recently carbon nanotubes (CNTs) have been gaining their importance as sensors for gases, temperature and chemicals. Advances in fabrication processes simplify the formation of CNT sensor on silicon substrate. We have integrated single wall carbon nanotubes (SWCNTs) with complementary metal oxide semiconductor process (CMOS) to produce a chip sensor system. The sensor prototype was designed and fabricated using a 0.30 um CMOS process. The main advantage is that the device has a voltage amplifier so the electrical measure can be taken and amplified inside the sensor. When the conductance of the SWCNTs varies in response to media changes, this is observed as a variation in the output tension accordingly.

  4. Photodetector based on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pavlov, A.; Kitsyuk, E.; Ryazanov, R.; Timoshenkov, V.; Adamov, Y.

    2015-09-01

    Photodetector based on carbon nanotubes (CNT) was investigated. Sensors were done on quartz and silicon susbtrate. Samples of photodetectors sensors were produced by planar technology. This technology included deposition of first metal layer (Al), lithography for pads formation, etching, and formation of local catalyst area by inverse lithography. Vertically-aligned multi-wall carbon nanotubes were directly synthesized on substrate by PECVD method. I-V analysis and spectrum sensitivity of photodetector were investigated for 0.4 μm - 1.2 μm wavelength. Resistivity of CNT layers over temperature was detected in the range of -20°C to 100°C.

  5. All carbon nanotubes are not created equal

    SciTech Connect

    Geohegan, David B; Puretzky, Alexander A; Rouleau, Christopher M

    2010-01-01

    This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However, a surprisingly wide disparity exists between the intrinsic properties determined under ideal conditions and the properties that carbon nanotubes exhibit in real world situations. The lack of uniformity in carbon nanotube properties is likely to be the main obstacle holding back the development of carbon nanotube applications. This tutorial addresses the nonuniformity of carbon nanotube properties from the synthesis standpoint. This synthesis-related nonuniformity is on top of the intrinsic chirality distribution that gives the ~1:2 ratio of metallic to semiconducting nanotubes. From the standpoint of carbon bonding chemistry the variation in the quality and reproducibility of carbon nanotube materials is not unexpected. It is an intrinsic feature that is related to the metastability of carbon structures. The extent to which this effect is manifested in carbon nanotube formation is governed by the type and the kinetics of the carbon nanotube synthesis reaction. Addressing this variation is critical if nanotubes are to live up to the potential already demonstrated by their phenomenal physical properties.

  6. EDITORIAL: Focus on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    2003-09-01

    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau, P Umek, K Hernadi, P Marcoux, B Lukic, Cs Mikó, M Milas, R Gaál and L Forró Transitional behaviour in the transformation from active end

  7. Synthesis of carbon nanotubes and nanotube forests on copper catalyst

    NASA Astrophysics Data System (ADS)

    Kruszka, Bartosz; Terzyk, Artur P.; Wiśniewski, Marek; Gauden, Piotr A.; Szybowicz, Mirosław

    2014-09-01

    The growth of carbon nanotubes on bulk copper is studied. We show for the first time, that super growth chemical vapor deposition method can be successfully applied for preparation of nanotubes on copper catalyst, and the presence of hydrogen is necessary. Next, different methods of copper surface activation are studied, to improve catalyst efficiency. Among them, applied for the first time for copper catalyst in nanotubes synthesis, sulfuric acid activation is the most promising. Among tested samples the surface modified for 10 min is the most active, causing the growth of vertically aligned carbon nanotube forests. Obtained results have potential importance in application of nanotubes and copper in electronic chips and nanodevices.

  8. Modified carbon nanotubes and methods of forming carbon nanotubes

    DOEpatents

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.

    2016-06-14

    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

  9. Formation of ice nanotube with hydrophobic guests inside carbon nanotube.

    PubMed

    Tanaka, Hideki; Koga, Kenichiro

    2005-09-01

    A composite ice nanotube inside a carbon nanotube has been explored by molecular-dynamics and grand canonical Monte Carlo simulations. It is made from an octagonal ice nanotube whose hollow space contains hydrophobic guest molecules such as neon, argon, and methane. It is shown that the attractive interaction of the guest molecules stabilizes the ice nanotube. The guest occupancy of the hollow space is calculated by the same method as applied to clathrate hydrates. PMID:16164361

  10. Vapor Sensors Using Olfactory Proteins Coupled to Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Lerner, Mitchell; Goldsmith, Brett; Mitala, Joe; Discher, Bohdana; Johnson, A. T. Charlie

    2010-03-01

    We have constructed bio-nano devices which combine mammalian olfactory proteins with carbon nanotubes to create a new class of vapor sensors. Olfactory proteins are a specific class of G-protein coupled receptors, and require a cell membrane or similar environment for proper function. Functionalization procedures have been developed to meet the challenges of routinely coupling such membrane proteins to nanotubes, while preserving the function of the protein. We have successfully isolated olfactory proteins and attached them to carbon nanotube transistors, which provide fast, all-electronic readout of analyte binding by the olfactory receptor. Several different olfactory proteins have been tested, each showing a different sensing response. This work opens the way for future coupling of biology to nanoelectronics and improved biomimetic chemical sensing. This work is supported by the DARPA RealNose Project and the Nano/Bio Interface Center

  11. Gate-voltage induced trions in suspended carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yoshida, Masahiro; Popert, Alexander; Kato, Yuichiro K.

    We observe trion emission from suspended carbon nanotubes where carriers are introduced electrostatically using field-effect transistor structures. The trion peak emerges below the E11 emission energy at gate voltages that coincide with the onset of bright exciton quenching. By investigating nanotubes with various chiralities, we verify that the energy separation between the bright exciton peak and the trion peak becomes smaller for larger diameter tubes. Trion binding energies that are significantly larger compared to surfactant-wrapped carbon nanotubes are obtained, and the difference is attributed to the reduced dielectric screening in suspended tubes. Work supported by JSPS (KAKENHI 24340066), the Canon Foundation, the Sasakawa Scientific Research Grant, and MEXT (Photon Frontier Network Program, Nanotechnology Platform). M.Y. is supported by ALPS.

  12. Hydrogen storage in carbon nanotubes.

    PubMed

    Hirscher, M; Becher, M

    2003-01-01

    The article gives a comprehensive overview of hydrogen storage in carbon nanostructures, including experimental results and theoretical calculations. Soon after the discovery of carbon nanotubes in 1991, different research groups succeeded in filling carbon nanotubes with some elements, and, therefore, the question arose of filling carbon nanotubes with hydrogen by possibly using new effects such as nano-capillarity. Subsequently, very promising experiments claiming high hydrogen storage capacities in different carbon nanostructures initiated enormous research activity. Hydrogen storage capacities have been reported that exceed the benchmark for automotive application of 6.5 wt% set by the U.S. Department of Energy. However, the experimental data obtained with different methods for various carbon nanostructures show an extreme scatter. Classical calculations based on physisorption of hydrogen molecules could not explain the high storage capacities measured at ambient temperature, and, assuming chemisorption of hydrogen atoms, hydrogen release requires temperatures too high for technical applications. Up to now, only a few calculations and experiments indicate the possibility of an intermediate binding energy. Recently, serious doubt has arisen in relation to several key experiments, causing considerable controversy. Furthermore, high hydrogen storage capacities measured for carbon nanofibers did not survive cross-checking in different laboratories. Therefore, in light of today's knowledge, it is becoming less likely that at moderate pressures around room temperature carbon nanostructures can store the amount of hydrogen required for automotive applications. PMID:12908227

  13. Effect of Carbon Nanotubes on Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Chen, Michelle; Ahmed, Asma; Black, Melanie; Kawamoto, Nicole; Lucas, Jessica; Pagala, Armie; Pham, Tram; Stankiewicz, Sara; Chen, Howard

    2010-03-01

    Carbon Nanotubes possess extraordinary electrical, mechanical, and thermal properties. Research on applying the carbon nanotubes for ultrasensitive detection, disease diagnosis, and drug delivery is rapidly developing. While the fundamental and technological findings on carbon nanotubes show great promise, it is extremely important to investigate the effect of the carbon nanotubes on human health. In our experiments, we introduce purified carbon nanotubes in suspension to ovary cells cultured from Hamsters. These cells are chosen since they show robust morphological changes associated with cytotoxicity that can easily be observed under a light microscope. We will discuss the toxicity of carbon nanotubes by characterizing the cell morphology and viability as a function of time and the concentration of carbon nanotube suspension.

  14. Carbon Nanotube Material Quality Assessment

    NASA Technical Reports Server (NTRS)

    Yowell, Leonard; Arepalli, Sivaram; Sosa, Edward; Niolaev, Pavel; Gorelik, Olga

    2006-01-01

    The nanomaterial activities at NASA Johnson Space Center focus on carbon nanotube production, characterization and their applications for aerospace systems. Single wall carbon nanotubes are produced by arc and laser methods. Characterization of the nanotube material is performed using the NASA JSC protocol developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA. A possible addition of other techniques such as XPS, and ICP to the existing protocol will be discussed. Changes in the quality of the material collected in different regions of the arc and laser production chambers is assessed using the original JSC protocol. The observed variations indicate different growth conditions in different regions of the production chambers.

  15. Plasma CVD of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance; Cruden, B.; Hash, D.; Meyyappan, M.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Carbon nanotubes(CNT) exhibit remarkable mechanical and unique electronic properties and thus have created excitement in the research community about their potential in electronics, computing, sensor and structural applications. Realization of these applications critically depends on the ability to control the properties(such as diameter, chirality) as well purity. We have investigated CNT growth using an inductively coupled plasma(ICP) process using hydrocarbon feedstock. The catalyst required for nanotube growth consists of thin sputtered layers of aluminum and iron(10 nm each) and aligned carbon nanotubes have been obtained. Optical emission diagnostics as well as a plasma modeling effort have been undertaken to understand growth mechanisms. This presentation will discuss growth characteristics under various pressure, power and feedgas compositions and our understanding from modeling and diagnostics.

  16. Carbon Nanotube Passive Intermodulation Device for Nonlinear Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Lerner, Mitchell; Perez, Israel; Rockway, John

    2014-03-01

    The navy is interested in designing RF front-ends for receivers to handle high power jammers and other strong interferers. Instead of blocking that energy or dissipating it as heat in filters or amplifiers, this project investigates re-directing that energy for harvesting and storage. The approach is based on channelizing a high power jamming signal into a passive intermodulation device to create intermodulation products in sub-band frequencies, which could then be harvested for energy. The intermodulation device is fabricated using carbon nanotube transistors and such devices can be modified by creating chemical defects in the sidewalls of the nanotubes and locally gating the devices with a slowly varying electric field. These effects controllably enhance the hysteretic non-linearity in the transistors IV behavior. Combining these components with a RF energy harvester on the back-end should optimize the re-use of inbound jamming energy while maximizing the utility of standard back end radio components.

  17. Conductance Oscillations in Squashed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Mehrez, H.; Anantram, M. P.; Svizhenko, A.

    2003-01-01

    A combination of molecular dynamics and electrical conductance calculations are used to probe the electromechanical properties of squashed metallic carbon nanotubes. We find that the conductance and bandgap of armchair nanotubes show oscillations upon squashing. The physical origin of these oscillations is attributed to interaction of carbon atoms with a fourth neighbor. Squashing of armchair and zigzag nanotubes ultimately leads to metallic behavior.

  18. Redox sorting of carbon nanotubes.

    PubMed

    Gui, Hui; Streit, Jason K; Fagan, Jeffrey A; Hight Walker, Angela R; Zhou, Chongwu; Zheng, Ming

    2015-03-11

    This work expands the redox chemistry of single-wall carbon nanotubes (SWCNTs) by investigating its role in a number of SWCNT sorting processes. Using a polyethylene glycol (PEG)/dextran (DX) aqueous two-phase system, we show that electron-transfer between redox molecules and SWCNTs triggers reorganization of the surfactant coating layer, leading to strong modulation of nanotube partition in the two phases. While the DX phase is thermodynamically more favored by an oxidized SWCNT mixture, the mildly reducing PEG phase is able to recover SWCNTs from oxidation and extract them successively from the DX phase. Remarkably, the extraction order follows SWCNT bandgap: semiconducting nanotubes of larger bandgap first, followed by semiconducting nanotubes of smaller bandgap, then nonarmchair metallic tubes of small but nonvanishing bandgap, and finally armchair metallic nanotubes of zero bandgap. Furthermore, we show that redox-induced surfactant reorganization is a common phenomenon, affecting nanotube buoyancy in a density gradient field, affinity to polymer matrices, and solubility in organic solvents. These findings establish redox modulation of surfactant coating structures as a general mechanism for tuning a diverse range of SWCNT sorting processes and demonstrate for the first time that armchair and nonarmchair metallic SWCNTs can be separated by their differential response to redox. PMID:25719939

  19. Conductance of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, Supriyo; Anatram, M. P.

    1998-01-01

    The recent report of quantized conductance in a 4 m long multiwalled nanotube (MWNT) raises the exciting possibility of ballistic transport at room temperature over relatively long distances. We argue that this is made possible by the special symmetry of the eigenstates of the lowest propagating modes in metallic nanotubes which suppresses backscattering. This unusual effect is absent for the higher propagating modes so that transport is not ballistic once the bias exceeds the cut-off energy for the higher modes, which is estimated to be approximately 75 meV for nanotubes of diameter approximately 15 nm. Also, we show that the symmetry of the eigenstates can significantly affect their coupling to the reservoir and hence the contact resistance. A simple model is presented that can be used to understand the observed conductance-voltage characteristics.

  20. Thermoelectrics: Carbon nanotubes get high

    NASA Astrophysics Data System (ADS)

    Crispin, Xavier

    2016-04-01

    Waste heat can be converted to electricity by thermoelectric generators, but their development is hindered by the lack of cheap materials with good thermoelectric properties. Now, carbon-nanotube-based materials are shown to have improved properties when purified to contain only semiconducting species and then doped.

  1. Terahertz detection and carbon nanotubes

    ScienceCinema

    Leonard, Francois

    2014-06-13

    Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

  2. Terahertz detection and carbon nanotubes

    SciTech Connect

    Leonard, Francois

    2014-06-11

    Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

  3. Carbon Nanotubes and Human Cells?

    ERIC Educational Resources Information Center

    King, G. Angela

    2005-01-01

    Single-walled carbon nanotubes that were chemically altered to be water soluble are shown to enter fibroblasts, T cells, and HL60 cells. Nanoparticles adversely affect immortalized HaCaT human keratinocyte cultures, indicating that they may enter cells.

  4. LDRD final report : chromophore-functionalized aligned carbon nanotube arrays.

    SciTech Connect

    Vance, Andrew L.; Yang, Chu-Yeu Peter; Krafcik, Karen Lee

    2011-09-01

    The goal of this project was to expand upon previously demonstrated single carbon nanotube devices by preparing a more practical, multi-single-walled carbon nanotube (SWNT) device. As a late-start, proof-of-concept project, the work focused on the fabrication and testing of chromophore-functionalized aligned SWNT field effect transistors (SWNT-FET). Such devices have not yet been demonstrated. The advantages of fabricating aligned SWNT devices include increased device cross-section to improve sensitivity to light, elimination of increased electrical resistance at nanotube junctions in random mat devices, and the ability to model device responses. The project did not achieve the goal of fabricating and testing chromophore-modified SWNT arrays, but a new SWNT growth capability was established that will benefit future projects. Although the ultimate goal of fabricating and testing chromophore-modified SWNT arrays was not achieved, the work did lead to a new carbon nanotube growth capability at Sandia/CA. The synthesis of dense arrays of horizontally aligned SWNTs is a developing area of research with significant potential for new discoveries. In particular, the ability to prepare arrays of carbon nanotubes of specific electronic types (metallic or semiconducting) could yield new classes of nanoscale devices.

  5. Carbon nanotubes by the metallocene route

    NASA Astrophysics Data System (ADS)

    Sen, Rahul; Govindaraj, A.; Rao, C. N. R.

    1997-03-01

    Pyrolysis of metallocenes such as ferrocene, cobaltocene and nickelocene, is shown to yield carbon nanotubes and metal-filled onion-like structures. Pyrolysis of benzene in the presence of a metallocene gives high yields of nanotubes, the wall thickness of the nanotubes depending on the metallocene content. Pyrolysis of benzene in the absence of any metal however gives monodispersed nanospheres of carbon rather than nanotubes.

  6. Endohedral impurities in carbon nanotubes.

    PubMed

    Clougherty, Dennis P

    2003-01-24

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale. PMID:12570507

  7. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.

    2003-01-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale.

  8. Carbon nanotubes and graphene towards soft electronics

    NASA Astrophysics Data System (ADS)

    Chae, Sang Hoon; Lee, Young Hee

    2014-04-01

    Although silicon technology has been the main driving force for miniaturizing device dimensions to improve cost and performance, the current application of Si to soft electronics (flexible and stretchable electronics) is limited due to material rigidity. As a result, various prospective materials have been proposed to overcome the rigidity of conventional Si technology. In particular, nano-carbon materials such as carbon nanotubes (CNTs) and graphene are promising due to outstanding elastic properties as well as an excellent combination of electronic, optoelectronic, and thermal properties compared to conventional rigid silicon. The uniqueness of these nano-carbon materials has opened new possibilities for soft electronics, which is another technological trend in the market. This review covers the recent progress of soft electronics research based on CNTs and graphene. We discuss the strategies for soft electronics with nano-carbon materials and their preparation methods (growth and transfer techniques) to devices as well as the electrical characteristics of transparent conducting films (transparency and sheet resistance) and device performances in field effect transistor (FET) (structure, carrier type, on/off ratio, and mobility). In addition to discussing state of the art performance metrics, we also attempt to clarify trade-off issues and methods to control the trade-off on/off versus mobility). We further demonstrate accomplishments of the CNT network in flexible integrated circuits on plastic substrates that have attractive characteristics. A future research direction is also proposed to overcome current technological obstacles necessary to realize commercially feasible soft electronics.

  9. Carbon-Nanotube Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Wong, Eric; Schlecht, Erich; Hunt, Brian; Siegel, Peter

    2006-01-01

    Schottky diodes based on semiconducting single-walled carbon nanotubes are being developed as essential components of the next generation of submillimeter-wave sensors and sources. Initial performance predictions have shown that the performance characteristics of these devices can exceed those of the state-of-the-art solid-state Schottky diodes that have been the components of choice for room-temperature submillimeter-wave sensors for more than 50 years. For state-of-the-art Schottky diodes used as detectors at frequencies above a few hundred gigahertz, the inherent parasitic capacitances associated with their semiconductor junction areas and the resistances associated with low electron mobilities limit achievable sensitivity. The performance of such a detector falls off approximately exponentially with frequency above 500 GHz. Moreover, when used as frequency multipliers for generating signals, state-of-the-art solid-state Schottky diodes exhibit extremely low efficiencies, generally putting out only micro-watts of power at frequencies up to 1.5 THz. The shortcomings of the state-of-the-art solid-state Schottky diodes can be overcome by exploiting the unique electronic properties of semiconducting carbon nanotubes. A single-walled carbon nanotube can be metallic or semiconducting, depending on its chirality, and exhibits high electron mobility (recently reported to be approx.= 2x10(exp 5)sq cm/V-s) and low parasitic capacitance. Because of the narrowness of nanotubes, Schottky diodes based on carbon nanotubes have ultra-small junction areas (of the order of a few square nanometers) and consequent junction capacitances of the order of 10(exp -18) F, which translates to cutoff frequency >5 THz. Because the turn-on power levels of these devices are very low (of the order of nano-watts), the input power levels needed for pumping local oscillators containing these devices should be lower than those needed for local oscillators containing state-of-the-art solid

  10. High performance thin film transistors based on regioregular poly(3-dodecylthiophene)-sorted large diameter semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Qian, Long; Xu, Wenya; Nie, Shuhong; Gu, Weibing; Zhang, Jianhui; Zhao, Jianwen; Lin, Jian; Chen, Zheng; Cui, Zheng

    2013-05-01

    In this work, a simple and rapid method to selectively sort semiconducting-SWCNTs (sc-SWCNTs) with large diameters using regioregular poly(3-dodecylthiophene) (rr-P3DDT) is presented. The absorption spectra and Raman spectra demonstrated that metallic species of arc discharge SWCNTs were effectively removed after interaction with rr-P3DDT in toluene with the aid of sonication and centrifugation. The sorted sc-SWCNT inks have been directly used to fabricate thin film transistors (TFTs) by dip-coating, drop-casting and inkjet printing. TFTs with an effective mobility of ~34 cm2 V-1 s-1 and on-off ratios of ~107 have been achieved by dip coating and drop casting the ink on SiO2/Si substrates with pre-patterned interdigitated gold electrode arrays. The printed devices also showed excellent electrical properties with a mobility of up to 6.6 cm2 V-1 s-1 and on-off ratios of up to 105. Printed inverters based on the TFTs have been constructed on glass substrates, showing a maximum voltage gain of 112 at a Vdd of -5 V. This work paves the way for making printable logic circuits for real applications.In this work, a simple and rapid method to selectively sort semiconducting-SWCNTs (sc-SWCNTs) with large diameters using regioregular poly(3-dodecylthiophene) (rr-P3DDT) is presented. The absorption spectra and Raman spectra demonstrated that metallic species of arc discharge SWCNTs were effectively removed after interaction with rr-P3DDT in toluene with the aid of sonication and centrifugation. The sorted sc-SWCNT inks have been directly used to fabricate thin film transistors (TFTs) by dip-coating, drop-casting and inkjet printing. TFTs with an effective mobility of ~34 cm2 V-1 s-1 and on-off ratios of ~107 have been achieved by dip coating and drop casting the ink on SiO2/Si substrates with pre-patterned interdigitated gold electrode arrays. The printed devices also showed excellent electrical properties with a mobility of up to 6.6 cm2 V-1 s-1 and on-off ratios of up to 105

  11. Carbon nanotubes for thermal interface materials in microelectronic packaging

    NASA Astrophysics Data System (ADS)

    Lin, Wei

    As the integration scale of transistors/devices in a chip/system keeps increasing, effective cooling has become more and more important in microelectronics. To address the thermal dissipation issue, one important solution is to develop thermal interface materials with higher performance. Carbon nanotubes, given their high intrinsic thermal and mechanical properties, and their high thermal and chemical stabilities, have received extensive attention from both academia and industry as a candidate for high-performance thermal interface materials. The thesis is devoted to addressing some challenges related to the potential application of carbon nanotubes as thermal interface materials in microelectronics. These challenges include: 1) controlled synthesis of vertically aligned carbon nanotubes on various bulk substrates via chemical vapor deposition and the fundamental understanding involved; 2) development of a scalable annealing process to improve the intrinsic properties of synthesized carbon nanotubes; 3) development of a state-of-art assembling process to effectively implement high-quality vertically aligned carbon nanotubes into a flip-chip assembly; 4) a reliable thermal measurement of intrinsic thermal transport property of vertically aligned carbon nanotube films; 5) improvement of interfacial thermal transport between carbon nanotubes and other materials. The major achievements are summarized. 1. Based on the fundamental understanding of catalytic chemical vapor deposition processes and the growth mechanism of carbon nanotube, fast synthesis of high-quality vertically aligned carbon nanotubes on various bulk substrates (e.g., copper, quartz, silicon, aluminum oxide, etc.) has been successfully achieved. The synthesis of vertically aligned carbon nanotubes on the bulk copper substrate by the thermal chemical vapor deposition process has set a world record. In order to functionalize the synthesized carbon nanotubes while maintaining their good vertical alignment

  12. Quantum transport in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.; Grove-Rasmussen, Kasper; Nygârd, Jesper; Flensberg, Karsten; Kouwenhoven, Leo P.

    2015-07-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike in conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and valley freedom. The interplay between the two is the focus of this review. The energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are explained, together with their consequences for transport measurements through nanotube quantum dots. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli blockade. This can be exploited to read out spin and valley qubits and to measure the decay of these states through coupling to nuclear spins and phonons. A second unique property of carbon nanotubes is that the combination of valley freedom and electron-electron interactions in one dimension strongly modifies their transport behavior. Interaction between electrons inside and outside a quantum dot is manifested in SU(4) Kondo behavior and level renormalization. Interaction within a dot leads to Wigner molecules and more complex correlated states. This review takes an experimental perspective informed by recent advances in theory. As well as the well-understood overall picture, open questions for the field are also clearly stated. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both be reduced to a low level.

  13. TRANSPORT SPECTROSCOPY OF CHEMICAL NANOSTRUCTURES: The Case of Metallic Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Liang, Wenjie; Bockrath, Marc; Park, Hongkun

    2005-05-01

    Transport spectroscopy, a technique based on current-voltage measurements of individual nanostructures in a three-terminal transistor geometry, has emerged as a powerful new tool to investigate the electronic properties of chemically derived nanostructures. In this review, we discuss the utility of this approach using the recent studies of single-nanotube transistors as an example. Specifically, we discuss how transport measurements can be used to gain detailed insight into the electronic motion in metallic single-walled carbon nanotubes in several distinct regimes, depending on the coupling strength of the contacts to the nanotubes. Measurements of nanotube devices in these different conductance regimes have enabled a detailed analysis of the transport properties, including the experimental determination of all Hartree-Fock parameters that govern the electronic structure of metallic nanotubes and the demonstration of Fabry-Perot resonators based on the interference of electron waves.

  14. Roping and wrapping carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ausman, Kevin D.; O'Connell, Michael J.; Boul, Peter; Ericson, Lars M.; Casavant, Michael J.; Walters, Deron A.; Huffman, Chad; Saini, Rajesh; Wang, Yuhuang; Haroz, Erik; Billups, Edward W.; Smalley, Richard E.

    2001-11-01

    Single-walled carbon nanotubes can be dispersed into solvents by ultrasonication to the point that primarily individual tubes, cut to a few hundred nanometers in length, are present. However, when such dispersions are filtered to a thick mat, or paper, only tangles of uniform, seemingly endless ropes are observed. The factors contributing to this "roping" phenomenon, akin to aggregation or crystallization, will be discussed. We have developed methods for generating "super-ropes" more than twenty times the diameter of those formed by filtration, involving the extraction of nanotube material from an oleum dispersion. Nanotubes have been solubilized in water, largely individually, by non-covalently wrapping them with linear polymers. The general thermodynamic drive for this wrapping involves the polymer disrupting both the hydrophobic interface with water and the smooth tube-tube interaction in aggregates. The nanotubes can be recovered from their polymeric wrapping by changing their solvent system. This solubilization process opens the door to solution chemistry on pristine nanotubes, as well as their introduction into biologically relevant systems.

  15. Carbon nanotube coatings as chemical absorbers

    DOEpatents

    Tillotson, Thomas M.; Andresen, Brian D.; Alcaraz, Armando

    2004-06-15

    Airborne or aqueous organic compound collection using carbon nanotubes. Exposure of carbon nanotube-coated disks to controlled atmospheres of chemical warefare (CW)-related compounds provide superior extraction and retention efficiencies compared to commercially available airborne organic compound collectors. For example, the carbon nanotube-coated collectors were four (4) times more efficient toward concentrating dimethylmethyl-phosphonate (DMMP), a CW surrogate, than Carboxen, the optimized carbonized polymer for CW-related vapor collections. In addition to DMMP, the carbon nanotube-coated material possesses high collection efficiencies for the CW-related compounds diisopropylaminoethanol (DIEA), and diisopropylmethylphosphonate (DIMP).

  16. Twisting Graphene into Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kit, Oleg O.; Tallinen, Tuomas; Mahadevan, L.; Timonen, Jussi; Koskinen, Pekka

    2012-02-01

    Carbon nanotubes are usually described as being rolled up from graphene sheets; this process, however, have never been realized experimentally. We showed that graphene can indeed be transformed into nanotube by twisting [1]. Further, we showed that tube formation can be well-explained within classical theory of elasticity---in fact the very mechanism of tube formation can be observed by twisting a strap from one's backpack (try now!). Furthermore, we showed that nanotube chirality may not only be predicted, but can also be controlled externally. The quantum molecular dynamic simulations at T=300K were achieved thanks to the revised periodic boundary conditions (RPBC) approach [2-3]. The structures similar to simulated have been recently observed experimentally [4]. This novel rote for nanotube formation opens new opportunities in nanomaterial manipulation not restricted to carbon alone. In the presentation, I will describe tube formation, as well as outline the easy and efficient technique for distorted nanostructures simulation, the RPBC approach. [4pt] [1] O. O. Kit et al. arXiv:1108.0048[0pt] [2] P. Koskinen & O. O. Kit PRL 105, 106401 (2010)[0pt] [3] O. O. Kit, L. Pastewka, P. Koskinen PRB 84, 155431 (2011)[0pt] [4] A. Chuvilin et al. Nature Materials 10, 687 (2011)

  17. Double-walled carbon nanotube processing.

    PubMed

    Moore, Katherine E; Tune, Daniel D; Flavel, Benjamin S

    2015-05-27

    Single-walled carbon nanotubes (SWCNTs) have been the focus of intense research, and the body of literature continues to grow exponentially, despite more than two decades having passed since the first reports. As well as extensive studies of the fundamental properties, this has seen SWCNTs used in a plethora of applications as far ranging as microelectronics, energy storage, solar cells, and sensors, to cancer treatment, drug delivery, and neuronal interfaces. On the other hand, the properties and applications of double-walled carbon nanotubes (DWCNTs) have remained relatively under-explored. This is despite DWCNTs not only sharing many of the same unique characteristics of their single-walled counterparts, but also possessing an additional suite of potentially advantageous properties arising due to the presence of the second wall and the often complex inter-wall interactions that arise. For example, it is envisaged that the outer wall can be selectively functionalized whilst still leaving the inner wall in its pristine state and available for signal transduction. A similar situation arises in DWCNT field effect transistors (FETs), where the outer wall can provide a convenient degree of chemical shielding of the inner wall from the external environment, allowing the excellent transconductance properties of the pristine nanotubes to be more fully exploited. Additionally, DWCNTs should also offer unique opportunities to further the fundamental understanding of the inter-wall interactions within and between carbon nanotubes. However, the realization of these goals has so far been limited by the same challenge experienced by the SWCNT field until recent years, namely, the inherent heterogeneity of raw, as-produced DWCNT material. As such, there is now an emerging field of research regarding DWCNT processing that focuses on the preparation of material of defined length, diameter and electronic type, and which is rapidly building upon the experience gained by the broader

  18. Carbon Nanotubes - Polymer Composites with Enhanced Conductivity using Functionalized Nanotubes

    NASA Astrophysics Data System (ADS)

    Ramasubramaniam, Rajagopal; Chen, Jian; Gupta, Rishi

    2003-03-01

    Individual carbon nanotubes show superior electrical, mechanical and thermal properties [1]. Composite materials using carbon nanotubes as fillers are predicted to show similar superior properties. However, realization of such composites has been plagued by poor dispersion of carbon nanotubes in solvents and in polymer matrices. We have developed a method to homogenously disperse carbon nanotubes in polymer matrices using functionalized nanotubes [2]. Thin films of functionalized single walled nanotubes (SWNT) - polystyrene composites and functionalized SWNT - polycarbonate composites were prepared using solution evaporation and spin coating. Both of the composites show several orders of magnitude increase in conductivity for less than 1 wt thresholds of the composites are less than 0.2 wt nanotubes. We attribute the enhanced conduction to the superior dispersion of the functionalized nanotubes in the polymer matrix and to the reduced nanotube waviness resulting from the rigid backbone of the conjugated polymer. References: [1]. R. H. Baughman, A. A. Zakhidov and W. A. de Heer, Science v297, p787 (2002); [2]. J. Chen, H. Liu, W. A. Weimer, M. D. Halls, D. H. Waldeck and G. C. Walker, J. Am. Chem. Soc. v124, p9034 (2002).

  19. Analytical modeling of glucose biosensors based on carbon nanotubes

    PubMed Central

    2014-01-01

    In recent years, carbon nanotubes have received widespread attention as promising carbon-based nanoelectronic devices. Due to their exceptional physical, chemical, and electrical properties, namely a high surface-to-volume ratio, their enhanced electron transfer properties, and their high thermal conductivity, carbon nanotubes can be used effectively as electrochemical sensors. The integration of carbon nanotubes with a functional group provides a good and solid support for the immobilization of enzymes. The determination of glucose levels using biosensors, particularly in the medical diagnostics and food industries, is gaining mass appeal. Glucose biosensors detect the glucose molecule by catalyzing glucose to gluconic acid and hydrogen peroxide in the presence of oxygen. This action provides high accuracy and a quick detection rate. In this paper, a single-wall carbon nanotube field-effect transistor biosensor for glucose detection is analytically modeled. In the proposed model, the glucose concentration is presented as a function of gate voltage. Subsequently, the proposed model is compared with existing experimental data. A good consensus between the model and the experimental data is reported. The simulated data demonstrate that the analytical model can be employed with an electrochemical glucose sensor to predict the behavior of the sensing mechanism in biosensors. PMID:24428818

  20. Method of making carbon nanotube composite materials

    DOEpatents

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2014-05-20

    The present invention is a method of making a composite polymeric material by dissolving a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes and optionally additives in a solvent to make a solution and removing at least a portion of the solvent after casting onto a substrate to make thin films. The material has enhanced conductivity properties due to the blending of the un-functionalized and hydroxylated carbon nanotubes.

  1. Multilayer Film Assembly of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Meyyappan, M.; Han, Jie; Arnold, J. (Technical Monitor)

    2000-01-01

    An approach to assemble multilayers of carbon nanotubes on a substrate is presented. Chemical vapor deposition using a transition metal catalyst formulation is used to grow the nanotubes. Results show a bilayer assembly of nanotubes each with a different density of tubes.

  2. Carbon Nanotubes: Molecular Electronic Components

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  3. Torsional Carbon Nanotube Artificial Muscles

    NASA Astrophysics Data System (ADS)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  4. From carbon nanobells to nickel nanotubes

    SciTech Connect

    Ma, S.; Srikanth, V. V. S. S.; Maik, D.; Zhang, G. Y.; Staedler, T.; Jiang, X.

    2009-01-05

    A generic strategy is proposed to prepare one dimensional (1D) metallic nanotubes by using 1D carbon nanostructures as the initial templates. Following the strategy, nickel (Ni) nanotubes are prepared by using carbon nanobells (CNBs) as the initial templates. CNBs are first prepared by microwave plasma enhanced chemical vapor deposition technique. Carbon/nickel core/shell structures are then prepared by electroplating the CNBs in a nickel-Watts electrolytic cell. In the final step, the carbon core is selectively removed by employing hydrogen plasma etching to obtain Ni nanotubes. The mechanism leading to Ni nanotubes is briefly discussed.

  5. EDITORIAL: Focus on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    2003-09-01

    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents <;A article="1367-2630/5/1/117">Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau

  6. LDRD final report on carbon nanotube composites

    SciTech Connect

    Cahill, P.A.; Rand, P.B.

    1997-04-01

    Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research.

  7. Understanding Charge Transport in Mixed Networks of Semiconducting Carbon Nanotubes.

    PubMed

    Rother, Marcel; Schießl, Stefan P; Zakharko, Yuriy; Gannott, Florentina; Zaumseil, Jana

    2016-03-01

    The ability to select and enrich semiconducting single-walled carbon nanotubes (SWNT) with high purity has led to a fast rise of solution-processed nanotube network field-effect transistors (FETs) with high carrier mobilities and on/off current ratios. However, it remains an open question whether it is best to use a network of only one nanotube species (monochiral) or whether a mix of purely semiconducting nanotubes but with different bandgaps is sufficient for high performance FETs. For a range of different polymer-sorted semiconducting SWNT networks, we demonstrate that a very small amount of narrow bandgap nanotubes within a dense network of large bandgap nanotubes can dominate the transport and thus severely limit on-currents and effective carrier mobility. Using gate-voltage-dependent electroluminescence, we spatially and spectrally reveal preferential charge transport that does not depend on nominal network density but on the energy level distribution within the network and carrier density. On the basis of these results, we outline rational guidelines for the use of mixed SWNT networks to obtain high performance FETs while reducing the cost for purification. PMID:26867006

  8. Understanding Charge Transport in Mixed Networks of Semiconducting Carbon Nanotubes

    PubMed Central

    2016-01-01

    The ability to select and enrich semiconducting single-walled carbon nanotubes (SWNT) with high purity has led to a fast rise of solution-processed nanotube network field-effect transistors (FETs) with high carrier mobilities and on/off current ratios. However, it remains an open question whether it is best to use a network of only one nanotube species (monochiral) or whether a mix of purely semiconducting nanotubes but with different bandgaps is sufficient for high performance FETs. For a range of different polymer-sorted semiconducting SWNT networks, we demonstrate that a very small amount of narrow bandgap nanotubes within a dense network of large bandgap nanotubes can dominate the transport and thus severely limit on-currents and effective carrier mobility. Using gate-voltage-dependent electroluminescence, we spatially and spectrally reveal preferential charge transport that does not depend on nominal network density but on the energy level distribution within the network and carrier density. On the basis of these results, we outline rational guidelines for the use of mixed SWNT networks to obtain high performance FETs while reducing the cost for purification. PMID:26867006

  9. Carbon nanotube atomic force microscopy probes

    NASA Astrophysics Data System (ADS)

    Yamanaka, Shigenobu; Okawa, Takashi; Akita, Seiji; Nakayama, Yoshikazu

    2005-05-01

    We have developed a carbon nanotube atomic force microscope probe. Because the carbon nanotube are well known to have high aspect ratios, small tip radii and high stiffness, carbon nanotube probes have a long lifetime and can be applied for the observation deep trenches. Carbon nanotubes were synthesized by a well-controlled DC arc discharge method, because this method can make nanotubes to have straight shape and high crystalline. The nanotubes were aligned on the knife-edge using an alternating current electrophoresis technique. A commercially available Si probe was used for the base of the nanotube probe. The nanotube probe was fabricated by the SEM manipulation method. The nanotube was then attached tightly to the Si probe by deposition of amorphous carbon. We demonstrate the measurement of a fine pith grating that has vertical walls. However, a carbon nanotube has a problem that is called "Sticking". The sticking is a chatter image on vertical like region in a sample. We solved this problem by applying 2 methods, 1. a large cantilever vibration amplitude in tapping mode, 2. an attractive mode measurement. We demonstrate the non-sticking images by these methods.

  10. Improved Process for Fabricating Carbon Nanotube Probes

    NASA Technical Reports Server (NTRS)

    Stevens, R.; Nguyen, C.; Cassell, A.; Delzeit, L.; Meyyappan, M.; Han, Jie

    2003-01-01

    An improved process has been developed for the efficient fabrication of carbon nanotube probes for use in atomic-force microscopes (AFMs) and nanomanipulators. Relative to prior nanotube tip production processes, this process offers advantages in alignment of the nanotube on the cantilever and stability of the nanotube's attachment. A procedure has also been developed at Ames that effectively sharpens the multiwalled nanotube, which improves the resolution of the multiwalled nanotube probes and, combined with the greater stability of multiwalled nanotube probes, increases the effective resolution of these probes, making them comparable in resolution to single-walled carbon nanotube probes. The robust attachment derived from this improved fabrication method and the natural strength and resiliency of the nanotube itself produces an AFM probe with an extremely long imaging lifetime. In a longevity test, a nanotube tip imaged a silicon nitride surface for 15 hours without measurable loss of resolution. In contrast, the resolution of conventional silicon probes noticeably begins to degrade within minutes. These carbon nanotube probes have many possible applications in the semiconductor industry, particularly as devices are approaching the nanometer scale and new atomic layer deposition techniques necessitate a higher resolution characterization technique. Previously at Ames, the use of nanotube probes has been demonstrated for imaging photoresist patterns with high aspect ratio. In addition, these tips have been used to analyze Mars simulant dust grains, extremophile protein crystals, and DNA structure.

  11. Physically unclonable cryptographic primitives using self-assembled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hu, Zhaoying; Comeras, Jose Miguel M. Lobez; Park, Hongsik; Tang, Jianshi; Afzali, Ali; Tulevski, George S.; Hannon, James B.; Liehr, Michael; Han, Shu-Jen

    2016-06-01

    Information security underpins many aspects of modern society. However, silicon chips are vulnerable to hazards such as counterfeiting, tampering and information leakage through side-channel attacks (for example, by measuring power consumption, timing or electromagnetic radiation). Single-walled carbon nanotubes are a potential replacement for silicon as the channel material of transistors due to their superb electrical properties and intrinsic ultrathin body, but problems such as limited semiconducting purity and non-ideal assembly still need to be addressed before they can deliver high-performance electronics. Here, we show that by using these inherent imperfections, an unclonable electronic random structure can be constructed at low cost from carbon nanotubes. The nanotubes are self-assembled into patterned HfO2 trenches using ion-exchange chemistry, and the width of the trench is optimized to maximize the randomness of the nanotube placement. With this approach, two-dimensional (2D) random bit arrays are created that can offer ternary-bit architecture by determining the connection yield and switching type of the nanotube devices. As a result, our cryptographic keys provide a significantly higher level of security than conventional binary-bit architecture with the same key size.

  12. Physically unclonable cryptographic primitives using self-assembled carbon nanotubes.

    PubMed

    Hu, Zhaoying; Comeras, Jose Miguel M Lobez; Park, Hongsik; Tang, Jianshi; Afzali, Ali; Tulevski, George S; Hannon, James B; Liehr, Michael; Han, Shu-Jen

    2016-06-01

    Information security underpins many aspects of modern society. However, silicon chips are vulnerable to hazards such as counterfeiting, tampering and information leakage through side-channel attacks (for example, by measuring power consumption, timing or electromagnetic radiation). Single-walled carbon nanotubes are a potential replacement for silicon as the channel material of transistors due to their superb electrical properties and intrinsic ultrathin body, but problems such as limited semiconducting purity and non-ideal assembly still need to be addressed before they can deliver high-performance electronics. Here, we show that by using these inherent imperfections, an unclonable electronic random structure can be constructed at low cost from carbon nanotubes. The nanotubes are self-assembled into patterned HfO2 trenches using ion-exchange chemistry, and the width of the trench is optimized to maximize the randomness of the nanotube placement. With this approach, two-dimensional (2D) random bit arrays are created that can offer ternary-bit architecture by determining the connection yield and switching type of the nanotube devices. As a result, our cryptographic keys provide a significantly higher level of security than conventional binary-bit architecture with the same key size. PMID:26900757

  13. Origin of Giant Ionic Currents in Carbon Nanotube Channels

    SciTech Connect

    Pang, Pei; Park, Jae Hyun nmn; Krstic, Predrag S; Lindsay, Stuart; He, Jin

    2011-01-01

    Fluid flow inside carbon nanotubes is remarkable: transport of water and gases is nearly frictionless, and the small channel size results in selective transport of ions. Very recently, devices have been fabricated in which one narrow single-walled carbon nanotube spans a barrier separating electrolyte reservoirs. Ion current through these devices is about 2 orders of magnitude larger than predicted from the bulk resistivity of the electrolyte. Electroosmosis can drive these large excess currents if the tube both is charged and transports anions or cations preferentially. By building a nanofluidic field-effect transistor with a gate electrode embedded in the fluid barrier, we show that the tube carries a negative charge and the excess current is carried by cations. The magnitude of the excess current and its control by a gate electrode are correctly predicted by the Poisson-Nernst-Planck-Stokes equations.

  14. Detecting Lyme disease using antibody-functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Dailey, Jennifer; Lerner, Mitchell; Goldsmith, Brett; Brisson, Dustin; Johnson, A. T. Charlie

    2011-03-01

    We combine antibodies for Lyme flagellar protein with carbon nanotube transistors to create an electronic sensor capable of definitive detection of Lyme disease. Over 35,000 cases of Lyme disease are reported in the United States each year, of which more than 23 percent are originally misdiagnosed. Rational design of the coupling of the biological system to the electronic system gives us a flexible sensor platform which we can apply to several biological systems. By coupling these antibodies to carbon nanotubes in particular, we allow for fast, sensitive, highly selective, electronic detection. Unlike antibody or biomarker detection, bacterial protein detection leads to positive identification of both early and late stage bacterial infections, and is easily expandable to environmental monitoring.

  15. A Taste Sensor Based on a Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Takagi, Keisuke; Hirata, Takamichi; Akiya, Masahiro

    A taste sensor consisting of a back-gate type field effect transistor(FET) chip based on carbon nanotube compound materials[poly(ethylene glycol)(PEG)-grafted single-walled carbon nanotubes(PEG-SWNTs)] was developed. The results of impedance measurements for five tastes (sourness, saltiness, bitterness, sweetness, and umami), are shown much difference for specific tastes which are difficult to identify by using Langmuir-Blodgett(LB)film. Moreover, the sensor is able to distinguish most of the experimental taste materials with a short response time. Characteristics of the sensor involve in taste material concentration , initial impedance and frequency characteristics. A clear difference is observed over five basic taste materials.

  16. Lipid Bilayers Covalently Anchored to Carbon Nanotubes

    PubMed Central

    Dayani, Yasaman; Malmstadt, Noah

    2012-01-01

    The unique physical and electrical properties of carbon nanotubes make them an exciting material for applications in various fields such as bioelectronics and biosensing. Due to the poor water solubility of carbon nanotubes, functionalization for such applications has been a challenge. Of particular need are functionalization methods for integrating carbon nanotubes with biomolecules and constructing novel hybrid nanostructures for bionanoelectronic applications. We present a novel method for the fabrication of dispersible, biocompatible carbon nanotube-based materials. Multi-walled carbon nanotubes (MWCNTs) are covalently modified with primary amine-bearing phospholipids in a carbodiimide-activated reaction. These modified carbon nanotubes have good dispersibility in nonpolar solvents. Fourier transform infrared (FTIR) spectroscopy shows peaks attributable to the formation of amide bonds between lipids and the nanotube surface. Simple sonication of lipid-modified nanotubes with other lipid molecules leads to the formation of a uniform lipid bilayer coating the nanotubes. These bilayer-coated nanotubes are highly dispersible and stable in aqueous solution. Confocal fluorescence microscopy shows labeled lipids on the surface of bilayer-modified nanotubes. Transmission electron microscopy (TEM) shows the morphology of dispersed bilayer-coated MWCNTs. Fluorescence quenching of lipid-coated MWCNTs confirms the bilayer configuration of the lipids on the nanotube surface and fluorescence anisotropy measurements show that the bilayer is fluid above the gel-to-liquid transition temperature. The membrane protein α-hemolysin spontaneously inserts into the MWCNT-supported bilayer, confirming the biomimetic membrane structure. These biomimetic nanostructures are a promising platform for the integration of carbon nanotube-based materials with biomolecules. PMID:22568448

  17. Plasticity and Kinky Chemistry of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Dzegilenko, Fedor

    2000-01-01

    Since their discovery in 1991, carbon nanotubes have been the subject of intense research interest based on early predictions of their unique mechanical, electronic, and chemical properties. Materials with the predicted unique properties of carbon nanotubes are of great interest for use in future generations of aerospace vehicles. For their structural properties, carbon nanotubes could be used as reinforcing fibers in ultralight multifunctional composites. For their electronic properties, carbon nanotubes offer the potential of very high-speed, low-power computing elements, high-density data storage, and unique sensors. In a continuing effort to model and predict the properties of carbon nanotubes, Ames accomplished three significant results during FY99. First, accurate values of the nanomechanics and plasticity of carbon nanotubes based on quantum molecular dynamics simulations were computed. Second, the concept of mechanical deformation catalyzed-kinky-chemistry as a means to control local chemistry of nanotubes was discovered. Third, the ease of nano-indentation of silicon surfaces with carbon nanotubes was established. The elastic response and plastic failure mechanisms of single-wall nanotubes were investigated by means of quantum molecular dynamics simulations.

  18. CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

    SciTech Connect

    Fischer, John, E.

    2009-07-24

    Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of

  19. Electrostatic gating in carbon nanotube aptasensors

    NASA Astrophysics Data System (ADS)

    Zheng, Han Yue; Alsager, Omar A.; Zhu, Bicheng; Travas-Sejdic, Jadranka; Hodgkiss, Justin M.; Plank, Natalie O. V.

    2016-07-01

    Synthetic DNA aptamer receptors could boost the prospects of carbon nanotube (CNT)-based electronic biosensors if signal transduction can be understood and engineered. Here, we report CNT aptasensors for potassium ions that clearly demonstrate aptamer-induced electrostatic gating of electronic conduction. The CNT network devices were fabricated on flexible substrates via a facile solution processing route and non-covalently functionalised with potassium binding aptamers. Monotonic increases in CNT conduction were observed in response to increasing potassium ion concentration, with a level of detection as low as 10 picomolar. The signal was shown to arise from a specific aptamer-target interaction that stabilises a G-quadruplex structure, bringing high negative charge density near the CNT channel. Electrostatic gating is established via the specificity and the sign of the current response, and by observing its suppression when higher ionic strength decreases the Debye length at the CNT-water interface. Sensitivity towards potassium and selectivity against other ions is demonstrated in both resistive mode and real time transistor mode measurements. The effective device architecture presented, along with the identification of clear response signatures, should inform the development of new electronic biosensors using the growing library of aptamer receptors.Synthetic DNA aptamer receptors could boost the prospects of carbon nanotube (CNT)-based electronic biosensors if signal transduction can be understood and engineered. Here, we report CNT aptasensors for potassium ions that clearly demonstrate aptamer-induced electrostatic gating of electronic conduction. The CNT network devices were fabricated on flexible substrates via a facile solution processing route and non-covalently functionalised with potassium binding aptamers. Monotonic increases in CNT conduction were observed in response to increasing potassium ion concentration, with a level of detection as low as 10

  20. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    NASA Technical Reports Server (NTRS)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  1. Covalent Sidewall Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Chiang, I.W.; Saini, R. K.; Mickelson, E. T.; Billups, W. E.; Hauge, R. H.; Margrave, J. L.

    2001-01-01

    Progress of fluorination of single-wall carbon nanotubes is being reported. Covalent attachment of alkyl groups including methyl, n-butyl and n-hexyl groups to the sidewalls of single wall carbon nanotubes (SWNTs) has been achieved. Quantitative measurement of the alkylation was done by thermal gravimetric analysis. FTIR, Raman and UV-Vis-NIR were used to characterize these alkylated SWNTs. Application of these nanotubes are being investigated-fibers, composites, batteries, lubricants, etc.

  2. Longitudinal solitons in carbon nanotubes

    SciTech Connect

    Astakhova, T. Yu.; Gurin, O. D.; Menon, M.; Vinogradov, G. A.

    2001-07-15

    We present results on soliton excitations in carbon nanotubes (CNT's) using Brenner's many-body potential. Our numerical simulations demonstrate high soliton stability in (10,10) CNT's. The interactions of solitons and solitary excitation with CNT defect are found to be inelastic if the excitations and defects length scales are comparable, resulting in a substantial part of soliton energy being distributed inhomogeneously over the defect bonds. In these solitary-excitation--cap collisions the local energy of a few bonds in the cap can exceed the average energy by an order of magnitude and more. This phenomenon, denoted the ''Tsunami effect,'' can contribute dynamically to the recently proposed ''kinky chemistry.'' We also present results of changes in the local density of states and variations in the atomic partial charges estimated at different time instants of the solitary-excitation Tsunami at the nanotube cap.

  3. Hydrogen Storage in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Gilbert, Joseph; Gilbert, Matthew; Naab, Fabian; Savage, Lauren; Holland, Wayne; Duggan, Jerome; McDaniel, Floyd

    2004-10-01

    Hydrogen as a fuel source is an attractive, relatively clean alternative to fossil fuels. However, a major limitation in its use for the application of automobiles has been the requirement for an efficient hydrogen storage medium. Current hydrogen storage systems are: physical storage in high pressure tanks, metal hydride, and gas-on-solid absorption. However, these methods do not fulfill the Department of Energy's targeted requirements for a usable hydrogen storage capacity of 6.5 wt.%, operation near ambient temperature and pressure, quick extraction and refueling, reliability and reusability.Reports showing high capacity hydrogen storage in single-walled carbon nanotubes originally prompted great excitement in the field, but further research has shown conflicting results. Results for carbon nanostructures have ranged from less than 1 wt.% to 70 wt.%. The wide range of adsorption found in previous experiments results from the difficulty in measuring hydrogen in objects just nanometers in size. Most previous experiments relied on weight analysis and residual gas analysis to determine the amount of hydrogen being adsorbed by the CNTs. These differing results encouraged us to perform our own analysis on single-walled (SWNTs), double-walled (DWNTs), and multi-walled carbon nanotubes (MWNTs), as well as carbon fiber. We chose to utilize direct measurement of hydrogen in the materials using elastic recoil detection analysis (ERDA). This work was supported by the National Science Foundation's Research Experience for Undergraduates and the University of North Texas.

  4. Ophthalmologial Applications of Carbon Nanotube Nanotechology

    NASA Technical Reports Server (NTRS)

    Loftus, David; Girten, Beverly (Technical Monitor)

    2002-01-01

    The development of an implantable device consisting of an array of carbon nanotubes on a silicon chip for restoration of vision in patients with macular degeneration and other retinal disorders is presented. The use of carbon nanotube bucky paper for retinal cell transplantation is proposed. This paper is in viewgraph form.

  5. Reinforcement and rupture behavior of carbon nanotubes-polymer nanofibers

    NASA Astrophysics Data System (ADS)

    Ye, Haihui; Lam, Hoa; Titchenal, Nick; Gogotsi, Yury; Ko, Frank

    2004-09-01

    High-resolution transmission electron microscopy examination of carbon nanotube-polyacrylonitrile composite fibers synthesized by electrospinning was conducted. Both single-wall carbon nanotubes and multi-wall carbon nanotubes have been used to reinforce the polymer fibers. A two-stage rupture behavior of the composite fibers under tension, including crazing of polymer matrix and pull-out of carbon nanotubes, has been observed. Carbon nanotubes reinforce the polymer fibers by hindering crazing extension, reducing stress concentration, and dissipating energy by pullout. Distribution of nanotubes in the polymer matrix and interfacial adhesion between nanotubes and polymers are two major factors to determine the reinforcement effect of carbon nanotubes in polymer fibers.

  6. Measurement of the rate of water translocation through carbon nanotubes.

    PubMed

    Qin, Xingcai; Yuan, Quanzi; Zhao, Yapu; Xie, Shubao; Liu, Zhongfan

    2011-05-11

    We present an approach for measuring the water flow rate through individual ultralong carbon nanotubes (CNTs) using field effect transistors array defined on individual tubes. Our work exhibits a rate enhancement of 882-51 and a slip length of 53-8 nm for CNTs with diameters of 0.81-1.59 nm. We also found that the enhancement factor does not increase monotonically with shrinking tube diameter and there exists a discontinuous region around 0.98-1.10 nm. We believe that these single-tube level results would help understand the intrinsic nanofluidics of water in CNTs. PMID:21462938

  7. Nanocapillarity and chemistry in carbon nanotubes

    SciTech Connect

    Ugarte, D.; Chatelain, A.; Heer, W.A. de

    1996-12-13

    Open carbon nanotubes were filled with molten silver nitrate by capillary forces. Only those tubes with inner diameters of 4 nanometers or more were filled, suggesting a capillarity size dependence as a result of the lowering of the nanotube-salt interface energy with increasing curvature of the nanotube walls. Nanotube cavities should also be less chemically reactive than graphite and may serve as nanosize test tubes. This property has been illustrated by monitoring the decomposition of silver nitrate within nanotubes in situ in an electron microscope, which produced chains of silver nanobeads separated by high-pressure gas pockets. 32 refs., 3 figs.

  8. Epitaxial Approaches to Carbon Nanotube Organization

    NASA Astrophysics Data System (ADS)

    Ismach, Ariel

    Carbon nanotubes have unique electronic, mechanical, optical and thermal properties, which make them ideal candidates as building blocks in nano-electronic and electromechanical systems. However, their organization into well-defined geometries and arrays on surfaces remains a critical challenge for their integration into functional nanosystems. In my PhD, we developed a new approach for the organization of carbon nanotubes directed by crystal surfaces. The principle relies on the guided growth of single-wall carbon nanotubes (SWNTs) by atomic features presented on anisotropic substrates. We identified three different modes of surface-directed growth (or 'nanotube epitaxy'), in which the growth of carbon nanotubes is directed by crystal substrates: We first observed the nanotube unidirectional growth along atomic steps ('ledge-directed epitaxy') and nanofacets ('graphoepitaxy') on the surface of miscut C-plane sapphire and quartz. The orientation along crystallographic directions ('lattice-directed epitaxy') was subsequently observed by other groups on different crystals. We have proposed a "wake growth" mechanism for the nanotube alignment along atomic steps and nanofacets. In this mechanism, the catalyst nanoparticle slides along the step or facet, leaving the nanotube behind as a wake. In addition, we showed that the combination of surface-directed growth with external forces, such as electric-field and gas flow, can lead to the simultaneous formation of complex nanotube structures, such as grids and serpentines. The "wake growth" model, which explained the growth of aligned nanotubes, could not explain the formation of nanotube serpentines. For the latter, we proposed a "falling spaghetti" mechanism, in which the nanotube first grows by a free-standing process, aligned in the direction of the gas flow, then followed by absorption on the stepped surface in an oscillatory manner, due to the competition between the drag force caused by the gas flow on the suspended

  9. Electronic sensitivity of carbon nanotubes to internal water wetting.

    PubMed

    Cao, Di; Pang, Pei; He, Jin; Luo, Tao; Park, Jae Hyun; Krstic, Predrag; Nuckolls, Colin; Tang, Jinyao; Lindsay, Stuart

    2011-04-26

    We have constructed devices in which the interior of a single-walled carbon nanotube (SWCNT) field-effect transistor acts as a nanofluidic channel that connects two fluid reservoirs, permitting measurement of the electronic properties of the SWCNT as it is wetted by an analyte. Wetting of the inside of the SWCNT by water turns the transistor on, while wetting of the outside has little effect. These observations are consistent with theoretical simulations that show that internal water both generates a large dipole electric field, causing charge polarization of the tube and metal electrodes, and shifts the valence band of the SWCNT, while external water has little effect. This finding may provide a new method to investigate water behavior at nanoscale. This also opens a new avenue for building sensors in which the SWCNT simultaneously functions as a concentrator, nanopore, and extremely sensitive electronic detector, exploiting the enhanced sensitivity of the interior surface. PMID:21452854

  10. A modified structure for MOSFET-like carbon nanotube FET

    NASA Astrophysics Data System (ADS)

    Zeydi, Maryam Mirasanloo; Yousefi, Reza

    2016-04-01

    In this paper, non-equilibrium Green's function method is used to investigate the characteristics of carbon nanotube field-effect transistors (CNTFETs). Leakage current resulted from band-to-band tunneling, and ambipolarity behaviors are among the known effects for CNTFET devices. To minimize these phenomena, a modified structure is presented in which density of source and drain in the transistor is reduced in steps while going toward the intrinsic channel. The proposed structure shows a better ambipolar property and less power-delay product at a given I ON/ I OFF ratio, and also less delay time at a given I ON compared with the available structure. Also, its other ON- and OFF-state characteristics are almost intact. Afterward, the effect of different factors on the behavior of the device and their optimal values such as channel length changes, chirality, dielectric constant, and gate length changes are investigated.

  11. Carbon nanotube growth density control

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  12. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis

    2003-03-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Treating the distortion within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value g_c. The effective potential in the symmetry-broken state is found to have O(2) symmetry, in agreement with numerical calculations. The consequences of such a distortion on electronic transport will be discussed.

  13. A tunable carbon nanotube polarizer.

    PubMed

    Kang, Byeong Gyun; Lim, Young Jin; Jeong, Kwang-Un; Lee, Kyu; Lee, Young Hee; Lee, Seung Hee

    2010-10-01

    The electro-optic response of a carbon nanotube (CNT) cluster has been investigated. The cluster absorbs incident light before stretching. In the presence of an electric field, the cluster starts stretching along the field direction and contracts back to its original stage when the applied voltage is removed. The stretched cluster absorbs and transmits incident light with its electric vector propagating parallel and perpendicular to the long axis of the stretched cluster, respectively. Utilizing this selective light absorption property of a CNT cluster, a tunable polarizer or non-emissive light modulator can be realized. PMID:20829567

  14. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  15. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2006-12-12

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  16. Carbon nanotube cathode with capping carbon nanosheet

    NASA Astrophysics Data System (ADS)

    Li, Xin; Zhao, Dengchao; Pang, Kaige; Pang, Junchao; Liu, Weihua; Liu, Hongzhong; Wang, Xiaoli

    2013-10-01

    Here, we report a vertically aligned carbon nanotube (VACNT) film capped with a few layer of carbon nanosheet (FLCN) synthesized by chemical vapor deposition using a carbon source from iron phthalocyanine pyrolysis. The square resistance of the VACNT film is significantly reduced from 1500 Ω/□ to 300 Ω/□ when it is capped with carbon nanosheet. The VACNT capped with carbon nanosheet was transferred to an ITO glass substrate in an inverted configuration so that the carbon nanosheet served as a flexible transparent electrode at the bottom and the VACNT roots served as emission tips. Because all of the VACNTs start growing from a flat silicon substrate, the VACNT roots are very neat and uniform in height. A field emission test of the carbon nanosheet-capped VACNT film proved that the CNT roots show better uniformity in field emission and the carbon nanosheet cap could also potentially serve as a flexible transparent electrode, which is highly desired in photo-assisted field emission.

  17. Electrostatic gating in carbon nanotube aptasensors.

    PubMed

    Zheng, Han Yue; Alsager, Omar A; Zhu, Bicheng; Travas-Sejdic, Jadranka; Hodgkiss, Justin M; Plank, Natalie O V

    2016-07-14

    Synthetic DNA aptamer receptors could boost the prospects of carbon nanotube (CNT)-based electronic biosensors if signal transduction can be understood and engineered. Here, we report CNT aptasensors for potassium ions that clearly demonstrate aptamer-induced electrostatic gating of electronic conduction. The CNT network devices were fabricated on flexible substrates via a facile solution processing route and non-covalently functionalised with potassium binding aptamers. Monotonic increases in CNT conduction were observed in response to increasing potassium ion concentration, with a level of detection as low as 10 picomolar. The signal was shown to arise from a specific aptamer-target interaction that stabilises a G-quadruplex structure, bringing high negative charge density near the CNT channel. Electrostatic gating is established via the specificity and the sign of the current response, and by observing its suppression when higher ionic strength decreases the Debye length at the CNT-water interface. Sensitivity towards potassium and selectivity against other ions is demonstrated in both resistive mode and real time transistor mode measurements. The effective device architecture presented, along with the identification of clear response signatures, should inform the development of new electronic biosensors using the growing library of aptamer receptors. PMID:27376166

  18. Vibration, buckling and impact of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pentaras, Demetris

    Natural frequencies of the double and triple-walled carbon nanotubes are determined exactly and approximately for both types. Approximate solutions are found by using Bubnov-Galerkin and Petrov-Galerkin methods. For the first time explicit expressions are obtained for the natural frequencies of double and triple-walled carbon nanotubes for different combinations of boundary conditions. Comparison of the results with recent studies shows that the above methods constitute quick and effective alternative techniques to exact solution for studying the vibration properties of carbon nanotubes. The natural frequencies of the clamped-clamped double-walled carbon nanotubes are obtained; exact solution is provided and compared with the solution reported in the literature. In contrast to earlier investigation, an analytical criterion is derived to establish the behavior of the roots of the characteristic equation. Approximate Bubnov-Galerkin solution is also obtained to compare natural frequencies at the lower end of the spectrum. Simplified version of the Bresse-Timoshenko theory that incorporates the shear deformation and the rotary inertia is proposed for free vibration study of double-walled carbon nanotubes. It is demonstrated that the suggested set yields extremely accurate results for the lower spectrum of double-walled carbon nanotube. The natural frequencies of double-walled carbon nanotubes based on simplified versions of Donnell shell theory are also obtained. The buckling behavior of the double-walled carbon nanotubes under various boundary conditions is studied. First, the case of the simply supported double-walled carbon nanotubes at both ends is considered which is amenable to exact solution. Then, approximate methods of Bubnov-Galerkin and Petrov-Galerkin are utilized to check the efficacy of these approximations for the simply supported double-walled carbon nanotubes. Once the extreme accuracy is demonstrated for simply supported conditions, the approximate

  19. 2D Carbon Nanotube Network: A New material for Electronics

    NASA Astrophysics Data System (ADS)

    Gruner, George

    2006-03-01

    This talk will focus on the electronic properties of two dimensional carbon nanotube networks, and on their application potential. Percolation issues, together with the frequency, and temperature dependent activity will be discussed. The network can be tuned from having semiconducting to metallic like behavior, and doping with electron withdrawing and donating species leads to networks with tailor-made electronic properties. The network is also highly transparent in the visible spectral range, this attribute -- together with simple room temperature fab processes -- opens up application opportunities in the area of electronics, opto-electronics, photovoltaics and sensors. Recent results on solar cells, OLEDs and smart windows will be reviewed. Field effect transistors that incorporate nanotube network conducting channels, together with complex functional devices that incorporate networks and functional molecules will also be discussed. Finally a comparison will be made with conventional and emerging materials that compete area of disposable, flexible and printable electronics.

  20. Aligned carbon nanotubes: from controlled synthesis to electronic applications.

    PubMed

    Liu, Bilu; Wang, Chuan; Liu, Jia; Che, Yuchi; Zhou, Chongwu

    2013-10-21

    Single-wall carbon nanotubes (SWNTs) possess superior geometrical, electronic, chemical, thermal, and mechanical properties and are very attractive for applications in electronic devices and circuits. To make this a reality, the nanotube orientation, density, diameter, electronic property, and even chirality should be well controlled. This Feature article focuses on recent achievements researchers have made on the controlled growth of horizontally aligned SWNTs and SWNT arrays on substrates and their electronic applications. Principles and strategies to control the morphology, structure, and properties of SWNTs are reviewed in detail. Furthermore, electrical properties of field-effect transistors fabricated on both individual SWNTs and aligned SWNT arrays are discussed. State-of-the-art electronic devices and circuits based on aligned SWNTs and SWNT arrays are also highlighted. PMID:23969970

  1. Cutting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ziegler, Kirk J.; Gu, Zhenning; Shaver, Jonah; Chen, Zheyi; Flor, Erica L.; Schmidt, Daniel J.; Chan, Candace; Hauge, Robert H.; Smalley, Richard E.

    2005-07-01

    A two-step process is utilized for cutting single-walled carbon nanotubes (SWNTs). The first step requires the breakage of carbon-carbon bonds in the lattice while the second step is aimed at etching at these damage sites to create short, cut nanotubes. To achieve monodisperse lengths from any cutting strategy requires control of both steps. Room-temperature piranha and ammonium persulfate solutions have shown the ability to exploit the damage sites and etch SWNTs in a controlled manner. Despite the aggressive nature of these oxidizing solutions, the etch rate for SWNTs is relatively slow and almost no new sidewall damage is introduced. Carbon-carbon bond breakage can be introduced through fluorination to ~C2F, and subsequent etching using piranha solutions has been shown to be very effective in cutting nanotubes. The final average length of the nanotubes is approximately 100 nm with carbon yields as high as 70-80%.

  2. Development of Carbon-Nanotube/Polymer Composites

    NASA Technical Reports Server (NTRS)

    Reynolds, Thomas A.

    2005-01-01

    A report presents a short discussion of one company's effort to develop composites of carbon nanotubes in epoxy and other polymer matrices. The focus of the discussion is on the desirability of chemically modifying carbon nanotubes to overcome their inherent chemical nonreactivity and thereby enable the formation of strong chemical bonds between nanotubes and epoxies (or other polymeric matrix materials or their monomeric precursors). The chemical modification is effected in a process in which discrete functional groups are covalently attached to the nanotube surfaces. The functionalization process was proposed by the company and demonstrated in practice for the first time during this development effort. The covalently attached functional groups are capable of reacting with the epoxy or other matrix resin to form covalent bonds. Furthermore, the company uses this process to chemically modify the nanotube surfaces, affording tunable adhesion to polymers and solubility in select solvents. Flat-sheet composites containing functionalized nanotubes demonstrate significantly improved mechanical, thermal, and electrical properties.

  3. Si/Ge hetero-structure nanotube tunnel field effect transistor

    SciTech Connect

    Hanna, A. N.; Hussain, M. M.

    2015-01-07

    We discuss the physics of conventional channel material (silicon/germanium hetero-structure) based transistor topology mainly core/shell (inner/outer) gated nanotube vs. gate-all-around nanowire architecture for tunnel field effect transistor application. We show that nanotube topology can result in higher performance through higher normalized current when compared to nanowire architecture at V{sub dd} = 1 V due to the availability of larger tunneling cross section and lower Shockley-Reed-Hall recombination. Both architectures are able to achieve sub 60 mV/dec performance for more than five orders of magnitude of drain current. This enables the nanotube configuration achieving performance same as the nanowire architecture even when V{sub dd} is scaled down to 0.5 V.

  4. Directional dark matter searches with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Capparelli, L. M.; Cavoto, G.; Mazzilli, D.; Polosa, A. D.

    2015-09-01

    A new solution to the problem of dark matter directional detection might come from the use of large arrays of aligned carbon nanotubes. We calculate the expected rate of carbon ions channeled in single-wall nanotubes once extracted by the scattering with a massive dark matter particle. Depending on its initial kinematic conditions, the ejected carbon ion may be channeled in the nanotube array or stop in the bulk. The orientation of the array with respect to the direction of motion of the Sun has an appreciable effect on the channeling probability. This provides the required anisotropic response for a directional detector.

  5. Characterization of Carbon Nanotube Reinforced Nickel

    NASA Technical Reports Server (NTRS)

    Gill, Hansel; Hudson, Steve; Bhat, Biliyar; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Carbon nanotubes are cylindrical molecules composed of carbon atoms in a regular hexagonal arrangement. If nanotubes can be uniformly dispersed in a supporting matrix to form structural materials, the resulting structures could be significantly lighter and stronger than current aerospace materials. Work is currently being done to develop an electrolyte-based self-assembly process that produces a Carbon Nanotube/Nickel composite material with high specific strength. This process is expected to produce a lightweight metal matrix composite material, which maintains it's thermal and electrical conductivities, and is potentially suitable for applications such as advanced structures, space based optics, and cryogenic tanks.

  6. Methods for producing reinforced carbon nanotubes

    DOEpatents

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2008-10-28

    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  7. Carbon nanotube fiber spun from wetted ribbon

    DOEpatents

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  8. Application of carbon nanotubes and graphene for digital and analog electronics

    NASA Astrophysics Data System (ADS)

    Badmaev, Alexander

    2011-07-01

    Carbon nanomaterials, one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene, exhibit the highest electron mobility (˜100,000 cm 2/V/s at room temperature) among all conductors, and huge current carrying capacity of more than 109 A/cm2. Additionally, single-atomic thickness provides ideal electrostatic geometry for field effect devices. These properties make carbon nanomaterials to be strong candidates to replace or supplement conventional semiconductors. Theoretical and experimental studies on individual nanotubes and graphene flakes demonstrated superior performance of carbon based field-effect transistors (FETs). However, in order to realize this potential in electronic applications, scalable synthesis and assembly of carbon nanomaterials, as well as further devices design and fabrication, still remain to be a significant challenge. In this thesis, I present our developments in order to overcome some of the critical problems in practical implementation of carbon based electronics. In our approaches, we address issues starting from the scalable controllable synthesis of carbon nanomaterials and their assembly, including design of electronic devices and material methods for their fabrication, and, finally, integration of these devices into functional circuits. This broad range of issues is tightly and often inseparably inter-connected with each other, as can be seen from an example of very large scale integrated (VLSI) silicon electronics, therefore, ultimately presenting one major goal of developing carbon based electronics. The structure of the thesis is as follows. Chapter 1 gives introduction to nano-scale carbon materials, their electronic properties and problems towards realization of carbon-based electronics. Chapter 2 presents chemical vapor deposition (CVD) methods for synthesis of carbon nanotubes and graphene. CVD synthesis methods proved to be highly promising for large scale synthesis of high quality carbon nanomaterials. The

  9. Carbon Nanotubes for Human Space Flight

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Files, Brad; Yowell, Leonard

    2003-01-01

    Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

  10. Defect-Free Carbon Nanotube Coils.

    PubMed

    Shadmi, Nitzan; Kremen, Anna; Frenkel, Yiftach; Lapin, Zachary J; Machado, Leonardo D; Legoas, Sergio B; Bitton, Ora; Rechav, Katya; Popovitz-Biro, Ronit; Galvão, Douglas S; Jorio, Ado; Novotny, Lukas; Kalisky, Beena; Joselevich, Ernesto

    2016-04-13

    Carbon nanotubes are promising building blocks for various nanoelectronic components. A highly desirable geometry for such applications is a coil. However, coiled nanotube structures reported so far were inherently defective or had no free ends accessible for contacting. Here we demonstrate the spontaneous self-coiling of single-wall carbon nanotubes into defect-free coils of up to more than 70 turns with identical diameter and chirality, and free ends. We characterize the structure, formation mechanism, and electrical properties of these coils by different microscopies, molecular dynamics simulations, Raman spectroscopy, and electrical and magnetic measurements. The coils are highly conductive, as expected for defect-free carbon nanotubes, but adjacent nanotube segments in the coil are more highly coupled than in regular bundles of single-wall carbon nanotubes, owing to their perfect crystal momentum matching, which enables tunneling between the turns. Although this behavior does not yet enable the performance of these nanotube coils as inductive devices, it does point a clear path for their realization. Hence, this study represents a major step toward the production of many different nanotube coil devices, including inductors, electromagnets, transformers, and dynamos. PMID:26708150

  11. Carbon nanotubes and nucleic acids: tools and targets

    NASA Astrophysics Data System (ADS)

    Onoa, Bibiana; Zheng, Ming; Dresselhaus, Mildred S.; Diner, Bruce A.

    2006-05-01

    Nucleic acids, with their intrinsic structural properties as well as their high specificity, are playing an important role in the rapid development of nano-technologies. In turn, these new technologies and their efficient performance enable fast and precise methods for detection of nucleic acids, improving the diagnosis of diseases and identification of pathogens. We discuss the use of nucleic acids to disperse and sort single walled carbon nanotubes (SWNTs), and carbon nanotube-based field effect transistors (CNT-FETs) to electrically detect specific nucleic acid sequences. Both DNA and RNA are efficient agents for dispersion and separation of SWNTs by diameter and chirality. Fractions enriched in a narrow band gap distribution of DNA:SWNT hybrids do not alter the electronic performance of field effect transistors. A CNT-FET fulfills the requirements for a nanosensing device that can greatly exceed the existing technologies. Electrical detection of specific nucleic acid sequence could potentially overcome the current limitations of optical detection, by increasing sensitivity and speed, while reducing sample manipulation, size, and cost.

  12. Applications and production of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hafner, Jason Howard

    Carbon nanotubes, a recently discovered form of carbon fiber with structural perfection similar to that of a fullerene molecule, have interesting electronic, chemical and mechanical properties due to their size and structure. Nanotubes have great potential as a bulk material for strong, lightweight composite materials, and as individual nano-scale tools or devices. Initial work on applications with individual multiwalled nanotubes as field emission sources and scanning force microscopy tips is described. The nanotubes display intriguing field emission behavior interpreted as the nanotube unraveling under the influence of the electric field. The unraveling process is believed to result in facile field emission from linear atomic carbon chains at the end of the nanotube. Such atomic wires represent an excellent field emitter. The work on multiwalled nanotube SFM tips was equally encouraging. The high aspect ratio of the nanotube allows it to image deep trenches inaccessible to commercially available Si pyramidal tips, and it reduces the interaction with the ambient water layer on the sample which perturbs image quality. The most remarkable advantage of nanotube SFM tips is a result of their mechanical properties. It was found that the nanotubes will remain rigid during normal imaging, but conveniently buckle to the side if circumstances arise which create large forces known to damage the tip and sample. This feature makes the tip more durable than Si tips, and is especially important for soft biological samples. In these two applications, as well as others, and in the measurements of novel nanotube properties, high quality, small diameter (0.5 to 2 nm) diameter single-walled nanotubes are most interesting. Such material can be produced slowly and in small amounts by catalytic arc vaporization and catalytic laser vaporization of graphite. It is well known that nanotubes can be mass produced by catalytic chemical vapor deposition (CCVD), but the product consists only

  13. Quantum conductance of carbon nanotube peapods

    SciTech Connect

    Yoon, Young-Gui; Mazzoni, Mario S.C.; Louie, Steven G.

    2003-08-01

    We present a first-principles study of the quantum conductance of hybrid nanotube systems consisting of single-walled carbon nanotubes (SWCNTs) encapsulating either an isolated single C60 molecule or a chain of C60 molecules (nanotube peapods). The calculations show a rather weak bonding interaction between the fullerenes and the SWCNTs. The conductance of a (10,10) SWCNT with a single C60 molecule is virtually unaffected at the Fermi level, but exhibits quantized resonant reductions at the molecular levels. The nanotube peapod arrangement gives rise to high density of states for the fullerene highest occupied molecular orbital and lowest unoccupied molecular orbital bands.

  14. Flightweight Carbon Nanotube Magnet Technology

    NASA Technical Reports Server (NTRS)

    Chapman, J. N.; Schmidt, H. J.; Ruoff, R. S.; Chandrasekhar, V.; Dikin, D. A.; Litchford, R. J.

    2003-01-01

    Virtually all plasma-based systems for advanced airborne/spaceborne propulsion and power depend upon the future availability of flightweight magnet technology. Unfortunately, current technology for resistive and superconducting magnets yields system weights that tend to counteract the performance advantages normally associated with advanced plasma-based concepts. The ongoing nanotechnology revolution and the continuing development of carbon nanotubes (CNT), however, may ultimately relieve this limitation in the near future. Projections based on recent research indicate that CNTs may achieve current densities at least three orders of magnitude larger than known superconductors and mechanical strength two orders of magnitude larger than steel. In fact, some published work suggests that CNTs are superconductors. Such attributes imply a dramatic increase in magnet performance-to-weight ratio and offer real hope for the construction of true flightweight magnets. This Technical Publication reviews the technology status of CNTs with respect to potential magnet applications and discusses potential techniques for using CNT wires and ropes as a winding material and as an integral component of the containment structure. The technology shortfalls are identified and a research and technology strategy is described that addresses the following major issues: (1) Investigation and verification of mechanical and electrical properties, (2) development of tools for manipulation and fabrication on the nanoscale, (3) continuum/molecular dynamics analysis of nanotube behavior when exposed to practical bending and twisting loads, and (4) exploration of innovative magnet fabrication techniques that exploit the natural attributes of CNTs.

  15. Multiwall carbon nanotube microcavity arrays

    NASA Astrophysics Data System (ADS)

    Ahmed, Rajib; Rifat, Ahmmed A.; Yetisen, Ali K.; Dai, Qing; Yun, Seok Hyun; Butt, Haider

    2016-03-01

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm2) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170-180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  16. Functionalization of carbon nanotubes with silver clusters

    NASA Astrophysics Data System (ADS)

    Cveticanin, Jelena; Krkljes, Aleksandra; Kacarevic-Popovic, Zorica; Mitric, Miodrag; Rakocevic, Zlatko; Trpkov, Djordje; Neskovic, Olivera

    2010-09-01

    In this paper, an advanced method of one-step functionalization of single and multi walled carbon nanotubes (SWCNTs and MWCNTs) using γ-irradiation was described. Two synthesis procedures, related with different reduction species, were employed. For the first time, poly(vinyl alcohol) PVA is successfully utilized as a source to reduce silver (Ag) metal ions without having any additional reducing agents to obtain Ag nanoparticles on CNTs. The decoration of carbon nanotubes with Ag nanoparticles takes place through anchoring of (PVA) on nanotube's surface. Optical properties of as-prepared samples and mechanism responsible for the functionalization of carbon nanotubes were investigated using UV-vis and FTIR spectroscopy, respectively. Decorated carbon nanotubes were visualized using microscopic techniques: transmission electron microscopy and scanning tunneling microscopy. Also, the presence of Ag on the nanotubes was confirmed using energy dispersive X-ray spectroscopy. This simple and effective method of making a carbon nanotube type of composites is of interest not only for an application in various areas of technology and biology, but for investigation of the potential of radiation technology for nanoengineering of materials.

  17. Carbon Nanotube Composites: Strongest Engineering Material Ever?

    NASA Technical Reports Server (NTRS)

    Mayeaux, Brian; Nikolaev, Pavel; Proft, William; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    The primary goal of the carbon nanotube project at Johnson Space Center (JSC) is to fabricate structural materials with a much higher strength-to-weight ratio than any engineered material today, Single-wall nanotubes present extraordinary mechanical properties along with new challenges for materials processing. Our project includes nanotube production, characterization, purification, and incorporation into applications studies. Now is the time to move from studying individual nanotubes to applications work. Current research at JSC focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. These nanoscale fibers present unique new challenges to composites engineers. Preliminary studies show good nanotube dispersion and wetting by the epoxy materials. Results of tensile strength tests will also be reported. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical uses.

  18. Purification of Carbon Nanotubes: Alternative Methods

    NASA Technical Reports Server (NTRS)

    Files, Bradley; Scott, Carl; Gorelik, Olga; Nikolaev, Pasha; Hulse, Lou; Arepalli, Sivaram

    2000-01-01

    Traditional carbon nanotube purification process involves nitric acid refluxing and cross flow filtration using surfactant TritonX. This is believed to result in damage to nanotubes and surfactant residue on nanotube surface. Alternative purification procedures involving solvent extraction, thermal zone refining and nitric acid refiuxing are used in the current study. The effect of duration and type of solvent to dissolve impurities including fullerenes and P ACs (polyaromatic compounds) are monitored by nuclear magnetic reasonance, high performance liquid chromatography, and thermogravimetric analysis. Thermal zone refining yielded sample areas rich in nanotubes as seen by scanning electric microscopy. Refluxing in boiling nitric acid seem to improve the nanotube content. Different procedural steps are needed to purify samples produced by laser process compared to arc process. These alternative methods of nanotube purification will be presented along with results from supporting analytical techniques.

  19. Deconvoluting hepatic processing of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  20. Functionalized carbon nanotubes: biomedical applications

    PubMed Central

    Vardharajula, Sandhya; Ali, Sk Z; Tiwari, Pooja M; Eroğlu, Erdal; Vig, Komal; Dennis, Vida A; Singh, Shree R

    2012-01-01

    Carbon nanotubes (CNTs) are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity. PMID:23091380

  1. Carbon Nanotube Based Light Sensor

    NASA Technical Reports Server (NTRS)

    Wincheski, russell A. (Inventor); Smits, Jan M. (Inventor); Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Ingram, JoAnne L. (Inventor)

    2006-01-01

    A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of electrically non-conductive material with the CNT-based conductors being distributed in a spaced apart fashion about a periphery of the first electrode. Each CNT-based conductor is coupled on one end thereof to the first electrode and extends away from the first electrode to terminate at a second free end. A second or gate electrode is positioned on the non-conductive material layer and is spaced apart from the second free end of each CNT-based conductor. Coupled to the first and second electrode is a device for detecting electron transfer along the CNT-based conductors resulting from light impinging on the CNT-based conductors.

  2. Photonics based on carbon nanotubes

    PubMed Central

    2013-01-01

    Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the efficiency and power consumption of saturable absorbers (SAs) based on SWCNT with SA based on conventional multiple quantum wells. For active applications, exceptional photoluminescence properties of SWCNT, such as excellent light-emission stabilities with temperature and excitation power, hold these nanometer-scale materials as prime candidates for future active photonics devices with superior performances. PMID:23803293

  3. Photonics based on carbon nanotubes.

    PubMed

    Gu, Qingyuan; Gicquel-Guézo, Maud; Loualiche, Slimane; Pouliquen, Julie Le; Batte, Thomas; Folliot, Hervé; Dehaese, Olivier; Grillot, Frederic; Battie, Yann; Loiseau, Annick; Liang, Baolai; Huffaker, Diana

    2013-01-01

    Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the efficiency and power consumption of saturable absorbers (SAs) based on SWCNT with SA based on conventional multiple quantum wells. For active applications, exceptional photoluminescence properties of SWCNT, such as excellent light-emission stabilities with temperature and excitation power, hold these nanometer-scale materials as prime candidates for future active photonics devices with superior performances. PMID:23803293

  4. Carbon nanotube polymer composition and devices

    DOEpatents

    Liu, Gao; Johnson, Stephen; Kerr, John B.; Minor, Andrew M.; Mao, Samuel S.

    2011-06-14

    A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

  5. Carbon nanotube heat-exchange systems

    DOEpatents

    Hendricks, Terry Joseph; Heben, Michael J.

    2008-11-11

    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  6. Quantum Transport of Electrons through Graphene and Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Das, Shambhu K.

    Quantum transport of electrons through graphene has attracted increased interest in the field of nano-technology. Quantum transport through mesoscopic systems explains a wide range of interesting experimental findings, such as: rectification, switching mechanism and transistor actions. We focused our research on the quantum transmission of electrons through graphene and carbon nanotubes. Graphene and nanotube devices operated between source and drain shows a peculiar negative differential resistance behavior (NDR) while drawing current-voltage characteristics. This property is used in many electronic devices. The main feature of graphene is that the electron has zero effective mass at Dirac points, but gains mass when the graphene sheet is folded into a nanotube. Scientists have analyzed the vanishing mass of the electron inside graphene and explain the observed mass gain through Higgs mechanism. We focus our study on the Klein Paradox which deals with the reflection probability greater than one as well as a negative transmission probability. This has been predicted by Oscar Klein and remained a mystery until 1929; the Klein Paradox finally was proven with experimental and theoretical evidence by Geim and Novoselov. In the case of graphene, conductivity is an exponential function of temperature, whereas nanotubes follow a power law. This is a very characteristic feature of quantum dots.

  7. Development of a Taste Sensor Based on a Carbon Nanotube-Polymer Composite Material

    NASA Astrophysics Data System (ADS)

    Hirata, Takamichi; Takagi, Keisuke; Akiya, Masahiro

    2007-04-01

    A taste sensor consisting of a back-gate type field effect transistor (FET) chip based on carbon nanotube compound materials [poly(ethylene glycol) (PEG)-grafted single-walled carbon nanotubes (PEG-SWNTs)] was developed. The results of impedance measurements for five tastes (sourness, saltiness, bitterness, sweetness, and umami), are shown much difference for specific tastes which are difficult to identify by using Langmuir-Blodgett (LB) film. Moreover, the sensor is able to distinguish most of the experimental taste materials with a short response time (˜60 s).

  8. Fundamental optical processes in armchair carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hároz, Erik H.; Duque, Juan G.; Tu, Xiaomin; Zheng, Ming; Hight Walker, Angela R.; Hauge, Robert H.; Doorn, Stephen K.; Kono, Junichiro

    2013-01-01

    Single-wall carbon nanotubes provide ideal model one-dimensional (1-D) condensed matter systems in which to address fundamental questions in many-body physics, while, at the same time, they are leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been recently paid to their optical properties, arising from 1-D excitons and phonons, which have been revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting carbon nanotubes. On the other hand, dynamical properties of metallic nanotubes have been poorly explored, although they are expected to provide a novel setting for the study of electron-hole pairs in the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes are truly gapless with massless carriers, ideally suited for dynamical studies of Tomonaga-Luttinger liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use post-synthesis separation methods based on density gradient ultracentrifugation and DNA-based ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes. Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic and unambiguous evidence that density gradient ultracentrifugation can enrich ensemble samples in armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the near-infrared and visible range, we show that interband absorption in armchair nanotubes is strongly excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of the broad, lower frequency (G-) feature is a result of resonance with non-armchair ``metallic'' nanotubes. These findings regarding the fundamental optical absorption and scattering processes in metallic carbon nanotubes

  9. Controlled Deposition and Alignment of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Ingram, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2009-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the . substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carver liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to The CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  10. Controlled Deposition and Alignment of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2012-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  11. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N; Geohegan, David Bruce

    2013-10-29

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  12. Filling of carbon nanotubes and nanofibres

    PubMed Central

    Gately, Reece D

    2015-01-01

    Summary The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications. PMID:25821693

  13. Method for manufacturing high quality carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Benavides, Jeanette M. (Inventor)

    2006-01-01

    A non-catalytic process for the production of carbon nanotubes includes supplying an electric current to a carbon anode and a carbon cathode which have been securely positioned in the open atmosphere with a gap between them. The electric current creates an electric arc between the carbon anode and the carbon cathode, which causes carbon to be vaporized from the carbon anode and a carbonaceous residue to be deposited on the carbon cathode. Inert gas is pumped into the gap to flush out oxygen, thereby preventing interference with the vaporization of carbon from the anode and preventing oxidation of the carbonaceous residue being deposited on the cathode. The anode and cathode are cooled while electric current is being supplied thereto. When the supply of electric current is terminated, the carbonaceous residue is removed from the cathode and is purified to yield carbon nanotubes.

  14. Method for nano-pumping using carbon nanotubes

    DOEpatents

    Insepov, Zeke; Hassanein, Ahmed

    2009-12-15

    The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

  15. Separated Carbon Nanotube Macroelectronics for Active Matrix Organic Light-Emitting Diode Displays

    NASA Astrophysics Data System (ADS)

    Fu, Yue; Zhang, Jialu; Wang, Chuan; Chen, Pochiang; Zhou, Chongwu

    2012-02-01

    Active matrix organic light-emitting diode (AMOLED) display holds great potential for the next generation visual technologies due to its high light efficiency, flexibility, lightweight, and low-temperature processing. However, suitable thin-film transistors (TFTs) are required to realize the advantages of AMOLED. Pre-separated, semiconducting enriched carbon nanotubes are excellent candidates for this purpose because of their excellent mobility, high percentage of semiconducting nanotubes, and room-temperature processing compatibility. Here we report, for the first time, the demonstration of AMOLED displays driven by separated nanotube thin-film transistors (SN-TFTs) including key technology components such as large-scale high-yield fabrication of devices with superior performance, carbon nanotube film density optimization, bilayer gate dielectric for improved substrate adhesion to the deposited nanotube film, and the demonstration of monolithically integrated AMOLED display elements with 500 pixels driven by 1000 SN-TFTs. Our approach can serve as the critical foundation for future nanotube-based thin-film display electronics.

  16. Separated carbon nanotube macroelectronics for active matrix organic light-emitting diode displays.

    PubMed

    Zhang, Jialu; Fu, Yue; Wang, Chuan; Chen, Po-Chiang; Liu, Zhiwei; Wei, Wei; Wu, Chao; Thompson, Mark E; Zhou, Chongwu

    2011-11-01

    Active matrix organic light-emitting diode (AMOLED) display holds great potential for the next generation visual technologies due to its high light efficiency, flexibility, lightweight, and low-temperature processing. However, suitable thin-film transistors (TFTs) are required to realize the advantages of AMOLED. Preseparated, semiconducting enriched carbon nanotubes are excellent candidates for this purpose because of their excellent mobility, high percentage of semiconducting nanotubes, and room-temperature processing compatibility. Here we report, for the first time, the demonstration of AMOLED displays driven by separated nanotube thin-film transistors (SN-TFTs) including key technology components, such as large-scale high-yield fabrication of devices with superior performance, carbon nanotube film density optimization, bilayer gate dielectric for improved substrate adhesion to the deposited nanotube film, and the demonstration of monolithically integrated AMOLED display elements with 500 pixels driven by 1000 SN-TFTs. Our approach can serve as the critical foundation for future nanotube-based thin-film display electronics. PMID:21942351

  17. Fabrication of nylon-6/carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Xu, C.; Jia, Z.; Wu, D.; Han, Q.; Meek, T.

    2006-05-01

    A new technique to fabricate nylon-6/carbon nanotube (PA6/CNT) composites is presented. The method involves a pretreatment of carbon nanotubes synthesized by catalytic pyrolysis of hydrocarbon and an improved in-situ process for mixing nanotubes with the nylon 6 matrix. A good bond between carbon nanotubes and the nylon-6 matrix is obtained. Mechanical property measurements indicate that the tensile strength of PA6/CNT composites is improved significantly while the toughness and elongation are somewhat compromised. Scanning electron microscopy (SEM) analysis of the fractured tensile specimens reveals cracking initiated at the wrapping of the CNTs PA6 layer/PA6 matrix interface rather than at the PA6/CNT interface.

  18. Carbon Nanotube Based Microfluidic Elements for Filtration and Concentration

    SciTech Connect

    Bakajin, O; Ben-Barak, N; Peng, J; Noy, A

    2003-06-25

    We have developed a method for integration of patterned arrays of carbon nanotubes or the ''nanotube mesh'' into microfabricated channels. The method includes standard lithographic methods for patterning and etching the substrate, followed by catalyst patterning, CVD deposition of nanotubes, and anodic bonding of coverslip top. We will describe a carbon nanotube filtering device fabricated using this method and discuss the use of carbon nanotube arrays as molecular concentration and separation media.

  19. Polymerization initated at sidewalls of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  20. Liquid crystal-carbon nanotubes mixtures

    NASA Astrophysics Data System (ADS)

    Popa-Nita, V.; Kralj, S.

    2010-01-01

    The self-organizing properties of nematic liquid crystals (LCs) can be used to align carbon nanotubes (CNTs) dispersed in them. In the previous paper [P. van der Schoot, V. Popa-Nita, and S. Kralj, J. Phys. Chem. B 112, 4512 (2008)], we have considered the weak anchoring limit of the nematic LC molecules at the nanotube's surface, where the CNT alignment is caused by the anisotropic interfacial tension of the nanotubes in the nematic host fluid. In this paper, we present the theoretical results obtained for strong enough anchoring at the CNT-LC interface for which the nematic ordering around nanotube is apparently distorted. Consequently, relatively strong long-range and anisotropic interactions can emerge within the system. In order to get insight into the impact of LC ordering on the alignment of nanotubes we treat the two mixture components on the same footing and combine Landau-de Gennes free energy for the thermotropic ordering of the liquid crystal and Doi free energy for lyotropic nematic ordering of carbon nanotubes caused by their mutually excluded volume. The phase ordering of the binary mixture is analyzed as a function of the volume fraction of the carbon nanotubes, the strength of coupling, and the temperature. We find that the degree of ordering of the nanorods can be tuned by raising or lowering the temperature or by increasing or decreasing their concentration.

  1. Carbon linear chains inside multiwalled nanotubes

    NASA Astrophysics Data System (ADS)

    Cazzanelli, E.; Caputi, L.; Castriota, M.; Cupolillo, A.; Giallombardo, C.; Papagno, L.

    2007-09-01

    Multiwalled carbon nanotubes have been deposited on graphite cathodes by using an arc discharge technique in He atmosphere, with the insertion of a catalytic Ni-Cr mixture as well as without catalysers. The topography of such deposition has been investigated by SEM, while a parallel micro-Raman study has revealed, in particular regions of the deposited cathodes, strong bands in the range 1780-1860 cm -1, assignable to linear carbon chains inside the nanotubes. The variation of intensity, frequency and bandwidth of such bands has been investigated, in relation with the spectral characters of the host multiwalled carbon nanotube. In the cathode deposited without catalyst a quite ordered configuration of multiwalled carbon nanotubes is obtained in the central zone, while the maximum concentration of linear carbon chains is found in a ring shaped zone just inside the border. In sample obtained with catalyst the deposited multiwalled carbon nanotubes appear always more disordered, and a remarkable concentration of carbon chains appears in some zones, with a more casual distribution.

  2. Modeling of carbon nanotubes and carbon nanotube-polymer composites

    NASA Astrophysics Data System (ADS)

    Pal, G.; Kumar, S.

    2016-01-01

    In order to meet stringent environmental, safety and performance requirements from respective regulatory bodies, various technology-based industries are promoting the use of advanced carbon nanotube (CNT) reinforced lightweight and high strength polymer nanocomposites (PNCs) as a substitute to conventional materials both in structural and non-structural applications. The superior mechanical properties of PNCs made up of CNTs or bundles of CNTs can be attributed to the interfacial interaction between the CNTs and matrix, CNT's morphologies and to their uniform dispersion in the matrix. In PNCs, CNTs physically bond with polymeric matrix at a level where the assumption of continuum level interactions is not applicable. Modeling and prediction of mechanical response and failure behavior of CNTs and their composites becomes a complex task and is dealt with the help of up-scale modeling strategies involving multiple spatial and temporal scales in hierarchical or concurrent manner. Firstly, the article offers an insight into various modeling techniques in studying the mechanical response of CNTs; namely, equivalent continuum approach, quasi-continuum approach and molecular dynamics (MD) simulation. In the subsequent steps, these approaches are combined with analytical and numerical micromechanics models in a multiscale framework to predict the average macroscopic response of PNCs. The review also discusses the implementation aspects of these computational approaches, their current status and associated challenges with a future outlook.

  3. Carbon Nanotube and Graphene Nanoelectromechanical Systems

    NASA Astrophysics Data System (ADS)

    Aleman, Benjamin Jose

    One-dimensional and two-dimensional forms of carbon are composed of sp 2-hybridized carbon atoms arranged in a regular hexagonal, honeycomb lattice. The two-dimensional form, called graphene, is a single atomic layer of hexagonally-bonded carbon atoms. The one-dimensional form, known as a carbon nanotube, can be conceptualized as a rectangular piece of graphene wrapped into a seamless, high-aspect-ratio cylinder or tube. This dissertation addresses the physics and applied physics of these one and two-dimensional carbon allotropes in nanoelectromechanical systems (NEMS). First, we give a theoretical background on the electrodynamics and mechanics of carbon nanotube NEMS. We then describe basic experimental techniques, such as electron and scanning probe microscopy, that we then use to probe static and dynamic mechanical and electronic behavior of the carbon nanotube NEMS. For example, we observe and control non-linear beam bending and single-electron quantum tunneling effects in carbon nanotube resonators. We then describe parametric amplification, self-oscillation behavior, and dynamic, non-linear effects in carbon nanotube mechanical resonators. We also report a novel approach to fabricate carbon nanotube atomic force microscopy (AFM) probes, and show that they can lead to exceptional lateral resolution enhancement in AFM when imaging both hard and soft (biological) materials. Finally, we describe novel fabrication techniques for large-area, suspended graphene membranes, and utilize these membranes as TEM-transparent, AFM-compatible, NEMS resonators. Laser-driven mechanical vibrations of the graphene resonators are detected by optical interferometry and several vibration harmonics are observed. A degeneracy splitting is observed in the vibrational modes of square-geometry resonators. We then attribute the observed degeneracy splitting to local mass inhomogeneities and membrane defects, and find good overall agreement with the developed theoretical model.

  4. Splitting and joining in carbon nanotube/nanoribbon/nanotetrahedron growth.

    PubMed

    Hasegawa, Takayuki; Kohno, Hideo

    2015-02-01

    We report a novel phenomenon for carbon nanotube growth that results in a new carbon nanotube morphology. A carbon nanotube grown via metal nanoparticle-catalyzed chemical vapor deposition splits into two flattened nanotubes during growth and the two flattened nanotubes merge to form a ring of carbon nanotube/nanoribbon. This novel process is revealed by transmission electron microscopy observations of the carbon nanostructures. We propose that the splitting-and-joining process involves only one metal catalyst nanoparticle and a self-folding mechanism that we have named the origami mechanism to explain the process and the formation of nanoribbons and nanotetrahedra. PMID:25559588

  5. Selective Functionalization of Carbon Nanotubes: Part II

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya; Khare, Bishun

    2010-01-01

    An alternative method of low-temperature plasma functionalization of carbon nanotubes provides for the simultaneous attachment of molecular groups of multiple (typically two or three) different species or different mixtures of species to carbon nanotubes at different locations within the same apparatus. This method is based on similar principles, and involves the use of mostly the same basic apparatus, as those of the methods described in "Low-Temperature Plasma Functionalization of Carbon Nanotubes" (ARC-14661-1), NASA Tech Briefs, Vol. 28, No. 5 (May 2004), page 45. The figure schematically depicts the basic apparatus used in the aforementioned method, with emphasis on features that distinguish the present alternative method from the other. In this method, one exploits the fact that the composition of the deposition plasma changes as the plasma flows from its source in the precursor chamber toward the nanotubes in the target chamber. As a result, carbon nanotubes mounted in the target chamber at different flow distances (d1, d2, d3 . . .) from the precursor chamber become functionalized with different species or different mixtures of species. In one series of experiments to demonstrate this method, N2 was used as the precursor gas. After the functionalization process, the carbon nanotubes from three different positions in the target chamber were examined by Fourier-transform infrared spectroscopy to identify the molecular groups that had become attached. On carbon nanotubes from d1 = 1 cm, the attached molecular groups were found to be predominantly C-N and C=N. On carbon nanotubes from d2 = 2.5 cm, the attached molecular groups were found to be predominantly C-(NH)2 and/or C=NH2. (The H2 was believed to originate as residual hydrogen present in the nanotubes.) On carbon nanotubes from d3 = 7 cm no functionalization could be detected - perhaps, it was conjectured, because this distance is downstream of the plasma source, all of the free ions and free radicals of

  6. New carbon nanotube antenna array simulation and fabrication

    NASA Astrophysics Data System (ADS)

    Zareie, Hosein; Davoudzadeh, Nima; Koohsorkhi, Javad; Mohajerzadeh, Shamsoddin; Rouhi, Nima

    2009-03-01

    A novel THz antenna structure, made of carbon nanotube arrays is suggested. Using CST MICROWAVE STUDIO (CST MWS), the capabilities of carbon nanotube terahertz (THz) antenna arrays have been simulated and this CNT antenna array has been fabricated.

  7. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  8. Conformational changes of fibrinogen in dispersed carbon nanotubes

    PubMed Central

    Park, Sung Jean; Khang, Dongwoo

    2012-01-01

    The conformational changes of plasma protein structures in response to carbon nanotubes are critical for determining the nanotoxicity and blood coagulation effects of carbon nanotubes. In this study, we identified that the functional intensity of carboxyl groups on carbon nanotubes, which correspond to the water dispersity or hydrophilicity of carbon nanotubes, can induce conformational changes in the fibrinogen domains. Also, elevation of carbon nanotube density can alter the secondary structures (ie, helices and beta sheets) of fibrinogen. Furthermore, fibrinogen that had been in contact with the nanoparticle material demonstrated a different pattern of heat denaturation compared with free fibrinogen as a result of a variation in hydrophilicity and concentration of carbon nanotubes. Considering the importance of interactions between carbon nanotubes and plasma proteins in the drug delivery system, this study elucidated the correlation between nanoscale physiochemical material properties of carbon nanotubes and associated structural changes in fibrinogen. PMID:22915854

  9. Release characteristics of selected carbon nanotube polymer composites

    EPA Science Inventory

    Multi-walled carbon nanotubes (MWCNTs) are commonly used in polymer formulations to improve strength, conductivity, and other attributes. A developing concern is the potential for carbon nanotube polymer nanocomposites to release nanoparticles into the environment as the polymer ...

  10. Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications

    NASA Technical Reports Server (NTRS)

    Thibeault, S. (Technical Monitor); Vaidyanathan, Ranji

    2004-01-01

    This viewgraph presentation provides information on the use of Extrusion Freeform Fabrication (EEF) for the fabrication of carbon nanotubes. The presentation addresses TGA analysis, Raman spectroscopy, radiation tests, and mechanical properties of the carbon nanotubes.

  11. Carbon Nanotube Tower-Based Supercapacitor

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya (Inventor)

    2012-01-01

    A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

  12. Carbon Nanotube-Based Permeable Membranes

    SciTech Connect

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  13. Agglomeration defects on irradiated carbon nanotubes

    SciTech Connect

    Steini Moura, Cassio; Balzaretti, Naira Maria; Amaral, Livio; Gribel Lacerda, Rodrigo; Pimenta, Marcos A.

    2012-03-15

    Aligned carbon nanotubes (CNT) were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  14. Electromagnetic SERS effect in carbon nanotube systems

    NASA Astrophysics Data System (ADS)

    Bondarev, I. V.; Gulyuk, A. V.

    2015-11-01

    Quantum electrodynamics theory of the resonance Raman scattering is developed for an atom in a close proximity to a carbon nanotube. The theory describes both weak and strong atomic coupling to nanotube plasmon near fields, and predicts a dramatic enhancement of the Raman intensity in the strong coupling regime. This resonance scattering is a manifestation of the surface enhanced Raman scattering effect, and can be used in designing efficient nanotube based optical sensing substrates for single atom detection, precision spontaneous emission control, and manipulation.

  15. Localized Excitons in Carbon Nanotubes.

    NASA Astrophysics Data System (ADS)

    Adamska, Lyudmyla; Doorn, Stephen K.; Tretiak, Sergei

    2015-03-01

    It has been historically known that unintentional defects in carbon nanotubes (CNTs) may fully quench the fluorescence. However, some dopants may enhance the fluorescence by one order of magnitude thus turning the CNTs, which are excellent light absorbers, in good emitters. We have correlated the experimentally observed photoluminescence spectra to the electronic structure simulations. Our experiment reveals multiple sharp asymmetric emission peaks at energies 50-300 meV red-shifted from that of the lowest bright exciton peak. Our simulations suggest an association of these peaks with deep trap states tied to different specific chemical adducts. While the wave functions of excitons in undoped CNTs are delocalized, those of the deep-trap states are strongly localized and pinned to the dopants. These findings are consistent with the experimental observation of asymmetric broadening of the deep trap emission peaks, which can result from scattering of acoustic phonons on localized excitons. Our work lays the foundation to utilize doping as a generalized route for wave function engineering and direct control of carrier dynamics in SWCNTs toward enhanced light emission properties for photonic applications.

  16. Bending fracture in carbon nanotubes.

    PubMed

    Kuo, Wen-Shyong; Lu, Hsin-Fang

    2008-12-10

    A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed. PMID:21730690

  17. Thermal Transport in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

    2011-10-01

    Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

  18. Carbon nanotube fiber terahertz polarizer

    NASA Astrophysics Data System (ADS)

    Zubair, Ahmed; Tsentalovich, Dmitri E.; Young, Colin C.; Heimbeck, Martin S.; Everitt, Henry O.; Pasquali, Matteo; Kono, Junichiro

    2016-04-01

    Conventional, commercially available terahertz (THz) polarizers are made of uniformly and precisely spaced metallic wires. They are fragile and expensive, with performance characteristics highly reliant on wire diameters and spacings. Here, we report a simple and highly error-tolerant method for fabricating a freestanding THz polarizer with nearly ideal performance, reliant on the intrinsically one-dimensional character of conduction electrons in well-aligned carbon nanotubes (CNTs). The polarizer was constructed on a mechanical frame over which we manually wound acid-doped CNT fibers with ultrahigh electrical conductivity. We demonstrated that the polarizer has an extinction ratio of ˜-30 dB with a low insertion loss (<0.5 dB) throughout a frequency range of 0.2-1.1 THz. In addition, we used a THz ellipsometer to measure the Müller matrix of the CNT-fiber polarizer and found comparable attenuation to a commercial metallic wire-grid polarizer. Furthermore, based on the classical theory of light transmission through an array of metallic wires, we demonstrated the most striking difference between the CNT-fiber and metallic wire-grid polarizers: the latter fails to work in the zero-spacing limit, where it acts as a simple mirror, while the former continues to work as an excellent polarizer even in that limit due to the one-dimensional conductivity of individual CNTs.

  19. Elastomer Reinforced with Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hudson, Jared L.; Krishnamoorti, Ramanan

    2009-01-01

    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  20. Does water dope carbon nanotubes?

    SciTech Connect

    Bell, Robert A.; Payne, Michael C.; Mostofi, Arash A.

    2014-10-28

    We calculate the long-range perturbation to the electronic charge density of carbon nanotubes (CNTs) as a result of the physisorption of a water molecule. We find that the dominant effect is a charge redistribution in the CNT due to polarisation caused by the dipole moment of the water molecule. The charge redistribution is found to occur over a length-scale greater than 30 Å, highlighting the need for large-scale simulations. By comparing our fully first-principles calculations to ones in which the perturbation due to a water molecule is treated using a classical electrostatic model, we estimate that the charge transfer between CNT and water is negligible (no more than 10{sup −4} e per water molecule). We therefore conclude that water does not significantly dope CNTs, a conclusion that is consistent with the poor alignment of the relevant energy levels of the water molecule and CNT. Previous calculations that suggest water n-dopes CNTs are likely due to the misinterpretation of Mulliken charge partitioning in small supercells.

  1. Electrical properties of multiwalled carbon nanotube film

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    The multiwalled carbon nanotube films examined in this study are produced by two methods: current annealing of carbon paper and dc magnetron sputtering. The conductivity and the temperature dependence of resistance of the samples are measured. The thermal conductivity of the film-substrate system is evaluated.

  2. Nerve agent detection using networks of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Novak, J. P.; Snow, E. S.; Houser, E. J.; Park, D.; Stepnowski, J. L.; McGill, R. A.

    2003-11-01

    We report the use of carbon nanotubes as a sensor for chemical nerve agents. Thin-film transistors constructed from random networks of single-walled carbon nanotubes were used to detect dimethyl methylphosphonate (DMMP), a simulant for the nerve agent sarin. These sensors are reversible and capable of detecting DMMP at sub-ppb concentration levels, and they are intrinsically selective against interferent signals from hydrocarbon vapors and humidity. We provide additional chemical specificity by the use of filters coated with chemoselective polymer films. These results indicate that the electronic detection of sub-ppb concentrations of nerve agents and potentially other chemical warfare agents is possible with simple-to-fabricate carbon nanotube devices.

  3. Quantitative analysis of the oxidation effects on the electrical characteristics of high-purity, large-diameter semiconducting carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Gao, Jia; Loo, Yueh-Lin

    2014-03-01

    Many attempts have been made to utilize carbon nanotubes for chemical, biological and gas sensing applications. Previous studies show that adsorbed ozone (O3) on carbon nanotubes can drastically influence their electrical characteristics. On the one hand, ozone act as p dopants; exposure thus leads to an increase in electrical conductivity. On the other hand, ozone readily oxidizes carbon nanotubes; this chemical reaction results in a decrease in conductivity. It remains ambiguous which process dominates and quantitative evaluation of these two effects is lacking. In this study, we elucidate the interaction between ozone and carbon nanotubes by evaluating the field-effect mobilities of polymer-sorted large diameter semiconducting carbon nanotubes based transistors. Upon exposure to ozone, we observe a positive shift in the threshold voltage from -0.7 to 11.7 V and a concurrent decrease of hole mobility from 2.5 to 0.5 cm2/Vs. Accordingly, the source-drain current exhibits a non-monotonic dependence on ozone exposure time. This dependence reveals that doping dominates the electrical characteristics of carbon nanotube transistors initially. Beyond 3-minutes of ozone exposure, chemical oxidation dominates, resulting in a progressive decrease in source-drain current.

  4. Optically enhanced charge transfer between C60 and single-wall carbon nanotubes in hybrid electronic devices.

    PubMed

    Allen, Christopher S; Liu, Guoquan; Chen, Yabin; Robertson, Alex W; He, Kuang; Porfyrakis, Kyriakos; Zhang, Jin; Briggs, G Andrew D; Warner, Jamie H

    2014-01-01

    In this article we probe the nature of electronic interactions between the components of hybrid C60-carbon nanotube structures. Utilizing an aromatic mediator we selectively attach C60 molecules to carbon nanotube field-effect transistor devices. Structural characterization via atomic force and transmission electron microscopy confirm the selectivity of this attachment. Charge transfer from the carbon nanotube to the C60 molecules is evidenced by a blue shift of the Raman G(+) peak position and increased threshold voltage of the transistor transfer characteristics. We estimate this charge transfer to increase the device density of holes per unit length by up to 0.85 nm(-1) and demonstrate further optically enhanced charge transfer which increases the hole density by an additional 0.16 nm(-1). PMID:24241690

  5. InAs/Si Hetero-Junction Nanotube Tunnel Transistors

    PubMed Central

    Hanna, Amir N.; Fahad, Hossain M.; Hussain, Muhammad M.

    2015-01-01

    Hetero-structure tunnel junctions in non-planar gate-all-around nanowire (GAA NW) tunnel FETs (TFETs) have shown significant enhancement in ‘ON’ state tunnel current over their all-silicon counterpart. Here we show the unique concept of nanotube TFET in a hetero-structure configuration that is capable of much higher drive current as opposed to that of GAA NW TFETs.Through the use of inner/outer core-shell gates, a single III-V hetero-structured nanotube TFET leverages physically larger tunneling area while achieving higher driver current (ION) and saving real estates by eliminating arraying requirement. Numerical simulations has shown that a 10 nm thin nanotube TFET with a 100 nm core gate has a 5×normalized output current compared to a 10 nm diameter GAA NW TFET. PMID:25923104

  6. Growth of semiconducting single-wall carbon nanotubes with a narrow band-gap distribution

    PubMed Central

    Zhang, Feng; Hou, Peng-Xiang; Liu, Chang; Wang, Bing-Wei; Jiang, Hua; Chen, Mao-Lin; Sun, Dong-Ming; Li, Jin-Cheng; Cong, Hong-Tao; Kauppinen, Esko I.; Cheng, Hui-Ming

    2016-01-01

    The growth of high-quality semiconducting single-wall carbon nanotubes with a narrow band-gap distribution is crucial for the fabrication of high-performance electronic devices. However, the single-wall carbon nanotubes grown from traditional metal catalysts usually have diversified structures and properties. Here we design and prepare an acorn-like, partially carbon-coated cobalt nanoparticle catalyst with a uniform size and structure by the thermal reduction of a [Co(CN)6]3− precursor adsorbed on a self-assembled block copolymer nanodomain. The inner cobalt nanoparticle functions as active catalytic phase for carbon nanotube growth, whereas the outer carbon layer prevents the aggregation of cobalt nanoparticles and ensures a perpendicular growth mode. The grown single-wall carbon nanotubes have a very narrow diameter distribution centred at 1.7 nm and a high semiconducting content of >95%. These semiconducting single-wall carbon nanotubes have a very small band-gap difference of ∼0.08 eV and show excellent thin-film transistor performance. PMID:27025784

  7. Carbon Nanotube Doped Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Raffaelle, Ryne P.; Difelice, Ron; van Derveer, William R.; Gennett, Tom; Maranchi, Jeff; Kumta, Prashant; Hepp, Aloysius F.

    2002-03-01

    We have characterized thin film lithium ion batteries that contain high purity single wall carbon nanotube-doped polymer anodes. Highly purified single-walled carbon nanotubes (SWCNT) were obtained through chemical refinement of soot generated by pulsed laser ablation. The purity of the nanotubes was determined via thermogravimetric analysis, two wavelength Raman spectroscopy, spectrophotometry, scanning electron microscopy and transmission electron microscopy. The specific surface area and lithium capacity of the SWCNT was compared to that of other conventional anode materials (i.e., carbon black, graphite, and multi-walled carbon nanotubes). The SWCNT exhibited a specific surface area that greatly exceeded the other carbonaceous materials. Anodes were prepared by casting thin films directly onto copper foil of several ionically conductive polymers (i.e., PAN, PVDF, PEO) doped with the SWCNT. The lithium-ion capacity of the materials was measured using a standard 3-electrode cell. The electrochemical discharge capacity of the purified single walled carbon nanotubes in PVDF was in excess of 1300 mAh/g after 30 charge/discharge cycles when tested using a current density of 20µA/cm^2. The SWCNT anodes were incorporated into all-polymer thin film batteries containing LiNiCoO_2-doped polymer cathodes. Cycling results on the various SWCNT polymer combinations will be presented.

  8. Chemical reactions confined within carbon nanotubes.

    PubMed

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors. PMID:27301444

  9. Measurement Challenges for Carbon Nanotube Material

    NASA Technical Reports Server (NTRS)

    Sosa, Edward; Arepalli, Sivaram; Nikolaev, Pasha; Gorelik, Olga; Yowell, Leonard

    2006-01-01

    The advances in large scale applications of carbon nanotubes demand a reliable supply of raw and processed materials. It is imperative to have a consistent quality control of these nanomaterials to distinguish material inconsistency from the modifications induced by processing of nanotubes for any application. NASA Johnson Space Center realized this need five years back and started a program to standardize the characterization methods. The JSC team conducted two workshops (2003 and 2005) in collaboration with NIST focusing on purity and dispersion measurement issues of carbon nanotubes [1]. In 2004, the NASA-JSC protocol was developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA [2]. This protocol is routinely used by several researchers across the world as a first step in characterizing raw and purified carbon nanotubes. A suggested practice guide consisting of detailed chapters on TGA, Raman, electron microscopy and NIR absorption is in the final stages and is undergoing revisions with input from the nanotube community [3]. The possible addition of other techniques such as XPS, and ICP to the existing protocol will be presented. Recent activities at ANSI and ISO towards implementing these protocols as nanotube characterization standards will be discussed.

  10. High-sensitive label-free biosensors based on single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Maehashi, Kenzo; Matsumoto, Kazuhiko

    2006-02-01

    DNA hybridization has sensitively been detected using carbon nanotube field-effect transistors (CNTFETs) in real time. After full-complementary DNA introduction, the source-drain current gradually increased while monitoring in real time. Full-complementary DNA with concentration as low as 1 fmol/L solution could be effectively detected. Our CNTFET-based biochip is a promising candidate for the development of an integrated, high-throughput, multiplexed DNA biosensor for medical, forensic and environmental diagnostics.

  11. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  12. Formation of Carbon Nanotubes in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Alford, J. M.; Mason, G. R.; Feikema, D. A.

    2001-01-01

    Even though nanotube science has become one of the worlds most rapidly advancing areas of research, very little is known about the processes involved in nanotube synthesis. To study the formation of carbon nanotubes in an environment unhindered by the buoyancy induced flows generated by the high temperatures necessary to vaporize carbon and grow nanotubes, we have designed a miniature carbon arc apparatus that can produce carbon nanotubes under microgravity conditions. During the first phase of this project, we designed, built, and successfully tested the mini carbon arc in both 1g and 2.2 sec drop tower microgravity conditions. We have demonstrated that microgravity can eliminate the strong convective flows from the carbon arc and we have successfully produced single-walled carbon nanotubes in microgravity. We believe that microgravity processing will allow us to better understand the nanotube formation process and eventually allow us to grow nanotubes that are superior to ground-based production.

  13. Mechanics of Carbon Nanotubes and their Polymer Composites

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Cho, K. J.; Srivastava, Deepak; Tang, Harry (Technical Monitor)

    2002-01-01

    Contents include the folloving: carbon nanotube (CNT): structures, application of carbon nanotubes, simulation method, Elastic properties of carbon nanotubes, yield strain of CNT, yielding under tensile stress, yielding: strain-rate and temperature dependence, yield strain under tension, yielding at realistic conditions, nano fibers, polymer CNT composite, force field, density dependency on temperature, diffusion coefficients, young modulus, and conclusions.

  14. Carbon nanotube suspensions, dispersions, & composites

    NASA Astrophysics Data System (ADS)

    Simmons, Trevor John

    Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although these structures are usually only a few nanometers wide, they can be grown up to centimeter lengths, and in massive quantities. CNTs can be produced in a variety of processes ranging from repeated combustion of organic material such as dried grass, arc-discharge with graphite electrodes, laser ablation of a graphitic target, to sophisticated chemical vapor deposition (CVD) techniques. CNTs are stronger than steel but lighter than aluminum, and can be more conductive than copper or semiconducting like silicon. This variety of properties has been matched by the wide variety of applications that have been developed for CNTs. Many of these applications have been limited by the inability of researchers to tame these structures, and incorporating CNTs into existing technologies can be exceedingly difficult and prohibitively expensive. It is therefore the aim of the current study to develop strategies for the solution processing and deposition of CNTs and CNT-composites, which will enable the use of CNTs in existing and emerging technologies. CNTs are not easily suspended in polar solvents and are extremely hydrophobic materials, which has limited much of the solution processing to organic solvents, which also cannot afford high quality dispersions of CNTs. The current study has developed a variety of aqueous CNT solutions that employ surfactants, water-soluble polymers, or both to create suspensions of CNTs. These CNT 'ink' solutions were deposited with a variety of techniques that have afforded many interesting structures, both randomly oriented as well as highly

  15. In situ tuning and probing the ambipolar field effect on multiwall carbon nanotubes

    SciTech Connect

    Chen, Li-Ying; Chang, Chia-Seng

    2014-12-15

    We report a method of fabricating ultra-clean and hysteresis-free multiwall carbon nanotube field-effect transistors (CNFETs) inside the ultra-high vacuum transmission electron microscope equipped with a movable gold tip as a local gate. By tailoring the shell structure of the nanotube and varying the drain-source voltage (V{sub ds}), we can tune the electronic characteristic of a multiwall CNFET in situ. We have also found that the Schottky barriers of a multiwall CNFET are generated within the nanotube, but not at the nanotube/electrode contacts, and the barrier height has been derived. We have subsequently demonstrated the ambipolar characteristics of the CNFET with concurrent high-resolution imaging and local gating.

  16. Carbon Nanotube Computer: Transforming Scientific Discoveries into Working Systems

    NASA Astrophysics Data System (ADS)

    Mitra, Subhasish

    2014-03-01

    The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy- delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. However, carbon nanotubes (CNTs) are subject to substantial inherent imperfections that pose major obstacles to the design of robust and very large-scale CNFET digital systems: (i) It is nearly impossible to guarantee perfect alignment and positioning of all CNTs. This limitation introduces stray conducting paths, resulting in incorrect circuit functionality. (ii) CNTs can be metallic or semiconducting depending on chirality. Metallic CNTs cause shorts resulting in excessive leakage and incorrect circuit functionality. A combination of design and processing technique overcomes these challenges by creating robust CNFET digital circuits that are immune to these inherent imperfections. This imperfection-immune design paradigm enables the first experimental demonstration of the carbon nanotube computer, and, more generally, arbitrary digital systems that can be built using CNFETs. The CNT computer is capable of performing multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we emulate 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This is the most complex carbon-based electronic system yet demonstrated. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next

  17. Carbon nanotube high-performance logic technology - challenges and current progress

    NASA Astrophysics Data System (ADS)

    Han, Shu-Jen

    2015-03-01

    In the last four decades, we have witnessed a tremendous information technology revolution originated from the relentless scaling of Si complementary metal-oxide semiconductor (CMOS) devices. CMOS scaling provides ever-improved transistor performance, density, power and cost, and will continue to bring new applications and functions to our daily life. However, the conventional homogeneous scaling of silicon devices has become very difficult, firstly due to the unsatisfactory electrostatic control from the gate dielectric. In addition, as we look forward to the technology nodes with sub-10 nm channel length, non-Si based channel materials will be required to provide continuous carrier velocity enhancement when the conventional strained-Si techniques run out of steam. Single-walled carbon nanotubes are promising to replace silicon as the channel material for high-performance electronics near the end of silicon scaling roadmap, with their superb electrical properties, intrinsic ultrathin body, and nearly transparent contact with certain metals. This talk discusses recent advances in modeling and experimental works that reveal the properties and potential of ultra-scaled nanotube transistors, separation and assembly techniques for forming nanotube arrays with high semiconducting nanotube purity and tight pitch separation, and engineering aspects of their implementation in integrated circuits and functional systems. A concluding discussion highlights most significant challenges from technology points of view, and provides perspectives on the future of carbon nanotube based nanoelectronics.

  18. Geometric and electronic structure of carbon nanotube networks: 'super'-carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Coluci, V. R.; Galvão, D. S.; Jorio, A.

    2006-02-01

    Structures of the so-called super-carbon nanotubes are proposed. These structures are built from single walled carbon nanotubes connected by Y-like junctions forming a 'super'-sheet that is then rolled into a seamless cylinder. Such a procedure can be repeated several times, generating a fractal structure. This procedure is not limited to carbon nanotubes, and can be easily modified for application to other systems. Tight binding total energy and density of states calculations showed that the 'super'-sheets and tubes are stable and predicted to present metallic and semiconducting behaviour.

  19. Detection of gas atoms with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Arash, B.; Wang, Q.

    2013-05-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  20. Detection of gas atoms with carbon nanotubes

    PubMed Central

    Arash, B.; Wang, Q.

    2013-01-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  1. Carbon Nanotube Bolometer for Absolute FTIR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Woods, Solomon; Neira, Jorge; Tomlin, Nathan; Lehman, John

    We have developed and calibrated planar electrical-substitution bolometers which employ absorbers made from vertically-aligned carbon nanotube arrays. The nearly complete absorption of light by the carbon nanotubes from the visible range to the far-infrared can be exploited to enable a device with read-out in native units equivalent to optical power. Operated at cryogenic temperatures near 4 K, these infrared detectors are designed to have time constant near 10 ms and a noise floor of about 10 pW. Built upon a micro-machined silicon platform, each device has an integrated heater and thermometer, either a carbon nanotube thermistor or superconducting transition edge sensor, for temperature control. We are optimizing temperature-controlled measurement techniques to enable high resolution spectral calibrations using these devices with a Fourier-transform spectrometer.

  2. Modelling Carbon Nanotubes-Based Mediatorless Biosensor

    PubMed Central

    Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

    2012-01-01

    This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

  3. Modelling carbon nanotubes-based mediatorless biosensor.

    PubMed

    Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

    2012-01-01

    This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

  4. Boron-Filled Hybrid Carbon Nanotubes

    PubMed Central

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  5. Nanocrystalline cobalt oxides for carbon nanotube growth

    NASA Astrophysics Data System (ADS)

    Guo, Kun; Jayatissa, Ahalapitiya H.; Jayasuriya, Ambalangodage C.

    2007-09-01

    Thin Films of nanocrystalline cobalt oxide were formed by sol-gel method. Structure, optical properties and surface properties of these films were investigated by numerous characterization techniques. These films were successfully fabricated on glass substrates below 500°C. . Micropatterns of cobalt oxide thin films were also fabricated on glass and silicon substrates by employing a lift-off method. Crystal size of these nanocrystalline cobalt films could be successfully controllable by varying the amount of cobalt precursors and number of layers. These films were used as the seeding layers for carbon nanotube growth in a CVD process By changing the concentration of monomer precursors in the solgel coating solutions, different size nanoclusters hence different size carbon nanotubes could be synthesized in CVD process. This method can be used for controlled growth of carbon nanotubes for many different applications. In this paper, detail of these experimental results will be presented.

  6. Boron-Filled Hybrid Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  7. Boron-Filled Hybrid Carbon Nanotubes.

    PubMed

    Patel, Rajen B; Chou, Tsengming; Kanwal, Alokik; Apigo, David J; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  8. Piezoresistive effect in carbon nanotube fibers.

    PubMed

    Lekawa-Raus, Agnieszka; Koziol, Krzysztof K K; Windle, Alan H

    2014-11-25

    The complex structure of the macroscopic assemblies of carbon nanotubes and variable intrinsic piezoresistivity of nanotubes themselves lead to highly interesting piezoresistive performance of this new type of conductive material. Here, we present an in-depth study of the piezoresistive effect in carbon nanotube fibers, i.e., yarnlike assemblies made purely of aligned carbon nanotubes, which are expected to find applications as electrical and electronic materials. The resistivity changes of carbon nanotube fibers were measured on initial loading, through the elastic/plastic transition, on cyclic loading and on stress relaxation. The various regimes of stress/strain behavior were modeled using a standard linear solid model, which was modified with an additional element in series to account for the observed creep behavior. On the basis of the experimental and modeling results, the origin of piezoresistivity is discussed. An additional effect on the resistivity was found as the fiber was held under load which led to observations of the effect of humidity and the associated water adsorption level on the resistivity. We show that the equilibrium uptake of moisture leads to the decrease in gauge factor of the fiber decrease, i.e., the reduction in the sensitivity of fiber resistivity to loading. PMID:25337627

  9. Carbon Nanotubes Synthesis Through Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Tirado, Pablo; Garcia, Rafael; Montes, Jorge; Melendrez, Rodrigo; Barboza, Marcelino; Contreras, Oscar

    2015-03-01

    Carbon nanotubes show a great potential of applications since there discovery by Iijima in 1991[1] due to their numerous physical-chemical properties such as their high weight to strength relationship, which make them ideal to use in high resistance compound materials, and in many other applications[2] In this work, a novel method for the synthesis of carbon nanotubes is presented, starting from an ultra-thin sheet of graphite synthesized by the chemical vapor decomposition technique (CVD), using ultra high purity methane and hydrogen at 1200°C in a horizontal quartz reactor. For the synthesis of carbon nanotubes, the graphite sheets were exposed to different doses of radiation, with the objective of breaking the graphite bonds and form carbon nanotubes; a Gammacell equipment model 220 Excel was used for the purpose, which counts with a radiation source of cobalt 60, and a current radiation rate of 0.9 Gy/seconds. The time of exposure to radiation was varied in each sample, according to the desired dose of radiation in each case, afterwards the samples were characterized using the Raman spectroscopy and TEM microscopy techniques with the objective of observing the kind of nanotubes formed, their morphology and their number of defects. Results will be shown during the poster session.

  10. Orientational Growth of Carbon Nanotube for Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S.; Cui, Y.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Since the superior properties of multi-wall carbon nanotubes (MWCNT) could improve numerous devices such as electronics and sensors, many efforts have been made in investigating the growth mechanism of MWCNT to synthesize high quality MWCNT. Most applications require uniform aligned CNT. In this presentation, a directional growth of CNT will be reported. Carbon nanotubes are synthesized using thermal chemical vapor deposition. Temperature and pressure are two important growth parameters for fabricating carbon nanotubes. It is found that the nanotube diameter distribution mainly depends on the growth-temperature. With the substrate surface normal either along or against the gravity vector, different growth orientations of MWCNT are observed by scanning electron microscopy although the Raman spectra are similar for samples synthesized at different locations. The sizes of these carbon nanotubes in each sample are quite uniform and the length of the tube is up to several tens of micrometers. These results suggest the gravitation effects in the growth of long and small diameter CNT.

  11. Molecular Dynamics Modeling of Carbon Nanotubes and Their Composites

    NASA Astrophysics Data System (ADS)

    Jensen, Lars R.; Pyrz, Ryszard

    2004-06-01

    The tensile modulus of individual nanotubes and nanotube-polypropylene composites has been determined using molecular dynamics simulations. Simulations of individual single-walled carbon nanotubes showed that their tensile modulus was dependent on the tube structure and the diameter if the diameter was below 1,6 nm. The tensile modulus was determined for an infinite single-walled carbon nanotube embedded in an amorphous polypropylene matrix and for a finite and capped single-walled carbon nanotube embedded in a polypropylene matrix. For the infinite nanotube-polypropylene system the modulus was found to correspond to the one given by the Voigt approximation. For the finite nanotube-polypropylene system the reinforcing effect of the nanotube was not very pronounced. A pull out simulation showed that the length of the nanotube in the simulation was much smaller than the critical length and hence no load transfer between the nanotube and the matrix existed.

  12. Lipid nanoscaffolds in carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Paukner, Catharina; Koziol, Krzysztof K. K.; Kulkarni, Chandrashekhar V.

    2013-09-01

    We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields.We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields. Electronic supplementary information (ESI) available: Additional wide angle X-ray scattering (WAXS) data on the alignment of lipid nanostructures, control and time resolved 2-d images of egg ovalbumin encapsulation and a summary picture of the present work. See DOI: 10.1039/c3nr02068a

  13. Scanning Gate Spectroscopy and its Application to Carbon Nanotube Defects

    PubMed Central

    Hunt, Steven R.; Wan, Danny; Khalap, Vaikunth R.; Corso, Brad L.; Collins, Philip G.

    2011-01-01

    A variation of scanning gate microscopy (SGM) is demonstrated in which this imaging mode is extended into an electrostatic spectroscopy. Continuous variation of the SGM probe’s electrostatic potential is used to directly resolve the energy spectrum of localized electronic scattering in functioning, molecular scale devices. The technique is applied to the energy-dependent carrier scattering that occurs at defect sites in carbon nanotube transistors, and fitting energy-resolved experimental data to a simple transmission model determines the electronic character of each defect site. For example, a phenolic type of covalent defect is revealed to produce a tunnel barrier 0.1 eV high and 0.5 nm wide. PMID:21280660

  14. Stable doping of carbon nanotubes via molecular self assembly

    SciTech Connect

    Lee, B.; Chen, Y.; Podzorov, V.; Cook, A.; Zakhidov, A.

    2014-10-14

    We report a novel method for stable doping of carbon nanotubes (CNT) based on methods of molecular self assembly. A conformal growth of a self-assembled monolayer of fluoroalkyl trichloro-silane (FTS) at CNT surfaces results in a strong increase of the sheet conductivity of CNT electrodes by 60–300%, depending on the CNT chirality and composition. The charge carrier mobility of undoped partially aligned CNT films was independently estimated in a field-effect transistor geometry (~100 cm²V⁻¹s⁻¹). The hole density induced by the FTS monolayer in CNT sheets is estimated to be ~1.8 ×10¹⁴cm⁻². We also show that FTS doping of CNT anodes greatly improves the performance of organic solar cells. This large and stable doping effect, easily achieved in large-area samples, makes this approach very attractive for applications of CNTs in transparent and flexible electronics.

  15. Electrically induced ambipolar spin vanishments in carbon nanotubes

    PubMed Central

    Matsumoto, D.; Yanagi, K.; Takenobu, T.; Okada, S.; Marumoto, K.

    2015-01-01

    Carbon nanotubes (CNTs) exhibit various excellent properties, such as ballistic transport. However, their electrically induced charge carriers and the relation between their spin states and the ballistic transport have not yet been microscopically investigated because of experimental difficulties. Here we show an electron spin resonance (ESR) study of semiconducting single-walled CNT thin films to investigate their spin states and electrically induced charge carriers using transistor structures under device operation. The field-induced ESR technique is suitable for microscopic investigation because it can directly observe spins in the CNTs. We observed a clear correlation between the ESR decrease and the current increase under high charge density conditions, which directly demonstrated electrically induced ambipolar spin vanishments in the CNTs. The result provides a first clear evidence of antimagnetic interactions between spins of electrically induced charge carriers and vacancies in the CNTs. The ambipolar spin vanishments would contribute the improvement of transport properties of CNTs because of greatly reduced carrier scatterings. PMID:26148487

  16. A carbon nanotube optical rectenna.

    PubMed

    Sharma, Asha; Singh, Virendra; Bougher, Thomas L; Cola, Baratunde A

    2015-12-01

    An optical rectenna--a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current--was first proposed over 40 years ago, yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale. Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads, but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna. Here we demonstrate an optical rectenna by engineering metal-insulator-metal tunnel diodes, with a junction capacitance of ∼2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (∼10 nm in diameter), which act as the antenna. Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna, a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory. Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current-voltage scans between 5 and 77 °C, indicating a potential for robust operation. PMID:26414198

  17. Ultralight multiwalled carbon nanotube aerogel.

    PubMed

    Zou, Jianhua; Liu, Jianhua; Karakoti, Ajay Singh; Kumar, Amit; Joung, Daeha; Li, Qiang; Khondaker, Saiful I; Seal, Sudipta; Zhai, Lei

    2010-12-28

    Ultralight multiwalled carbon nanotube (MWCNT) aerogel is fabricated from a wet gel of well-dispersed pristine MWCNTs. On the basis of a theoretical prediction that increasing interaction potential between CNTs lowers their critical concentration to form an infinite percolation network, poly(3-(trimethoxysilyl) propyl methacrylate) (PTMSPMA) is used to disperse and functionalize MWCNTs where the subsequent hydrolysis and condensation of PTMSPMA introduces strong and permanent chemical bonding between MWCNTs. The interaction is both experimentally and theoretically proven to facilitate the formation of a MWCNT percolation network, which leads to the gelation of MWCNT dispersion at ultralow MWCNT concentration. After removing the liquid component from the MWCNT wet gel, the lightest ever free-standing MWCNT aerogel monolith with a density of 4 mg/cm(3) is obtained. The MWCNT aerogel has an ordered macroporous honeycomb structure with straight and parallel voids in 50-150 μm separated by less than 100 nm thick walls. The entangled MWCNTs generate mesoporous structures on the honeycomb walls, creating aerogels with a surface area of 580 m(2)/g which is much higher than that of pristine MWCNTs (241 m(2)/g). Despite the ultralow density, the MWCNT aerogels have an excellent compression recoverable property as demonstrated by the compression test. The aerogels have an electrical conductivity of 3.2 × 10(-2) S·cm(-1) that can be further increased to 0.67 S·cm(-1) by a high-current pulse method without degrading their structures. The excellent compression recoverable property, hierarchically porous structure with large surface area, and high conductivity grant the MWCNT aerogels exceptional pressure and chemical vapor sensing capabilities. PMID:21090673

  18. A carbon nanotube optical rectenna

    NASA Astrophysics Data System (ADS)

    Sharma, Asha; Singh, Virendra; Bougher, Thomas L.; Cola, Baratunde A.

    2015-12-01

    An optical rectenna—a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current—was first proposed over 40 years ago, yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale. Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads, but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna. Here we demonstrate an optical rectenna by engineering metal-insulator-metal tunnel diodes, with a junction capacitance of ˜2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (˜10 nm in diameter), which act as the antenna. Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna, a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory. Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current-voltage scans between 5 and 77 °C, indicating a potential for robust operation.

  19. Crosstalk analysis of carbon nanotube bundle interconnects.

    PubMed

    Zhang, Kailiang; Tian, Bo; Zhu, Xiaosong; Wang, Fang; Wei, Jun

    2012-01-01

    Carbon nanotube (CNT) has been considered as an ideal interconnect material for replacing copper for future nanoscale IC technology due to its outstanding current carrying capability, thermal conductivity, and mechanical robustness. In this paper, crosstalk problems for single-walled carbon nanotube (SWCNT) bundle interconnects are investigated; the interconnect parameters for SWCNT bundle are calculated first, and then the equivalent circuit has been developed to perform the crosstalk analysis. Based on the simulation results using SPICE simulator, the voltage of the crosstalk-induced glitch can be reduced by decreasing the line length, increasing the spacing between adjacent lines, or increasing the diameter of SWCNT. PMID:22340628

  20. Laser ablative synthesis of carbon nanotubes

    DOEpatents

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2010-03-02

    An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

  1. Modeling of Current-Voltage Characteristics in Large Metal-Semiconducting Carbon Nanotube Systems

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryon A. (Technical Monitor)

    2000-01-01

    A model is proposed for two observed current-voltage (I-V) patterns in recent experiment with a scanning tunneling microscope tip and a carbon nanotube [Collins et al., Science 278, 100 (1997)]. We claim that there are two contact modes for a tip (metal)-nanotube (semiconductor) junction depending whether the alignment of the metal and the semiconductor band structures is (1) variable (vacuum-gap) or (2) fixed (touching) with V. With the tip grounded, the tunneling case in (1) would produce large dI/dV with V > 0, small dI/dV with V < 0, and I = 0 near V = 0 for an either n- or p-nanotube. However, the Schottky mechanism in (2) would result in forward current with V < 0 for an n-nanotube, while with V > 0 for an p-nanotube. The two observed I-V patterns are thus entirely explained by a tip-nanotube contact of the two types, where the nanotube must be n-type. We apply this model to the source-drain I-V characteristics in a long nanotube-channel field-effect-transistor with metallic electrodes at low temperature [Zhou et al., Appl. Phys. Lett. 76, 1597 (2000)], and show that two independent metal-semiconductor junctions in series are responsible for the observed behavior.

  2. Carbon Nanotube-Enhanced Carbon-Phenenolic Ablator Material

    NASA Technical Reports Server (NTRS)

    Kikolaev, P.; Stackpoole, M.; Fan, W.; Cruden, B. A.; Waid, M.; Moloney, P.; Arepalli, S.; Arnold, J.; Partridge, H.; Yowell, L.

    2006-01-01

    This viewgraph presentation reviews the use of PICA (phenolic impregnated carbon ablator) as the selected material for heat shielding for future earth return vehicles. It briefly reviews the manufacturing of PICA and the advantages for the use of heat shielding, and then explains the reason for using Carbon Nanotubes to improve strength of phenolic resin that binds carbon fibers together. It reviews the work being done to create a carbon nanotube enhanced PICA. Also shown are various micrographic images of the various PICA materials.

  3. Geckolike high shear strength by carbon nanotube fiber adhesives

    NASA Astrophysics Data System (ADS)

    Maeno, Y.; Nakayama, Y.

    2009-01-01

    Carbon nanotube adhesives can adhere strongly to surfaces as a gecko does. The number of carbon nanotube layers is an important determinant of the contact area for adhesion. Balancing the catalyst ratio and buffer layer used for chemical vapor deposition processing controls the number of carbon nanotube layers and their distribution. The features of carbon nanotubes determine the shear strength of adhesion. Carbon nanotubes with a broad distribution of layers exhibit enhanced shear strength with equivalent adhesive capability to that of a natural Tokay Gecko (Gekko gecko)

  4. The Use of Plasma Vortexes in Creating Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Leith, Alexander; Alexander Leith Collaboration

    2016-03-01

    Carbon nanotubes have been created in a variety of ways such as arc discharge, laser ablation, and chemical vapor deposition (CVD). Each of these techniques has been proven to produce carbon nanotubes in small quantities in a lab setting. This is the problem that we have been addressing. Over the course of 16 months, we have been working on a new method of carbon nanotube production that is based around fluid dynamics and plasma. We have created the basic components to test this new way to produce carbon nanotubes. This research will ideally provide a new avenue for carbon nanotube production. Worked with Dr. Randal Tagg of the University of Colorado Denver.

  5. Computational Nanomechanics of Carbon Nanotubes and Composites

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Wei, Chenyu; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Nanomechanics of individual carbon and boron-nitride nanotubes and their application as reinforcing fibers in polymer composites has been reviewed with interplay of theoretical modeling, computer simulations and experimental observations. The emphasis in this work is on elucidating the multi-length scales of the problems involved, and of different simulation techniques that are needed to address specific characteristics of individual nanotubes and nanotube polymer-matrix interfaces. Classical molecular dynamics simulations are shown to be sufficient to describe the generic behavior such as strength and stiffness modulus but are inadequate to describe elastic limit and nature of plastic buckling at large strength. Quantum molecular dynamics simulations are shown to bring out explicit atomic nature dependent behavior of these nanoscale materials objects that are not accessible either via continuum mechanics based descriptions or through classical molecular dynamics based simulations. As examples, we discus local plastic collapse of carbon nanotubes under axial compression and anisotropic plastic buckling of boron-nitride nanotubes. Dependence of the yield strain on the strain rate is addressed through temperature dependent simulations, a transition-state-theory based model of the strain as a function of strain rate and simulation temperature is presented, and in all cases extensive comparisons are made with experimental observations. Mechanical properties of nanotube-polymer composite materials are simulated with diverse nanotube-polymer interface structures (with van der Waals interaction). The atomistic mechanisms of the interface toughening for optimal load transfer through recycling, high-thermal expansion and diffusion coefficient composite formation above glass transition temperature, and enhancement of Young's modulus on addition of nanotubes to polymer are discussed and compared with experimental observations.

  6. Compressed carbon nanotubes: A family of new multifunctional carbon allotropes

    PubMed Central

    Hu, Meng; Zhao, Zhisheng; Tian, Fei; Oganov, Artem R.; Wang, Qianqian; Xiong, Mei; Fan, Changzeng; Wen, Bin; He, Julong; Yu, Dongli; Wang, Hui-Tian; Xu, Bo; Tian, Yongjun

    2013-01-01

    The exploration of novel functional carbon polymorphs is an enduring topic of scientific investigations. In this paper, we present simulations demonstrating metastable carbon phases as the result of pressure induced carbon nanotube polymerization. The configuration, bonding, electronic, and mechanical characteristics of carbon polymers strongly depend on the imposed hydrostatic/non-hydrostatic pressure, as well as on the geometry of the raw carbon nanotubes including diameter, chirality, stacking manner, and wall number. Especially, transition processes under hydrostatic/non-hydrostatic pressure are investigated, revealing unexpectedly low transition barriers and demonstrating sp2→sp3 bonding changes as well as peculiar oscillations of electronic property (e.g., semiconducting→metallic→semiconducting transitions). These polymerized nanotubes show versatile and superior physical properties, such as superhardness, high tensile strength and ductility, and tunable electronic properties (semiconducting or metallic). PMID:23435585

  7. Improved Method of Purifying Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D.

    2004-01-01

    An improved method of removing the residues of fabrication from carbon nanotubes has been invented. These residues comprise amorphous carbon and metal particles that are produced during the growth process. Prior methods of removing the residues include a variety of processes that involved the use of halogens, oxygen, or air in both thermal and plasma processes. Each of the prior methods entails one or more disadvantages, including non-selectivity (removal or damage of nanotubes in addition to removal of the residues), the need to dispose of toxic wastes, and/or processing times as long as 24 hours or more. In contrast, the process described here does not include the use of toxic chemicals, the generation of toxic wastes, causes little or no damage to the carbon nanotubes, and involves processing times of less than 1 hour. In the improved method, purification is accomplished by flowing water vapor through the reaction chamber at elevated temperatures and ambient pressures. The impurities are converted to gaseous waste products by the selective hydrogenation and hydroxylation by the water in a reaction chamber. This process could be performed either immediately after growth or in a post-growth purification process. The water used needs to be substantially free of oxygen and can be obtained by a repeated freeze-pump-thaw process. The presence of oxygen will non-selectively attach the carbon nanotubes in addition to the amorphous carbon.

  8. Carbon Nanostructure-Based Field-Effect Transistors for Label-Free Chemical/Biological Sensors

    PubMed Central

    Hu, PingAn; Zhang, Jia; Li, Le; Wang, Zhenlong; O’Neill, William; Estrela, Pedro

    2010-01-01

    Over the past decade, electrical detection of chemical and biological species using novel nanostructure-based devices has attracted significant attention for chemical, genomics, biomedical diagnostics, and drug discovery applications. The use of nanostructured devices in chemical/biological sensors in place of conventional sensing technologies has advantages of high sensitivity, low decreased energy consumption and potentially highly miniaturized integration. Owing to their particular structure, excellent electrical properties and high chemical stability, carbon nanotube and graphene based electrical devices have been widely developed for high performance label-free chemical/biological sensors. Here, we review the latest developments of carbon nanostructure-based transistor sensors in ultrasensitive detection of chemical/biological entities, such as poisonous gases, nucleic acids, proteins and cells. PMID:22399927

  9. Single-walled carbon nanotube networks for flexible and printed electronics

    NASA Astrophysics Data System (ADS)

    Zaumseil, Jana

    2015-07-01

    Networks of single-walled carbon nanotubes (SWNTs) can be processed from solution and have excellent mechanical properties. They are highly flexible and stretchable. Depending on the type of nanotubes (semiconducting or metallic) they can be used as replacements for metal or transparent conductive oxide electrodes or as semiconducting layers for field-effect transistors (FETs) with high carrier mobilities. They are thus competitive alternatives to other solution-processable materials for flexible and printed electronics. This review introduces the basic properties of SWNTs, current methods for dispersion and separation of metallic and semiconducting SWNTs and techniques to deposit and pattern dense networks from dispersion. Recent examples of applications of carbon nanotubes as conductors and semiconductors in (opto-)electronic devices and integrated circuits will be discussed.

  10. Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration

    SciTech Connect

    2010-03-01

    Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

  11. Scanning gate microscopy of electronic inhomogeneities in single-walled carbon nanotube (SWCNT) devices

    NASA Astrophysics Data System (ADS)

    Hunt, Steven R.; Collins, Phillip G.

    2010-03-01

    The electronic properties of graphitic carbon devices are primarily determined by the contact metal and the carbon band structure. However, inhomogeneities such as substrate imperfections, surface defects, and mobile contaminants also contribute and can lead to transistor-like behaviors. We experimentally investigate this phenomena in the 1-D limit using metallic single-walled carbon nanotubes (SWCNTs) before and after the electrochemical creation of sidewall defects. While scanning gate microscopy readily identifies the defect sites, the energy-dependence of the technique allows quantitative analysis of the defects and discrimination of different defect types. This research is partly supported by the NSF (DMR 08-xxxx).

  12. Quantum Monte Carlo calculations for carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Luu, Thomas; Lähde, Timo A.

    2016-04-01

    We show how lattice quantum Monte Carlo can be applied to the electronic properties of carbon nanotubes in the presence of strong electron-electron correlations. We employ the path-integral formalism and use methods developed within the lattice QCD community for our numerical work. Our lattice Hamiltonian is closely related to the hexagonal Hubbard model augmented by a long-range electron-electron interaction. We apply our method to the single-quasiparticle spectrum of the (3,3) armchair nanotube configuration, and consider the effects of strong electron-electron correlations. Our approach is equally applicable to other nanotubes, as well as to other carbon nanostructures. We benchmark our Monte Carlo calculations against the two- and four-site Hubbard models, where a direct numerical solution is feasible.

  13. Synthesis and Integration of Nanostructured Carbon: Carbon Nanotube-Polymer Nanocomposites and Graphene

    NASA Astrophysics Data System (ADS)

    Gulotty, Richard Stephen

    Nanostructured carbon, in the form of tubes or sheets, exhibits exceptional thermal and electrical properties. Graphene, a single atomic sheet of hexagonal sp2 bonded carbon, posesses a thermal conductivity higher than diamond, with an extremely high electron mobility. Carbon nanotubes (CNT), which are tubes composed of one or more graphene sheets, also posess high thermal conductivity and electron mobility. One of the major problems facing the application of nanomaterials is integration into already existing material systems. A second challenge is controlled synthesis of nanomaterials. In this dissertation research novel methods were investigated for coupling carbon nanotubes to polymer matrices, as well as new approaches for controlling the synthesis of graphene and reduced graphene oxide like carbon (R-GOC) on copper (Cu) foils via chemical vapor deposition. It was determined that carboxylic functionalization of carbon nanotubes was effective in improving the coupling of CNTs to polymer matrices, affecting the thermal transport of the resulting CNT-polymer nanocomposites. From the CVD studies it was established that the cooling phase gases flowed after deposition influence the growth mechanics of graphene on Cu foil. Further CVD studies showed that methane may be decomposed directly onto quartz to form reduced graphene oxide like carbon thin films. The obtained thermal characterization results are important for development of CNTs as fillers for composite pastes with high thermal conductivity, and the results of the CVD studies are important for developing further understanding of growth mechanics of bilayer graphene and other nanostructured carbon. In addition to the fundamental study of CVD synthesis of graphene and R-GOC, this dissertation work includes engineering of graphene and R-GOC to various applications, including the development of the thinnest flexible transistor with active materials made from all-2D materials, as well as large-scale electron

  14. CARBON NANOTUBES IN MICROWAVE ENVIRONMENT-IGNITION AND RECONSTRUCTION

    EPA Science Inventory

    The unusual property of single-walled carbon nanotubes (SWNT), multi-wall (MWNT) nanotubes and Buckminsterfullerene (C-60) is observed upon exposure to microwave-assisted ignition. Carbon nanotubes known for a range of mechanical and electronic properties because of their unique...

  15. Deconvoluting hepatic processing of carbon nanotubes.

    PubMed

    Alidori, Simone; Bowman, Robert L; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L J; Ulmert, Hans David S; Brea, Elliott J; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A; McDevitt, Michael R

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  16. Deconvoluting hepatic processing of carbon nanotubes

    PubMed Central

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  17. In-line manufacture of carbon nanotubes

    DOEpatents

    Brambilla, Nicol Michele; Signorelli, Riccardo; Martini, Fabrizio; Corripio Luna, Oscar Enrique

    2015-04-28

    Mass production of carbon nanotubes (CNT) are facilitated by methods and apparatus disclosed herein. Advantageously, the methods and apparatus make use of a single production unit, and therefore provide for uninterrupted progress in a fabrication process. Embodiments of control systems for a variety of CNT production apparatus are included.

  18. Functionalized carbon nanotubes for potential medicinal applications

    PubMed Central

    Zhang, Yi; Bai, Yuhong; Yan, Bing

    2016-01-01

    Functionalized carbon nanotubes display unique properties that enable a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity. PMID:20451656

  19. Reactions over catalysts confined in carbon nanotubes.

    PubMed

    Pan, Xiulian; Bao, Xinhe

    2008-12-21

    We review a new concept for modifying the redox properties of transition metals via confinement within the channels of carbon nanotubes (CNTs), and thus tuning their catalytic performance. Attention is also devoted to novel techniques for homogeneous dispersion of metal nanoparticles inside CNTs since these are essential for optimization of the catalytic activity. PMID:19048128

  20. Photothermal effects of immunologically modified carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Griswold, Ryan T.; Henderson, Brock; Goddard, Jessica; Tan, Yongqiang; Hode, Tomas; Liu, Hong; Nordquist, Robert E.; Chen, Wei R.

    2013-02-01

    Carbon nanotubes have a great potential in the biomedical applications. To use carbon nanotubes in the treatment of cancer, we synthesized an immunologically modified single-walled carbon nanotube (SWNT) using a novel immunomodifier, glycated chitosan (GC), as an effective surfactant for SWNT. This new composition SWNT-GC was stable due to the strong non-covalent binding between SWNT and GC. The structure of SWNT-GC is presented in this report. The photothermal effect of SWNT-GC was investigated under irradiation of a near-infrared laser. SWNT-GC retained the optical properties of SWNT and the immunological properties of GC. Specifically, the SWNT-GC could selectively absorb a 980-nm light and induce desirable thermal effects in tissue culture and in animals. It could also induce tumor cell destruction, controlled by the laser settings and the doses of SWNT and GC. Laser+SWNT-GC treatment could also induce strong expression of heat shock proteins on the surface of tumor cells. This immunologically modified carbon nanotube could be used for selective photothermal interactions in noninvasive tumor treatment.

  1. Conductance of AFM Deformed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Svizhenko, Alexei; Maiti, Amitesh; Anatram, M. P.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on the electrical conductivity of carbon nanotubes upon deformation by atomic force microscopy (AFM). The density of states and conductance were computed using four orbital tight-binding method with various parameterizations. Different chiralities develop bandgap that varies with chirality.

  2. Chemistry of Carbon Nanotubes for Everyone

    ERIC Educational Resources Information Center

    Basu-Dutt, Sharmistha; Minus, Marilyn L.; Jain, Rahul; Nepal, Dhriti; Kumar, Satish

    2012-01-01

    Carbon nanotubes (CNTs) have the extraordinary potential to change our lives by improving existing products and enabling new ones. Current and future research and industrial workforce professionals are very likely to encounter some aspects of nanotechnology including CNT science and technology in their education or profession. The simple structure…

  3. Scalable dielectrophoresis of single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fitzhugh, William A.

    Single Walled Carbon Nanotubes (SWNTs) have attracted much attention as a candidate material for future nano-scale 'beyond silicon' devices. However industrial scale operations have been impeded by difficulties in separating the metallic and semiconducting species. This paper addresses the use of highly inhomogeneous alternating electric fields, dielectrophoresis, to isolate SWNT species in scaled systems. Both numerical and experimental methods will be discussed.

  4. Heat Transport in Liquid Polyester Resin with Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Vales-Pinzón, C.; Quiñones-Weiss, G.; Alvarado-Gil, J. J.; Medina-Esquivel, R. A.

    2015-11-01

    Carbon nanotubes represent one of the most important materials in nanoscience and nanotechnology, due to their outstanding structural, mechanical, electrical, and thermal properties. It has been shown that when incorporated in a polymeric matrix, carbon nanotubes can improve its physical properties. In this work, thermal-diffusivity measurements of composite materials, prepared by mixing carbon nanotubes in liquid polyester resin, were performed by means of the thermal-wave resonant cavity. The results show an increase of the thermal diffusivity when the volume fraction of carbon nanotubes grows. It is also shown that this increase depends strongly on the diameter of the nanotubes.

  5. Carbon Nanotubes: From Symmetry to Applications

    NASA Astrophysics Data System (ADS)

    Damnjanović, M.

    In this chapter, we show how the concept of symmetry gives theoretical explanation of the properties, which made carbon nanotubes (NTs) one of the most interesting materials of nanotechnology. First, in Sect. 3.1, we consider basic facts on single-wall carbon nanotubes (SWCNTs), including their configuration and symmetry. Then, we discuss double-wall nanotubes.Next, Sect. 3.2 is devoted to elementary symmetry-based physical properties. More precisely, we explain the energy spectrum of electrons and phonons, showing that as the consequence of the symmetry, energies must be arranged in the so-called bands. Elementary properties of these band structures may be a priory discussed, yielding easily famous conducting law, showing strong dependence of conductivity on the type of nanotube. Conserved quantum numbers enable us to extract selection rules for various physical processes. This way, radial breathing mode appears to be very important for the characterization of the samples by Raman spectroscopy. Also, optical properties are derived.Finally, in Sect. 3.3, mutual interaction between the walls of double-wall nanotubes is discussed. It is explained why this interaction is very weak, which is used to propose nanomachines with almost superslippery parts.

  6. Pure carbon nanoscale devices: Nanotube heterojunctions

    SciTech Connect

    Chico, L.; Crespi, V.H.; Benedict, L.X.; Louie, S.G.; Cohen, M.L. |

    1996-02-01

    Introduction of pentagon-heptagon pair defects into the hexagonal network of a single carbon nanotube can change the helicity of the tube and alter its electronic structure. Using a tight-binding method to calculate the electronic structure of such systems we show that they behave as nanoscale metal/semiconductor or semiconductor/semiconductor junctions. These junctions could be the building blocks of nanoscale electronic devices made entirely of carbon. {copyright} {ital 1996 The American Physical Society.}

  7. Electrical transport measurements of individual bismuth nanowires and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jang, Wan Young

    have also studied electric transport measurements of carbon nanotubes grown in AAO templates. These vertically grown carbon nanotubes (CNTs) are useful for field emission device. In addition, ultra-density vertical CNT transistor arrays have also been proposed based on these nanotube structures. To realize these interesting electronic applications, a detailed understanding of the electronic transport properties of the nanotubes is needed. In particular, nanotubes grown in the AAO templates are known to possess significant amount of structural disorder. It is thus important to elucidate the effect of disorder on the electronic properties of these nanotubes. Electrical transport measurements of individual carbon nanotubes are studied, The four-terminal resistance at room temperature scales linearly with the nanotube length indicating diffusive nature of transport. The conductance shows an exp[(-1/T)1/3] dependence on temperature T, suggesting that two-dimensional variable-range hopping is the dominant conduction mechanism. The maximum current density carried by these nanotubes is on the order of 106 A/cm 2.

  8. Accelerating Gas Adsorption on 3D Percolating Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Hui; Wen, Chenyu; Zhang, Youwei; Wu, Dongping; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-02-01

    In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an SWCNT network in the transistor channel, which in turn results in a 7-fold shorter time constant of adsorption with the composite. The description of gas adsorption developed in the present work is generic for all semiconductors and the demonstrated composite with 3D percolating SWCNTs dispersed in functional polymer represents a promising new type of material for advanced gas sensors.

  9. Accelerating Gas Adsorption on 3D Percolating Carbon Nanotubes

    PubMed Central

    Li, Hui; Wen, Chenyu; Zhang, Youwei; Wu, Dongping; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-01-01

    In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an SWCNT network in the transistor channel, which in turn results in a 7-fold shorter time constant of adsorption with the composite. The description of gas adsorption developed in the present work is generic for all semiconductors and the demonstrated composite with 3D percolating SWCNTs dispersed in functional polymer represents a promising new type of material for advanced gas sensors. PMID:26888337

  10. Single-Walled Carbon-Nanotubes-Based Organic Memory Structures.

    PubMed

    Fakher, Sundes; Nejm, Razan; Ayesh, Ahmad; Al-Ghaferi, Amal; Zeze, Dagou; Mabrook, Mohammed

    2016-01-01

    The electrical behaviour of organic memory structures, based on single-walled carbon-nanotubes (SWCNTs), metal-insulator-semiconductor (MIS) and thin film transistor (TFT) structures, using poly(methyl methacrylate) (PMMA) as the gate dielectric, are reported. The drain and source electrodes were fabricated by evaporating 50 nm gold, and the gate electrode was made from 50 nm-evaporated aluminium on a clean glass substrate. Thin films of SWCNTs, embedded within the insulating layer, were used as the floating gate. SWCNTs-based memory devices exhibited clear hysteresis in their electrical characteristics (capacitance-voltage (C-V) for MIS structures, as well as output and transfer characteristics for transistors). Both structures were shown to produce reliable and large memory windows by virtue of high capacity and reduced charge leakage. The hysteresis in the output and transfer characteristics, the shifts in the threshold voltage of the transfer characteristics, and the flat-band voltage shift in the MIS structures were attributed to the charging and discharging of the SWCNTs floating gate. Under an appropriate gate bias (1 s pulses), the floating gate is charged and discharged, resulting in significant threshold voltage shifts. Pulses as low as 1 V resulted in clear write and erase states. PMID:27598112

  11. Accelerating Gas Adsorption on 3D Percolating Carbon Nanotubes.

    PubMed

    Li, Hui; Wen, Chenyu; Zhang, Youwei; Wu, Dongping; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-01-01

    In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an SWCNT network in the transistor channel, which in turn results in a 7-fold shorter time constant of adsorption with the composite. The description of gas adsorption developed in the present work is generic for all semiconductors and the demonstrated composite with 3D percolating SWCNTs dispersed in functional polymer represents a promising new type of material for advanced gas sensors. PMID:26888337

  12. Carbon nanotubes on a spider silk scaffold

    PubMed Central

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-01-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations. PMID:24022336

  13. Carbon nanotubes on a spider silk scaffold

    NASA Astrophysics Data System (ADS)

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-09-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

  14. Carbon nanotubes on a spider silk scaffold.

    PubMed

    Steven, Eden; Saleh, Wasan R; Lebedev, Victor; Acquah, Steve F A; Laukhin, Vladimir; Alamo, Rufina G; Brooks, James S

    2013-01-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations. PMID:24022336

  15. Adjustable thermal conductivity in carbon nanotube nanofluids

    NASA Astrophysics Data System (ADS)

    Xie, Huaqing; Chen, Lifei

    2009-05-01

    Homogeneous and stable nanofluids have been produced by suspending well dispersible multi-walled carbon nanotubes (CNTs) into ethylene glycol base fluid. CNT nanofluids have enhanced thermal conductivity and the enhancement ratios increase with the nanotube loading and the temperature. Thermal conductivity enhancement was adjusted by ball milling and cutting the treated CNTs suspended in the nanofluids to relatively straight CNTs with an appropriate length distribution. Our findings indicate that the straightness ratio, aspect ratio, and aggregation have collective influence on the thermal conductivity of CNT nanofluids.

  16. Transmission Through Carbon Nanotubes with Polyhedral Caps

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Govindan, T. R.

    1999-01-01

    We study electron transport between capped carbon nanotubes and a substrate, and relate this transport to the local density of states in the cap. Our results show that that the transmission probability mimics the behavior of the density of states at all energies except those that correspond to localized states. For a capped carbon nanotube that is not connected to a substrate, the localized states do not couple to the coexisting continuum states. However, close proximity of a substrate causes hybridization between these states. As a result, new transmission paths open from substrate states to nanotube continuum states via the localized states in the cap. We show that the interference between various paths gives rise to transmission antiresonances with the minimum equal to zero at the energy of the localized state. The presence of defects in the tube places close to the cap transforms antiresonances into resonances. Depending on the spatial position of defects, these resonant states are capable of carrying a large current. The results of this paper are of relevance to carbon nanotube based studies on molecular electronics and probe tip applications.

  17. Functionalization of vertically aligned carbon nanotubes

    PubMed Central

    Snyders, Rony; Colomer, Jean-François

    2013-01-01

    Summary This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs). The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers) to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs. PMID:23504581

  18. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes.

    PubMed

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M; Hároz, Erik H; Doorn, Stephen K; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M; Adams, W Wade; Hauge, Robert H; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm(2)) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 10(6) nanotubes in a cross-sectional area of 1 μm(2). The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios. PMID:27043199

  19. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M.; Hároz, Erik H.; Doorn, Stephen K.; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M.; Adams, W. Wade; Hauge, Robert H.; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm2) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 106 nanotubes in a cross-sectional area of 1 μm2. The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios.

  20. Selective functionalization and loading of biomolecules in crystalline silicon nanotube field-effect-transistors

    NASA Astrophysics Data System (ADS)

    Kwon, Soonshin; Chen, Zack C. Y.; Noh, Hyunwoo; Lee, Ju Hun; Liu, Hang; Cha, Jennifer N.; Xiang, Jie

    2014-06-01

    Crystalline silicon nanotubes (Si NTs) provide distinctive advantages as electrical and biochemical analysis scaffolds through their unique morphology and electrical tunability compared to solid nanowires or amorphous/non-conductive nanotubes. Such potential is investigated in this report. Gate-dependent four-probe current-voltage analysis reveals electrical properties such as resistivity to differ by nearly 3 orders of magnitude between crystalline and amorphous Si NTs. Analysis of transistor transfer characteristics yields a field effect mobility of 40.0 cm2 V-1 s-1 in crystalline Si NTs. The hollow morphology also allows selective inner/outer surface functionalization and loading capability either as a carrier for molecular targets or as a nanofluidic channel for biomolecular assays. We present for the first time a demonstration of internalization of fluorescent dyes (rhodamine) and biomolecules (BSA) in Si NTs as long as 22 μm in length.Crystalline silicon nanotubes (Si NTs) provide distinctive advantages as electrical and biochemical analysis scaffolds through their unique morphology and electrical tunability compared to solid nanowires or amorphous/non-conductive nanotubes. Such potential is investigated in this report. Gate-dependent four-probe current-voltage analysis reveals electrical properties such as resistivity to differ by nearly 3 orders of magnitude between crystalline and amorphous Si NTs. Analysis of transistor transfer characteristics yields a field effect mobility of 40.0 cm2 V-1 s-1 in crystalline Si NTs. The hollow morphology also allows selective inner/outer surface functionalization and loading capability either as a carrier for molecular targets or as a nanofluidic channel for biomolecular assays. We present for the first time a demonstration of internalization of fluorescent dyes (rhodamine) and biomolecules (BSA) in Si NTs as long as 22 μm in length. Electronic supplementary information (ESI) available: Modelling (Fig. S1) and

  1. Adsorption of Gases on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mbaye, Mamadou Thiao

    This research focus in studying the interaction between various classical and quantum gases with novel carbon nanostructures, mainly carbon nanotubes (CNTs). Since their discovery by the Japanese physicist Sumio Iijima [1] carbon nanotubes have, experimentally and theoretically, been subjected to many scientific investigation. Studies of adsorption on CNTs are particularly directed toward their better usage in gas storage, gas separation, catalyst, drug delivery, and water purification. We explore the adsorption of different gases entrapped in a single, double, or multi-bundles of CNTs using computer simulations. The first system we investigate consists of Ar and Kr films adsorbed on zigzag or armchair nanotubes. Our simulations revealed that Kr atoms on intermediate size zigzag NTs undergo two phase transitions: A liquid-vapor (L→V), and liquid-commensurate (L→CS) with a fractional coverage of one Kr atoms adsorbed for every four carbon atoms. For Ar on zigzag and armchair NTs, the only transition observed is a L→V. In the second problem, we explore the adsorption of CO2 molecules in a nanotube bundle and calculate the isosteric heat of adsorption of the entrapped molecules within the groove. We observed that the lower the temperature, the higher the isosteric of adsorption. Last, we investigate the adsorption of hydrogen, Helium, and Neon gases on the groove site of two parallel nanotubes. At low temperature, the transverse motion on the plane perpendicular to the tubes' axis is frozen out and as a consequence, the heat capacity is reduced to 1/2. At high temperature, the atoms gain more degree of freedom and as a consequence the heat capacity is 5/2.

  2. Diffusion through Carbon Nanotube Semipermeable membranes

    SciTech Connect

    Bakajin, O

    2006-02-13

    The goal of this project is to measure transport through CNTs and study effects of confinement at molecular scale. This work is motivated by several simulation papers in high profile journals that predict significantly higher transport rates of gases and liquids through carbon nanotubes as compared with similarly-sized nanomaterials (e.g. zeolites). The predictions are based on the effects of confinement, atomically smooth pore walls and high pore density. Our work will provide the first measurements that would compare to and hopefully validate the simulations. Gas flux is predicted to be >1000X greater for SWNTs versus zeolitesi. A high flux of 6-30 H2O/NT/ns {approx} 8-40 L/min for a 1cm{sup 2} membrane is also predicted. Neutron diffraction measurements indicate existence of a 1D water chain within a cylindrical ice sheet inside carbon nanotubes, which is consistent with the predictions of the simulation. The enabling experimental platform that we are developing is a semipermeable membrane made out of vertically aligned carbon nanotubes with gaps between nanotubes filled so that the transport occurs through the nanotubes. The major challenges of this project included: (1) Growth of CNTs in the suitable vertically aligned configuration, especially the single wall carbon nanotubes; (2) Development of a process for void-free filling gaps between CNTs; and (3) Design of the experiments that will probe the small amounts of analyte that go through. Knowledge of the behavior of water upon nanometer-scale confinement is key to understanding many biological processes. For example, the protein folding process is believed to involve water confined in a hydrophobic environment. In transmembrane proteins such as aquaporins, water transport occurs under similar conditions. And in fields as far removed as oil recovery and catalysis, an understanding of the nanoscale molecular transport occurring within the nanomaterials used (e.g. zeolites) is the key to process optimization

  3. Carbon Nanotubes: Measuring Dispersion and Length

    SciTech Connect

    Fagan, Jeffrey A.; Bauer, Barry J.; Hobbie, Erik K.; Becker, Matthew L.; Hight-Walker, Angela; Simpson, Jeffrey R.; Chun, Jaehun; Obrzut, Jan; Bajpai, Vardhan; Phelan, Fred R.; Simien, Daneesh; Yeon Huh, Ji; Migler, Kalman B.

    2011-03-01

    Advanced technological uses of single-wall carbon nanotubes (SWCNTs) rely on the production of single length and chirality populations that are currently only available through liquid phase post processing. The foundation of all of these processing steps is the attainment of individualized nanotube dispersion in solution; an understanding of the collodial properties of the dispersed SWCNTs can then be used to designed appropriate conditions for separations. In many instances nanotube size, particularly length, is especially active in determining the achievable properties from a given population, and thus there is a critical need for measurement technologies for both length distribution and effective separation techniques. In this Progress Report, we document the current state of the art for measuring dispersion and length populations, including separations, and use examples to demonstrate the desirability of addressing these parameters.

  4. Electrical characterization of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Berliocchi, Marco; Brunetti, Francesca; Di Carlo, Aldo; Lugli, Paolo; Orlanducci, Silvia; Terranova, Maria Letizia

    2003-04-01

    Single Wall Carbon Nanotubes (SWCNTs) based nanotechnology appears to be promising for future nanoelectronics. The SWCNT may be either metallic or semiconducting and both metallic and semiconducting types of SWCNTs have been observed experimentally. This gives rise to intriguing possibilities to put together semiconductor-semiconductor and semiconductor-metal junctions for diodes and transistors. The potential for nanotubes in nanoelectronics devices, displays and nanosensors is enormous. However, in order to realize the potential of SWCNTs, it is critical to understand the properties of charge transport and to control phase purity, elicity and arrangement according to specific architectures. We have investigated the electrical properties of various SWCNTs samples whit different organization: bundles of SWCNTs, SWCNT fibres and different membranes and tablets obtained using SWCNTs purified and characterized. Electrical characterizations were carried out by a 4155B Agilent Semiconductor Parameter Analyser. In order to give a mechanical stability to SWCNTs fibres and bundles we have used a nafion matrix coating, so an electrical characterization has been performed on samples with and without this layer. I-V measurements were performed in vacuum and in air using aluminium interdigitated coplanar-electrodes (width=20mm or 40mm) on glass substrates. The behaviour observed is generally supralinear with currents of the order of mA in vacuum and lower values in air with the exception of the tablet samples where the behaviour is ohmic, the currents are higher and similar values of current are detected in air and vacuum.

  5. Ag-catalysed cutting of multi-walled carbon nanotubes.

    PubMed

    La Torre, A; Rance, G A; Miners, S A; Herreros Lucas, C; Smith, E F; Fay, M W; Zoberbier, T; Giménez-López, M C; Kaiser, U; Brown, P D; Khlobystov, A N

    2016-04-29

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes. PMID:26987452

  6. Ag-catalysed cutting of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    La Torre, A.; Rance, G. A.; Miners, S. A.; Herreros Lucas, C.; Smith, E. F.; Fay, M. W.; Zoberbier, T.; Giménez-López, M. C.; Kaiser, U.; Brown, P. D.; Khlobystov, A. N.

    2016-04-01

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  7. Electrochemical Characterization of Carbon Nanotubes for Fuel Cell MEA's

    NASA Technical Reports Server (NTRS)

    Panagaris, Jael; Loyselle, Patricia

    2004-01-01

    Single-walled and multi-walled carbon nanotubes from different sources have been evaluated before and after sonication to identify structural differences and evaluate electrochemical performance. Raman spectral analysis and cyclic voltammetry in situ with QCM were the principle means of evaluating the tubes. The raman data indicates that sonication in toluene modifies the structural properties of the nanotubes. Sonication also affects the electrochemical performance of single-walled nanotubes and the multi-walled tubes differently. The characterization of different types of carbon nanotubes leads up to identifying a potential candidate for incorporating carbon nanotubes for fuel cell MEA structures.

  8. Carbon Nanotubes for Space Photovoltaic Applications

    NASA Technical Reports Server (NTRS)

    Efstathiadis, Harry; Haldar, Pradeep; Landi, Brian J.; Denno, Patrick L.; DiLeo, Roberta A.; VanDerveer, William; Raffaelle, Ryne P.

    2007-01-01

    Carbon nanotubes (CNTs) can be envisioned as an individual graphene sheet rolled into a seamless cylinder (single-walled, SWNT), or concentric sheets as in the case of a multi-walled carbon nanotube (MWNT) (1). The role-up vector will determine the hexagonal arrangement and "chirality" of the graphene sheet, which will establish the nanotube to be metallic or semiconducting. The optoelectronic properties will depend directly on this chiral angle and the diameter of the SWNT, with semiconductor types exhibiting a band gap energy (2). Characteristic of MWNTs are the concentric graphene layers spaced 0.34 nm apart, with diameters from 10-200 nm and lengths up to hundreds of microns (2). In the case of SWNTs, the diameters range from 0.4 - 2 nm and lengths have been reported up to 1.5 cm (3). SWNTs have the distinguishable property of "bundling" together due to van der Waal's attractions to form "ropes." A comparison of these different structural types is shown in Figure 1. The use of SWNTS in space photovoltaic (PV) applications is attractive for a variety of reasons. Carbon nanotubes as a class of materials exhibit unprecedented optical, electrical, mechanical properties, with the added benefit of being nanoscale in size which fosters ideal interaction in nanomaterial-based devices like polymeric solar cells. The optical bandgap of semiconducting SWNTs can be varied from approx. 0.4 - 1.5 eV, with this property being inversely proportional to the nanotube diameter. Recent work at GE Global Research has shown where a single nanotube device can behave as an "ideal" pn diode (5). The SWNT was bridged over a SiO2 channel between Mo contacts and exhibited an ideality factor of 1, based on a fit of the current-voltage data using the diode equation. The measured PV efficiency under a 0.8 eV monochromatic illumination showed a power conversion efficiency of 0.2 %. However, the projected efficiency of these junctions is estimated to be > 5 %, especially when one considers the

  9. Inhaled carbon nanotubes reach the subpleural tissue in mice

    NASA Astrophysics Data System (ADS)

    Ryman-Rasmussen, Jessica P.; Cesta, Mark F.; Brody, Arnold R.; Shipley-Phillips, Jeanette K.; Everitt, Jeffrey I.; Tewksbury, Earl W.; Moss, Owen R.; Wong, Brian A.; Dodd, Darol E.; Andersen, Melvin E.; Bonner, James C.

    2009-11-01

    Carbon nanotubes are shaped like fibres and can stimulate inflammation at the surface of the peritoneum when injected into the abdominal cavity of mice, raising concerns that inhaled nanotubes may cause pleural fibrosis and/or mesothelioma. Here, we show that multiwalled carbon nanotubes reach the subpleura in mice after a single inhalation exposure of 30 mg m-3 for 6 h. Nanotubes were embedded in the subpleural wall and within subpleural macrophages. Mononuclear cell aggregates on the pleural surface increased in number and size after 1 day and nanotube-containing macrophages were observed within these foci. Subpleural fibrosis unique to this form of nanotubes increased after 2 and 6 weeks following inhalation. None of these effects was seen in mice that inhaled carbon black nanoparticles or a lower dose of nanotubes (1 mg m-3). This work suggests that minimizing inhalation of nanotubes during handling is prudent until further long-term assessments are conducted.

  10. Carbon nanotube materials from hydrogen storage

    SciTech Connect

    Dillon, A.C.; Bekkedahl, T.A.; Cahill, A.F.

    1995-09-01

    The lack of convenient and cost-effective hydrogen storage is a major impediment to wide scale use of hydrogen in the United States energy economy. Improvements in the energy densities of hydrogen storage systems, reductions in cost, and increased compatibility with available and forecasted systems are required before viable hydrogen energy use pathways can be established. Carbon-based hydrogen adsorption materials hold particular promise for meeting and exceeding the U.S. Department of Energy hydrogen storage energy density targets for transportation if concurrent increases in hydrogen storage capacity and carbon density can be achieved. These two goals are normally in conflict for conventional porous materials, but may be reconciled by the design and synthesis of new adsorbent materials with tailored pore size distributions and minimal macroporosity. Carbon nanotubes offer the possibility to explore new designs for adsorbents because they can be fabricated with small size distributions, and naturally tend to self-assemble by van der Waals forces. This year we report heats of adsorption for hydrogen on nanotube materials that are 2 and 3 times greater than for hydrogen on activated carbon. The hydrogen which is most strongly bound to these materials remains on the carbon surface to temperatures greater than 285 K. These results suggest that nanocapillary forces are active in stabilizing hydrogen on the surfaces of carbon nanotubes, and that optimization of the adsorbent will lead to effective storage at higher temperatures. In this paper we will also report on our activities which are targeted at understanding and optimizing the nucleation and growth of single wall nanotubes. These experiments were made possible by the development of a unique feedback control circuit which stabilized the plasma-arc during a synthesis run.

  11. Sagnac interference in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bishara, Waheb; Refael, Gil; Bockrath, Marc

    2008-10-01

    The Sagnac interference mode arises when two interfering counterpropogating beams traverse a loop, but with their velocities detuned by a small amount 2u , with vR/L=vF±u . In this paper we perform a perturbative nonequilibrium calculation of Sagnac interference in single-channel wires as well as armchair nanotube loops. We study the dependence of the Sagnac conductance oscillations on temperature and interactions. We find that the Sagnac interference is not destroyed by strong interactions, but becomes weakly dependent on the velocity detuning u . In armchairs nanotubes with typical interaction strength, 0.25≤g≤0.5 , we find that the necessary temperature for observing the interference effect, TSAG is also only weakly dependent on the interaction, and is enhanced by a factor of 8 relative to the temperature necessary for observing Fabry-Pérot interference in the same system, TFP .

  12. Synthesis of Carbon Nanotubes Using Sol Gel Route

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, Tarek

    2002-12-01

    Since 1990, carbon nanotubes were discovered and they have been the object of intense scientific study ever since. A carbon nanotube is a honeycomb lattice rolled into a cylinder. The diameter of a carbon nanotube is of nanometer size and the length is in the range of micrometer. Many of the extraordinary properties attributed to nanotubes, such as tensile strength and thermal stability, have inspired predictions of microscopic robots, dent-resistant car bodies and earthquake-resistant buildings. The first products to use nanotubes were electrical. Some General Motors cars already include plastic parts to which nanotubes were added; such plastic can be electrified during painting so that the paint will stick more readily. Two nanotube-based lighting and display products are well on their way to market. In the long term, perhaps the most valuable applications will take further advantage of nanotubes' unique electronic properties. Carbon nanotubes can in principle play the same role as silicon does in electronic circuits, but at a molecular scale where silicon and other standard semiconductors cease to work. There are several routes to synthesize carbon nanotubes; laser vaporization, carbon arc and vapor growth. We have applied a different route using sol gel chemistry to obtain carbon nanotubes. This work is patent-pending.

  13. Mesoscale mechanics of twisting carbon nanotube yarns.

    PubMed

    Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J

    2015-03-12

    Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle. PMID:25732328

  14. A Structural Transition of Carbon Nanotubes?

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S.; Cui, Y.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The superior properties of carbon nanotubes (CNT) are good for many applications. A possible temperature-related structural transition is found in the CNT, which may suggest new applications of CNT. CNT materials have been synthesized on Si substrates by pulsed laser vaporization in various temperatures and pressures. Raman spectroscopy and scanning electron microscopy are used to determine the CNT structure and morphology. It is found that the formation of nanotubes depends strongly on the growth temperatures and high quality multi-wall and single-wall nanotubes were produced at 700 and 990 C, respectively. The radial breath modes of Raman spectra measured in the range of 50 cm(exp -1) to 300 cm(exp -1), indicate that one of samples grown at 700 C is to be dependent on the excitation intensity. The spectra of the sample suggest that the structure is similar to that of multi-wall nanotubes at low excitation intensity (2.5 kW per square centimeter) and it converts to the structure of single-wall nanotubes at higher intensity (25 kW per square centimeter). Measurements taken while cycling the light intensity suggests a reversible transition.

  15. Osmotic water transport through carbon nanotube membranes

    PubMed Central

    Kalra, Amrit; Garde, Shekhar; Hummer, Gerhard

    2003-01-01

    We use molecular dynamics simulations to study osmotically driven transport of water molecules through hexagonally packed carbon nanotube membranes. Our simulation setup comprises two such semipermeable membranes separating compartments of pure water and salt solution. The osmotic force drives water flow from the pure-water to the salt-solution compartment. Monitoring the flow at molecular resolution reveals several distinct features of nanoscale flows. In particular, thermal fluctuations become significant at the nanoscopic length scales, and as a result, the flow is stochastic in nature. Further, the flow appears frictionless and is limited primarily by the barriers at the entry and exit of the nanotube pore. The observed flow rates are high (5.8 water molecules per nanosecond and nanotube), comparable to those through the transmembrane protein aquaporin-1, and are practically independent of the length of the nanotube, in contrast to predictions of macroscopic hydrodynamics. All of these distinct characteristics of nanoscopic water flow can be modeled quantitatively by a 1D continuous-time random walk. At long times, the pure-water compartment is drained, and the net flow of water is interrupted by the formation of structured solvation layers of water sandwiched between two nanotube membranes. Structural and thermodynamic aspects of confined water monolayers are studied. PMID:12878724

  16. Carbon nanotubes as long ballistic conductors

    NASA Astrophysics Data System (ADS)

    White, C. T.; Todorov, T. N.

    1998-05-01

    Early theoretical work on single-walled carbon nanotubes predicted that a special achiral subset of these structures known as armchair nanotubes should be metallic. Tans et al. have recently confirmed these predictions experimentally and also showed directly that coherent electron transport can be maintained through these nanowires up to distances of at least 140nm. But single-walled armchair nanotubes are one-dimensional conductors with only two open conduction channels (energy subbands in a laterally confined system that cross the Fermi level). Hence, with increasing length, their conduction electrons ultimately become localized owing to residual disorder in the tube which is inevitably produced by interactions between the tube and its environment. We present here calculations which show, however, that unlike normal metallic wires, conduction electrons in armchair nanotubes experience an effective disorder averaged over the tube's circumference, leading to electron mean free paths that increase with nanotube diameter. This increase should result in exceptional ballistic transport properties and localization lengths of 10µm or more for tubes with the diameters that are typically produced experimentally.

  17. Mesoscale mechanics of twisting carbon nanotube yarns

    NASA Astrophysics Data System (ADS)

    Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J.

    2015-03-01

    Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle.

  18. Spectroscopic study of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Curran, Seamus; Weldon, Declan N.; Blau, Werner J.; Zandbergen, Henny W.; Kastner, J.; Kuzmany, Hans

    1994-11-01

    We present a comprehensive experimental study of the vibrational spectra of nanotubes. There are two main lines observed in the Raman spectrum, one positioned at 1350 cm-1, the D line, and the other at 1580 cm-1, the G line. Both these lines are very similar to those seen with disordered graphite. The disorder induced D line is very weak compared to the G line which is indicative of high crystalline materials. The position and intensity of the D line strongly depends on the energy of the exciting laser. This dispersion effect was also observed for graphitic particles and may be explained by a photoselective resonance process of nanotubes with different sizes. There are two optically active modes in the Infrared spectrum for highly orientated polycrystalline graphite which are the E1u and A2u modes. The E1u mode is positioned at 1587 cm-1 while the A2u mode is positioned at 868 cm-1. The Infrared spectrum of the nanotubes shows both modes although the E1u mode is downshifted to 1575 cm-1.

  19. Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon

    NASA Technical Reports Server (NTRS)

    Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.

    2012-01-01

    The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

  20. Imaging the operation of a carbon nanotube charge sensor at the nanoscale.

    PubMed

    Brunel, David; Mayer, Alexandre; Mélin, Thierry

    2010-10-26

    Carbon nanotube field effect transistors (CNTFETs) are of great interest for nanoelectronics applications such as nonvolatile memory elements (NVMEs) or charge sensors. In this work, we use a scanning-probe approach based on a local charge perturbation of CNTFET-based NVMEs and investigate their fundamental operation from combined transport, electrostatic scanning probe techniques and atomistic simulations. We experimentally demonstrate operating devices with threshold voltages shifts opposite to conventional gating and with almost unchanged hysteresis. The former effect is quantitatively understood as the emission of a delocalized image charge pattern in the nanotube environment, in response to local charge storage, while the latter effect points out the dominant dipolar nature of hysteresis in CNTFETs. We propose a simple model for charge sensing using CNTFETs, based on the redistribution of the nanotube image charges. This model could be extended to gas or biosensing, for example. PMID:20866060