Bulletin of the American Physical Society
2006 APS March Meeting
Monday–Friday, March 13–17, 2006; Baltimore, MD
Session V18: Focus Session: Carbon Nanotubes: Transport IV |
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Sponsoring Units: DMP Chair: Michael Fuhrer, University of Maryland Room: Baltimore Convention Center 315 |
Thursday, March 16, 2006 11:15AM - 11:51AM |
V18.00001: 2D Carbon Nanotube Network: A New material for Electronics Invited Speaker: 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. [Preview Abstract] |
Thursday, March 16, 2006 11:51AM - 12:03PM |
V18.00002: Understanding 1/f noise in carbon nanotube devices Yu-Ming Lin, Joerg Appenzeller, Joachim Knoch, Zhihong Chen, Phaedon Avouris Nanotubes and nanowires provide an ideal platform to study the electronic behavior of low-dimensional systems. Although a great deal has been learned about the electronic properties of nanotubes and nanowires, little is known about their noise characteristics. We have characterized the 1/f noise behavior of nano-devices consisting of individual single-walled semiconducting carbon nanotubes. Two types of carbon nanotube field-effect transistors (CNFETs) are fabricated and investigated in order to distinguish between the impacts of the contact and bulk channel on the noise. The first type of CNFET is a back-gated device where the conductance is entirely modulated by the Schottky barriers (SBs) at the nanotube/metal interfaces, while the second type of CNFET incorporates an additional gate electrode so that the device switching can be achieved through the bulk channel of the nanotube. We have also fabricated SB-CNFETs with very different channel lengths using a \textit{single} nanotube in order to elucidate the impact of scattering on 1/$f$ noise. The results indicate that that 1/$f$ noise in a 1D system with quasi-ballistic transport behavior provides a measure of the total number of transport carriers in the channel. Morover, the intrinsic 1/$f$ noise amplitude of individual single-walled carbon nanotube is, in fact, not larger than that of most bulk materials. [Preview Abstract] |
Thursday, March 16, 2006 12:03PM - 12:15PM |
V18.00003: Time-Dependent Transport in Carbon Nanotube Transistors Yupeng Chen, Jing Guo, Thomas Wu Recently, very high frequency properties of carbon nanotube field-effect transistors (FETs) are attracting extensive research interests due to their high mobility and near ballistic transport [1 -- 4]. To explore the performance limit of CNTFETs for very high frequency applications, it is important to understand time-dependent transport in CNTFETs. Self-consistent, quasi-static quantum simulations have been applied to assess the high-frequency performance [4]. However, the validity of quasi-static approximation needs to be examined. In addition, a full-time dependent simulation is necessary to examine some very important characteristics, such as frequency-dependent conductance. Our study on AC characteristics of CNTFETs is based on solving a full time-dependent quantum transport equation for CNTFETs using the finite difference time domain (FDTD) method for the first time. The dependence of small signal transconductance and gate capacitance on the frequency of the applied bias is examined. The intrinsic cut-off frequency, a device metric important for radio-frequency (RF) applications, and the intrinsic switching time, a metric important for digital switch applications, are computed using the full time-dependent simulations. The validity of the widely used quasi-static approximation is examined. [Preview Abstract] |
Thursday, March 16, 2006 12:15PM - 12:27PM |
V18.00004: Carbon Nanotube Low Power Integrated Circuit. Zhihong Chen, Joerg Appenzeller, Yu-Ming Lin, Jennifer Sippel-Oakley, Andrew G. Rinzler, Jinyao Tang, Shalom J. Wind, Paul M. Solomon, Phaedon Avouris Identifying a material that can outperform silicon in terms of device density, power consumption and performance is one of the main goals of today's nano-electronics effort. Carbon nanotubes are considered to offer the greatest potential in this context. So far, the emphasis has been on fabricating and characterizing individual nanotube devices. A critical next step is the construction of integrated circuits. Complementary metal-oxide semiconductor (CMOS) technology is the dominant approach for microprocessors, memories, and many other applications, in particular due to its small power consumption. Here, we demonstrate the first CMOS-type, high performance, multiple components logic circuit based on a single carbon nanotube molecule. [Preview Abstract] |
Thursday, March 16, 2006 12:27PM - 12:39PM |
V18.00005: Electron Transport in Carbon Nanotube Devices with Several Narrow Top-Gates Joseph Sulpizio, Charis Quay, Zvonimir Bandic, David Goldhaber-Gordon Carbon nanotubes provide an excellent system for studying one-dimensional (1D) electron systems, known as Luttinger liquids. We report on the nanofabrication of carbon nanotube devices with several narrow top-gates, and provide initial electron transport measurements. Using the top-gates to induce tunable tunnel barriers within the nanotubes, we aim to probe electron-electron interactions by measuring transport across the devices. Fine control over the properties of such devices should enable the further study of other interesting quantum properties of 1D systems (e.g. spin-charge separation). [Preview Abstract] |
Thursday, March 16, 2006 12:39PM - 12:51PM |
V18.00006: Probing Chemical Potentials in Solution with Carbon Nanotube Transistors Lisa Larrimore, Suddhasattwa Nad, Xinjian Zhou, H\'{e}ctor Abru\~{n}a, Paul McEuen We have used single-walled carbon nanotube transistors to sense redox-active transition metal complexes in a conducting liquid environment. The molecules shift the gate voltage dependence of the nanotube conductance. This shift depends logarithmically on the ratio of oxidized to reduced molecules, which is changed and measured using traditional electrochemical methods. We attribute this signal primarily to the changing electrostatic potential of the solution as set by the water-gate wire, and not to a local interaction between the molecules and the nanotube. [Preview Abstract] |
Thursday, March 16, 2006 12:51PM - 1:03PM |
V18.00007: Conductance switching in carbon nanotube transistors induced by electrochemical reactions Jaan Mannik, Brett R. Goldsmith, Alexander A. Kane, Philip G. Collins Carbon nanotube transistors provide a promising architecture for studying biomolecular dynamics at the single molecule level. To achieve this goal, single bioactive molecules must be integrated into the circuits in a controllable and reliable way. While techniques can be borrowed from bulk chemical functionalization, we focus on the controlled production of a single, chemically-functional site on the sidewall of an operational nanotube transistor circuit. Our approach allows real-time, in situ monitoring of electrical signals from the transistor in order to discern reaction events. Using an electrochemical cell biased under oxidizing or reducing conditions, we have observed sharp, reversible conductance switching events consistent with single-site reactions. The reactions have well-defined electrochemical thresholds, which provides an electronic means to control their production. The dynamics of the switching events, including the rates and degree of reversibility, changes in different electrolyte solutions. This work is partly supported by NSF grant EF-0404057. [Preview Abstract] |
Thursday, March 16, 2006 1:03PM - 1:15PM |
V18.00008: Integration of Carbon Nanotubes with III-V(110) Surfaces Laura Ruppalt, Joseph Lyding We have used scanning tunneling microscopy (STM) to investigate the unique electronic and physical properties of individual isolated carbon nanotubes dispersed onto semiconducting III-V substrates in an ultrahigh vacuum (UHV) environment. Pristine III-V(110) surfaces were obtained through in situ cleavage, with single-walled carbon nanotubes (SWNTs) subsequently deposited via an UHV-compatible Dry Contact Transfer process[1]. Room temperature STM imagery confirms the intact transfer of individual tubes to the surface, while STM-enabled nanomanipulation suggests a substrate-induced stabilization of isolated SWNTs aligned along the (1bar 1 0) crystallographic direction, in registration with the substrate sublattice rows. Additionally, current image tunneling spectroscopy (CITS) maps of these SWNT/III-V(110) systems yield correlated topographic and electronic information with subnanometer resolution that provide evidence of the sensitivity of local nanotube electronic character to both inherent features of the nanotube as well as to proximal features of the underlying support substrate. [1]P.M. Albrecht and J.W. Lyding, APL 83, 5029 (2003). [Preview Abstract] |
Thursday, March 16, 2006 1:15PM - 1:27PM |
V18.00009: Graphene Nanostructures, Fabrication, Physics and Devices. Li Lu, S. P. Liu, L. W. Liu, F. Zhou, H. F. Yang, H. Li, Z. Jin, A. Z. Jin, J. Miao, W. J. Kong, J. H. Fang, C. Z. Gu, Y. X. Weng, Q. K. Xue, S. Wang, L.-M. Peng, B. Jiang, Q. S. Zheng We propose to construct nanoelectronic circuits by directly tailoring graphite, and demonstrate the feasibility of this idea by fabricating specially designed multi-terminal graphene patterns down to a minimum strip width of 50 nm. Electron tunneling measurement confirms the formation of quasi-one-dimensional subbands due to the effect of quantum size confinement. This new approach would in the future provide an efficient way of producing numerous layers of identical graphene nanoelectronic circuits. [Preview Abstract] |
Thursday, March 16, 2006 1:27PM - 1:39PM |
V18.00010: Electrical Transport in Carbon Nanotubes with Chirality Changes B. Chandra, Y. Wu, H. Han, M. Huang, L. Huang, S. O'Brien, T.F. Heinz, J. Hone We present electrical transport measurements of individual single-wall carbon nanotubes in which the chiral indices (n,m) are not fixed along the nanotube length.~ The nanotube structures are first probed by Rayleigh scattering spectroscopy, after which the tube is transferred to a substrate by a mechanical transfer process.~ Electrical leads are then fabricated by e-beam lithography.~ The transport behavior is measured in various sections of the tube to probe the behavior of the molecular junctions. [Preview Abstract] |
Thursday, March 16, 2006 1:39PM - 1:51PM |
V18.00011: Miniature Organic Transistors with Carbon Nanotubes as Quasi-One-Dimensional Electrodes. Pengfei Qi, Ali Javey, Marco Rolandi, Qian Wang, Erhan Yenilmez, Hongjie Dai As the dimensions of electronic devices approach those of molecules, the size, geometry and chemical composition of the contact electrodes play increasingly dominant roles in device functions. It is shown here that single-walled carbon nanotubes (SWNT) can be used as quasi one-dimensional (1D) electrodes to construct organic field effect transistors (FET) with molecular scale width (about 2 nm) and channel length (1 to 3 nm). An important feature owing to the quasi 1D electrode geometry is the favorable gate electrostatics that allows for efficient switching of ultra-short organic channels. This affords room temperature conductance modulation by orders of magnitude for organic transistors that are only several-molecules in length, with switching characteristics superior to similar devices with lithographically patterned metal electrodes. With nanotubes, covalent carbon-carbon bonds could be utilized to form contacts to molecular materials. The unique geometrical, physical and chemical properties of carbon nanotube electrodes may lead to various interesting molecular devices. [Preview Abstract] |
Thursday, March 16, 2006 1:51PM - 2:03PM |
V18.00012: Microwave Conductivity of Single Wall Carbon Nanotube Arrays C. Highstrete, Mark Lee, E.A. Shaner, F.E. Jones, A.A. Talin, D.B. Robinson, P.M. Dentinger We have developed a coplanar waveguide (CPW) platform compatible with both broadband (0.01 to 50 GHz) microwave scattering parameter measurements and directed assembly of carbon nanotubes (CNTs) and semiconductor nanowires. Utilizing AC dielectrophoresis and lithographic masking techniques, single-wall CNTs prepared with single-stranded DNA as a surfactant were assembled in localized parallel arrays between CPW signal and ground electrodes. This places the CNTs parallel to the electric field in the propagating region where coupling to the CNT conductivity alters the impedance of the CPW. The conductivity of the CNT arrays is deduced from scattering parameter measurements before and after assembly of the CNTs. Preliminary measurements show that at least some types of CNT material have a small but definite high-frequency loss that increases with frequency. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Thursday, March 16, 2006 2:03PM - 2:15PM |
V18.00013: Computer Simulations for a Novel Topological Defect on Carbon Nanotube Takazumi Kawai, Susumu Okada, Kei Kuwabara, Kota Daigoku, Kyoko Nakada, Yoshiyuki Miyamoto Topological defects in carbon nanotubes do not just causes a nuisance to the nanotube devices, but they sometimes provide new and interesting properties to them. Since the defect physics of nanotube is just in the early stage of research, it is very important to verify the stability and electronic properties of such defects theoretically prior to experiments. Here, we performed TBMD simulations for defect formations by C${_2}$ molecule irradiation. Although C${_2}$ molecule often bounce back even with a high kinetic energy of $\sim$20 eV, it irradiates several famous defects such as mono-vacancy, di- vacancy, and also Stone-Wales defect. In similar simulations, we also found a novel defect structure, where C${_2}$ molecule is incorporated into sp${^2}$ network of nanotube. Thermal stability of the nanotubes with the defects is similar to that of intact ones. Interestingly, DFT-LSDA calculations showed that nanotubes with a line of the novel topological defects are found to cause a magnetic ordering, where the polarized electron spins are localized around the defect and ferromagnetically aligned along the tube axis. This work was in part performed under the management of Nano Carbon Technology project supported by NEDO. [Preview Abstract] |
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