Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session A26: Focus Session: Nanotubes and Nanowires: Carbon Nanotube Transistors |
Hide Abstracts |
Sponsoring Units: DMP Chair: Jie Liu, Duke University Room: LACC 501B |
Monday, March 21, 2005 8:00AM - 8:12AM |
A26.00001: Double-wall carbon nanotube quasi-ballistic conduction Hisashi Kajiura, Houjin Huang, Alexey Bezryadin We demonstrated room-temperature quasi-ballistic electron conduction in double-wall carbon nanotubes (DWNTs) produced using a modified arc-discharge method [1]. Conductance dependence on the length of DWNT was measured by submerging the sample into liquid mercury. The conductance versus length plots show plateaus, indicating weak dependence of the electrical resistance of the DWNTs on the length of the nanotubes segment connecting electrodes. We infer a mean free path between 0.6 -- 10 micron meter for 80{\%} of the tubes, which is in good agreement with the results of calculations based on the electron scattering by acoustic-phonons and by disorder. [1] H. Kajiura et al. Chem Phys Lett 398(2004)476-9. [Preview Abstract] |
Monday, March 21, 2005 8:12AM - 8:24AM |
A26.00002: Directional growth of Single-Walled Carbon Nanotubes for Nanotube-on-Insulator Applications Song Han, Xiaolei Liu, Chongwu Zhou Dense arrays of highly aligned carbon nanotubes were synthesized by chemical vapor deposition on flat crystalline substrate surfaces. The nanotube orientation was found to favor certain crystalline directions of the substrate, regardless of the gas flow direction. This is in sharp contrast to the randomly oriented growth of nanotubes on Si/SiO$_{2}$ substrates. These nanotubes are commonly tens of micrometers long, and the inter-tube spacing is typically around 200 nm, which can be controlled to certain degree. In addition, a second layer of nanotubes can be grown along the gas flow direction atop the first layer by carrying out a second round of CVD synthesis. This observation, as a side proof, supports the hypothesis that the substrate-nanotube interaction plays an important role. Our synthesis of dense arrays of well aligned and evenly spaced carbon nanotubes paves the way toward large-scale assembling of nanotube-on-insulator (NOI) devices and circuits, in analogy to the silicon-on-insulator (SOI) approach adopted by the semiconductor industry. [Preview Abstract] |
Monday, March 21, 2005 8:24AM - 8:36AM |
A26.00003: Band Engineering of Partially Exposed Carbon Nanotube Field-Effect Transistors Xiaolei Liu, Zhicheng Luo, Song Han, Tao Tang, Daihua Zhang, Chongwu Zhou We present a new approach to engineer the band structure of carbon nanotube field-effect transistors via selected area chemical gating. By exposing the center part or the contacts of the nanotube devices to oxidizing or reducing gases, a good control over the threshold voltage and subthreshold swing has been achieved. Our experiments reveal that NO$_{2}$ shifts the threshold voltage higher while NH$_{3}$ shifts it lower for both center- exposed and contact-exposed devices. However, modulations to the subthreshold swing are in opposite directions for center-exposed and contact-exposed devices: NO$_{2}$ lowers the subthreshold swing of the contact-exposed devices, but increases that of the center-exposed devices; In contrast, NH$_ {3 }$reduces the subthreshold swing of the center-exposed devices, but increases that of the contact-exposed devices. A model has been developed based on Langmuir isotherm, and the experimental results can be well explained. [Preview Abstract] |
Monday, March 21, 2005 8:36AM - 9:12AM |
A26.00004: Carbon nanotube electronics and opto-electronics Invited Speaker: Carbon nanotubes (CNTs) have ideal properties for applications in nano/opto-electronics. Strong emphasis has been placed on the fabrication of CNT field-effect transistors (CNTFETs) with very promising results. CNTFETs, however, still have weak points. Specifically, charge-transfer at the CNT-metal interfaces leads to the formation of Schottky barriers. Also, upon scaling of the gate insulator, unipolar CNTFETs turn ambipolar (a-CNTFETs) with large OFF currents. I will discuss how we eliminated these problems by chemical (charge-transfer doping), or electrostatic doping of the contact regions. The resulting CNTFETs have excellent characteristics. a-CNTFETs are particularly valuable in photonics. When electrons and holes are injected from the opposite terminals of a a-CNTFET, a fraction of them recombine radiatively, producing a single CNT light source. Unlike conventional p-n diodes, a-CNTFETs are not doped and there is no fixed p-n interface. By spatially resolving the emission we show that the light can be translated along the CNTFET by varying the gate voltage. Study of the properties of the emission as a function of applied bias provides new insights on the electrical transport in CNTs. Stationary light spots are also observed. Finally, single CNT photoconductivity spectra and theoretical modeling are used to understand the nature of the excited states of the CNTs. In collaboration with: J. Appenzeller, J. Chen, M. Freitag, C. Klinke, Y.-M. Lin, V. Perebeinos, J. Tersoff, J. Tsang. [Preview Abstract] |
Monday, March 21, 2005 9:12AM - 9:24AM |
A26.00005: Diameter dependence of carbon nanotube transistor performance Zhihong Chen, Joerg Appenzeller, Joachim Knoch, Yu-ming Lin, Phaedon Avouris As has been shown before, single wall carbon nanotube field-effect transistors (CNFETs) behave as Schottky barrier devices. The important question however is, what barrier height has to be overcome for current injection. So far, no detailed study exists that explains the impact of nanotube type and metal contacts in this context. Here we present the first statistical analysis of the dependence of on-current in a CNFET on the aforementioned two parameters. We show that a large data set of more than 100 devices can be consistently explained within a model that relates the on-current to a distinct Schottky barrier height which is determined quite reproducible by the nanotube diameter and the source/drain metal contact. Our study allows to identify the desired combination of tube diameter and type of metal that allows for optimum device performance of a CNFET. [Preview Abstract] |
Monday, March 21, 2005 9:24AM - 9:36AM |
A26.00006: Dual-Gated Carbon Nanotube Field-Effect Transistors with Tunable Polarities Yu-Ming Lin, Joerg Appenzeller, Phaedon Avouris In this paper, we present a novel design for carbon nanotube field-effect transistors (CNFETs). This design allows us to obtain a p-i-p (or n-i-n) doping profile along the tube. Our CNFET structure is based on a back-gated geometry. An additional middle gate electrode is patterned between the source and drain contacts, so that the segments of the nanotube near the source/drain contacts can be electrically and/or chemically doped in a self-aligned fashion. The potential of outer and middle nanotube segments is independently controlled by the back gate and middle gate, respectively. By controlling the potential of the nanotube in the outer regions, p- or n-type CNFETs can be obtained on the same device. The dual-gated CNFETs exhibit bulk switching behavior, rather than switching dominated by the Schottky barriers at the contacts, and show excellent performance close to theoretical limits. [Preview Abstract] |
Monday, March 21, 2005 9:36AM - 9:48AM |
A26.00007: Investigation of Schottky Barrier Behaviors between Semiconductive Single-Walled Carbon Nanotubes and Different Metals Chenguang Lu, Jie Liu, Lei An Single Walled Carbon nanotubes are very promising material for nanoelectronics. Schottky barrier contact are made to SWNT through Al or Ti electrode while the other end of SWNTs are ohmically contacted by Au. Electronic transport through Schottky barriers are studied and competition between tunneling and thermionic emission are control with a back gate voltage. Schottky barrier diodes are made by SWNT and low work function metals for the first time. [Preview Abstract] |
Monday, March 21, 2005 9:48AM - 10:00AM |
A26.00008: Effect of Metal-Carbon Nanotube Interface in Carbon Nanotube Devices Zhengfan Zhang, Venkat Chandrasekhar The four-terminal contact resistance of individual multiwalled carbon nanotubes with Au/Ti electrodes was measured at low temperature. The contact resistance as a function of bias voltage showed large asymmetric behavior. At zero bias, the contact resistance showed large variations with gate voltage. The origin of this asymmetric behavior and the the correlation between nanotube device resistance and contact resistance will be discussed. [Preview Abstract] |
Monday, March 21, 2005 10:00AM - 10:12AM |
A26.00009: Carbon-nanotube-based single electron memories processed by double self-assembly Vincent Bouchiat, Laetitia Marty, Cecile Naud, Aurore Bonhomme, Emmanuel Andre, Antonio Iaia, Emmanuelle Richard, Anne-Marie Bonnot We demonstrate wafer-scale integration and operation of single electron memories based on carbon nanotube field effect transistors (CNFETs). Our method involves a two step double self assembly process. The first step consists of a Hot-Filament CVD growth and in situ electrical connection of single walled carbon nanotubes on a predefined submicron catalytic template acting as contact electrodes. We obtain a overall integration yield of semiconducting carbon nanotubes exhibiting field effect that can exceed 50{\%} for 9000 devices on a 2 inches wafer. The second step is a wet step which consists of local functionalization and controlled attachment of a colloidal gold bead of radius 15nm on the nanotube. The sample is then coated with parylene dielectric followed by deposition of a top gate electrode aligned with respect to the nanotubes. The bead acts as a storage node for the memory while the CNFETs operated in the subthreshold regime behave as electrometers with exponential amplification. Operation of devices with retention of single charge quantum is successfully demonstrated at liquid helium temperature. Depending on the nanotube-dot coupling, the transfer of a single electron into the gold dot can lead up to one order of magnitude increase of the CNFET channel current. [Preview Abstract] |
Monday, March 21, 2005 10:12AM - 10:24AM |
A26.00010: High-frequency characterization of SWNT array FETs R. Caldwell, J. Hone, K. Shepard We discuss measurements of the high-frequency response of FET devices made from parallel arrays of SWNTs. Dense parallel arrays are grown by rapid-heating CVD using CO as a feedstock. Interdigitated finger pads are laid down to yield high-current devices. Devices are converted to pure semiconducting behavior by a selective burning technique, and are still able to carry currents in excess of 20 milliamperes. S-parameter testing using a high frequency network analyzer allows for full frequency characterization of the devices. [Preview Abstract] |
Monday, March 21, 2005 10:24AM - 10:36AM |
A26.00011: Carbon Nanotube Devices for GHz to THz Applications Peter Burke, Zhen Yu, Shengdong Li In this talk I will present an overview of the high-frequency applications of carbon nanotubes, one realization of nano-electronic devices, and where the challenges and opportunities lie in this new field. Specifically, I will first discuss the passive RF circuit models of one-dimensional nanostructures as interconnects[1]. Next, I will discuss circuit models of the ac performance of active 1d transistor structures, leading to the prediction that THz cutoff frequencies should be possible[2]. We recently demonstrated the operation of nanotube transistors at 2.6 GHz[3]. Third, I discuss the radiation properties of 1d wires, which could form antennas linking the nanoworld to the macroworld[4]. This could completely remove the requirements for lithographically defined contacts to nanotube and nanowire devices, one of the greatest unsolved problems in nanotechnology. [1] P.J. Burke "An RF Circuit Model for Carbon Nanotubes" IEEE Transactions on Nanotechnology 2(1), 55-58 (2003). [2] P.J. Burke, ``AC Performance of Nanoelectronics: Towards a Ballistic THz Nanotube Transistor'' Solid State Electronics, 48(10), 1981-1986 (2004). [3] Shengdong Li, Zhen Yu, Sheng-Fen Yeng, W.C. Tang, Peter J. Burke, ``Carbon Nanotube Transistor Operation at 2.6 GHz'' Nano Letters, 4(4), 753-756 (2004). [4] Peter J. Burke, Shengdong Li, Zhen Yu ''Quantitative theory of nanowire and nanotube antenna performance,'' http://xxx.lanl.gov/abs/cond-mat/0408418 (cond-mat/0408418) (2004). [Preview Abstract] |
Monday, March 21, 2005 10:36AM - 10:48AM |
A26.00012: Exploration of optical and electronic properties of SWNT networks for device applications Kai Xiao, Matthew Garrett, Ilia Ivanov, Alex Puretzky, Stephen Jesse, Phillip Britt, Douglas Lowndes, David Geohegan Interconnected networks of single-walled carbon nanotubes (SWNTs) are rapidly gaining attention for macroscale electronics applications such as transparent conductive coatings or wiring, as well as printable transistors and sensors. In contrast to individual SWNT devices which must overcome the chirality and geometry variations inherent in most samples, networks of SWNT bundles naturally provide an ensemble average of semiconducting and metallic nanotubes which despite the advantages in processing must, however, be tailored for the particular application. SWNT networks have been deposited from solutions containing purified, laser-vaporization grown nanotubes onto optically transparent substrates for combined electrical and optical characterization. Specially-designed electrode structures were used to simultaneously perform UV-VIS-NIR spectroscopy and electrical characterization. Raman spectroscopy and scanning electron microscopy (SEM) were used to characterize the alignment and morphology of the networks. [Preview Abstract] |
Monday, March 21, 2005 10:48AM - 11:00AM |
A26.00013: Massive Nano-Assembly Method for Integrated Device Structures Based on Nanotubes and Nanowires Minbaek Lee, Seong Myung, Jiwoon Im, Sun Namkung, Kyung-Eun Byun, Seunghun Hong Recent dramatic progress of nanotechnology allows us to combine carbon nanotubes and nanowires with conventional microelectronic devices to build a generation of new nanoscale devices. However, a major stumbling block holding back their industrial applications is a lack of massive assembly method for integrated device fabrication. One promising nano-manufacturing method is the 'surface-programmed assembly' process. In this strategy, surface molecular patterns are utilized to direct the assembly of nanowires onto specific locations of general substrates with precise orientations [1]. This talk will discuss how one can utilize surface-programmed assembly strategy to ‘position’ and ‘align’ a large number of 1D nanostructures (e.g. carbon nanotubes, metal oxide nanowires, etc) on general substrates (e.g. gold, silicon oxide, Al, etc) to build large-scale integrated device structures. Future prospect and possible applications of this strategy also will be discussed. [1] S. Rao, L. Huang, W. Setyawan, and S. Hong Nature 425, 36-37 (2003) [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700