Bulletin of the American Physical Society
2008 APS March Meeting
Volume 53, Number 2
Monday–Friday, March 10–14, 2008; New Orleans, Louisiana
Session S35: Focus Session: Nanotechnology I |
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Sponsoring Units: FIAP Chair: Keith Williams, University of Virginia Room: Morial Convention Center 227 |
Wednesday, March 12, 2008 2:30PM - 2:42PM |
S35.00001: Deep UV Pattern Definition in PMMA Brian Burke, Timothy Herlihy, Andrew Spisak, Keith Williams We have patterned polymethyl methacrylate (PMMA) resist by exposing it with the fifth harmonic (213 nm) of an Nd:YAG source through metallized apertures in contact with the resist. Interference patterns with both near- and far-field origins were observed. In order to test the contrast and uniformity of exposure, we deposited germanium onto developed areas to form arrays with feature sizes of approximately 200 nm. We present a straightforward model for interference effects generated in our process, and discuss opportunities for direct-write lithography through single apertures. [Preview Abstract] |
Wednesday, March 12, 2008 2:42PM - 2:54PM |
S35.00002: Low Temperature Growth of ZnO Nanorods by Chemical Bath Method Matt Baumer, Parameswar Hari, Daryl Spencer ZnO nanorods grown by chemical bath deposition (CBD) methods are of great interest in photonic and electronic device applications because they offer low cost, low temperature techniques compared to conventional vapor deposition and sputtering methods. Our past studies of ZnO nanorods were grown by CBD on indium tin oxide (ITO) coated glass substrates employed heating of an equimolar solution of Zinc (II) nitrate and hexamethylenetramine solution at 95 C. Morphology of ZnO nanorods exhibited both open and closed hexagonal shape under various deposition conditions at or above 95 C. Currently we are studying the effect substrates~ on the morphology of the~ nanorods grown by chemical bath technique. We are using glass coated with tin oxide, aluminum, as well as solid molybdenum as~substrates. We will use scanning electron microscopy and atomic force microscopy to map the changes in morphology of nanorods grown on various substrates. We will present quantitative data on changes in cluster size and shape of nanorods as the growth substrate is varied. [Preview Abstract] |
Wednesday, March 12, 2008 2:54PM - 3:06PM |
S35.00003: Nano-assembly and Controlled Release Kinetics of Nanoelements from Nanoporous Templates E. Gultepe, D. Nagesha, J. McNulty, S. Sridhar Nanotemplates and nanoparticles have potential for use in the area of nanomanufacturing and biomedical applications. We are using highly ordered nanoporous alumina as a template for drug delivery and to assemble nanoelements such as latex beads and single wall carbon nanotubes (SWNT) by the means of electrophoresis and/or dielectrophoresis. The results of 100{\%} assembly of latex beads and controlled elution of drugs from nanoporous templates will be discussed. Vertically assembled SWNT and with the I-V characteristic as 3D interconnects, will also be presented. We have developed a variety of platforms incorporating superparamagnetic iron oxide nanoparticles for targeted delivery, magnetic hyperthermia and as a contrast agent for magnetic resonance imaging. The results of cell studies on these platforms will be discussed. [Preview Abstract] |
Wednesday, March 12, 2008 3:06PM - 3:18PM |
S35.00004: Ionic PN and PNP junctions -- Diodes and Transistors Eric Kalman, Ivan Vlassiouk, Pavel Apel, Zuzanna Siwy There are well-known devices for controlling the transport of electrons, but very few control ions in a solution. We have prepared ionic diodes and transistors that function in a similar manner to their semiconductor analogues. Ionic PN junctions were created by surface patterning single conical nanopores in polymer films, so that the pore walls are split into two sections: one with positive charge, and the other with negative. These diodes can achieve rectification degrees of several hundreds. Ionic PNP junctions were created by surface patterning single double-conical nanopores in polymer films with tip diameter between 2 and 6 nm, so that the pore walls are split into three sections: the two areas near the large pore openings which are positively charged, while the center of the pore, near the pore tip, is negatively charged. This device works in a similar fashion to a semiconducting BJT transistor, and we show that we can control the electric potential chemically in a manner sufficient to gate the ion current through the device. [Preview Abstract] |
Wednesday, March 12, 2008 3:18PM - 3:30PM |
S35.00005: Metallic glass nanowire Koji Nakayama, Yoshihiko Yokoyama, Guoqiang Xie, Qingsheng Zhang, Mingwei Chen, Toshio Sakurai, Akihisa Inoue Metallic glass nanowires were spontaneously created on the fracture surfaces that were produced by a conventional mechanical test. The presence of the nanowires is directly related to the one-dimensional meniscus configuration with a small viscosity at high temperatures and to the wide supercooled liquid region of the metallic glass. The electron microscopic observations demonstrate the diameters, the lengths, and the amorphous structural states, and the energy dispersive X-ray reveals the chemical components. In addition, we found that round ridges are constructed from nanotubes. The finding of amorphous nanostructures provides not only fundamental understanding of fracture processes but also give a new insight into nano-science and engineering. [Preview Abstract] |
Wednesday, March 12, 2008 3:30PM - 3:42PM |
S35.00006: CO Gas Sensing with ZnO Nanowire Mat Sirisha Chava, Daqing Zhang, Chris Berven In the past decade, significant advances have been made in the synthesis of ZnO nanostructures. Here, we report the electrical properties of a gas sensor constructed from mats of ZnO nanowires grown on sapphire substrate that showed reversible response to CO exposure. The sensor is a two-terminal design, where the terminals consist of two 25 $\mu $m diameter gold wires laid parallel on the nanowire mat about $\sim $2 mm apart. The nanowires had an average diameter of 50 nm with lengths of about 10 $\mu $m. The mat was about 20 $\mu $m thick and extended over area of about 1 cm$^{2}$. When exposed to Ar, CO$_{2}$, H$_{2}$ no significant changes in the current-voltage (I-V) behavior of the mat were observed. But CO exposure resulted in a dramatic increase in electrical conductivity, with the current increasing by about a factor of four. The response was reversible after evacuation. I-V measurement of the substrate showed near zero current (I $\le $ 100 fA) under vacuum, indicating that all of the current was through the nanowires. The I-V characteristics were acquired with a source-measure unit and the bias voltage was swept over the range of -5 V to +5 V with a typical step size of 50 mV. Typical currents when exposed to CO were in the range of 40 nA. [Preview Abstract] |
Wednesday, March 12, 2008 3:42PM - 3:54PM |
S35.00007: Mechanical Properties of Nanometric Wire of Water. Manhee Lee, Baekman Sung, Wonho Jhe Water has been one of the perfect newtonian viscous liquids, which are exactly described by navier-stokes equation. Recently, it, however, was found that the effective shear viscosity of water confined between mica crystals at 10nm thickness is very different from the one of 3-dimensional bulk water. While some researchers have measured very high viscoelasticity of the confined liquid. the other researchers reported the fluidic nature of water confined between mica surfaces at $<$3.5 nm interfacial separation like bulk-water viscosity. These conflicting results concerning the mechanical properties of nanometric water have been continually reported for the past several years. None of them clearly clarified the mechanical properties of nanometric water, and the detailed behavior of the viscoelasticity within a tip-sample separation less than 1 nm has not been measured. Here, we present the mechanical properties of nanometric water with a spatial resolution less than 0.1nm such as viscoelasticity, dissipation energy, and phase transitions. [Preview Abstract] |
Wednesday, March 12, 2008 3:54PM - 4:06PM |
S35.00008: Growth of Periodic Arrays of Vertically Aligned Carbon Nanotube on Glass Trilochan Paudel, Jakub Rybczynski, Zhifeng Ren Periodic arrays of vertically aligned carbon nanotubes on glass have been grown by dc plasma enhanced chemical vapor deposition on patterned Nickel dots prepared by polystyrene nanosphere lithography. A thin buffer layer of Titanium was first coated on cleaned high temperature C1737 Aluminosilicate glass substrates and then a monolayer of self-assembled polystyrene spheres was deposited on the glass. Through the polystyrene spheres, a hexagonal pattern of triangular Nickel dots was obtained after removing the spheres. The sphere size and Nickel thicknesses consequently determine the diameter and the site density of carbon nanotubes. The successful growth of carbon nanotubes on glass substrates with good periodicity and alignment are crucible to bio-sensor and solar cell applications. [Preview Abstract] |
Wednesday, March 12, 2008 4:06PM - 4:18PM |
S35.00009: Feedback Cooling of a Massive Resonator, Quartz Tuning-fork, in Air. Baekman Sung, Manhee Lee, Wonho Jhe Recently, the cooling of a mechanical resonator through active feedback control has been interested for many researchers and the experiment for a cantilever cooling by using feedback control in vacuum has been done by M.Poggio et al [1]. While the recent cooling experiments have been done by tiny cantilever in vacuum, we performed the feedback cooling experiment in air by using a very massive harmonic oscillator, a tuning fork, which has been used as an useful force sensor due to its high stiffness and dynamic oscillation property in scanning probe microscopy (SPM) such as near field scanning optical microscopy, atomic force microscopy (AFM) [2]. This technique is expected to study the low temperature micro state effect of macrosopic object in air. // [1] M.Poggio, C.L.Degen, H.J.Mamim, and D.Rugar, PRL 99,017201 (2007). [2] F. J. Giessibl, S. Hembacher, M. Herz, Ch. Schiller, and J. Mannhart, Nanotechnology 15, S79 (2004). [Preview Abstract] |
Wednesday, March 12, 2008 4:18PM - 4:30PM |
S35.00010: Molecular quantum-dot cellular automata--from molecular structure to circuit dynamics Yuhui Lu, Craig Lent Quantum-dot cellular automata (QCA) [1] provides a transistor-less paradigm for molecular electronics. In the QCA approach, binary information is stored in the charge configuration of single cells, and transferred via Coulomb coupling between neighboring cells. Single-molecule QCA cells can be realized by using as quantum dots the localized states of mixed-valence complexes. Several candidate QCA molecules have been synthesized and shown to have the required field-induced switching properties [2]. We report progress towards a hierarchic dynamic theory of QCA circuits. We use \textit{ab initio} techniques to calculate the relevant molecular electronic structure, and extract parameters for a simpler Hamiltonian to describe switching behavior. We then apply a coherence vector formalism to model interaction with the thermal environment and generate a circuit-dynamic description. [1] C. S. Lent, P. D. Tougaw, W. Porod, and G. H. Bernstein, Nanotechnology, vol. 4, pp. 49, 1993. [2] H. Qi, S. Sharma, Z. Li, G. L. Snider, A. O. Orlov, C. S. Lent, and T. P. Fehlner, J.Am.Chem.Soc., vol. 125, pp. 15250, 2003. [Preview Abstract] |
Wednesday, March 12, 2008 4:30PM - 4:42PM |
S35.00011: Theory of Individual Carbon Nanotube Deposition by Nanoscopic Lenses Sheng Liu, Amit Goyal, Zafar Iqbal, Gordon A. Thomas, Reginald C. Farrow, Linus A. Fetter The accurate positioning of an individual vertically aligned carbon nanotube (CNT) is a challenge for nanofabrication. We have successfully deposited individual CNTs into sub-100nm diameter SiN$_{x}$ windows on metal interconnects using electrophoresis in conjunction with the nanoscopic lens effect. The dynamics of the deposition of nanotubes under different CMOS compatible manufacturing conditions was modeled using 2D and 3D finite element analysis. Surface charge accumulation and saturation is the key determinant of the strength of the nanoscopic lens. The modeling predicts that there is an easily obtainable range of conditions where only one nanotube will be deposited in round windows using current generation lithography. Deposition in a slotted window geometry yields a limited number of nanotubes that have an average spacing which is a function of the geometry of the slot and randomly approaching nanotubes. Early integration of vertical carbon based logic with CMOS is feasible. [Preview Abstract] |
Wednesday, March 12, 2008 4:42PM - 4:54PM |
S35.00012: CMOS based fabrication of single electron devices on a large scale. Vishva Ray, Ramkumar Subramanian, Pradeep Bhadrachalam, Seong Jin Koh Fabrication of single electron devices requires device components (a Coulomb island, source and drain electrodes) to be arranged with nanoscale precision. This has been so far carried out utilizing techniques such as e-beam lithography, shadow evaporation, electromigration, and scanning probe microscopy, which are not suitable for large-scale fabrication for practical use. Here we present new single electron device architecture and its large-scale fabrication within the framework of CMOS fabrication technology. This has been done by employing vertical electrode configuration where the source and drain electrode separation is controlled with nanoscale precision over an entire wafer. Colloidal Au nanoparticles of 10-20 nm diameter were used as Coulomb islands positioned between the source and drain electrodes. We observed clear Coulomb blockade and Coulomb staircase at room temperature for 10 nm Au nanoparticles with charging energies of $\sim $50 meV, in good agreement with self-capacitance values of 10 nm Au particle. The experimental I-V characteristics also agree well with simulated I-Vs carried out using the orthodox theory. [Preview Abstract] |
Wednesday, March 12, 2008 4:54PM - 5:06PM |
S35.00013: A QCM study of the dynamics and frictional properties of physisorbed polystyrene microspheres on a AU(111) Surface Iyam Lynch, Jacqueline Krim, Jessica McNutt The notion of transporting micro/nano objects has been of interest to the scientific community since the early days of nanotechnology. Progress in this area requires an understanding of the frictional behavior of these objects when they are in motion. In this study we have analyzed the behavior of 5$\mu $m diameter polystyrene spheres physisorbed on the electrode of a quartz crystal microbalance (QCM) in orientations normal and parallel to gravity. By varying the driving voltage of the QCM, the samples exhibit a frequency response with respect to the crystal amplitude (``decoupling curve''). This decoupling curve gives information about the motion of the spheres on the surface and leads to the calculation of the particles sliptime which gives rise to the frictional force between the particles and surface. Optical observations show that the particle motion is dependent on the oscillation direction of the QCM and gravity to a lesser extent. Quantitative comparisons of the friction force and the optically observed sliding motion have been performed and will be reported on. [Preview Abstract] |
Wednesday, March 12, 2008 5:06PM - 5:18PM |
S35.00014: Dynamic behavior of inter-puls time intervals of neuron-like pulses in a GaAs/InGaAs multi-quantum well structure. Aruna Weerasekara, Steven Matsik, Gennady Cymbalyuk, A. G. Unil Perera Neuron-like triggered pulses in a GaAs/InGaAs multi-quantum well (MQW) structure, which shows an s-type negative differential resistance (SNDR), was investigated. Dynamic behavior of inter-pulse time intervals (IPTIs) was studied by analyzing first return maps, power spectra, and correlation dimension. First return maps of the IPTIs show an interesting grouping pattern at slower pulse rates. The grouping behavior can be empirically modeled using oscillatory behavior of the pulsing threshold level of the MQW structure. This pattern of IPTIs is similar to that of thermoreceptors in fish and mammals. Under different operational conditions, correlation dimension of 8.0, 8.5, and 10.0 were obtained by calculating the correlation integrals. The obtained correlation dimensions suggest that this system possesses a higher dimensional behavior. [Preview Abstract] |
Wednesday, March 12, 2008 5:18PM - 5:30PM |
S35.00015: Using a quantum point contact as a sensitive detector of cantilever motion M. Poggio, M.P. Jura, C.L. Degen, M.A. Topinka, H.J. Mamin, D. Goldhaber-Gordon, D. Rugar We demonstrate the use of a GaAs quantum point contact (QPC) as a sensitive displacement detector with the ability to resolve the thermal motion of an ultrasoft micromechanical oscillator. The displacement measurement is made by positioning the tip of a metal-coated Si cantilever $\sim $100 nm above a QPC. The application of a small voltage to the lever causes it to gate the conductance through the QPC. As a result, motion of the cantilever's tip modulates the conductance. By measuring this modulation, we achieve a displacement resolution better than 10$^{-12}$ m/Hz$^{1/2}$, which is comparable to the resolution achieved by low power optical interferometry. The flexibility of an on-chip QPC as a sensor of cantilever displacement has a number of potential applications including magnetic resonance force microscopy, the detection of displacement for cantilevers with dimensions smaller than the optical diffraction limit, and the cooling of mechanical resonators through feedback. [Preview Abstract] |
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