Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 58, Number 12
Friday–Saturday, October 18–19, 2013; Denver, Colorado
Session K4: Materials Physics II: Carbon |
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Chair: Kristen Buchanan, Colorado State University Room: 253 |
Saturday, October 19, 2013 11:15AM - 11:39AM |
K4.00001: Recent advances in block copolymer mesoscale modeling: Numerical Self-Consistent Field Theory Simulations Invited Speaker: Scott Sides Using block copolymers as mesoscale templates has potential applications for improved photovoltaic devices, fuel-cells and many others where the long-range order and orientation of the copolymer phase-separated domains is crucial. Self-consistent field theory (SCFT) for dense polymer melts has been highly successful in describing complex morphologies in block copolymers. Field-theoretic simulations based on SCFT theory are able to access large length and time scales that are difficult or impossible for particle-based simulations such as molecular dynamics. This talk will present recent results using PolySwift++, an object-oriented, high-performance framework for developing new SCFT algorithms. Included is an overview of a hybrid-SCFT algorithm for studying nanocomposites. This hybrid method allows simulations where the copolymer is treated within the field-theory framework, while the nanoparticle positions and orientations are included explicitly. [Preview Abstract] |
Saturday, October 19, 2013 11:39AM - 11:51AM |
K4.00002: Nano-imaging of graphene plasmons Justin Gerber, Brian O'Callahan, Samuel Berweger, Markus Raschke Graphene plasmonics provides strong and wavelength-tunable spatial confinement of electromagnetic fields at mid-infrared frequencies. Near-field imaging of standing wave surface plasmon polariton (SPP) spatial distributions has been recently achieved by scattering-type scanning near-field optical microscopy ($s$-SNOM). The spatial patterns are a result of the interference of plasmons launched by the sharp scanning probe tip with counter-propagating plasmons reflected from graphene edges. We present a full phase and amplitude resolved near-field characterization of SPP propagation and reflection off edges, defects, and grain boundaries.~Using mid-infrared excitation at $\lambda_{\mathrm{exc}} =$ 10.8$\mu $m, we measure deep sub-wavelength periodicity in the spatial distribution of the near-field~with plasmon wavelength on the order of~$\lambda_{\mathrm{p}} =$ 250 nm. The standing amplitude and phase patterns can be fully described based on a simple near-field SPP cavity model. [Preview Abstract] |
Saturday, October 19, 2013 11:51AM - 12:03PM |
K4.00003: Atomic Layer Deposition of Tungsten on Carbon Nanotubes Jason Anderson, Collin Brown, David Allred Microelectromechanical systems (MEMS) fabrication traditionally uses the same limited methods and materials as those used in the silicon-based microelectronics industry. In order to make MEMS out of a richer suite of materials, such as metals, Brigham Young University researchers are investigating chemical vapor deposition and atomic layer deposition of patterned carbon nanotube (CNT) forests, using the surface of the carbon nanotubes as nucleation sites for metal deposition. Our goal has been to fill in spaces between CNTs by atomistic deposition, thus creating a CNT-composite material possessing the original pattern of the CNT forest. We have attempted to do this using tungsten hexafluoride and hydrogen. As deposited the materials are not pure metals, but contain substantial amounts of carbon and oxygen. Most recently tungsten fluoride via both CVD and ALD is being used to attempt creation of purer tungsten structures. Efforts to remove impurities as well as the electrical and mechanical properties of the resulting composite material will be reported. [Preview Abstract] |
Saturday, October 19, 2013 12:03PM - 12:15PM |
K4.00004: The low-pressure, chemical vapor deposition of Si02 layers using CO2 as the oxygen source with applications to CNT-MEMS growth Kenneth Hinton Deposited silica (SiO$_{2})$ has a number of applications for microfabricated structures, particularly those based on coating carbon nanotube forests. Members of our group have, for example, reported on the fabrication and use of SiO$_{2}$-coated carbon nanotube forests (CNT-MEMS) to prepare liquid chromatography plates of record efficiency. SiO$_{2}$ also has extremely low thermal conductivity and stiff, coated, carbon nanotube forests could be used as thermal barrier layers. We have examined two novel methods for the LPCVD of SiO$_{2}$ and oxygen-rich amorphous silicon. Both methods are based on the hypothesis that carbon dioxide could be used as the source of oxygen in preparing the material. In the case of oxygen-rich amorphous silicon (a-Si:O) we used silane as the silicon source, and the case of SiO$_{2}$ used dichlorosilane. We deposited the a-Si:O material at about 800K while the Si02 from SiH2Cl2 , was deposited at about 1000 K. Depositions were done at low pressure, about 200 millitorr for the a-SI:O and at about 1 to 4 Torr for the SiO$_{2}$. The substrates in all cases were three-inch single-crystal silicon wafers. We subsequently examined the deposited material using variable-angle, spectroscopic ellipsometry (VASE-John A. Woollam M 1000) for of thickness and optical constants and SEM structure and composition. The dichlorosilane deposition of SiO$_{2}$ suffered from vanishingly small deposition rates at very low pressures at 1000 K and the incorporation of ``snow'' into the films in the case of depositions done at higher pressures. We found little evidence of carbon incorporation. [Preview Abstract] |
Saturday, October 19, 2013 12:15PM - 12:27PM |
K4.00005: Carbon nano-fuses for permanent data storage Kevin Laughlin In today's world, just about everything is in digital form. This includes things like pictures of family and friends, ancestral work, music, movies, and much more. Unfortunately, the way to store data has typically been put it on a hard drive, thumb drive, or CD. What many people don't know is that these ways of data storage can only hold data reliably for about 7 years. The goal of permanent data storage is that the data gets written once and it will always be there when you need it. We have been working on a solid-state solution to this problem. The permanent data storage devices are an array of nano-fuses that are made of a thin carbon film that is 20-40nm thick, and varying from 250-1000nm wide. The carbon pads were created using an electron beam lithography technique to etch out the pattern, and carbon was then evaporated onto the device. Voltages above 6 volts were then pulsed or ramped across these fuses, oxidizing the carbon and causing a break in the fuse. Memory elements consist of a nano-fuse, and breaking a fuse will change the bit from a 1 to a 0. After the fuses were broken, they were analyzed with an SEM and an AFM. It has been found that these carbon nano-fuses are a good possibility for the future solid-state permanent data storage devices. [Preview Abstract] |
Saturday, October 19, 2013 12:27PM - 12:39PM |
K4.00006: Ab Initio Study of Graphene Functionalized with Benzyne Sanjiv Jha, Igor Vasiliev, Igor Magedov, Liliya Frolova, Nikolai Kalugin The electronic and structural properties of carbon nanomaterials can be affected by chemical functionalization. We apply {\it ab initio} computational methods based on density functional theory to study the covalent functionalization of graphene with benzyne. Our calculations are carried out using the SIESTA electronic structure code combined with the generalized gradient approximation for the exchange correlation functional. The calculated binding energies, densities of states, band structures, and phonon frequencies of graphene functionalized with benzyne are analyzed in comparison with the available experimental data. Our calculations show that the reactions of [2+2] and [2+4] cycloaddition of benzyne to the surface of pristine graphene are exothermic with the binding energies of -0.73 eV and -0.58 eV, respectively. [Preview Abstract] |
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