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Carbon nanotubes for biomolecular sensing and photovoltaicsMohamamd Ali, Mahmoudzadeh Ahmadi Nejad 11 1900 (has links)
A computational investigation of some optoelectronic applications of carbon nanotubes (CNT) is presented, including CNT-based solar cells and biosensors. The results could be used to evaluate the performance of CNT devices and clarify the necessity of further experimental research in this area. A coaxially-gated CNT field-effect transistor (CNFET) forms the basic structure of the devices modeled in this thesis. Diffusive transport is present in long-channel devices, as in our case, while the quantum mechanical effects are mainly present in the form of tunneling from Schottky-barrier contacts at the metal-CNT interfaces. Band-to-band recombination of electron-hole pairs (EHP) is assumed to be the source of electroluminescence. In a first-order approximation, protein-CNT interactions are modeled as the modification of the potential profile along the longitudinal axis of CNTs due to electrostatic coupling between partial charges, in the oxide layer of the CNFET, and the nanotube. The possibility of electronic detection is evaluated. The electroluminescence of the CNT is proposed as an optical detection scheme due to its sensitivity to the magnitude and the polarity of the charge in the oxide. The validity of the model is argued for the given models. A value for the minimum required size of a computational window in a detailed simulation is derived. The structure of an electrostatically gated p-i-n diode is simulated and investigated for photovoltaic purposes. The absorbed power from the incident light and the interaction between the nanotubes is modeled with COMSOL. The results are interpreted as a generation term and introduced to the Drift-Diffusion Equation (DDE). We have observed behavior similar to that in an experimentally-realized device. The performance of CNT-based solar cells under standard AM 1.5 sunlight conditions is evaluated in the form of an individual solar cell and also in an array of such devices.
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First-principles studies of metal-carbon nanotube systemsZhuang, Houlong. January 2007 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2008. / Title proper from title frame. Also available in printed format.
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Study of composite interface strength and crack growth monitoring using carbon nanotubesBily, Mollie A. January 2009 (has links) (PDF)
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2009. / Thesis Advisor(s): Kwon, Young W. "September 2009." Description based on title screen as viewed on November 04, 2009. Author(s) subject terms: Carbon Nanotubes, CNTs, Carbon Fiber Composite, Fiberglass Composite, Crack Propagation, Mode II, Health Monitoring, Resistance Testing Includes bibliographical references (p. 77-78). Also available in print.
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Low-temperature Raman spectroscopy of 0.4 nm single-walled carbon nanotubes /Mok, Siu Man. January 2004 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 144-145). Also available in electronic version. Access restricted to campus users.
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Electronic and vibrational properties of ultrasmall single-walled carbon nanotubes /Li, Zhaoming. January 2004 (has links)
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 112-123). Also available in electronic version. Access restricted to campus users.
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Theoretical investigation of carbon nanotube devices for millimeter/submillimeter wave analog circuitsDaggett, Josephine Anne. January 2009 (has links) (PDF)
Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: James P. Becker. Includes bibliographical references (leaves 96-98).
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Electron transport in carbon nanotube and graphene /Zhang, Qiucen. January 2008 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 62-67). Also available in electronic version.
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Carbon nanotube : manufacturing process design and its use in gas sensors /Ma, Anson Wing Kui. January 2005 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 84-94). Also available in electronic version.
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Fabrication and optical characterization of nanostructures formed inside AlPO4-5 zeolite single crystals /Ye, Jianting. January 2006 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / On t.p. "4" is subscript. Includes bibliographical references. Also available in electronic version.
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The Role of Carbon Nanotubes in the Hydrogenation of Carbon MonoxideJeffers, Matt 01 December 2010 (has links)
This paper presents the culmination of an investigation on carbon nanotubes as catalysts for the hydrogenation of carbon monoxide. Carbon nanotubes (CNTs) have been found to have extraordinary physical properties and the potential for use in a variety of applications. They have been utilized as catalyst supports in many reactions, including the conversion of syngas to ethanol. The specific role played by CNTs in these reactions, aside from that of a support structure, has not been evaluated, however. Presented here are parametric studies on Fischer-Tropsch Synthesis with carbon nanotubes as active catalysts. The use of as-produced CNTs (containing trace amounts of iron from the synthesis process) resulted in a 100-fold increase in carbon monoxide conversion per unit mass of catalyst over a traditional Fe-Zn-K/γ-alumina catalyst. This value (CO conversion per unit mass of catalyst) was raised to nearly 1500 times as high as for Fe-Zn-K/γ-alumina when purified CNTs were used in the same FT synthesis. Because iron is a primary catalyst in the FT synthesis, it can be argued that the iron in the CNTs was responsible for the catalytic behavior. However, the iron content in the MWNTs (0.014 g, ≈ 5 mass%) and SWNTs (0.04 g, ≈ 27 mass%) compared to that of the traditional iron-loaded alumina support (2.5 g, ≈ 12.5 mass%), strongly suggests that iron alone cannot be responsible for the catalysis. Although single-walled nanotube (SWNT) catalysts provided high CO conversion, methane represented the bulk of the products. Conversely, multi-walled nanotubes (MWNTs) produced mostly liquid hydrocarbons and oxygenates, indicating that the CNT structure is an important factor in the hydrogenation of CO. The parametric experiments show that temperature, pressure and the syngas composition all play key roles in the distribution of liquid products. In general, an increase in temperature correlated to an increase in hydrocarbon chain length and the formation of more alcohols; above a certain temperature, the distribution shifted to 100% alcohols. Likewise, lower pressures resulted in hydrocarbons of shorter carbon chain length and at higher pressures, more alcohols were formed. Studies were also conducted on the effect of syngas composition and the effect of different types of CNTs. Syngas with 1:1 ratio (H2:CO) produced longer hydrocarbon chains than those produced by 3:1 syngas. The type of CNTs used in FT also affected the products but no clear relationships could be discerned.
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