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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
611

Zno nanowires for sensing and power generation for system-on-package technology

Liu, Jin 23 October 2008 (has links)
As the science and technology advance, people are looking for new discoveries to solve the existing problems and improve the quality of life. In this processes of development, nanoscience and nanotechnology have attracted technologists' attention and turned out to be one of the most promising technologies that could have a revolutionary impact. Znic Oxide (ZnO) nanostructures, in particular nanowires (NWs), have the potential to be one of such revolutionary material. ZnO is a piezoelectric, transparent and semiconducting material. With a direct band gap of 3.37eV and large excitation binding energy (60meV), ZnO exhibits near-UV emission, and transparent conductivity. ZnO NWs, with all of the properties of bulk ZnO, have other properties that are distinct to nanoscale material. All of these make ZnO NWs a very unique material that has many potential applications in system miniaturization. System-on-package (SOP) technology is a new concept developed to solve the integration problem in microelectronic industry. SOP technology paradigm provides system-level miniaturization in a package size that makes today's hand-held devices into multi-functional systems, with applications ranging from computing, wireless communications, health care to personal security. The SOP is a system miniaturization technology that ultimately integrates nanoscale thin film components for batteries, thermal structures, active and passive components in low cost organic packaging substrates, leading to micro to nanoscale modules and systems. The goal of this research is to investigate and utilize the unique properties of ZnO NWs and apply them to the fabrication of devices that can be integrated with SOP platform. The issues include developing techniques to manipulate and align ZnO NWs; developing contact preparation method to improve the contact conductance for the fabrication of ZnO NW based devices. Also, the investigation of the oxygen diffusion coefficient in ZnO NWs is carried out, which serves as the basis of ZnO NWs for sensing applications. Two practical applications, which include fabricating and characterizing SOP compatible ZnO NW based bio-sensor and SOP compatible ZnO NW based nano-generator, are evaluated. Finally the remaining work beyond the scope of the thesis is outlined.
612

Fabrication of surface micro- and nanostructures for superhydrophobic surfaces in electric and electronic applications

Xiu, Yonghao 10 November 2008 (has links)
In our study, the superhydrophobic surface based on biomimetic lotus leave is explored to maintain the desired properties for self-cleaning. In controlling bead-up and roll-off characteristics of water droplets the contact angle and contact angle hysteresis were very important and we investigated the determining conditions on different model surfaces with micro- and nanostructures. Two governing equations were proposed, one for contact angle based on Laplace pressure and one for contact angle hysteresis based on Young-Dupré equation. Based on these understanding on superhydrophobicity, possible applications of the superhydrophobicity for self-cleaning and water repellency were explored and application related technical issues were addressed. Based on our understanding of the roughness effect on superhydrophobicity (both contact angle and hysteresis), structured surfaces from polybutadiene, polyurethane, silica, and Si etc were successfully prepared. For engineering applications of superhydrophobic surfaces, stability issues regarding UV, mechanical robustness and humid environment need to be investigated. Among these factors, UV stability is the first one to be studied. Silica surfaces with excellent UV stability were prepared. UV stability on the surface currently is 5,500 h according the standard test method of ASTM D 4329. No degradation on surface superhydrophobicity was observed. New methods for preparing superhydrophobic and transparent silica surfaces were investigated using urea-choline chloride eutectic liquid to generate fine roughness and reduce the cost for preparation of surface structures. Another possible application for self-cleaning in photovoltaic panels was investigated on Si surfaces by construction of the two-scale rough structures followed by fluoroalkyl silane treatment. Regarding the mechanical robustness, epoxy-silica superhydrophobic surfaces were prepared by O2 plasma etching to generate enough surface roughness of silica spheres followed by fluoroalkyl silane treatment. A robustness test method was proposed and the test results showed that the surface is among the most robust surfaces for the superhydrophobic surfaces we prepared and currently reported in literature.
613

Electrochromic Nickel – Tungsten Oxides : Optical, Electrochemical and Structural Characterization of Sputter-deposited Thin Films in the Whole Composition Range

Green, Sara January 2012 (has links)
This thesis investigates the electrochromic NixW1-x oxide thin film system, where 0 < x < 1. The thin films were deposited by reactive DC magnetron co-sputtering from one Ni and one W metal target. In addition, Ni oxide was deposited with water vapor added to the sputtering gas. The different compositions were structurally characterized by X-ray diffraction, X-ray photoelectron-, Rutherford backscattering- and Raman spectroscopy. Possible nanostructures were studied by ellipsometry together with effective medium theory. Optical and electrochemical properties were investigated by spectrophotometry and cyclic voltammetry in 1 M lithium perchlorate in propylene carbonate (Li-PC). Li-PC electrolyte was used as it is being compatible with both W and Ni oxides. Few studies have previously been made on Ni oxides in Li-PC. Films with high Ni content, 0.85 < x < 1, were polycrystalline and all other films were amorphous. W-rich films, x < 0.5, consisted of a mixture of W oxide and NiWO4 -phases, and the Ni-rich samples, x > 0.5, probably consisted of hydrated Ni oxide and NiWO4 -phases. Films with 0 < x < 0.3 showed electrochromic properties similar to W oxide, and films with 0.7 < x < 1 behaved as Ni oxide. For 0.4 < x < 0.7 no optical change was seen. At the border of cathodic electrochromic and non-electrochromic behavior, i.e. x ~ 0.4, the sample behaved as an optically passive intercalation material. The transmittance change was 0.45 and 0.15 for the W-rich and Ni-rich films, respectively. Ni addition to W oxide improved the coloration efficiency. For the Ni-rich films the charge insertion/extraction and optical modulation was low and an aging effect resulted in strong bleaching of the samples. The advantage of W addition to Ni oxide was that the transparency at the bleached state was enhanced. Moreover, it was found that the hydrous character of the Ni oxide had a large impact on the electrochromic performance, both when electrochemically cycled in KOH and in the non-aqueous Li-PC.
614

Investigation of Nanostructured Thin Films on Surface Acoustic Wave and Conductometric Transducers for Gas Sensing Applications.

Arsat, Rashidah, rashidah.arsat@student.rmit.edu.au January 2009 (has links)
In this thesis, the author proposed and developed nanostructured materials based Surface Acoustic Wave (SAW) and conductometric transducers for gas sensing applications. The device fabrication, nanostructured materials synthesis and characterization, as well as their gas sensing performance have been undertaken. The investigated structures are based on two structures: lithium niobate (LiNbO3) and lithium tantalate (LiTaO3). These two substrates were chosen for their high electromechanical coupling coefficient. The conductometric structure is based on langasite (LGS) substrate. LGS was selected because it does not exhibit any phase transition up to its melting point (1470°C). Four types of nanostructured materials were investigated as gas sensing layers, they are: polyaniline, polyvinylpyrrolidone (PVP), graphene and antimony oxide (Sb2O3). The developed nanostructured materials based sensors have high surface to volume ratio, resulting in high sensitivity towards di¤erent gas species. Several synthesis methods were conducted to deposit nanostructured materials on the whole area of SAW based and conductometric transducers. Electropolymerization method was used to synthesize and deposit polyaniline nanofibers on 36° YX LiTaO3 and 64° YX LiNbO3 SAW substrates. By varying several parameters during electropolymerization, the effect on gas sensing properties were investigated. The author also extended her research to successfully develop polyaniline/inorganic nanocomposites based SAW structures for room temperature gas sensing applications. Via electrospinning method, PVP fibres and its composites were successfully deposited on 36° YX LiTaO3 SAW transducers. Again in this method, the author varied several parameters of electrospinning such as distance and concentration, and investigated the effect on gas sensing performance. Graphene-like nano-sheets were synthesized on 36° YX LiTaO3 SAW devices. This material was synthesized by spin-coating graphite oxide (GO) on the substrate and then exposin g the GO to hydrazine to reduce it to graphene. X-ray photoelectron spectroscopy (XPS) and Raman characterizations showed that the reduced GO was not an ideal graphene. This information was required to understand the properties of the deposited graphene and link its properties to the gas sensing properties. Thermal evaporation method was used to grow Sb2O3 nanostructures on LGS conductometric transducers. Using this method, different nanoscale structures such as nanorods and lobe-like shapes were found on the gold interdigitated transducers (IDTs) and LGS substrate. The gas sensing performance of the deposited nanostructured Sb2O3 based LGS conductometric sensors was investigated at elevated temperatures. The gas sensing performance of the investigated nanostructured materials/SAW and conductometric structures provide a way for further investigation to future commerciallization of these types of sensors.
615

Strain mediated self-assembly of ceramic nano islands

Rauscher, Michael D., January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 166-174).
616

Novel tissue scaffolds comprising nano- and micro-structures

Ng, Robin, January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 208-232).
617

Design et synthèse de peptides macrocycliques pour le développement de nanopores moléculaires /

Blanchette, Jean-Philippe. January 2008 (has links) (PDF)
Thèse (M.Sc.)--Université Laval, 2008. / Bibliogr.: f. 95-97. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.
618

Experiments on mesoscopic electron transport in carbon nanotubes

Nygård, Jesper. January 1900 (has links) (PDF)
Thesis (Ph.D.)--Københavns universitet, 1996. / Ph.d. afhandling, Københavns Universitet Med litteraturhenvisninger Title from title screen (viewed on July 9, 2008). Title from document title page. Includes bibliographical references. Available in PDF format via the World Wide Web.
619

Molecular Imaging of Amyloid Beta Proteins by Polymeric Nanoparticles in Mouse Models of Alzheimer's Disease

Roney, Celeste January 2006 (has links)
Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2006. / Vita. Bibliography: p.210-222
620

ZnO nanotip-based acoustic wave sensors

Zhang, Zheng. January 2008 (has links)
Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Electrical and Computer Engineering." Includes bibliographical references (p. 150-157).

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