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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.
1

Solution phase synthesis and characterization of III-V, II-VI and CdSe.₀₈Te.₉₂ semiconductor nanowires

Fanfair, Dayne Dustan, 1978- 01 October 2012 (has links)
There are many advantages to the solution phase synthesis of semiconductor nanowires, the most notable of which are the ease of scalability and the production of nanowires in higher yields than those typically obtained in chemical vapor deposition (CVD) based processes. The solution phase synthesis of high quality, high aspect ratio (>100) narrow diameter semiconductor nanowires depends sensitively on three parameters: the diameter of the nanocrystals utilized to promote (seed) nanowire growth, molecular precursor decomposition kinetics and the choice of solvent in which the nanowires are grown. Bismuth is a low melting point (270 °C) semimetal and thus an ideal candidate for the solution-liquid-solid (SLS) growth of nanowires. A bismuth nanocrystal synthesis was developed that affords nanocrystals with average diameters from 4 - 20 nm. The nanocrystal diameter is controlled by varying the capping ligand (TOPO) to bismuth molar ratio. The synthesis of Au2Bi nanocrystals was also studied as it also affords small diameter (~ 2 nm) nanocrystals that are suitable for SLS nanowire growth. Molecular precursor decomposition kinetics can have a significant impact on nanowire yield and quality. Precursors that decompose too quickly can produce relatively large diameter nanowires, while precursors that decompose too slowly can produce nanowires with a highly tortuous morphology as a result of a high density of crystallographic defects. The choice of molecular precursor for the synthesis of III-V and II-VI nanowires was investigated. The solvent in which nanowires are grown can also have a significant effect on nanowire yield, quality and morphology. Coordinating solvents such as alkylphosphine oxides and alkylamines can interact with the atoms, or atomic complexes, that constitute nanowires and thus mediate the nanowire growth rate. In some instances, for example InAs nanowires grown in TOPO, this interaction can completely quench nanowire growth. This solvent effect has been investigated for the growth of III-V and II-VI nanowires. Solvents can also affect nanowire morphology. Branched ZnSe nanowires, i.e. hybrid nanostructures in which ZnSe nanorods grow epitaxially from the surface of ZnSe nanowires, are synthesized in trioctylamine whereas TOPO suppresses this branched growth. Finally, a mechanism which allows for the synthesis of narrow diameter nanowires seeded by much larger diameter nanocrystals is investigated. Bismuth nanocrystals with an average diameter of ~ 20 nm are utilized to promote the growth of narrow diameter (~ 6 nm) CdSe.₀₈Te.₉₂ nanowires. / text
2

Solution phase synthesis and characterization of III-V, II-VI and CdSe.₀₈Te.₉₂ semiconductor nanowires

Fanfair, Dayne Dustan, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.
3

A Quad BGO Detector for High Resolution Positron Tomography

Roney, J. Michael 01 1900 (has links)
No description available.
4

Nucleation and equilibration via surface diffusion : an experimental study : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physics in the University of Canterbury /

McCarthy, David N. January 2008 (has links)
Thesis (Ph. D.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. 158-165). Also available via the World Wide Web.

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