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Yoel Fink. Deng, Daosheng Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Massachusetts Institute of Technology. Department of Materials Science and Engineering 2010-10-29T18:17:35Z 2010-10-29T18:17:35Z 2010 2010 http://hdl.handle.net/1721.1/59705 668422375 Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010. Cataloged from PDF version of thesis. Includes bibliographical references (p. 107-112). One-dimensional nanostructures with high aspect-ratios and nanometer cross-sectional dimensions have been the focus of recent studies in the persistent drive to miniaturize devices. Conventional bottom-up methods such as vapor-liquid-solid growth have been widely applied for the fabrication of uniform and high quality nanowires. Two challenges toward nanoelectronics and other applications remain: on the single-nanowire level, precisely manipulating an individual nanowire for the sophisticated functionalities, and on the multiple-nanowire level, integrating nanowires into designed architecture at large scale. Thus, an alternative approach with the capacity to achieve ordered and extended nanowires is highly desirable. In this thesis, we observe an intriguing phenomenon that a cylindrical shell upon reaching a characteristic thickness breaks up into filament arrays during optical-fiber thermal drawing. This structural evolution occurs exclusively in the cross-sectional plane, while the uniformity along the axial direction remains intact. We demonstrate crystalline semiconductor nanowires by post-drawing annealing procedure and characterize their electrical and optoelectric properties for the devices such as optical switch. This top-down thermal drawing approach provides new opportunities for nanostructure fabrication with high throughput and at low cost, and offers promising applications in renewable energy and data storage. In order to understand the stability (or instability) of thin shells and filaments, we explore a physical mechanism during the complicated thermal drawing. A perspective of capillary instability from fluid mechanics is focused. Axial stability of continuous filaments is consistent with capillary instability. Axial stability of a thicker cylindrical shell arises from large radius and high viscosity. These results provide theoretical guidance in the understanding of attainable feature sizes and in materials selection to expand the potential functionalities of devices in microstructured fibers. by Daosheng Deng. Ph.D. 112 p. eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Materials Science and Engineering. In-fiber semiconductor filament arrays Thesis application/pdf Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="768c0047-c036-45bf-8141-adfa9030cc10"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>In-fiber semiconductor filament arrays</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2010</PublicationDate> <Authors> <Author> <DisplayName>Deng, Daosheng</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Materials Science and Engineering.</Keyword> <Abstract>One-dimensional nanostructures with high aspect-ratios and nanometer cross-sectional dimensions have been the focus of recent studies in the persistent drive to miniaturize devices. Conventional bottom-up methods such as vapor-liquid-solid growth have been widely applied for the fabrication of uniform and high quality nanowires. Two challenges toward nanoelectronics and other applications remain: on the single-nanowire level, precisely manipulating an individual nanowire for the sophisticated functionalities, and on the multiple-nanowire level, integrating nanowires into designed architecture at large scale. Thus, an alternative approach with the capacity to achieve ordered and extended nanowires is highly desirable. In this thesis, we observe an intriguing phenomenon that a cylindrical shell upon reaching a characteristic thickness breaks up into filament arrays during optical-fiber thermal drawing. This structural evolution occurs exclusively in the cross-sectional plane, while the uniformity along the axial direction remains intact. We demonstrate crystalline semiconductor nanowires by post-drawing annealing procedure and characterize their electrical and optoelectric properties for the devices such as optical switch. This top-down thermal drawing approach provides new opportunities for nanostructure fabrication with high throughput and at low cost, and offers promising applications in renewable energy and data storage. In order to understand the stability (or instability) of thin shells and filaments, we explore a physical mechanism during the complicated thermal drawing. A perspective of capillary instability from fluid mechanics is focused. Axial stability of continuous filaments is consistent with capillary instability. Axial stability of a thicker cylindrical shell arises from large radius and high viscosity. These results provide theoretical guidance in the understanding of attainable feature sizes and in materials selection to expand the potential functionalities of devices in microstructured fibers.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>