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" Electrochemical Fabrication of High-aspect Ratio Nanostructures "
Dryden, Daniel Max
Islam, M Saif
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Latin Dissertation
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English
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| Record Number
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1052572
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| Doc. No
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TL51689
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| Main Entry
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Dryden, Daniel Max
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| Title & Author
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Electrochemical Fabrication of High-aspect Ratio Nanostructures\ Dryden, Daniel MaxIslam, M Saif
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| College
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University of California, Davis
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| Date
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2019
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| Degree
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Ph.D.
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2019
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| Note
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199 p.
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| Abstract
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High-aspect ratio micro- and nanostructures enhance the performance of electronic devices including power electronics, optoelectronics, and energy devices such as solar cells, capacitors, and radioisotope batteries, through size reduction and new device architectures. Electrochemical techniques provide means to fabricate such structures through deposition and etching. Electrochemical approaches were used to fabricate and analyze metal, semiconductor, and hybrid micro- and nanostructures. Cobalt-nickel films and nanowires were deposited via templated deposition from citrate baths, creating novel fluted nanowires. Solvent complexation was investigated in the anomalous deposition of cobalt over nickel. Photogalvanic etching of n-type gallium nitride using an alkaline etchant and persulfate oxidizer was optimized for the fabrication of pillar and mesa structures. Optimal etching parameters were investigated for smooth and defect-selective etching, and control over smooth etching was achieved by heating the etchant bath. Bath acidification was mitigated with buffering salts, more than tripling the bath lifetime and achieving etch rates in excess of 200 nm/min. Etching with alternative oxidizers was demonstrated, and phosphate salts were introduced as a new class of etchant that enabled etching under neutral pH conditions. Platinum films were electrodeposited directly onto n-type gallium nitride, and nucleation conditions were optimized to improve film quality and reduce stress-induced delamination. Design guidelines were proposed for assessing the etching techniques applicable to next-generation materials and devices. These techniques show promise for new methods and mechanisms of vertical and nanostructured device fabrication.
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Engineering
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Materials science
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Nanotechnology
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Islam, M Saif
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University of California, Davis
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