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Ph.D. Defense Wednesday, May 9, 2007 ENG II – Room 202 3:00PM Title: Fabrication and Characterization of One-Dimensional Functional Nanostructures Abstract: Various types of the fabrication processes of one-dimensional nano-heterostructures made of biological and inorganic materials are developed in this research. Along with the fabrications, elemental analyses and electrical measurements characterize the nanostructures fabricated for practical application integration. Nucleic acids and viruses play important roles during the development of one-dimensional nanoscale biomaterials. Peptide nucleic acids (PNA) possess the same base pairs of deoxyribonucleic acid but a neutral backbone that affords stronger hybridization and better stability in base pairing. The metallization of PNA with platinum nanoparticles via electroless chemical reduction is reported. Platinum ions form a nucleation center on the PNA fragments followed by a reduction and then grow into metal nanoparticles. Functionalization of nucleic acids by electroless chemical reduction followed by the conjugation with carbon nanotubes makes this biomaterial applicable in resonant tunneling diodes. Nanostructured viruses are attractive templates in ordering quantum dots for constructing self-assembled building blocks towards next generation electronic devices. So far, only a few types of electronic devices have been fabricated from biomolecules due to the lack of charge transport through biomolecular junctions. We show novel electronic memory effect by incorporating platinum nanoparticles over Tobacco Mosaic Virus. The memory effect is based on conductance switching which leads to the occurrence of bistable states with an on/off ration larger than three orders of magnitude. The mechanism of this process in attributed to charge trapping in the nanoparticles for data storage and a tunneling process in the high conductance state. The electrochemical techniques are extended for the fabrication of one-dimensional inorganic nano-heterostructures. Multi-segmented platinum-cupric oxide nanowires are synthesized by potential modulated electrochemical deposition. The metal-semiconductor nano-heterostructures demonstrate the potential for three-dimensional integration of nanoelectronic devices. A novel technique assisted by porous templates is developed to synthesize core-shell nanowires electrochemically. The core-shell nanowires concept is exploited in hydrogen production and renewable energy application |
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