Synthesis and Characterization of Functional One Dimensional Nanostructures
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One- dimensional (1D) nanostructures have received growing interest due to their unique physical and chemical properties and promising nanodevice applications, as compared with their bulk counterparts. Complex 1D nanostructures with tunable properties and functionalities have been successfully fabricated and characterized in this thesis. I will show our recent efforts on precise controlled 1D nanostructures by template- assisted electrochemical synthesis as well as fundamental understanding of their physical behavior and growth mechanism of as-synthesized nanostructures. Particularly, three topics are presented: Firstly, a constant current (CC) based anodization technique is newly demonstrated to fabricate and control the structure of an anodic aluminum oxide (AAO) template. This technique has enabled the formation of long- range self- ordered hexagonal nanopore patterns with broad range of tunability of interpore distance (Dint). In addition, the combination of CC based anodization and conventional CV anodization can offer a fast, simple, and flexible methodology to achieve new degrees of freedom for engineering planar nanopore structures. This work also facilitates our understanding of the self- ordering mechanism of alumina membranes and complex nanoporous structure. Secondly, functional 1D nanostructures including pure metallic, magnetic and semiconducting nanowires and their heterostructure are demonstrated by versatile template- based electrochemical deposition under feasible control. This study has enabled the creation of high quality and well- controlled 1D nanostructures that can be applied as a model system for understanding unique 1D physics. Some preliminary investigations including exciton confinement, anisotropic magnetism and surface plasmon resonance are also presented. Lastly, a novel and universal non-epitaxial growth of metal-semiconductor core-shell lattice-mismatched hybrid heterostructures is presented. Importantly, a new mechanical stress driven crystalline growth mechanism is developed to account for non-epitaxial shape and monocrystalline evolution kinetics.