Special One-Dimensional Nanostructures Based On Metal Oxides:Synthesis And Devices

One-dimensional nanostructures have properties of surface effect, quantum size effect and quantum tunnel effect, leading to advantages of unique optical, electrical chemical, thermal and magnetic properties. More novel effects are founded as well, such as optical switch effect, nanowire-grid polarization effect, field emission effect, thermo electric effect, piezoelectric effect, hydrogen storage and sensing property. Along with the researches, methods of morphology, size and composition control is becoming more and more advanced, special constructions also bring about corresponding special functions. Highly individualized controllable synthesis and manipulation not only focuses on novel morphologies but also elabotate and quantifiable processes to satisfy harsh and distinctive requirements. This thesis simply rebuilds reaction systems for the CVD method, syhthesizes multi special metal oxide nanostructures, and studies the photoluminescence, wettability and finite-element ananysis, fabricates high-performance eletron and optoelectronic devices. The main contents are describled as follows.Ga2O3nanorings. A facile low-melting-point metal spheres assisted method was developed to synthesize metal oxide nanorings on a large scale. When two-step-heating method used, single nanorings obtained; when fast-heating-vaporing-transport method used, ring-in-ring obtained. The process also works for SnO2and In2O3. Photoluminescence of Ga2O3nanorins is tested, a strong emission centered at around570nm is founded. Finally, transistors are fabricated and tested, controllability of gate bias is not ideal also with a threshold voltage of84V, because of the polycrystal structure.In2O3nanospirals. Usinig a tube-in-tube laser ablation chemical vapor deposition method, we synthesize self-assebled kinked In2O3nanospirals and multikinked nanowires. For the synthesis of kined In2O3nanospirals, a small quartz tube with one end closed is used, while a small quartz tube with open ends is used for the synthesis of multikinked In2O3nanowires. As-synthesized nanostructures show ultrafast photoinduced reversible wettability switching behavior. Single nanostructure-based field-effect transistors are fabricated and mobilities higher than243cm2/(V·s) and207cm2/(V·s) are obtained.Ultrathin In2O3nanowires. Using a laser-ablation chemical vapor deposition method, we synthesize single-crystal In2O3nanowires with diameter below4nm. The as-synthesized ultrathin In2O3nanowires act as the ultrathin branches of hierarchical In2O3nanostructures and show fast photoinduced switching surface wettability behaviors, and the contact angle decreses to0°in10min. Transparent thin-film transistors are fabricated using the product, and the device conductance is1-2order higher than the average conductance of the In2O3single nanowire devices.SnO2ladder-like nanowires. We synthesize interesting ladder-like mental oxide nanowires, including In2O3, SnO2, ZnO, and Ga2O3, via a facile chemical vapor deposition method. Single ladder-like NW-based field-effect transistors and photodetectors of SnO2are fabricated in order to investigate their electrical transport and light absorption properties. FETs build on ladder-like NWs operate in a depletion mode. The ladder-like NWs also give higher carrier concentrations than conventional single nanowires. Finite-difference time-domain simulations have been performed on the ladder-like NWs and the results reveal a great enhancement of light absorption with both transverse-electric and transverse-magnetic polarization modes, which is in good agreement with the experimental results.