Controlled Preparation And Characteristic Of SnO₂ One-Dimensional Nanostructures

SnO₂ is a typical metal oxide semiconductor with a wlde band-gap(Eg=3.6ev, at 300k). One-dimensional SnO₂ nanostructures have attractedextraordinary attention for their special physical properties and potentialapplications in optoelectronic devices, gas sensors, transparent electrode,solar cell, and etc. Due to the subtle relationship between the propertiesand microstructures, it is a very important topic how to obtainone-dimensional SnO₂ nanostructures with specific microstructures byimproving preparation methods.In this thesis, by adjusting experimental conditions such as theingredient of source material and the oxygen density in the carrier gas inchemical vapor deposition, one-dimensional SnO₂ nanostructures(including nanowires, nanorods, nanobelts and nanoneedles) withcontrollable diameters were successfully prepared by chemical vapordeposition method. Experimental results also indicate that the growthmechanism of one-dimensional SnO₂ nanostructures depends on therelative proportion of Sn and O₂ near the growth point, which can bemodified directly by adjusting the proportion of SnO in the sourcematerial or the density of oxygen in the carrier gas.We have also successfully synthesized well-aligned SnO₂ self-assembly microstructures/nanostructures (such as dendrite-like andcuvette-brush-like) through adjusting the gas pressure in the growthchamber or the position of the substrate for collecting sample. The growthmechanism of the as-synthesized self-assembly SnO₂ microstructures/nanostructures are discussed, which depend on the higher density of thereactant saturation vapor.Gas sensors based on doped SnO₂ film show excellent selectivity andsensitivity in gas sensing. In order to further improve selectivity andsensitivity, enhance work stability, and reduce work temperature of gassensors based on SnO₂, we succeeded in synthesizing Mo-doped SnO₂one-dimensional nanostructures, and try to use them as sensing part. Atthe same time, We investigated the optimization preparation condition forSnO₂ nanostructures doping with high melting-point metal by chemicalvapor deposition method.