Aligned Rutile TiO₂Nanorods:Facile Synthesis And Field Emission

One-dimensional TiO₂nanorods are ideal emitters due to their intrinsic propertiesof low work function （4.5eV）, sharpened tip apexes, high aspect ratio, and idealelectronic transmission channels. However, few works about their field emission havebeen reported because it is difficult to synthesize TiO₂nanorods that suit to be emitters,and their structure parameters are also hard to be modulated. Thereby, a new route tofabricate TiO₂nanorods as emitters is needed. Based on our research group previouswork, this dissertation titled “aligned rutile TiO₂nanorods: facile synthesis and fieldemission” focuses on the fabrication and field-emission properties of aligned rutileTiO₂nanorod array films. Mainly works and results are as following:1)The fabrication of aligned rutile TiO₂nanorods. A simple two-step technique,first anodization in an ethylene glycol solution and then oxidation in a low-pressureatmosphere by CVD, was developed to synthesize aligned TiO₂nanorods. Themorphology, crystalline structure and current versus voltage characteristics of theas-grown specimens were characterized by using of scanning electron microscopy,X-ray diffraction, transmission electron microscopy and Keithley semiconductorcharacterization system, respectively. It is found that the aligned TiO₂nanorod arrayswith smooth surface are rutile phase with a preferential growth direction of [110], andtheir tops possess the sharpened tip apexes. And the nanorods rooted from Ti substrateshow ohmic contact with substrate. The growth mechanism and the field-emissionproperties were investigated.2)The optimization of field-emission property of aligned rutile TiO₂nanorods.The aligned rutile TiO₂nanorod films were synthesized by two-step technique, andthe effect of anodization time on their structure parameters and field-emissionproperties was studied. It is found that the anodization time can easily adjust structureparameters such as the aspect ratio and density, which are beneficial for optimizingtheir FE properties. When the anodization time increases from30to480s, the turn-onfield of TiO₂nanorods decreases firstly from5.46V/μm to1.78V/μm and thenincreases to6.46V/μm, so does the threshold field; The optimized sample of anodized120s exhibits excellent field-emission properties involving both a low turn-on field of 1.78V/μm, a high field enhancement factor （4757） and a good FE stability.