Influence of Anatase-Rutile Phase Transformation on Dielectric Properties of Sol-Gel Derived TiO_2 Thin Films

摘要

Effects of annealing temperature on the structural and dielectric properties of sol-gel derived TiO_2 thin films were systematically investigated. Thin films annealed at various temperatures showed pure or mixed phases of anatase and rutile. As-deposited films started crystallization below 600℃ and fully crystallized into the anatase phase at 800℃, followed by transformation to the rutile phase above 850℃. Dielectric properties of thin films with various phases were studied by LCR-meter using the metal-insulator-metal (MIM) structure. Dielectric constants of thin films increased from 40 to 147 as the portion of rutile phase increased from 0 to 95%, while dielectric losses decreased from 0.011 to 0.001. Temperature dependence of dielectric constants of thin films was also investigated. The dielectric properties of TiO_2 thin films were discussed in terms of phase constitution, crystallinity, and preferred orientation.