The ion-beam-sputtering method was used to deposit TiO<sub>2</sub>-SiO<sub>2</sub> mixed films on silica substrates. The SiO<sub>2</sub> concentration ranged from 0 to 17%, and the refractive index ranged from ∼2.7 to ∼2.3 in visible wavelength. All the structures of the as-deposited films were amorphous. The refractive index and the extinction coefficient decreased with increased SiO<sub>2</sub> concentration. High temperature annealing reduced the optical absorption for all films. There was a phase transition from amorphous to polycrystalline anatase at high temperature. Surface roughness, and thus optical scattering, increased drastically with the appearance of the phase transition. The phase transition temperature was higher for films with higher SiO<sub>2</sub> concentration. The ion-beam-sputtered TiO<sub>2</sub>-SiO<sub>2</sub> mixed film could sustain higher temperature annealing, resulting in lower extinction coefficient, than that of the ion-beam-sputtered pure TiO<sub>2</sub> film. The phase diagram of the mixed film system was given.
© 1999 Optical Society of America
(310.3840) Thin films : Materials and process characterization
Shiuh Chao, Wen-Hsiang Wang, Min-Yu Hsu, and Liang-Chu Wang, "Characteristics of ion-beam-sputtered high-refractive-index TiO2-SiO2 mixed films," J. Opt. Soc. Am. A 16, 1477-1483 (1999)