Low-temperature preparation of high-n TiO ₂ thin film on glass by pulsed laser deposition

Single-phase rutile-type TiO ₂ thin films with a high refractive index (n) and a low extinction coefficient (k) prepared on glass are expected to improve the performance of anti-reflection coatings. In this study, TiO ₂ thin films were prepared by the pulsed laser deposition (PLD) method at temperatures ranging from room temperature to 600 °C under an oxygen partial pressure of 1-9 Pa or a 10 ^-5 Pa vacuum, and their crystal structure, microstructure and optical properties were investigated. A single-phase rutile-type TiO ₂ thin film was successfully prepared on a glass substrate by depositing at room temperature in a vacuum followed by post-annealing at 450 °C in air. A nanocrystalline oxygen-deficient phase in the as-deposited films plays an important role in the formation of the single rutile phase during post-annealing. The single-phase rutile-type TiO ₂ thin films showed excellent optical properties, with n = 3.14 and k < 0.05 at λ = 400 nm.