Optical properties of pulsed laser deposited rutile titanium dioxide films on quartz substrates determined by Raman scattering and transmittance spectra

Optical response of rutile TiO₂ films grown under different laser energy by pulsed laser deposition has been investigated by Raman scattering and spectral transmittance. Dielectric functions in the photon energy range of 1.24-6.5 eV have been extracted by fitting the experimental data with the Adachi's model [S. Adachi, Phys. Rev. B 35, 7454 (1987)]. The refractive index dispersion in the transparent region is mainly ascribed to the higher A1 - A2 electronic transitions for the rutile TiO₂ films. Owing to slightly different crystalline structures and film densities, the optical band gap linearly increases with increasing packing density. The phenomena were confirmed by different theoretical evaluation methods.