Pitak Eiamchai, Pongpan Chindaudom, Artorn Pokaipisit, Pichet Limsuwan

A spectroscopic ellipsometry study of TiO₂ thin films prepared by ion-assisted electron-beam evaporation

Current Applied Physics 9 (2009) 707–712

Film characterization based on variable-angle spectroscopic ellipsometry (VASE) is desirable in order to understand physical and optical characteristics of thin films. A number of TiO₂ film samples were prepared by ion-assisted electron-beam evaporation with 200 nm nominal thickness, 2.0 Å/s deposition rate and 8 sccm oxygen flow rate. The samples were maintained at 250 °C during the deposition, and annealed in air atmosphere afterwards. As-deposited and annealed films were analyzed by VASE, spectrophotoscopy and X-ray diffractometry. From ellipsometry modeling process, the triple-layer physical model and the Cody–Lorentz dispersion model offer the best results. The as-deposited films are inhomogeneous, with luminous transmittance and band gap of 62.37% and 2.95 eV. The 300 °C and 500 °C are transition temperatures toward anatase and rutile phases, respectively. Increasing temperature results in an increase of refractive index, transmittance percentage and band gap energy. At 500 °C, the highest refractive index and band gap energy are obtained at 2.62 and 3.26 eV, respectively. The developed VASE-modeling process should be able to characterize other TiO2 films, using similar physical and optical modeling considerations.

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Cited Articles

1. Franta D., Ohlídal I., Petrýdes D.,
   Optical characterization of TiO₂ thin films by the combined method of spectroscopic ellipsometry and spectroscopic photometry,
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