Spectroscopic ellipsometry characterization of TiO 2 thin films prepared by the sol–gel method

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TiO 2 thin films were prepared on SiO 2/Si(100) substrates by the sol–gel process. XRD results indicate that the major phase of TiO 2 thin films is anatase. The surface morphology and cross-section are observed by FE-SEM. The surface of thin films is dense, free of cracks and flat. The average grain size is about 60–100 nm in diameter. The thickness of single layer TiO 2 thin films is about 60 nm, which increases with the concentration of solution. Ellipsometric angles ψ, Δ are investigated by spectroscopic ellipsometry. The optical constant and the thickness of TiO 2 thin films are fitted according to Cauchy dispersion model. The results reveal that the refractive index and the extinction coefficient of TiO 2 thin films in wavelength above 800 nm are about 2.09–2.20 and 0.026, respectively. The influences of processing conditions on the optical constants and thicknesses of TiO 2 thin films are also discussed.