Optical properties of titanium oxide films obtained by cathodic arc plasma deposition

Structural and optical properties of nanometric titanium oxide (Ti_xO_y) films obtained by cathodic arc plasma deposition were investigated. Phase analysis by x-ray diffraction and Fourier-transform infrared spectroscopy showed the presence of anatase, rutile, Ti₂O₃,Ti₄O₇ and amorphous phases. Scanning electron microscopy images showed well-developed surface morphology with nano-patterns. Spectroscopic ellipsometry revealed film thicknesses of 53 and 50 nm, variable refractive indices dependent on the light wavelength and close to zero extinction coefficients for wavelengths higher than 500 nm. On the basis of ultraviolet–visible spectroscopy data and using the Tauc equation, band gap values for direct and indirect electron transitions were determined.