Optical constants of e-beam evaporated titanium dioxide thin films in the 25.5-to 612-eV energy region

The optical constants of titanium dioxide (TiO2) have been experimentally determined at energies in the extreme ultraviolet and soft X-ray spectral regions, from 25.5 to 612 eV. Measuring angle-dependent reflectance of amorphous TiO2 thin films with synchrotron radiation at the BEAR beamline of Synchrotron ELETTRA. The experimental reflectivity profiles were fitted to the Fresnel equations using a genetic algorithm applied to a least-square curve fitting method, obtaining values for δ and β. We compared our measurements with tabulated data. All samples were grown on Si (100) substrates by the electron-beam evaporation technique, with a substrate temperature of 150°C and deposition rates of 0.3 to 0.5 Å/s. Complete films characterization have been carried out with structural (XRD, ellipsometry, and profilometry), compositional (X-ray photoelectron spectroscopy), and morphological (atomic force microscopy) analyses.