Influence of the hydrogen content on the optical properties of TiOx thin films.

In this work, dark Ti(O_xH)_y films were obtained by DC magnetron reactive sputtering under different oxygen partial pressures (P_O2) starting from a high base pressure chamber atmosphere (10⁻⁵ mbar) with the purpose of investigating the visible light absorption dependence of the hydrogen content and stoichiometry. The TiO_x film compositions, thicknesses, and elemental depth profiles were measured by ion beam analysis (IBA) techniques in a self-consistent approach. The optical properties were investigated by visible and near-infrared spectrophotometry, and the crystallography was examined by small-angle X-ray diffraction. The films deposited at a low P_O2 were dark, and as the partial oxygen pressure increases, they became transparent. The IBA showed that the hydrogen content exponentially decreased as the P_O2 increased. The optical constants for the films, n and k, are dependent on oxygen and hydrogen ratio as well as the optical band gap that can be modulated from 0.40 to 3.25 eV, and thus a significant improved PEC activity. These modulations may be useful for optical or electronic devices as a variable semiconductor or dielectric layer. [ABSTRACT FROM AUTHOR]