Semiconductive properties of titanium anodic oxide films in McIlvaine buffer solution

The semiconductive properties of anodic oxide films grown on titanium surface at different formation potentials: 1.0, 2.0, 3.0 and 4.0 V were investigated by means of electrochemical impedance spectroscopy and cyclic voltammetry in McIlvaine buffers at pH 2, 4 and 5. The passive films show a Mott-Schottky behavior typical for an n-type semiconductor at the studied potential range with a high concentration of donors. On increasing the film formation potential, the flat band potential and the donor density decrease. Further, lower flat band potentials were obtained for higher pH buffer. These experimental results were related to the film thickness and composition. The influence of film thickness on the oxidation reactions taking place at the titanium electrodes covered by oxide film was evaluated.