The influence of the growth rate on the semiconductive properties of titanium anodic oxide films

The semiconductive property of the anodic oxide films on titanium formed by potential sweep oxidation at various sweep rates is investigated by AC impedance in 0.1 mol dm −3 sulfuric acid solution. The dielectric constant and donor density of the oxide films change with the sweep rate. The dielectric constant increases and the donor density decreases with increase of the sweep rate. The dependence may be interpreted by the degree of hydration of the film. The oxide film formed by the higher sweep rate is more hydrated. High content of the hydrating water or an OH − bridge in the film may introduce a relatively high dielectric constant and low donor density.