A Current Instability in TiO2 Thin Film

Abstract

The current instability is observed in the sputtered TiO₂ thin films of Au-TiO₂-Ti sandwich system under the application of positive bias on Au electrode. The process of the present current instability is studied in relation to the hydrogen ion conduction in the TiO₂ thin films. As a result, the process is conjectured as follows: 1) dissociation of adsorbed water at Au-TiO₂ interface, 2) injection of H⁺ into TiO₂ at the positive bias, 3) migration of H⁺ through TiO₂ under the applied field. Dissociation of water results from a coarse texture of the film surface. From the current response at the recovery of the current instability, the diffusion activation energy of H⁺ in the TiO₂ films is estimated at 0.07 eV which is in good agreement with the value in TiO₂ single crystal.