Ionic and electronic defects in a-BaTiO3 thin films studied by transient and steady state conductivity measurements

International audienceConduction mechanisms in BaTiO3 films deposited at low temperatures on Cu electrodes have been investigated in transient and steady regimes as a function of temperatures and electric field. This work aims to identify possible defects which govern the leakage current. Electrical measurements reveal that Space Charge Limited Current (SCLC) constitutes the main leakage mechanism in both the transient and the steady regimes. Based on the theory of SCLC, two types of defects can be detected. At higher temperatures, oxygen vacancies constitute the main defects which migrate across the film to generate an ionic leakage current. Diffusion of these defects is thermally activated with an activation energy around 1 eV. Moreover, at lower temperatures the J-E measurements reveals the presence of a discrete set of shallow traps at 0.45 eV below the conduction band with an effective density of 4 × 1022 m-3