The leakage current response of high-permittivity columnar-grown (Ba,Sr)TiO3 thin films was studied at elevated temperatures under a direct-current load. A thermally activated current was observed, prior to the onset of resistance degradation with an activation energy of 1.1eV. A point defect model was used to calculate the migration of electronic and ionic defects under the direct-current field, as well as the current response of the system. It was found that the peak in current was caused not by a space-charge-limited transient of O vacancies, but was related to a modulation of the electronic conductivity upon O vacancy redistribution. It was also shown that, after redistribution of the electronic and ionic defects, no further increase in conductivity took place in the simulation.

Oxygen Vacancy Migration and Time-Dependent Leakage Current Behavior of Ba0.3Sr0.7TiO3 Thin Films. R.Meyer, R.Liedtke, R.Waser: Applied Physics Letters, 2005, 86[11], 112904 (3pp)