Improvement of energy density in SrTiO3 film capacitor via self-repairing behavior

Self-repairing behavior of SrTiO3 film capacitor was explored to improve the energy density. With Au and Al being deposited on SrTiO3 thin films as top electrode, the breakdown processes were investigated by a real-time optical microscope system. A high electric field of the electrode edge attributed to edge effect provided the “trigger factor” for the self-repairing behavior. Absorbed water not only provided “mobile phase” for self-repairing process which significantly enhanced breakdown strength but also, and equally important, it supplied additional polarization charges to raise dielectric constant. As a result of the concurrent increase in Eb and εr, a higher energy density of 15.7 J/cm3 is achieved. A leakage current platform was observed in the self-repairing process and the thickness of a new layer Al2O3 film generated from self-repairing process was estimated according to Ohm's law and breakdown strength. Using relative humidity dependence of breakdown voltage, the maximum breakdown field was explored to realize the optimum self-repairing capability.