Manipulating leakage behavior via thickness in epitaxial BaZr_0.35Ti_0.65O₃thin film capacitors

High quality, epitaxial Ba(Zr0.35Ti0.65)O3 thin films were fabricated via radio frequency magnetron sputtering technique. The leakage current density vs electric field (J-E) tests were conducted using the device structures with Pt top electrodes and Nb-doped SrTiO3 bottom electrodes. The conduction mechanism of the films and the J-E characteristic that changed from the asymmetric structure to the relative symmetric structure were investigated. Analysis of the thin film leakage behavior suggests that, at low electric field, the conduction mechanisms are mainly bulk-limited Ohmic and space-charge-limited current. When the electric field is higher, the interface-limited Schottky emission and the Fowler-Nordheim (FN) tunneling as the dominant conduction mechanism occur for the films with a thickness below 166 nm and only FN tunneling for the films with the thickness of 300 and 400 nm. In addition, the asymmetric structure is strongly dependent on the large relative value of the Schottky barrier height between the positive and negative biases. Moreover, increasing the electric field range used to generate the bulk-limited conduction behavior and decreasing the current density induced by the interface-limited conduction through increasing the film thickness are beneficial for the films to obtain a high breakdown strength and a large energy storage density, as well as excellent efficiency.