Oxygen transport during annealing of Pb(Zr,Ti)O₃ thin films in O₂ gas and its effect on their conductivity

Lead zirconate titanate (PZT) thin films were deposited in a reactive argon/oxygen gas mixture by radio-frequency-magnetron sputtering. The use of a metallic target allows us to control the oxygen incorporation in the PZT thin film and also, using oxygen 18 as a tracer, to study the oxygen diffusion in the thin films. Electrical properties and crystallization were optimized with a 90-nm PZT thin film grown on RuO₂ electrodes. These PZT films, annealed with a very modest thermal budget (550 °C) show very low leakage current densities (J = 2 × 10⁻⁸ A/cm² at 1 V). In this article we show that a strong correlation exists between the oxygen composition in the PZT film and the leakage current density.