RF magnetron sputtered La3+-modified PZT thin films: Perovskite phase stabilization and properties

In this work, we report the preparation of lanthanum-modified lead zirconate titanate (PLZT) thin films in pure perovskite phase by RF magnetron sputtering. Various deposition parameters such as target-to-substrate spacing, sputtering gas composition, deposition temperature, post-deposition annealing temperature and time have been optimized to obtain PLZT films in pure perovskite phase. The films prepared in pure argon at 100 W RF power without external substrate heating exhibit pure perovskite phase after rapid thermal annealing (RTA) at 700 °C for 5 min. The film prepared at 225 °C substrate temperature also exhibits pure perovskite phase after RTA at 700 °C for 2 min. SIMS depth profile performed on one of the pure perovskite films (RTA at 700 °C for 5 min) shows very good stoichiometric uniformity of all elements of PLZT. The surface morphology of the films was examined using SEM and AFM. The dielectric, ferroelectric and electrical properties of the pure perovskite films were also investigated in detail. The remanent polarization for the films annealed at 700 °C for 5 and 2 min were found to be 15 and 13.5 μC cm−2, respectively. Both the films have high DC resistivity of the order of 1011 Ω cm at the electric field of ∼80 kV cm−1.