Chemical Processing and Characterization of Ferroelectric (K,Na)NbO3 Thin Films

Abstract

Lead-free ferroelectric K0.5Na0.5NbO3 (KNN) thin films have been synthesized by the chemical solution deposition. The optimization of excess amounts of K and Na in KNN precursor solutions was found to be effective for achieving perovskite KNN single-phase thin films with improved leakage current properties. It was revealed from Raman spectroscopic analysis data that a change in scattering mode was observed for the KNN thin films fabricated under various processing conditions. This change was due to the chemical composition fluctuation of K and Na in the KNN thin films after heat treatment. The leakage current and ferroelectric properties of the perovskite KNN thin films were strongly affected by the excess amounts of K and Na as well as the heating conditions of the precursor films. Optimized KNN thin films with 10 mol % excess K and Na exhibited a ferroelectric polarization–electric field (P–E) hysteresis loop with 2Pr and 2Ec values of 14 µC/cm2 and 140 kV/cm, respectively.