Lattice-strain engineered KxNa1-xNbO3 thin films near the morphotropic phase boundary for enhanced electrical properties

Tailoring of lattice strain by controlling background oxygen gas pressure in PLD deposited K0.5Na0.5NbO3 thin film has been critically investigated. Oxygen gas pressure induced lattice strain significantly influences the structure, morphology, and electrical properties of K0.5Na0.5NbO3 thin films. The in-plane compressive stress and dense micro structured morphology favors superior electrical and ferroelectric properties in the K0.5Na0.5NbO3 film. The film deposited at optimum gas pressure (200 mTorr) exhibited uniformly distributed dense microstructures, low leakage current (6.73 x 10−7 A/cm2 at 150 kV/cm), high saturated and remanent polarization (Ps = 71 μC/cm2 and Pr = 24 μC/cm2, respectively). Besides, a high Curie temperature (Tc = 410 °C), high dielectric constant with low dielectric loss (ε= 1218 and tanδ = 0.18, respectively), and ac conductivity (1 x 10−5 Sm−1) at 1 kHz were obtained for the optimized K0.5Na0.5NbO3 thin film at room temperature.