Effect of excessive K and Na on the dielectric properties of (K,Na)NbO3 thin films

•Excessive K and Na are added in precursor to compensate their volatilization.•Optimal excess values of K and Na are 6 mol% and 17 mol%, respectively (abbreviated to KNN(6,17)).•KNN(6,17) thin film has relatively smaller loss value of 3.3%.•The leakage current density of KNN(6,17) thin film is 4.3 × 10− 7 A/cm2.

For the deposition of (K0.48Na0.52)NbO3 (KNN) thin films, excessive K and Na are added in precursor to compensate their volatilization during annealing process. In this work, the effects of excessive K and Na on the dielectric and leakage current properties of the KNN films were studied systemically. The leakage current and dielectric properties of the KNN films are strongly affected by excess amounts of K and Na as well as the annealing conditions. When K and Na are excessive by 6 mol% and 17 mol% respectively, the KNN(6,17) thin films show the smallest leakage current density of 1.8 × 10− 6 A/cm2 at 50 kV/cm and the lowest dielectric loss of 3.3%.