Effect of sputtering pressure on structural and dielectric tunable properties of BaSn0.15Ti0.85O3 thin films grown by magnetron sputtering

Lead−free ferroelectric BaSn0.15Ti0.85O3 (BTS) thin films are grown on Pt-coated Si substrates by magnetron sputtering at 650 °C, the effect of sputtering pressure on the microstructural, surface morphological, dielectric properties and leakage characteristic is systematically investigated. XRD analysis shows the crystallinity of BTS thin films with perovskite structure can be improved by appropriate control of the sputtering pressure. The surface morphology analyses reveal that grain size and roughness can be affected by sputtering pressure. The BTS thin films prepared at sputtering pressure of 3.0 Pa exhibit a low dispersion parameter of 0.006, a medium dielectric constant of ~357, a high dielectric tunability of 65.7%@ 400 kV/cm and a low loss tangent of 0.0084 @ 400 kV/cm. Calculation of figure of merit (FOM) displays a high value of 84.1, and the measurement of leak current shows a very low value of 4.39 × 10-7 A/cm2 at 400 kV/cm. The results indicate that BTS thin film deposited sputtering pressure of 3.0 Pa is an excellent candidate for electrically steerable applications