Pulsed laser deposition and characterization of highly tunable (1−x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 thin films grown on LaNiO3/Si substrate

Abstract

The structural and electric properties of Ba(Zr0.2Ti0.8)O3 {BZT}, (Ba0.7Ca0.3)TiO3 {BCT} and 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 {BCZT50} thin films grown on LaNiO3 coated Si(100) substrate by pulsed laser deposition (PLD) were thoroughly investigated. XRD results revealed relatively higher (100) preferred orientation and higher crystallinity for BCZT50 film in comparison to BZT and BCT thin films. FESEM showed that the average grain size of BCZT50 thin film is larger than that of BZT and BCT thin films. The optimal composition BCZT50 also exhibited maximum spontaneous polarization (Pm), maximum remanant polarization (Pr), minimum coercive field (Ec), maximum dielectric constant εr(0) and maximum tunability (nr). The increase in nr, εr(0) and polarization P(E) for BCZT50 thin film is attributed to (100) preferred orientation, microstructural homogeneity, large grain growth and most importantly to its proximity to the morphotropic phase boundary (MPB) causing very low energy barrier for polarization rotation and lattice distortion. It is also observed that BCZT50 thin film exhibits low leakage current density and good fatigue endurance as compared to BZT and BCT thin films.