Ferroelectric and microstructural characteristics of Ba0.6Sr0.4TiO3 thin films prepared by RF magnetron sputtering

The microstructures and ferroelectric properties of Ba0.6Sr0.4TiO3 (BST) thin films prepared by RF magnetron sputtering were investigated. By adjusting deposition conditions, the ratio of Ba:Sr is near to the value of the ceramic target. Ninety degree domains in BST thin films were observed by piezoresponse force microscopy (PFM). It is found that the domain configuration of 28 nm grain is different from that of 33 nm grain. At 1 kHz the dielectric constant and the tunability of the Ba0.6Sr0.4TiO3 film with thickness 500 nm are 1267 and 29.5%, respectively. The remnant polarization (Pr) and the coercive electric field (Ec) of the BST film are 0.6 μC/cm2 and 12.1 kV/cm at room temperature, respectively. The results show that the ɛr-E and P-E curves are asymmetric, and show an electric field shift toward the negative side. It is implied that there are asymmetric potential barriers at the upper and bottom interfaces.