Enhanced ferroelectric and dielectric properties of BiFeO3–PbTiO3 thin films grown via a sol–gel multilayer deposition method

Abstract

BiFeO3–PbTiO3 (BF–PT) solid solution thin films were deposited on LaNiO3/SiO2/Si substrates by a sol–gel multilayer deposition method in a super clean room with rapid thermal annealing (RTA) technique. XRD patterns of all the films demonstrate a single perovskite phase. The induced orientation of LaNiO3 substrates leads to highly (100) oriented texture. Cross-section SEM and EDS pictures confirmed that the BFPT-based films are about 230 nm thickness and had formed a dense and uniform solid solution. Film with a ratio of BF:PT = 1:2 (BFPT1-2) possesses best ferroelectric properties. A saturated hysteresis loop with a remnant polarization of 66 μC/cm2 measured at room temperature was obtained, much higher than that of BFPT7030 thin film, which was prepared by depositing BFPT7030 sol directly on LaNiO3/SiO2/Si substrates without multilayer deposition. BFPT1-2 thin films also showed better dielectric and leakage current properties than BFPT7030 thin film in the test range of electric field and frequency. BFPT1-2 thin films exhibit lowest leakage current and loss tangent, indicating that a high quality of BFPT1-2 thin film was successfully prepared by multilayer deposition method with a RTA technique with heating rate of 1 °C/s.