Electrical and pyroelectric properties of in-plane polarized lead lanthanum titanate thin film

Abstract

Pb[sub 0.9]La[sub 0.1]Ti[sub 0.975]O₃ (PLT10) thin films were deposited on SiO₂ /Si(100) substrates coated with a ZrO₂ buffer layer. Studies by x-ray diffraction and scanning electron microscopy reveal that the ZrO₂ film consists of both tetragonal and monoclinic phases, with the tetragonal phase being the dominant one. The PLT10 film has a perovskite structure and the grains in the film have a rather uniform size of about 50 nm. By using interdigital transducer (IDT) electrodes the in-plane electrical properties, hysteresis loop, and pyroelectric coefficient of the PLT10 film were measured. The dielectric constant and loss factor vary only slightly with frequency in the range 10³-10[sup 6] Hz, with the loss factor being less than 0.01 over the entire range. The leakage current density is lower than 2x10[sup -8]A/cm² at a bias field of 5 kV/cm. The remnant polarization and coercive field are 12.6 µC/cm² and 9.93 kV/cm, respectively. The film exhibits a reasonably high pyroelectric coefficient (95 µC/m²K) after it has been poled by applying 120 V ac at 0.1 Hz across the IDT electrodes.