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

Abstract

Pb 0.9 La 0.1 Ti 0.975 O 3 (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 103–106 Hz, with the loss factor being less than 0.01 over the entire range. The leakage current density is lower than 2×10−8 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/m2 K) after it has been poled by applying 120 V ac at 0.1 Hz across the IDT electrodes.