Pyroelectric properties of laser ablated lanthanum-doped lead titanate thin films for smart sensors

Abstract

Lanthanum modified lead titanate thin films with 20% of lanthanum content (PLT20) were prepared by laser ablation deposition technique. For the films deposited at 300° C, crystallization was induced by Rapid thermal annealing (RTA) process. The dielectric and electrical properties of PLT20 films were studied. The pyroelectric current was measured using Byer-Roundy technique. The RTA annealed films showed a dielectric constant of 482 and a loss factor of 0.033 at room temperature at 100 kHz frequency. The RTA annealed and insitu films showed 1100 x 10^-6 Cm^-2 K^-1 and 609 × 10^-6 Cm^-2K^-1 as pyroelectric coefficients respectively. A large pyroelectric coefficient of value 35000 µ Cm^-2 K^-1 was observed for the in-situ grown films at transition temperature. The figures of merit of current (F_i), voltage (F_v) and detectivity (F_D) were calculated for both the films and the obtained values for the in-situ grown thin films were 1.9 × 10^-10 CmJ^-1, 0.088 m² C^-1, 5.38 × 10^-5 pa^-1/2 respectively. The difference in the pyroelectric properties for the films was discussed and the effect of temperature on dielectric and pyroelectric properties were studied to understand the suitability of these thin film composition for the application of pyroelectric detectors.