Calcium lead titanate thin films for pyroelectric detection

Abstract

Pyroelectric detectors are the class of thermal detectors which change their spontaneous polarization when there is a change in temperature. The change in the spontaneous polarization occurs due to the absorption of infrared radiation which eventually produces a voltage. This work demonstrates the deposition and characterization of calcium modified lead titatante (Pb_1-xCa_xTiO₃, PCT) thin films for using them as materials of pyroelectric thermal detectors. The PCT thin films were sputtered using an RF sputter system in Ar:O₂ environment at room temperature. The thin films were grown on Au electrode. The capacitance was formed by using Au electrodes on top of PCT thin films which were fabricated by sputtering and liftoff. The PCT films were annealed at 450, 500, 550 and 600 °C in O₂ environment for 15 minutes. Energy dispersive spectroscopy was done to determine the atomic composition of PCT films. Variations of capacitance, pyroelectric voltage, loss tangent and pyroelectric current between the temperature range 303 K to 353 K were determined. The PCT films were annealed at 550 °C showed the highest value of pyroelectric current and pyroelectric coefficient of 2.45 × 10^-12 A and 1.99 μC/m²K respectively at room temperature. The loss tangent did not change much with temperature for all the PCT samples.