The fabrication and characterization of (Pb,Ca)TiO3 pyroelectric thin films with different Ca contents

Abstract

This study uses radio-frequency sputtering methods to deposit lead titanate thin films with different contents of Ca on Pt∕Ti∕SiO2∕Si substrates to form Pb1−xCaxTiO3 (PCT) thin films. The PCT thin films contained different amounts of Ca in order to examine the influence of the Ca content on the properties of thin films. Analysis of the electrical properties of the PCT thin films revealed that their relative permittivities, dissipation factors, and pyroelectric coefficients tend to increase with the Ca content. On the other hand, the coercive field and remnant polarization decreased with an increase in the Ca content. In addition, the measured data indicated that the figure of merit for voltage (Fv) and the figure of merit for detectivity (FD) of a PCT (30) thin film are the highest with values of 0.033m2C−1 and 0.862×10−6(m3J−1)1∕2, respectively. Therefore, the PCT (30) thin film was evaluated as the best composition for manufacturing pyroelectric infrared (PIR) sensors. PCT thin films were also used to fabricate thermal PIR sensors by surface machining technology. The detectivity measurement showed that the PIR sensor with PCT (30) thin films has the highest value of D* (1.29×107cmHz1∕2∕W) at 0.3Hz.