Pyroelectric Characteristics of Thin PbTiO_3 and La-Modified PbTiO_3 Films on Platinum Films for Infrared Sensors

摘要

In this work, we grew leadtitanate (PbTiO_3) and La-modified PbTiO_3 thin films on platinized silicon (Si(100? substrates under controlled substrate tempera- ture and ambient by a modifiedjet-vapor deposition (JVD) process described in this paper. The x-ray diffraction patterns obtained from these films showed a single-phase perovskite structure. We examined locally homogeneity and thick- ness of these films through the comparative use oflaser Raman spectroscopy. We also collected Raman and x-ray data on pure PbTiO_3, as well as prepared lead zirconate titanate (PZT) (54/46), and PZT (50/50) films using the JVD process. This paper discusses the temperature variations of the pyroelectric and dielec- tric properties of three compositions of La-modified PbTiO_3 films containing 5.2% to 15% of La, respectively, with a view toward studying the effect of La in place ofPb on these electrical properties. We detected significant pyroelectric currents on all three La-modified PbTiO_3 films before performing poling treat- ments, and observed pyroelectric coefficients as high as 84 nC/cm2.oC in the poled La-doped PbTiO_3 films containing 5.2% La. The pyroelectric coefficient and dielectric constant varied significantly with La content. We compared the calculated figures of merit, which were based on the measured physical proper- ties, with pure PbTiO_3 as well as PZT and lead lanthanide zirconate titanate (PLZT) films. These properties just described illustrate that these films would be suitable for IR detectors.