Pyroelectric Properties of La-modified Lead Titanate Thin Film Detectors

Abstract

High-performance pyroelectric infrared (IR) detectors have been fabricated without the back side etching process using La-modified lead titanate (PLT) thin films. PLT thin films were deposited on (111)-oriented Pt thin film on SiO 2 /Si(100) substrates by a diol-based sol-gel process. The randomly oriented PLT thin film exhibits a relatively small dielectric constant and a large pyroelectric coefficient without poling treatment. The pyroelectric characteristics of point detectors with various La contents as a function of modulation frequency are compared. It was found that the PLT(10) detector has a large voltage responsivity of 3330 (V/W) at 20 Hz. The specific detectivity ( D * ) at 100 Hz is 6.2×10 7 cmHz 1/2 /W. The results showed that Pb 1- x La x Ti 1- x /4 O 3 thin film with x =0.10 [PLT(10)] was most suitable for use as a pyroelectric IR detector.