Influences of thin Ni layer on the electrical and absorption properties of PZT thin film pyroelectric IR sensors

A solid precursor was used to prepare ferroelectric lead zirconate titanate (PZT) 30/70 thin films using the sol–gel deposition method. To apply PZT thin films for uncooled pyroelectric IR sensors, a Ni layer was deposited onto the PZT thin films, serving both as a selective absorption layer and as the top electrode. The absorption properties of such Ni coated multi-layered pyroelectric sensors were studied in the visible and infrared wavelength ranges. The maximum absorption coecient of this type of IR sensor was measured to be 0.8 at 0.633 lm and 0.7 at 4 lm wavelength, re-spectively. A striking asymmetric polarization hysteresis loop in these PZT thin films with Ni as the top electrode was observed as a direct consequence. This asymmetric polarization was attributed to cause the dierence in the dynamic pyroelectric responses in these Ni/PZT/Pt films, poled either positively or negatively before the measurement. Ó 2000 Published by Elsevier Science B.V. All rights reserved. 1