Structural and pyroelectric properties of sol-gel derived multiferroic BFO thin films

Multiferroic BFO/PZT multilayer films were fabricated by spin-coating method on the (1 1 1)Pt/Ti/SiO2/Si substrate alternately using PZT(30/70), PZT(70/30) and BFO alkoxide solutions. The structural and ferroelectric properties were investigated for uncooled infrared detector applications. The coating and heating procedure was repeated six times to form BFO/PZT multilayer films. All films showed the typical XRD patterns of the perovskite polycrystalline structure without presence of the second phase such as Bi2Fe4O3. The thickness of BFO/PZT multilayer film was about 200-220 nm. The ferroelectric properties such as dielectric constant, remnant polarization and pyroelectric coefficient were superior to those of single composition BFO film, and those values for BFO/PZT(70/30) multilayer film were 288, 15.7 mu C/cm(2) and 9.1 x 10(-9) C/cm(2) K at room temperature, respectively. Leakage current density of the BFO/PZT(30/70) multilayer film was 3.3 x 10(-9) A/cm(2) at 150 kV/cm. The figures of merit, F-v for the voltage responsivity and F-D for the specific detectivity, of the BFO/PZT(70/30) multilayer film were 6.17 x 10(-11) Ccm/J and 6.45 x 10(-9) Ccm/J, respectively. (C) 2011 Elsevier Ltd. All rights reserved.