Sol-gel PZT and Mn-doped PZT thin films for pyroelectric applications

Abstract

Thin films of ferroelectric lead zirconate titanate (PbZr0.3Ti0.7O3 PZT30/70) and manganese-doped lead zirconate titanate ((Pb(Zr0.3Ti0.7)1-xMnx)O3, where x = 0.01, PM01ZT30/70; and x = 0.03, PM03ZT30/70) have been prepared using sol-gel processing techniques. These materials can be used as the pyroelectric thin films in uncooled infrared detectors. The thin films were prepared via a sol-gel route based on a hybrid solvent of methanol and ethanol with acetic acid, ethanolamine and ethylene glycol as additives. The final solution is non-moisture sensitive and stable. Films deposited on Pt/Ti/SiO2/Si substrates and annealed on a hot plate at 500-530 °C for a few minutes were seen to fully crystallize into the required perovskite phase and showed excellent ferroelectric behaviour, demonstrated by reproducible hysteresis loops (Pr = 33-37 µC cm-2, Ec( + ) = 70-100 kV cm-1, Ec(-) = -170 to -140 kV cm-1). The pyroelectric coefficient (p) was measured using the Byer-Roundy method. At 20 °C, p was 2.11×10-4 C m-2 K-1 for PZT30/70, 3.00×10-4 C m-2 K-1 for PM01ZT30/70 and 2.40×10-4 C m-2 K-1 for PM03ZT30/70 thin films. The detectivity figure-of-merit (FD) was 1.07×10-5 Pa-0.5 for PZT30/70, 3.07×10-5 Pa-0.5 for PM01ZT30/70 and 1.07×10-5 Pa-0.5 for PM03ZT30/70. These figures compare well with values reported previously.