Characterization of highly preferred Pb(Zr,Ti)O3 thin films on La0.5Sr0.5CoO3 and LaNi0.6Co0.4O3 electrodes prepared at low temperature

Abstract

La0.5Sr0.5CoO3 (LSCO) and LaNi0.6Co0.4O3 (LNCO) thin films were deposited on Pt/Ti/SiO2/Si substrates by DC reactive sputtering at 450 degreesC and were annealed at temperatures ranging from 550 degreesC to 750 degreesC for 30 min in an O-2 ambient to improve the crystallinity of the films and to reduce their resistivity. LSCO and LNCO thin films were successfully prepared at temperatures as low as 450 degreesC. Pb(Zr0.48Ti0.52)O-3 (PZT) thin films of 150 nm thickness were deposited on the LSCO and LNCO electrodes by DC reactive sputtering at a substrate temperature of 550 degreesC. PZT films grown on LSCO and LNCO electrodes showed a (001) preferred orientation and had a uniform matrix of densely packed round grains. The leakage current density remained on the order of 10(-7)-10(-9) A/cm(2) at an applied voltage below 5 V. PZT thin films grown on LSCO/Pt showed a remanent polarization (2P(r)) of about 46-52 muC/cm(2), and a coercive voltage of about 1 V. PZT thin films grown on LNCO/Pt electrodes showed a lower coercive voltage (<0.6 V) and a smaller remanent polarization (2P(r)) of about 28.8 muC/cm(2) than those of PZT films grown on LSCO/Pt. LSCO/Pt and LNCO/Pt electrodes were essential for lowering the crystallization temperature as well as for obtaining good electrical properties of PZT capacitors.