Ferroelectric properties of PZT films on LaNiO3 bottom electrode deposited under different oxygen partial pressure

LaNiO3 (LNO) films were deposited on by RF magnetron sputtering of Ni metal target and La metal chips on top of it under Ar and O-2 atmosphere at different oxygen partial pressures (20, 25, 30, 35, and 40% oxygen). The resistivity of the LNO films increased with the increasing oxygen partial pressure. This is attributed to the reduction of oxygen vacancy concentration. About 150 nm thick Pb(Zr0.35Ti0.65)O-3 (PZT) ferroelectric thin films were spin coated on the LNO films with subsequent post annealing. To find out the relationship, the electrical properties of the PZT/LNO thin film capacitors and the oxygen partial pressure, the P-E curve, X-ray diffraction, microstructure, leakage current density, and fatigue property were investigated as a function of oxygen partial pressure. An optimal remanent polarization and lowest leakage current density of the PZT capacitor has been obtained when its LNO thin film bottom electrode was deposited at 30% oxygen partial pressure. The microstructure of the LNO film deposited at 30% oxygen partial pressure had columnar structure, while the ones deposited under other conditions had granular structure. The ferroelectric properties of the PZT/LNO capacitor are critically affected by the structure of LNO bottom electrode, and they are excellent when optimally processed as discussed above. (c) 2005 Elsevier Ltd. All rights reserved.