PbZr 0.53 Ti 0.47 O 3 (PZT) Thin Films on La 0.5 Sr 0.5 CoO 3 (LSCO) Bottom Electrodes Prepared by Chemical Solution Dep
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U12.17.1
PbZr0.53Ti0.47O3 (PZT) Thin Films on La0.5Sr0.5CoO3 (LSCO) Bottom Electrodes Prepared by Chemical Solution Deposition and Annealed at Different Temperatures Barbara Malic, Sasa Javoric, Marija Kosec, Ricardo Jiménez1 and Carlos Alemany1 Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia; 1 Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
ABSTRACT
PbZr0.53Ti0.47O3 (PZT) films on La0.5Sr0.5CoO3 (LSCO) /Pt electrodes crystallize in the perovskite phase at 550°C. Cross section SEM shows a columnar grain structure of PZT films on fine-grained LSCO. The ferroelectric response of the heterostructures depends on the annealing temperature of the LSCO layer. The remanent polarization and coercive field of the PZT annealed at 550 oC deposited on LSCO annealed at 800 oC are 25 µC/cm2 and 99 kV/cm respectively, comparable to the values obtained for PZT films on platinized silicon substrate.
INTRODUCTION
The functional response of ferroelectric thin films strongly depends on the electrode material. Lead zirconate titanate (PZT)-based thin films exhibit better fatigue characteristics when in contact with conducting oxide electrodes than with platinum. (La,Sr)CoO3 (LSCO) is an attractive material for oxide electrodes due to its pseudo - cubic perovskite structure with lattice parameters close to PZT and low electrical resistivity at room temperature1,2. While there are frequent reports on physical deposition methods to prepare LSCO bottom electrodes, only a few studies on Chemical Solution Deposition (CSD) of LSCO have been made 3,4. In our earlier research LSCO thin-film electrodes deposited on the platinized silicon substrates (so called hybrid LSCO/Pt electrodes) have been prepared by a water-based CSD method. The nitrate-based solution of the constituent metal ions was modified by the addition of polyvinylalcohol (PVA) thus resulting in the improved wetting of the platinized substrates in comparison to purely inorganic solution 5. Optimisation of both PVA average molecular weight and PVA content resulted in dense LSCO layers with the perovskite crystal structure after heat treatment at 650 oC. PZT 53/47 thin films prepared by CSD were deposited on the LSCO/Ptsubstrates and they crystallized in the perovskite phase at/above 500 oC 6. The aim of the present work was to prepare LSCO layers on platinized silicon substrates at different annealing temperatures, namely between 650 and 800 oC and further to deposit on these substrates PZT 53/47 thin films. We expected that with higher annealing temperature the crystallinity of the LSCO layers would be improved. The ferroelectric response of the PZT/LSCO/Pt heterostructures is studied with respect to the LSCO annealing temperature and compared with PZT films deposited on platinized substrate as a reference.
U12.17.2
EXPERIMENTAL
The La0.5Sr0.5CoO3 (LSCO) precursor-solution (0.5 M) was prepared by dissolving respective nitrates in deionized water and adding 9 weight % of polyvinyl alcohol (PVA, MW = 24 000). Further experimen
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