Solution chemistry effects in Pb(Zr, Ti)O3 thin film processing

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Abstract
Ferroelectric thin films in the PZT compositional family were prepared by two different solution deposition methodologies. The approaches were based on the use of carboxylate and alkoxide precursors, and acetic acid. Solution aging and mixing order effects on thin film microstructure and ferroelectric properties were studied. Films prepared from 15 day old solutions had a lower remanent polarization (1.4 μC/cm2) and higher coercive field (256 kV/cm) than films prepared from 1 day old solutions (Pr = 18.7 μC/cm2; Ec = 55.2 kV/cm). Raman, FTIR, and NMR spectroscopies were employed to confirm the role of acetic acid in the process, and to begin to understand why changes in solution chemistry can so dramatically affect the resulting film microstructure and properties. FTIR spectroscopy indicated that in addition to acting as a solvent, acetic acid also serves as a chemical modifier in the two processes. That is, it reacts with the alkoxide precursors on a molecular level, replacing the alkoxy ligands. Ester formation was also observed by both FTIR and NMR spectroscopy. The formation of this by-product implies the simultaneous formation of water, and therefore, in-situ hydrolysis and condensation of the precursors.