Apparent thickness effect on properties of ferroelectric PZT thin layers

The properties of thin layer ferroelectric appear to differ, sometimes considerably, from those of bulk ceramics of the same composition. Most notably, a broadening of the temperature dependent dielectric anomaly, an increase in the coercive field and a decrease in the remnant polarization are frequently reported. Recent advances in processing thin layers by chemical methods, and in sol-gel processing in particular, have resulted in the capability of fabricating thin layer ferroelectrics in which variations in phase composition and microstructure can be controlled and minimized. In this work, single phase perovskite thin layers of lead zirconate titanate (PZT) with a composition near the morphotropic phase boundary (Zr/Ti = 53/47) were deposited onto platinized silicon substrates by spin-casting pre-hydrolyzed alkoxide solutions. Ferroelectric and dielectric properties are reported as a function of layer thickness and discussed in terms of an interface effect, series impedance model, and the accompanying development of microstructure.