Influence of processing parameters on the growth characteristics and ferroelectric properties of sputtered PZT thin films on stainless steel substrates

Thin PZT films are synthesized on platinized stainless steel substrates by radio frequency magnetron sputtering. Based on the results of X-ray diffractometry, field-emission scanning electron microscopy and analytical scanning/transmission electron microscopy with semi-quantitative elemental mapping using energy dispersive X-ray spectrum imaging and line-scanning, the post-annealing growth of perovskite phase in sputtered PZT films has been scrutinized as a function of film processing conditions. It is observed that working pressure, sputtering gas composition and post-annealing heating rate directly affect the phase transformation trend, film morphology, crystallographic orientation and ferroelectric properties of the PZT films. Development of a thin secondary phase/layer enriched with Fe and lean in Pb and oxygen at the PZT/Pt interface has been confirmed. Processing of films at a working pressure of ∼0.7 Pa with an argon/oxygen gas composition of 90:10 followed by a fast and short duration air-annealing at a temperature of ∼650 °C is found to be the most suitable conditions for growing (1 1 1)-oriented perovskite PZT films on platinized stainless steel substrates for which about ∼35 μC cm−2 remanent polarization and ∼125 kV cm−1 coercive field have been realized under an applied field of ∼300 kV cm−1. Structural changes as a function of film processing conditions have been correlated with ferroelectric characteristics of the PZT films.