Influence of processing conditions on the structure, composition and ferroelectric properties of sputtered PZT thin films on Ti-substrates

PZT thin (similar to 500nm) films are synthesized on titanium (Ti) substrates by r.f. magnetron sputtering under various processing conditions. Present work aims to investigate the influence of working pressure and post-annealing temperature on the quality of the films. Phase evolution, surface morphology with local chemical composition and dielectric/ferroelectric properties of PZT films have been studied as the functions of working pressure and post-annealing temperature. A working pressure of similar to 0.7 Pa and a post-crystallization temperature of similar to 650 degrees C are found to be the optimum processing conditions for growing perovskite PZT films on Ti-substrates. Irrespective of processing conditions, however, all PZT films on Ti-substrates show poor electrical response. Depth dependent change in the chemical states of Pb, Zr, Ti and oxygen within the PZT films and across the PZT/Ti interfaces has also been scrutinized by XPS depth profiling. It is observed that within PZT films, Pb exists both in Pb2+ and Pb-0 (metallic-Pb) states. Surfaces of the PZT films are found to be enriched with a thin (similar to 60 nm) Pb-deficient and Zr-rich pyrochlore/fluorite (Py/Fl) phase. Existence of a thin titanium oxide layer in the form of a TiO2/TiO stack has also been confirmed at the PZT/Ti interface. Processing conditions dependant structural modifications have been correlated with the dielectric and ferroelectric properties of the films. (C) 2013 Elsevier B.V. All rights reserved.