Characterization of sol-gel Pb(Zr_0.53Ti_0.47)O₃films in the thickness range 0.25–10 μm

Films of nominal composition Pb(Zr_0.53Ti_0.47)O₃(PZT) in the thickness range 0.25−10 μm have been fabricated on Pt/Ti/SiO₂/Si substrates using a propanediol-based sol-gel route. The spun-on coatings were prefired at 350 and 600 °C between successive depositions before firing the multilayer stack at 700 °C for 15 min. The variations in crystallite orientation, microstructure, and dielectric and ferroelectric properties were determined as a function of film thickness. For a constant applied field of 150 kV cm⁻¹, remanent polarization decreased progressively from 35 to 17 μC cm⁻²as film thickness decreased in the range 10–0.25 μm; values of coercive field were reasonably constant, 18–19 kV cm⁻¹, for films between 2 and 10 μm, but increased sharply below 2 μm, reaching 46 kV cm⁻¹for a 0.25 μm film. Relative permittivity (ε_r) decreased from approximately 1400 to approximately 940 with most of the reduction occurring in films less than 2 μm in thickness. These trends are discussed in terms of the presumed influence of interfacial phenomena on the measured electrical response.