Growth and characterization of lead-free piezoelectric BaZr0.2Ti0.8O3–Ba0.7Ca0.3TiO3 thin films on Si substrates

Lead-free piezoelectric BaZr0.2Ti0.8O3–Ba0.7Ca0.3TiO3 (BCZT) thin films were grown on La0.7Sr0.3MnO3-buffered Si (0 0 1) by off-axis RF magnetron sputtering at temperatures ranging from 550 to 810 °C. In this article, we present the detailed investigation on structure, leakage current behaviors and electromechanical properties of BCZT thin films. The crystallographic texture and grain size of the as-grown thin films are strongly dependent on the growth temperature, which consequently affects the leakage behaviors and local electromechanical properties. The crystallographic orientation becomes better and the grain size increases when increased the substrate temperature. The dominant leakage mechanism is found to be space-charge-limited conduction at low electric field, while a Fowler-Nordheim tunneling is confirmed in high electric field region for the films deposited at 710 °C and 810 °C. The increasing growth temperature also leads to remarkable improvement in the local electromechanical properties of the films. The BCZT film deposited at an optimal temperature of 810 °C exhibits a considerably high effective piezoelectric coefficient d33,f of 94 ± 4 pm/V, which is comparable to that of a typical lead zirconate titanate thin film.