Enhanced electrical and fatigue properties of La-modified (100)-oriented PZT thin films with various Zr/Ti ratio

Pb1−x(LaxZryTi1−y)O3 (PLZT) (x = 0%, 2%, 4%; y = 0.45, 0.52, 0.60) thin films were fabricated by sol–gel process to investigate the effects of La-doped and Zr/Ti ratio on crystalline orientation, microstructure, and electrical properties of lead zirconate titanate films. The results of X-ray diffraction analysis showed that the orientation of the films with various La concentration change with the Zr/Ti ratio. The Zr-rich composition (y = 0.60) with the fixed 2% La doping concentration has the most (100) preferential orientation. Scanning electron microscope analysis showed that the films exhibit dense perovskite structure when the doping concentration was less than 4%. The maximum dielectric constant (1364.65 at 100 Hz), optimized ferroelectric properties, and a low leakage current density of 8.63 × 10−8 A cm−2 were obtained for 2% La-doped film with a Zr/Ti ratio of 60/40. The lowest value of coercive field (Ec) was generated in the film fabricated with a Zr/Ti ratio of 52/48 when the La doping concentration was 2%. Fatigue resistance was also improved with 2% La dopant for the films processed by a Zr/Ti ratio of 52/48 and 60/40.