Effects of lanthanum doping on the microstructure and electrical properties of sol-gel derived Pb1-3x/2Lax(Zr0.5Ti0.5)O3 thin films

Effects of lanthanum doping on the microstructure and electric properties of Pb(Zr0.5Ti0.5)O3 films have been investigated. The films with x=0, 0.01, 0.02, and 0.03 were prepared by a 2-methoxyethanol-based sol-gel method on Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrate. X-ray diffraction (XRD) patterns show that the all the films crystallize in perovskite phase and are (1 0 0)-oriented. Results of fine (2 0 0) scan XRD suggest that lanthanum doping plays a role in stabilizing film tetragonal phase, which is in agreement with the results observed in bulk materials. The ferroelectric and dielectric properties indicate that dielectric loss and remnant polarization (Pr) of the films are improved by the addition of lanthanum doping. Loss tangents of the film undoped and the film with x=0.03 at 10 kHz are 0.025 and 0.015, respectively. The corresponding Pr values at 380 kV/cm are 14 and 18 μC/cm2, respectively. Possible explanations for the variations of electric properties have also been discussed.