Effects of WO_3 dopant on the structure and electrical properties of Pb_(0.97)La_(0.03)(Zr_(0.52)Ti_(0.48))O_3 thin films

摘要

Pb_(0.97)La_(0.03)(Zr_(0.52)Ti_(0.48))O_3+xWO_3 at % (x=0, 0:2, 0.5, 1, and 2) (PLWZT) thin films are deposited on Pt-Ti-SiO_2-Si substrates using a sol-gel process. We demonstrate that WO_3 dopant plays a significant role on the structure and electrical properties of the PLWZT films. X-ray diffraction (XRD) analyses show that the PLWZT films undergo a dramatic tetragonal-to-cubic crystalline phase transformation with a small amount of WO_3 additives. X-ray photoelectron spectroscopy (XPS) study shows that the chemical state of W changes with varying concentration of WO_3 in the films. Moreover, PLWZT films with a small amount of WO_3 doping (0.2 at %) show a decreased conductivity with an improved remnant polarization value of 30 μC/cm~2. In addition, compared to the base (PLZT) film, such doping concentration also leads to significantly improved fatigue characteristics. A defect chemistry mechanism indicating the reduction of oxygen vacancies by the substitution of W for Ti at different doping concentrations has been proposed to explain the observed experimental results.