Fatigue and dielectric properties of undoped and Ce doped PZT thin films

Ce doping improves the ferroelectric properties of sol-gel derived PZT thin films by facilitating easier domain wall movement. It also decreases the l eakage current densities by reducing the concentration of free carriers thr ough a decrease in concentration of Pb and O vacancies. Ce-PZT films retain good dielectric dispersion characteristics since the concentration of defe cts and defect dipoles are reduced. Ce doping dramatically improves the fat igue resistance of PZT thin films. We have studied the frequency dependence of fatigue behavior and shown that the loss of polarization due to fatigue follows a universal scaling behavior with N/f(2), where N is the number of the switching cycles and f is the frequency. The origin of the scaling is attributed to the drift of oxygen vacancies, which is the rate limiting pro cess in the growth of the interface layer responsible for fatigue. Empirica l fits for both undoped and cerium doped samples show that switchable polar ization follows a stretched exponential decay with time or N/f. Cerium dopi ng is believed to improve fatigue resistance by impeding the motion of oxyg en vacancies.