Simulation of oxygen vacancy induced phenomena in ferroelectric thin films

The role of oxygen vacancy in lead–titanate–zirconate ferroelectric thin film has been numerically simulated using the two-dimensional four-state Potts model. On one hand, the presence of an oxygen vacancy in a perovskite cell strongly influences the displacement of the Ti4+ ion. Hence the vacancy–dipole coupling must be considered in the switching mechanism. On the other hand, a space charge layer is established by the inhomogeneous distribution of oxygen vacancies through trapping charge carriers. Consequently, the thickness dependence of the coercive field and remanent polarization are reproduced in the presence of this oxygen vacancy distribution. Frequency, temperature, and driving voltage-dependent polarization fatigue behaviors are also simulated.