The role of the O vacancy in ferroelectric thin films was numerically simulated by using the 2-dimensional 4-state Potts model. The presence of an O vacancy in a perovskite cell strongly influenced the displacement of the Ti4+ ion. Hence, vacancy–dipole coupling had to be considered in the switching mechanism. On the other hand, a space charge layer was established by the inhomogeneous distribution of O vacancies through trapping charge carriers. As a result, the thickness dependence of the coercive field and remanent polarization were reproduced in the presence of this O vacancy distribution. Frequency, temperature and driving voltage-dependent polarization fatigue behaviors were also simulated.

Simulation of Oxygen Vacancy Induced Phenomena in Ferroelectric Thin Films. K.T.Li, V.C.Lo: Journal of Applied Physics, 2005, 97[3], 034107 (8pp)