Preisach model for the simulation of ferroelectric capacitors

The emerging ferroelectric technology needs a reliable model for the simula tion of the ferroelectric capacitors. This model would play a crucial role in designing new ferroelectric nonvolatile memories. As a main requirement, such a model must allow the calculation of the polarization variations for an arbitrary voltage applied to the ferroelectric. However, in spite of th e large efforts made in modeling, most of the existing solutions fail to sa tisfy the above requirement or lack a minimal physical background. To addre ss these problems, we developed a model based on a ferroelectric interpreta tion of the Preisach theory of hysteresis. In this articles, we try to eluc idate how this theory, initially developed for ferromagnetic particles, can be adapted to the ferroelectric materials, despite the many differences be tween the two. Because the Preisach theory assumes a distribution of the co ercitive voltages, we try to clarify its physical meaning in the case of th e ferroelectric materials and propose a methodology to determine this distr ibution experimentally. To facilitate the implementation of the model, the experimental results are then fitted by an analytic function and the whole bidimensional distribution is calculated using a linear approximation. To e valuate the validity of the model, we performed simulations using the Spect re (R) circuit simulator and the results are in very good agreement with th e measurements for the saturated hysteresis loops. The differences existing for the partial loops are mainly due to the linear approximation used for the Preisach distribution. This model can be successfully used for the desi gn of the real memories. (C) 2001 American Institute of Physics.