Thickness dependence of switching time and coercive field in ferroelectric thin films

The switching time and the coercive field in the polarization reversal of ferroelectric (FE) films have been investigated theoretically using the Landau Devonshire free energy expression and the Landau Khalatnikov dynamic equation in this work. Our numerical data show that the switching time is an exponential function of the applied field, and the function implies that there is a definite coercive field in the switching of a FE film. The effects of the thickness and the surface parameter delta on the switching time and the coercive field have been studied, and we found that the coercive field and the switching time could either decrease or increase with decreasing film thickness in film with surface conditions of positive delta or negative delta, respectively. These results are consistent with the switching phenomena reported in experiments regarding the film thickness dependence of the coercive field and the switching time. (C) 2011 American Institute of Physics. [doi:10.1063/1.3576110]