Influence of mobile charged defects on the dielectric non-linearity of thin ferroelectric PZT films

The capacity-voltage (C-V) characteristics of thin ferroelectric PZT films are investigated, varying the rate of change of the control voltage in a wide range. It is established that the distance between the maxima of the C-V characteristics decreases as the rate of the voltage change is decreased. This effect is caused by the decrease of the coercive field due to the spatial separation of mobile charge carriers under the action of the control field and the accumulation of charged defects in the near-electrode regions of the films. Parameters characterizing the formation of the bulk charge in the films (concentration and mobility of oxygen vacancies) are estimated. The estimations made are consistent with the literature data.