Mobile defect contribution to the dielectric non-linearity of PZT ferroelectric thin films

Effect of the speed of bias voltage variation nu on the dielectric non-line arity of metal-PZT-metal thin film capacitors has been studied. A distance DeltaV between two maxima of C-V dependence on the voltage scale, character istic for ferroelectric phase, as a function of the nu value was investigat ed. It was established that decreasing nu value led to DeltaV decrease: Del taV = 1.8-2.0 V when nu = 1.6x10(4) V/s, and DeltaV congruent to 1.0 V when nu = 6.5x10(-2) V/s. The DeltaV(nu) dependence can be explained by the dec reasing of the coercive field of the film due to the migration of charged m obile defects such as the doubly ionized oxygen vacancies, and the formatio n of space charge regions near the electrodes. Using the experimental data some parameters of the migration process were evaluated: the concentration of oxygen vacancies and their mobility were found to be about 10(24) m(-3) and 10(-11) m(2)/Vs, respectively. These values are close to the data publi shed in the literature obtained using the alternative methods of investigat ion.