Polarization Reversal Characteristics in Capacitors with a Metal/Insulator/Ferroelectric/Metal Structure

A metal/insulator/ferroelectric/metal structure was fabricated using a covering of approximately 10 nm thick of an insulating polystyrene film on a ferroelectric poly(vinylidene fluoride-trifluoroethylene) film. To fabricate several samples, the thickness of the ferroelectric film was held constant while the thickness of the insulating film was varied from 8 to 24 nm. The polarization– voltage relationships were measured to extract the main parameters, in this case the remanent polarization, depolarization, coercive voltage and biased voltage values. As the insulating film becomes thicker, the remanent polarization and coercive voltage values tended to increase. On the other hand, depolarization and biased voltage values decreased. By analyzing the above mentioned parameters, a certain optimum insulator thickness could be predicted. This work shows that metal/insulator/ferroelectric/metal devices are more useful than metal/ferroelectric/metal capacitors.