Polarization screening in polymer ferroelectric films: Uncommon bulk mechanism

Charge compensation at the interface is a fundamental phenomenon determining the operation conditions of thin-film devices incorporating ferroelectrics. The underlying mechanisms have been thoroughly addressed in perovskite ferroelectrics where the charge compensation originates from injection through the interface-adjacent layer. Here, we demonstrate that polarization screening in the polymer ferroelectric polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) films can be dominated by charge injection through the bulk, unlike ferroelectric oxides. The experimental evidence relies on polarization imprint under applied field and time-dependence of the dielectric constant. A linearized electrostatic model correctly accounts for the observed trends and links their occurrence to the unique properties of P(VDF-TrFE). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754146]