Observation of charge compensated polarization zones in polyvinylindenfluoride (PVDF) films by piezoelectric acoustic step wave response

A high resolution (2 μm) acoustic step-wave probing techniques has been developed to investigate the inhomogeneous distribution of the piezoelectric response of incompletely corona poled 85 μm thick PVDF films. We observe persistent polarization zones or layers of 20–40 μm width within the films which are electrostatically compensated by charge accumulation at the polarization zone boundaries. The zone development is explained by charge-trapping in proportion to polarization