We investigated the thickness effect on ferroelectric properties of vinylidene fluoride (VDF)/trifluoroethylene (TrFE) copolymer films in the region of 9.7-230 nm. Film thickness was estimated from cross-sectional transmission electron microscope (TEM) images. Relative permittivity calculated using precise thickness measurements decreased from 10 to 5.3 with decreasing thickness. Remnant polarization gradually decreased from 80 to 34mC/m2 with decreasing thickness, whereas maximum polarization was almost constant. These results suggested the existence of a dead layer with a low permittivity at the interface between the VDF/TrFE copolymer films and electrodes. Finally, the thickness of the dead layer was estimated to be 4.1nm by assuming the existence of two layers with different permittivities.
ASJC Scopus subject areas