Polarization Switching Dynamics of Vinylidene Fluoride/Trifluoroethylene Copolymer Thin Films under High Electric Field at Various Temperatures

The polarization switching times of vinylidene fluoride (VDF)/trifluoroethylene (TrFE) copolymer thin films with a thickness of 40 nm were measured at temperatures ranging from $-50$ to 50 °C and applied fields ranging from 75 to 600 MV/m. The switching time was drastically reduced by increasing the applied field at all temperatures. The relationship between the switching time and the reciprocal applied field obeyed the exponential law in the low-field region and the power law in the high-field region. The threshold field between the exponential law and the power law became monotonically lower with decreasing temperature. Furthermore, the exponent value in the power law increased with decreasing temperature. This seems to be caused by a change in domain growth from two-dimensional-like to three-dimensional-like or in nucleation mechanism with decreasing temperature.