The Processing and Polarization Reversal Dynamics of Thin Film Poly(vinylidene) Fluoride

摘要

Many ferroelectric devices benefit from the ability to deposit thin ferroelectric layers. Poly(vinylidene) fluoride (PVDF) is the prototypical ferroelectric polymer, but processing of thin film ferroelectric PVDF remains a challenge due to the formation of large voids in the film during traditional thin film processing. The research described in this dissertation starts by investigating the origin of these voids. The cause of these voids is found to be caused by vapor induced phase separation (VIPS). Guided by the thermodynamics of VIPS, a process is then designed to produce void-free ferroelectric PVDF thin films on polar and non-polar substrates. The films are shown to have a high remnant polarization (~6.5 C m--2). The later part of this dissertation is focused on understanding the temperature and structural phase dependent kinetics of polarization switching in PVDF films. A polarization switching model is developed with considerations of Avrami nucleation and growth, local electric fields, temperature and structural phase. The kinetics of polarization switching are shown to follow a universal behavior when correctly accounting for temperature and structural phase.