Polarization fatigue characteristics in VDF/TrFE copolymer thin films with Au electrodes

The copolymer of vinylidene fluoride (VDF) with trifluoroethylene (TrFE) has attracted much interest due to the potential use in nonvolatile memory devices with easy formability. A repetitive application of electric stress causes a decrease of switchable polarization. This phenomenon, referred to as fatigue, is one of the primary sources of concern in the ferroelectric memory devices. Having realized that a conventional Al electrode suppresses the leakage current for the existence of the oxidation layer but induces severe thickness effect, we investigated the fatigue characteristics in VDF/TrFE copolymer thin films with Au electrodes. In this work, we report on the finding of three fatigue stages and discuss the fatigue mechanisms in relation to the structural changes.