Ferroelectric Polymer Gate Transistor as a Model System for Exploring the Mechanisms of the Retention Loss

An attractive combination of properties of the ferroelectric copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)), including a relatively high spontaneous polarization and low dielectric constant as well as low processing temperature makes this material useful for studying the ferroelectric gate operation for 1T nonvolatile ferroelecetric memory applications. Here we explore a silicon-based ferroelectric field effect transistor with P(VDF-TrFE) gate showing a persistent switching of the drain current with the "on"/"off" current ratio of 10(3)-10(2) and retention exceeding 5 days. The physical mechanism of the retention loss has been addressed by monitoring the drain current relaxation in combination with the time-resolved piezo-force scanning probe microscopy. The results suggest that the retention loss is controlled by the polarization screening due to the charge injection into the interface-adjacent layer rather than the polarization loss due to the depolarization effect.