On the scaling behavior of organic ferroelectric copolymer PVDF-TrFE for memory application

We report an interesting scaling trend in the switching time and the switching voltage of the organic ferroelectric copolymer PVDF-TrFE as a function of the device area. We have found that shrinking the lateral dimensions of the ferroelectric film results in a dramatic decrease in the switching time and the switching voltage. The phenomenological theory, that explains this abnormal scaling trend, involves in-plane interaction of the polymeric chains of the two-dimensional Langmuir-Blodgett (LB) films of the copolymer PVDF-TrFE interchain and intrachain coupling results in a weak power-law dependence of the switching field on the device area (E^SWαA_CH ^0.1) which is ultimately responsible for the decrease in the switching time and switching voltage. For this scaling study we have used the organic ferroelectric copolymer as the top gate dielectric of a field-effect transistor structure with poly silicon nanowires as channel material. The gated channel area was varied by more than two orders of magnitude (0.04 -5 μm ²) while the thickness of the ferroelectric copolymer film was kept constant at 100 nm. Our findings are believed to be of importance to both, the fundamental understanding of non-equilibrium processes in correlated condensed matter systems and the technological use of ferroelectric copolymers for non volatile memory applications.