Ordered Ferroelectric PVDF-TrFE Thin Films by High Throughput Epitaxy for Nonvolatile Polymer Memory

摘要

High throughput epitaxy of a thin ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) film is demonstrated on a molecularly ordered poly(tetrafluoroethylene) (PTFE) substrate based on spin coating method over the area of a few centimeter square. The lattice match between (010)(PVDF-TrFE) and (100)(PTFE) results in b and c axes of PVDF-TrFE crystals preferentially parallel to a and c of PTFE, respectively and consequently produces global ordering of the edge-on PVDF-TrFE crystalline lamellae aligned perpendicular to the rubbing direction of PTFE, its c-axis. The epitaxially grown PVDF-TrFE film is successfully incorporated for arrays of ferroelectric capacitors that exhibit not only the significant reduction of ferroelectric thermal hysteresis but also the descent remanent polarization at very low effective operating voltage of +/- 5 V maintained to 88% of its initial value after number of fatigue cycles of 5 x 10(8) in the mode of bipolar pulse switching. A ferroelectric field effect transistor memory with epitaxially grown PVDF-TrFE layer as gate dielectric shows the saturated I-V hysteresis with bistable on/off ratio of approximately 10(2).