The preparation and ferroelectric properties of defect-free ultrathin films of vinylidene fluoride oligomer

Abstract

Articles you may be interested inThe effect of electroactive interlayer on the ferroelectric properties in poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin filmsThe ultrathin, defect-free ferroelectric films of vinylidene fluoride oligomer were fabricated by vapor deposition. A narrow substrate temperature window was found to get high quality ferroelectric films. Ferroelectric phase was obtained when the substrate temperature was −90°C. The ferroelectric phase is stable at room temperature, even after annealing at 120°C for 30 min. A full memory stack based on the ferroelectric VDF oligomer may work as nonvolatile random access memory with superhigh density due to the smaller crystal grain comparing with that of poly͑vinylidene fluoride-trifluoethylene͒ ͓P͑VDF-TrFE͔͒ copolymers. The cell shows prominent ferroelectric properties even as the thickness of VDF oligomer film is down to 60 nm with a coercive field of 95 MV/m and a remnant polarization of 125 mC/ m 2 . After 1 ϫ 10 5 cycles of switching, no ferroelectric degradation was observed, the ratio of polarization before and after fatigue is close to 1, which is in contrast to P͑VDF-TrFE͒ thin film where the ferroelectric degradation starts after 1 ϫ 10 4 times of switching. The pulse polarization test shows that switching takes place as fast as a few microseconds to reach 90% of the saturated polarization. At 60°C and 8 V operating voltage, the cell still shows excellent fatigue property.

Molecule-displacive ferroelectricity in organic supramolecular solids

“…For nonvolatile RAM applications, ferroelectric polymers and oligomers [e.g. poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-trifluoethylene) (P(VDF-TrFE)), and so on], have been studied intensively due to their low cost, flexibility and the possible multilayer structure212526. Although their switching time is considerably short, being of 10 –6 –10 –8 second order at room temperature if the applied field is sufficiently high, their hysteresis measurements can be made practically at low frequencies (1–10 Hz) because of the critical heat generation associated with hysteresis loss21.…”

Thin reduced graphene oxide interlayer with a conjugated block copolymer for high performance non-volatile ferroelectric polymer memory

“…Additional benefits of polymeric interlayers such as cost effective fabrication based on solution processes and interfacial compatibility with ferroelectric polymer have made them very attractive for the purpose. Alternatively to overcome the issue of relatively low dielectric constants of majority of polymers which frequently resulted in very high device operation voltage, conducting polymer interlayers have been proposed in the architecture of metal/ferroelectric/metal (MFM) capacitors such as poly(3,4-ethylene dioxythiophene) (PEDOT) [26,30,36,37], polypyrrole [10,27] and polyaniline (PANI) [38]. For instance, the improved fatigue property of MFM capacitors was obtained with an ultra-thin (ca.…”

Solution‐derived ferroelectric vinylidene fluoride oligomer thin films with large polarization

“…Limited efforts are reported in the literature to investigate VDF oligomer films with relatively large polarization. However, these films are all prepared with evaporation techniques under very special and inconvenient conditions such as cooling to liquid nitrogen temperature8–10 or with specific substrates (e.g. KBr or KCl) 11.…”