Ferroelectric properties of the organic films of poly(vinylidene fluoride-trifluoroethylene blended with inorganic Pb(Zr, Ti)O_3

摘要

Precursor films based on poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and P(VDF-TrFE) blended with Pb(Zr,Ti)O_3 were spin-coated on Si-substrates and subsequently annealed at 170 ℃. X-ray diffraction studies showed that the amorphous precursor films crystallize to the 7-phase P(VDF-TrFE) without involving the formation of other polymorphs when the P(VDF-TrFE) is blended with Pb(Zr,Ti)O_3, resulting in phase mixtures composed of a crystalline γ-phase P(VDF-TrFE) and an amorphous Pb(Zr,Ti)O_3. A larger memory window width and higher accumulation capacitance, as well as a lower leakage current density are induced by the blended Pb(Zr,Ti)O_3 within the low operating voltage ranges from -3.0 to 3.0 V and from -2.0 to 2.0 V for 20 wt% and 40 wt% Pb(Zr,Ti)O_3 blending, respectively. These improvements not only in the hyster-etic capacitance-voltage characteristics but also in the leakage current density-electric field are directly correlated with the phase mixtures, their volume fraction, dipole moments, and formation of interface layer between the blended film and Si substrate.