Role of Amorphous Pb(Zr,Ti)O_3 (PZT) in Determining the Ferroelectric Properties of PZT-Blended Poly(Vinylidene Fluoride-Trifluoroethylene) (P(VDF-TrFE) Thin Films

摘要

Precursor films based on poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and P(VDF-TrFE) blended with Pb(Zr,Ti)C>3 were deposited on Si (100) substrates by spin-coating, and subsequently annealed at 443 K for 0.5 h. These films were then characterized using X-ray diffraction, atomic force microscopy and capacitance-voltage curves. Blending the precursor films of Pb(Zr,Ti)C>3 with P(VDF-TrFE) led to the formation of an amorphous oxide whose concentration was proportional to the Pb(Zr,Ti)O3 content. This resulted in extension of the memory-window width with a large voltage difference ranging from 0.07 V to 4.5 V for metal-ferroelectric-silicon capacitors. Moreover, the formation of the amorphous oxide resulted in parallel shifts toward positive or negative voltages in the capacitance-voltage curves because of the fixed negative or positive charge of the oxide at the ferroelectric/Si-substrate interface. These tunable ferroelectric properties open up possibilities for diverse applications and are essential for functional devices, as well as for the commercialization of nonvolatile high-density FeRAM devices.