Impacts Of Electrode Materials On Structural And Physical Properties Of P(VDF-TRFE) Organic Ferroelectric Thin Films

Poly vinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] copolymer organic films wereprepared by Sol-Gel method on different bottom electrode materialss which werehad beenpreviously fabricated by rf magnetron sputtering. Subsequently, Pt or Al films, used as topelectrode, wasere grown on the P(VDF-TrFE) film using a shadow mask by magnetronsputtering at room temperature so that various kinds of and the capacitors with differentheterostructure were constructed. Impacts of electrode materials on structural and physicalproperties of P(VDF-TrFE) organic ferroelectric thin films have been investigated using x-raydiffraction (XRD), atomic force microscope (AFM), a Keithley2601System Source Meter,and a Precision LC/100ferroelectric tester (Radiant Technologies).The thickness dependence of Al/P(VDF-TrFE)/Al heterojunction capacitor was studied. Itis found that the capacitor, annealed for4hours at135℃, possesses good ferroelectricproperty. The remanent polarization and coercive voltage are7.6μC/cm~2and45.7V,respectively. Moreover, the remanent polarization of the capacitor increases with the decreaseof the measured frequency. The leakage current density of the capacitor is5.73×106A/cm~2at40V and, it is attriubed to the ohmic conduction behavior for the leakage mechanism. Noobvious decrease in polarization was found up to109cycles, indicating that the capacitorpossesses very good fatigue-resistance.The P(VDF-TrFE) film with2%concentration was further preapred on the Pt, Ti-Al andZnO film, and Pt or Al was used as the top electrodes of the capacitors. It is found that thePt/P(VDF-TrFE)/Pt capacitor yielded the highest polarization among the capacitors withvarious bottom electrodes. Futhermore, the capacitors with ZnO or Ti-Al bottom electrodepossess ferroelectric properties, indicating that both materials may be used as the bottomelectrode for organic ferroelectric capacitors.