Investigation Of Preparation And Physical Properties Of P(VDF-TrFE) And P(VDF-TrFE)/FePt Multiferroic Composite Films

P(VDF-TrFE) heterostructures are fabricated by magnetron sputtering and Sol-Gel method on different substrates.Influences of technological parameterson and different substrates on the microstructure and physical properties of P(VDF-TrFE) heterostructures are studied by x-ray diffraction (XRD), atomic force microscope (AFM), vibrating sample magnetometer (VSM) and ferroelectric tester (Precision LC unit).(1)Fabricate Al/P(VDF-TrFE)/Al/Si heterostructures, Impacts of technological parameterson on the structural and ferroelectric property of the heterostructures have been investigated systemically. It is found that the remanent polarization (Pr) of P(VDF-TrFE) capacitors is enhance with increases of the Albottom electrode.When the thickness of Al bottom electrode is 200 nm, the remanent polarization is 28 mC/m2; Ferroelectricity appears a trend that increased firstly and then decreased with increases of annealing temperature(125℃,130℃,135℃,140℃), when zhe annealing temperature is 135℃, the remanent polarization turn maximum is 37.1 mC/m2; In the condision of the thickness(200 nm) and annealing temperature(135℃) being determined, It is found that when the consistence is 5%, whether applied voltage or polarization is a better choice, the remanent polarization is 30.5 mC/m2. Leakage current mechanism of the Al/P(VDF-TrFE)/Al/Si ferroelectric capacitor is further investigated, it is found that Al/P(VDF-TrFE)/Al/Si corresponds to Poole-Frenkel emission behavior at low electric field and Schottky emission at higher electric field.(2)Ni Al films used as the bottom electrode layers are prepared on Si(100) at room temperature by magnetron sputtering method, and P(VDF-TrFE) copolymer film is prepared by following optimum annealing temperature.It is found that it is possible to prepare P(VDF-TrFE)copolymer film which have ferroelectric in the Ni Al bottom electeodes.In addition, we found that the remanent polarization (Pr) of P(VDF-TrFE) capacitors is enhance with increases of the Ni-Albottom electrode.When the thickness of Ni Al film is 36 nm, leakage current density of P(VDF-TrFE) copolymer film is 2.09×10-5 A/cm2.Leakage current mechanism of the Al/P(VDF-TrFE)/Ni-Al/Si ferroelectric capacitor is further investigated, it is found that Al/P(VDF-TrFE)/Ni-Al/Si corresponds to Ohmic conduction behavior at low electric field and Schottky emission at higher electric field.(3)FePt films which have magnetism used as the bottom electrode layers are prepared on Si(100) at room temperature by DC magnetron sputtering, and P(VDF-TrFE) copolymer film is prepared in this bottom electrode, further obtain multiferroic composite films.It is found that P(VDF-TrFE) films can be grown in the FePt film and the remanent polarization achieved 16.8mC/m2, leakage current density of P(VDF-TrFE) copolymer film is 1.98×10-3A/cm2. Ferroelectricity appears a trend that increased firstly and then decreased with increases of annealing temperature,when zhe annealing temperature is 135℃,properties are best, such as the remanent polarization turn maximum is 14.2 mC/m2, leakage current density achieved 10-4.