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1071-F03-05

Fabrication and Characterization of Ferroelectric Polymer/TiO2/Al-doped ZnO Structures Koji Aizawa OEDS R&D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa, 921-8501, Japan ABSTRACT Fabrication and characterization of 700-nm-thick poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)]/TiO2/Al-doped ZnO (AZO) structures on a glass substrate were introduced. In this study, the sputtered TiO2 films as insulator were used for the reduction of leakage current. The leakage current density of the fabricated Pt/P(VDF/TrFE)/170nm-thick TiO2/AZO and Pt/P(VDF/TrFE)/AZO structures were approximately 3.9 and 8.7 nA/cm2 at the applied voltage of 10 V, respectively. In the polarization vs. voltage characteristics, the fabricated Pt/P(VDF/TrFE)/TiO2/AZO structures showed hysteresis loops caused by ferroelectric polarization. The remnant polarization 2Pr and coercive voltage 2VC measured from a saturated hysteresis loop at the frequency of 50 Hz were approximately 12 µC/cm2 and 105 V, respectively. These results suggest that the insertion of TiO2 film is available for reducing the leakage current without changing the ferroelectric properties of the P(VDF/TrFE) film. INTRODUCTION Ferroelectric-gate field effect transistors (FeFETs) have attracted much attention for memory applications because of nonvolatile data retention and nondestructive data readout [1]. Up to now, ferroelectric oxides such as Pb(Zr, Ti)O3 and SrBi2Ta2O9 were used as an insulator of FeFET [2,3]. However, these films were deposited at the temperature above 500 oC in order to grow the ferroelectric phase and realize the good ferroelectric properties. On the other hand, the ferroelectric polymer as a gate insulator of the FeFET was one of the promising candidates for nonvolatile memory applications [4]. It is expected that the ferroelectric polymer-gate FETs are widely used in the applications such as flat panel displays and flexible integrated circuits because the polymer films are deposited at low temperature on the plastic or glass substrates. Poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] copolymer is promising as ferroelectric polymer of the FeFETs due to large remnant polarization of 10 µC/cm2 and low temperature growth under 140 oC [5,6]. In P(VDF/TrFE), TrFE is introduced in order to enhance the growth of the ferroelectric phase (β phase), while the leakage current of this polymer is increased by the leakage path formed in a TrFE molecule [6]. It is known that the gate leakage current deteriorates the device performance of the FeFETs. Recently, polymer dielectric/ferroelectric double-layer gate insulator was used for reducing the gate leakage in the FeFETs with ZnO film as a semiconductor [7]. In this study, characterization of the P(VDF/TrFE) films deposited on the TiO2/Al-doped ZnO (AZO) structures was investigated. In these structures, the TiO2 film is used as an insulator for reducing the leakage current. EXPERIMENT 270-nm-thick AZO films were prepared on the glass substrates at the temperature of 20