Fabrication and Characterization of Ferroelectric Polymer/TiO2/Al-doped ZnO Structures

Characterization of 700-nm-thick poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)]/TiO2/Al-doped ZnO (AZO) structures on a glass substrate were investigated. 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)/AZO and Pt/P(VDF/TrFE)/170-nm-thick TiO2/AZO structures were approximately 8.7 and 3.9 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 gate leakage current without changing the ferroelectric properties.