Displacement current analysis of carrier behavior in pentacene field effect transistor with poly(vinylidene fluoride and tetrafluoroethylene) gate insulator

The carrier injection mechanism was investigated using a field effect transistor (FET) system with a ferroelectric gate insulator: poly(vinylidene fluoride and tetrafluoroethylene). The carrier injection and the turnover voltage of the spontaneous polarization were measured by application of ramp gate voltage with various sweep rates. Three peaks appeared in the gate current-gate voltage characteristics (I_g-V_g) because of the turnover of the spontaneous polarization and the long-range carrier motion of injected carriers. We accounted for the peaks generated and analyzed the I_g-V_g characteristics. For FETs with Al electrodes, the increase in the sweep rate caused a larger turnover voltage. For FETs with Au electrodes, the turnover voltage was constant. Results show that the difference of the injection property well accounted for these results.