Pentacene Field-Effect Transistor with Ferroelectric Gate Insulator as Maxwell–Wagner Effect Element

Abstract

The behavior of charges in pentacene field-effect transistors (FETs) with a ferroelectric gate insulator [copolymer of vinylidene fluoride and tetrafluoroethylene, i.e., P(VDF-TeFE)] was investigated. Two peaks appeared in the Igs–Vgs characteristics at Vds = 0 V. Analyzing the behavior of the charges in the pentacene FETs revealed that the first peak appearing at the lower Vgs is ascribed to the exhaustion of accumulated holes at the pentacene/P(VDF-TeFE) interface in the direction from the interface to the source and drain electrodes in response to the electric field formed in pentacene. On the other hand, the second peak appearing at the higher Vgs is ascribed to the turn-over of the spontaneous polarization of the P(VDF-TeFE). However, a threshold voltage shift due to the spontaneous polarization that was small compared with the expected shift suggests that the turn-over of the spontaneous polarization is partial. A mechanism of the turn-over of spontaneous polarization is analyzed in terms of the Maxwell–Wagner effect.