Electrical Properties of Double Organic Films for FRAM

Organic thin-film transistors were fabricated with poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer and cyanoethylpullulan (CyEPL) for the dielectrics. The influence of the double-organic-ferroelectric-layer structure composed of all ferroelectric dielectrics below regioregular poly(3-hexylthiophene) was investigated. The capacitance-voltage (C-V) hysteresis and flatband-voltage shift were found at −5 to +5 V, depending on the field direction. A difference in the transfer characteristic was observed as the effect of the P(VDF-TrFE))/(CyEPL) sandwich structure on the channel layer. Both the space charge at p-Si and the polarization due to the trapped charges affected the field across the ferroelectric dielectrics.