Switching dynamics in ferroelectric vinylidene fluoride-trifluoroethylene copolymer thin film with α,ω-dihexylsexithiophene semiconductor layer

Ferroelectric switching dynamics in thin vinylidene fluoride- trifluoroethylene copolymer films with an organic semiconductor α,ω-dihexylsexithiophene layer have been investigated on the basis of the measurements of the electrical properties including D-E hysteresis loop, switching characteristics, and capacitance changes. The authors elucidate that the full polarization reversal can be accomplished and the depletion is maintained at zero bias field. The time domain measurement together with capacitance measurements enables the evaluation of the close relationship between polarization reversal and carrier behavior in semiconductor layer. Polarization reversal toward the negative side under negative voltage progresses rapidly owing to the accumulation of majority carriers. Polarization reversal toward the positive side proceeds through two-step reversals. The mechanism of the two-step switching is explained by the depolarization field induced by the uncompensated polarization charge due to the formation of the depletion layer.