Gate-Induced Thermally Stimulated Current on the Ferroelectric-like Dielectric Properties of (BEDT-TTF)(TCNQ) Crystalline Field Effect Transistor

A gate-induced thermally stimulated current (TSC) on β′-(BEDT-TTF)(TCNQ) crystalline FET were conducted to elucidate the previously observed ferroelectric-like behaviors. TSC which is symmetric for the polarization of an applied VPG and has a peak at around 285 K was assigned as a pyroelectric current. By integrating the pyroelectric current, temperature dependence of the remnant polarization charge was obtained and the existence of the ferroelectric phase transition at 285 K was clearly demonstrated. We have tentatively concluded that the phase transition between dimer Mott insulator and charge ordered phase occurred at around the interface of organic crystal and substrate.