Experimental observation of negative capacitance in organic/ferroelectric capacitor for steep switching MOSFET

Although negative capacitance field-effect transistor attracts a lot of attention as a promising steep switching device, negative capacitance had never been directly measured in capacitor network. In this work, an organic/ferroelectric capacitor is fabricated using poly(vinylidene fluoride-trifluoroethylene) with a molar ratio of 75/25 in order to experimentally verify the existence of negative capacitance and to demonstrate internal voltage amplification in capacitor network. The ferroelectric capacitor is connected to a dielectric capacitor in series to stabilize negative capacitance. By measuring the voltage characteristics of two capacitors connected in series, it is confirmed that negative capacitance in the ferroelectric capacitor originates from the polarization transition of ferroelectric material that occurs at a coercive voltage or higher. In addition, since the voltage difference in the ferroelectric capacitor is decreased by polarization trabsition in the negative capacitance region, the voltage across the dielectric capacitor is sharply increased. As a result, an internal voltage gain of ∼ 1.3 is experimentally observed.