Chemical bonding states at the polymer/metal interface and their effects on the capacitance-voltage characteristics of the ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer thin films

The electrical and ferroelectric properties with different amounts of chemical bonding states at the polymer/metal interface were examined quantitatively in a ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) film sandwiched between the top and bottom electrodes on which the surface had been modified by rapid thermal processing in a N2 atmosphere. The capacitors with the heat-treated bottom electrodes at different temperatures showed a lower charge storing capacitance. Ultraviolet photoelectron spectroscopy showed that the capacitance enhancement and field shift to lower coercive value resulted from the relatively larger increase in anions (N,O) than cations (Ti) and the reduction of NC bonding in the reaction product (TiNxOy) on the surface of the bottom electrode, respectively.