Rough FTO Electrode Interface Effect Upon Ferroelectric Switching Dynamics in Ag/P(VDF-HFP)/FTO Capacitor Structures

Rough FTO electrode interface effect upon the characteristic ferroelectric polarization parameters and switching dynamics in Ag/P(VDF-HFP)/FTO junctions is systematically evaluated by varying electric field amplitude and frequency. Structural and microstructural studies confirm the ferroelectric phase formation of P(VDF-HFP) on FTO surface. Tilted rectangular P-E loops have been recorded in the applied fields ranging over 156.25-468.75 MV/m measured between 250 mHz and 5 Hz frequency ranges. Giant saturation of 21.7 mu C/cm(2) and remnant polarization of 34.9 mu C/cm(2) has been noted at low frequencies due to the influence of high electric field induced leakage currents. The coercive field, saturation and remnant polarization response with increase in electric field amplitude and frequency of the applied signal are well fitted with classic domain growth model proposed by Kolmogorov-Avrami-Ishibashi. A switching time scales of 32.2-693 ms has been observed for forward switching while for backward switching it is noted as 22.1-618.8 ms, when measured at frequencies from 5 Hz to 250 mHz. Furthermore, the tilted P-E loops are attributed to the excessive leakage currents due to the high surface roughness of FTO bottom electrode.