Internal Bias Field in Ferroelectric Polymer Thin Film for Nonvolatile Memory Applications

Coercive voltages (V-C, the voltage which makes remanent polarization zero in ferroelectrics) of metal-ferroelectric polymer-metal capacitors were measured with different pulse periods. From the measured V-C, coercive fields (E-C, normalized V-C for thickness) and internal bias fields (E-BIAS) were calculated. Although E-C was found to be nearly constant with thickness, E-BIAS increased as thickness decreased. Based on these findings, it appears that E-BIAS can be induced from interface phenomenon and greatly affects retention performance in thin ferroelectric films used for nonvolatile memory devices.