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.