Extraction of Polarization-Dependent Damping Constant for Dynamic Evaluation of Ferroelectric Films and Devices

Damping constant ξ
_FE
is the key parameter that determines the maximum operating speed of the negative capacitance ferroelectric field-effect transistor (NC-FET). While most studies assume a constant ξ
_FE
of a specific ferroelectric material, in this letter, we propose a method to extract ξ
_FE
value which is dependent on its polarization. This method applies to both Miller model (positive capacitance) and Landau model (negative capacitance). It enables further analysis on dynamic characteristics of a ferroelectric film and therefore NC-FET. We apply this method to Pb(Zr
_0.4
Ti
_0.6
)O
₃
(PZT) and P(VDF-TrFE) and find that ξ
_FE
reduces during polarization switching as compared with pre-switching. In addition, PZT exhibits a weaker damping effect than P(VDF-TrFE). Finally, the ξ
_FE
values of various ferroelectrics are compared. A wide range of ξ
_FE
values is observed, even for the same material. This indicates that ξ
_FE
is likely to vary with ferroelectric materials and their dimensions.