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

Abstract

Damping constant $\xi _{\text {FE}}$ 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 $\xi _{\text {FE}}$ of a specific ferroelectric material, in this letter, we propose a method to extract $\xi _{\text {FE}}$ 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(Zr0.4Ti0.6)O3(PZT) and P(VDF-TrFE) and find that $\xi _{\text {FE}}$ reduces during polarization switching as compared with pre-switching. In addition, PZT exhibits a weaker damping effect than P(VDF-TrFE). Finally, the $\xi _{\text {FE}}$ values of various ferroelectrics are compared. A wide range of $\xi _{\text {FE}}$ values is observed, even for the same material. This indicates that $\xi _{\text {FE}}$ is likely to vary with ferroelectric materials and their dimensions.