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

Damping constant xi(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(FE) of a specific ferroelectric material, in this letter, we propose a method to extract xi(FE) value which is dependent on its polarization. This method applies to both Mille rmodel (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)O-3(PZT) and P(VDF-TrFE) and find that xi(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(FE) values of various ferroelectrics are compared. A wide range of xi(FE) values is observed, even for the same material. This indicates that xi(FE) is likely to vary with ferroelectric materials and their dimensions.