A simulation based comparative study of the polarization hysteresis of the ferroelectric capacitor using various ferroelectric models is presented. A 2-dimensional finite element device-level model was implemented using SILVACO's ATLAS device simulator to generate the polarization hysteresis characteristics for Au/Poly(vinylidene fluoride-trifluoroethylene)/Au metal-insulator-metal (MIM) device. Landau free energy expression for electric field in terms of polarization is also implemented in MATLAB to produce the polarization hysteresis curves of monocrystalline and polycrystalline ferroelectrics. The main drawback of previous models was their inability to predict polarization saturation at the same electric field limits as compared with measurements taken from a recently fabricated ferroelectric capacitor. A new model for ferroelectric polarization hysteresis based on curve fitting algorithm is derived that forces the polarization to be saturated at the desired electric field. The MATLAB simulation of this model and the experimental hysteresis is compared which shows an excellent level of agreement. The capacitance hysteresis of the ferroelectric capacitor is also analyzed using the MATLAB simulation. The new polarization hysteresis model that uses four-point fit method is used to derive the mathematical expression for large-signal capacitance. Landau-Khalatnikov kinetic equation is used for deriving mathematical expression for small-signal capacitance. The capacitance simulation results agreed fairly well with physical measurements from a Au-P(VDF-TrFE)-Au capacitor.
Date of publication
Shrestha, Bikash, "Modeling Polarization and Capacitance Hysteresis of Ferroelectric Capacitors" (2012). Electrical Engineering Theses. Paper 10.