A CIRCUIT MODEL FOR A THIN-FILM FERROELECTRIC MEMORY DEVICE

Thin film ferroelectric memory devices have displayed ideal memory characteristics such as nonvolat ility, radiation hardness and fast switching times. The simulation of the digital circuits using thin film ferroelectric memory devices necessitates an equivalent circuit model for these thin film device structures. The basic switching characteristics of a device is nonlinear in nature and requires a generating source in the equivalent circuit model. This current source is related to the polarization current as a function of time. The capacitance-voltage and hysteresis data on capacitor type device structures suggest the existance of an interfacial layer at the metal-ferroelectric interface. The interfacial layers are characterized by appropriate RC networks. The bulk ferroelectric material is modeled as a linear capacitance (dielectric) in parallel with a bulk resistance in parallel with the current generating source. This equivalent circuit model is simulated on the IBM 4381 mainframe computer using SPICE. The simulation results are compared with the actual switching characteristics observed on the oscilloscope. There appears to be an excellent agreement between the simulated results and experimental results. © 1991, Taylor & Francis Group, LLC. All rights reserved.