Equivalent circuit analysis of a ferroelectric-photoconductor memory device

Abstract

An analysis of an equivalent circuit representing a ferroelectric photoconductor memory device has been performed. The purpose of this work is to provide a basis for describing the transient switching characteristics of the ferroelectric-photoconductor memory element. Two models describing the polarization reversal in the ferroelectric have been investigated. The first model assumes that the polarization charge is a nonlinear function of the voltage that is applied to the ferroelectric. This represents a simple generalization of an RC model for which the ferroelectric is assumed to have a well defined threshold field and allows one to qualitatively describe the partial switching of the ferroelectric. The second model of polarization reversal assumes that domain wall motion is activated, described adequately by the sidewise motion of domains, and dependent upon the instantaneous electric field in the ferroelectric domain. Domain statistics involving domain overlap as well as polarization reversal conditions are imposed to realistically describe the state of the ferroelectric as it traverses a hysteresis loop. The time dependence of the polarization, current, and voltage is examined and voltage is examined and attention focussed on polarization switching time as an important device parameter. Nonsaturated switching increases this speed and the feasibility of operating the device in this mode is discussed. Copyright © 1972 by The Institute of Electrical and Electronics Engineers, Inc.