Equivalent-circuit modeling of ferroelectric switching devices

Abstract

A compact equivalent-circuit model for ferroelectric switching devices is derived from a general model for local charge displacements. The general model consists of a matrix of repeat units describing local dissipationless charge displacements (electrostatic channel), as well as dissipative charge displacements (electrochemical channel), the channels being coupled due to the electrical charge of the moving species. The derived model for ferroelectric charge displacements is used to simulate both hysteresis and transient characteristics, and applied to two devices: (i) a ferroelectric capacitor and (ii) a ferroelectric memory field-effect transistor. The circuits are programmed in SPICE-derived analysis software. We find that experimental hysteresis data obtained on Pb(Zr,Ti)O3 ceramic capacitors and on thin-film transistors with a SnO2:Sb semiconductor and a Pb(Zr,Ti)O3 ferroelectric insulator can be reproduced and interpreted with the equivalent-circuit models.