Ferroelectric space charge capacitor analog memory

Abstract

A ferroelectric space charge capacitor analog memory device includes a pair of spaced first and second electrodes; a ferroelectric dielectric disposed between the electrodes; and a signal source for applying to the dielectric a write signal equal to or greater than the coercive voltage to write the dielectric into a predetermined polarization state in the range from zero to maximum coerced polarization and to establish, proximate the interface between the dielectric and each electrode, a space charge region having a charge opposite to that applied to the electrode, with a neutral region between the space charge regions, the relative sizes of the neutral and space charge regions defining the capacitance of the dielectric, the neutral region having an internal polarization field opposite to that represented by the space charge regions; a bias source for applying to the dielectric a bias voltage less than the coercive voltage at a rate slower than the rate of space charge formation to define the capacitance level representative of the predetermined polarization state; the signal source for introducing to the dielectric a read signal at a rate faster than the rate of space charge formation which together with the bias voltage is less than the coercive voltage; and a current detector responsive to the introduction of the read signal to the dielectric for determining the capacitance level representative of the predetermined polarization state.