Ferroelectric space charge capacitor memory

Abstract

A ferroelectric space charge capacitor memory device includes a pair of spaced first and second electrodes; a ferroelectric dielectric disposed between the electrodes; a coercive voltage supply for applying a coercive voltage to the dielectric to write the dielectric into one of two polarization states and to establish in each polarization state in the dielectric a space charge region proximate each electrode having a charge opposite to that of 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 voltage supply for applying to the dielectric a bias voltage less than the coercive voltage at a rate lower than the rate of space charge formation to define a capacitance level representative of one of the polarization states; a pulse generator 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 sensor responsive to the introduction of the read signal to the dielectric for determining the capacitance level representative of one of the polarization states.