Bimodal operation of ferroelectric and electret memory cells and devices

Abstract

In a method for enhancing the data storage capability of ferroelectric or electret memory cell which has been applied to storage of data and attained an imprint condition, suitable voltage pulses are used for evoking a temporary relaxation of the imprint condition into a volatile polarization state that can be discriminated from the imprinted polarization state in a non-destructive readout operation. Sequences of one or more voltage pulses are used to evoke readout signals respectively indicative of a non-volatile and a volatile polarization state of the memory cell, but without altering said polarization states. Imprinted memory cells can be overwritten to effect a temporary and volatile storage of data in a memory device in a ferroelectric or electret memory device by assigning a first logical value to imprinted memory cells and a second logical value by transferring selected to memory cells transferred into a relaxed volatile state, whereby the stored logical values can be discriminated by the detecting the difference in dynamic response of respectively imprinted and relaxed memory cells.