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Storage Element for Machine Use

IP.com Disclosure Number: IPCOM000076852D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Fleisher, H: AUTHOR [+2]

Abstract

The use of a chalcogenide layer 10 in conjunction with a ferroelectric layer 12 permits this optical memory to operate very rapidly and have four possible storage states.

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Storage Element for Machine Use

The use of a chalcogenide layer 10 in conjunction with a ferroelectric layer 12 permits this optical memory to operate very rapidly and have four possible storage states.

The chalcogenide layer 10 is placed with the ferroelectric layer 12 and a noncontinuous film 18 between two electrodes 14 and 16. While it remains unilluminated the chalcogenide layer 10 is in a high resistance state, so that when voltage is applied between the electrodes 14 and 16 only a fraction of it is dropped across the ferroelectric layer 12. This voltage drop across the ferroelectric layer 12 is insufficient to change the direction of polarization of the ferroelectric layer. However, when the chalcogenide layer is suitably illuminated, it goes into a conductive state that causes most of the voltage applied between electrodes 14 and 16 to be dropped across the ferroelectric layer 12. In this case, the voltage is sufficient to change the direction of polarization of the ferroelectric layer from an upward to a downward direction and vice versa. The noncontinuous film localizes the voltage drop through the ferroelectric layer. The chief advantage of this as opposed to using a conventional photoconductor, is the higher switching time that is possible.

The change in resistance of the chalcogenide layer is transitory if the applied light energy is low. However, when the radiation used exceeds some threshold (relating to both time and intensity), the change that oc...