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Ferroelectric Photoconductor

IP.com Disclosure Number: IPCOM000074091D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Mayadas, AF: AUTHOR

Abstract

The essential features of a prior ferroelectric-photoconductor device are shown. A photoconductor film P and a ferroelectric film F are in intimate contact, e.g., by successive deposition. These films are sandwiched between two electrodes as shown. A transparent electrode film is established on film P and a conducting substrate is established on film F. Writing is accomplished by impinging a light beam onto the photoconductor P and applying a voltage pulse from a pulse generator simultaneously across the sandwich structure. The resistance of the area of the photoconductor activated by the light drops markedly so that the applied voltage appears across an equivalent area of the ferroelectric F causing it to switch states.

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Ferroelectric Photoconductor

The essential features of a prior ferroelectric-photoconductor device are shown. A photoconductor film P and a ferroelectric film F are in intimate contact, e.g., by successive deposition. These films are sandwiched between two electrodes as shown. A transparent electrode film is established on film P and a conducting substrate is established on film F. Writing is accomplished by impinging a light beam onto the photoconductor P and applying a voltage pulse from a pulse generator simultaneously across the sandwich structure. The resistance of the area of the photoconductor activated by the light drops markedly so that the applied voltage appears across an equivalent area of the ferroelectric F causing it to switch states. The locally switched area in the ferroelectric defines a bit which can be read destructively by reading the stored charge which appears as voltage V across the load resistor. Generally, two insulators in contact do not form an ohmic contact. Therefore, there is a space charge region between P and F and much of the applied voltage is dropped across this region, even when P is in the conductive state. This in turn causes incomplete switching in F with detrimental consequences for information retrieval.

In accordance with the principles hereof, a physically continuous but electrically discontinuous film of a suitable material, e.g., Ta, is established between the P layer and the F layer which provides ohmic contact with...