Ferroelectric/photoconductor storage device with an interface layer

Claim 2

A photoelectric data recording apparatus comprising: a memory element having a top conductive electrode in electrical contact with a first layer of photoconductive and electroluminescent material in electrical contact with a discontinuous interface layer in electrical contact with a second layer of ferroelectric material in electrical contact with a conductive substrate, said top electrode and said discontinuous interface layer being blocking contacts with said photoconductor in the dark and injecting in the light; means for applying unidirectional voltage pulses of first and second polarities across said stacked layers, said voltage pulses being of a magnitude incapable of switching domains of said ferroelectric material in darkness but capable of switching the polarity of domains of said ferroelectric layer coincidentally with the radiation of said photoconductive and electroluminescent layer; means for energizing said first layer with radiant energy capable of switching the resistance thereof to produce a luminescence therein in response to the switching of domains in said second layer; and means operable for coordinating the application of said potentials and said radiant energy means for producing the switching of domains in said second layer in accordance with a predetermined pattern indicative of data to be recorded.

Claim 3

A photoelectric data recording apparatus comprising: a memory element having successively electrically contacting layers of a conductive substrate, ferroelectric material, discontinuous interface layer, photoconductor and top conductive electrode, said top electrode and said discontinuous interface layer being blocking contacts with said photoconductors in the dark and injecting in the light; means for applying unidirectional voltage pulses of first and second polarities across said layers, said potentials being of a magnitude incapable of switching domains of said ferroelectric layer in darkness but capable of switching the polarity of domains of said ferroelectric layer coincidentally with the radiation of said photoconductive layer; means for energizing said photoconductive layer with radiant energy capable of switching said photoconductive layer from a non-conducting to a conductinG state; and means operable for coordinating said pulse applying means and said radiant energy means for producing a read-in switching of domains in said ferroelectric layer in accordance with a predetermined data pattern; means for effecting a relative movement of said memory element and said radiant energy means; and said coordinating means selectively operating said radiant energy means coincidentally with the application of said voltage pulse and in timed relation with said relative movement.

Claim 4

A photoelectric data recording apparatus comprising: a memory element having successively electrically contacting layers of a conductive substrate, ferroelectric material, discontinuous interface layer, photoconductor and top conductive electrode, said top electrode and said discontinuous interface layer being blocking contacts with said photoconductors in the dark and injecting in the light; means for applying unidirectional voltage pulses of first and second polarities across said layers, said potentials being of a magnitude incapable of switching domains of said ferroelectric layer in darkness but capable of switching the polarity of domains of said ferroelectric layer coincidentally with the radiation of said photoconductive layer; means for energizing said photoconductive layer with radiant energy capable of switching said photoconductive layer from a non-conducting to a conductinG state; and means operable for coordinating said pulse applying means and said radiant energy means for producing a read-in switching of domains in said ferroelectric layer in accordance with a predetermined data pattern; means for effecting a relative movement of said memory element and said radiant energy means; and said coordinating means selectively operating said radiant energy means coincidentally with the application of said voltage pulse and in timed relation with said relative movement.

Claim 5

A photoelectric data recording apparatus in accordance with claim 2 which further comprises storage readout means including means for applying a voltage pulse of said second polarity across said memory element, means for scanning said photoconductive layer of said memory element with a constant beam from said energizing means coincidentally with the application of said potential of said second polarity, means for sensing electric pulses generated by domains switched in said ferroelectric layer, and output means responsive to said sensing means for recording said domain pulses in another form.

Claim 6

A photoelectric data recording apparatus comprising: a memory element having successively electrically contacting layers of a conductive substrate, ferroelectric material, discontinuous interface layer, photoconductor and top conductive electrode, said top conductive electrode and said discontinuous interface layer being blocking contacts with said photoconductor in the dark and injecting in the light, means for applying unidirectional potentials of first and second second polarities across said layers comprising electrode means in contact with the exposed surface of said superposed layers, said potentials being of a magnitude incapable of switching domains of said ferroelectric material in darkness but capable of switching the polarity of the domains of said ferroelectric layer coincidentally with the radiation of said photoconductor layer, said electrode means in contact with said photoconductive layer being transparent and adapted to form plural recording tracks in said memory element, said means for applying said potentials further including a reversible polarity switching means connectable to said electrode means; means for energizing said photoconductive layer with radiant energy capable of switching said photoconductor layer from a non-conducting to a conducting state, said energizing means including means for generating plural beams of radiant energy onto said photoconductive layer in the regions of said plural recording tracks provided by said transparent conductive electrode means; and means operable for coordinating the application of said potentials and said radiant energy means including means for selectively pulsing said beam generating means in accordance with a predetermined pattern whereby parallel domains are switchable in plural record tracks in said ferroelectric layer of said memory element.

Claim 7

A photoelectric data recording apparatus comprising: a memory element having successively electrically contacting layers of a conductive substrate, ferroelectric material, discontinuous interface layer, photoconductor and top conductive electrode, said top conductive electrode and said discontinuous interface layer being blocking contacts with said photoconductor in the dark and injecting in the light, means for applying unidirectional potentials of first and second second polarities across said layers comprising electrode means in contact with the exposed surface of said superposed layers, said potentials being of a magnitude incapable of switching domains of said ferroelectric material in darkness but capable of switching the polarity of the domains of said ferroelectric layer coincidentally with the radiation of said photoconductor layer, said electrode means in contact with said photoconductive layer being transparent and adapted to form plural recording tracks in said memory element, said means for applying said potentials further including a reversible polarity switching means connectable to said electrode means; means for energizing said photoconductive layer with radiant energy capable of switching said photoconductor layer from a non-conducting to a conducting state, said energizing means including means for generating plural beams of radiant energy onto said photoconductive layer in the regions of said plural recording tracks provided by said transparent conductive electrode means; and means operable for coordinating the application of said potentials and said radiant energy means including means for selectively pulsing said beam generating means in accordance with a predetermined pattern whereby parallel domains are switchable in plural record tracks in said ferroelectric layer of said memory element.

Claim 8

A photoelectric data apparatus in accordance with claim 4 in which said photoconductive layer is formed of an electroluminescent phosphor and said radiant energy means generates ultraviolet radiation.

Claim 9

A photoelectric data apparatus in accordance with claim 4 in which said energizing means includes means for producing plural beams of said radiant energy for projection onto one or more track regions of said memory elements, and said coordinating means includes means for selectively operating said beam producing means in accordance with a predetermined multiple bit data pattern.

Claim 10

A photoelectric data apparatus in accordance with claim 4 further comprising read-out means including means operable for sensing luminescent pulses producible in said photoconductive layer in response to switching of domains in said ferroelectric layer.

Claim 11

A photoelectric data recording apparatus comprising: a memory element having successively electrically contacting layers of a conductive substrate, ferroelectric material, discontinuoUs interface layer, photoconductor and top conductive electrode, said top electrode and said discontinuous interface layer being blocking contacts with said photoconductor in the dark and injecting in the light; means for applying unidirectional voltage pulses of first and second polarities across said layers, said potentials being of a magnitude incapable of switching domains of said ferroelectric layer in darkness but capable of switching the polarity of domains of said ferroelectric layer coincidentally with the radiation of said photoconductive layer; means for energizing said photoconductive layer with radiant energy capable of switching said photoconductive layer from a non-conducting to a conducting state; and means operable for coordinating said potential applying means and said radiant energy means for producing the switching of domains in said ferroelectric layer in accordance with a predetermined data pattern including means for effecting a relative movement of said memory element and said radiant energy means; and means for selectively operating said radiant energy means in timed relation with said relative movement.

Claim 12

A photoelectric data recording apparatus comprising: a memory element having successively electrically contacting layers of a conductive substrate, ferroelectric material, discontinuoUs interface layer, photoconductor and top conductive electrode, said top electrode and said discontinuous interface layer being blocking contacts with said photoconductor in the dark and injecting in the light; means for applying unidirectional voltage pulses of first and second polarities across said layers, said potentials being of a magnitude incapable of switching domains of said ferroelectric layer in darkness but capable of switching the polarity of domains of said ferroelectric layer coincidentally with the radiation of said photoconductive layer; means for energizing said photoconductive layer with radiant energy capable of switching said photoconductive layer from a non-conducting to a conducting state; and means operable for coordinating said potential applying means and said radiant energy means for producing the switching of domains in said ferroelectric layer in accordance with a predetermined data pattern including means for effecting a relative movement of said memory element and said radiant energy means; and means for selectively operating said radiant energy means in timed relation with said relative movement.

Claim 13

A photoelectric data recording apparatus in accordance with claim 8 in which said energizing means includes means for producing a radiant energy beam projectable onto the photoconductive layer of said memory element, and said means for effecting relative movement includes means for directing said beam projecting means along said photoconductive layer in a single recording track region, and said means for selectively operating said radiant energy means includes means for producing a series of beam pulses in timed relation with said relative movement in accordance with a series multiple bit data pattern.

Claim 14

The memory element of claim 8 wherein said top electrode and discontinuous interface layer are chosen from non +3 valence metal and said photoconductor is chosen from the II-VI compounds and III-V compounds.

Claim 15

The memory element of claim 8 wherein said top electrode and said discontinuous interface layer are individually chosen from the group consisting of Au, Pt, Ag, and Cu, and said photoconductor is chosen from the group consisting of II-VI and III-V compounds.

Claim 16

The memory element of claim 8 wherein said discontinuous interface layer is a metal film between 10-100 A thickness and non-electrically conducting in the plane parallel to the layers comprising said memory element.

Claim 17

The memory element of claim 8 wherein said discontinuous interface layer comprises a series of islands physically isolated from each other, each of said islands being smaller in area than the area of the light beam used to address said memory element.

Claim 18

The memory element of claim 8 wherein said ferroelectric material is a solid solution of lead ferroniobate, bismuth ferrate, lead zirconate and lanthanum ferrate.

Claim 19

The memory element of claim 14 wherein said element is heat treated to reduce asymmetry in switching characteristics.