JP2603621B2 - Information storage element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is capable of inputting and storing information by light, reading out the stored information content as a time-series electric signal, and storing the stored information content. The present invention relates to an information storage element capable of erasing and returning to a state before storage.

(Prior Art) Conventionally, as an optical information storage / reproduction system for storing and reproducing optical information, a combination of an imaging element such as a CCD and a storage means such as a magnetic tape, and an optical disk system are known. However, in the former case, the imaging device must integrate a large number of devices such as switching FETs in addition to the photoelectric conversion device, and requires a complicated manufacturing process. Must transfer information from the image sensor to the storage means.

Further, in the latter case, that is, in the optical disk system, no satisfactory system has yet been established for rewriting stored information.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and allows information to be input and stored by light, and the stored information is sometimes swept by a light beam for reading. An object of the present invention is to provide a novel information storage element which can be read out as a series of electric signals, erases stored information contents, returns to a state before storage, and stores the information again.

(Means for Solving the Problems) Hereinafter, the present invention will be described.

As described above, the information storage element provided by the present invention can input information by light and electrically store the information, and sweeps the stored information content as a time-series electric signal by sweeping with a light beam for reading. Can be read, and
The stored optical information contents can be erased and returned to the state before the storage.

The information storage element has a photoelectric conversion layer, a storage layer, and a pair of electrodes.

The information storage element of the present invention can be formed in a one-dimensional form, that is, in a strip shape, and can store optical information in the longitudinal direction, or can be formed in a two-dimensional form, and a two-dimensional matrix is included in the area thereof. Optical information can also be stored in a symmetrical, concentric track or spiral form.

The photoelectric conversion layer has a function of photoelectrically converting input optical information and is formed as a layer. This photoelectric conversion layer may be, for example, a layer in which minute photodiodes are densely arranged one-dimensionally or two-dimensionally, or may be formed as a continuous layer of a photoconductive substance. You may comprise. When the photoelectric conversion layer is configured as an aggregate of photodiodes, the direction of each diode is set to the layer thickness direction.

Further, the photoelectric conversion layer may have a composite structure having a plurality of layers in the thickness direction.

The memory holding layer is provided in close contact with one surface of the photoelectric conversion layer. The function of this memory holding layer is to store the photoelectric conversion state in the photoelectric conversion layer as an electrical state. That is, when light is applied to the photoelectric conversion layer, a photoelectric conversion state corresponding to the optical information is generated in the photoelectric conversion layer when the light includes intensity-modulated and wavelength-modulated information.
The storage holding layer generates an electrical state corresponding to the photoelectric conversion state and stores the electrical state, thereby storing optical information contents. When light sweeps the photoelectric conversion layer at a substantially constant intensity, a voltage between a pair of electrodes described later is changed,
The information is sequentially stored in the record holding layer. In this case, the light irradiation is used to specify the location of the sequential storage. In the present invention, these two cases are collectively referred to as "input and store information by light". Note that the memory holding layer has a composite structure having two or more layers.

The pair of electrodes is provided so as to sandwich the photoelectric conversion layer and the storage layer that are stacked as described above.

When inputting and reading information, the photoelectric conversion layer must be irradiated with light. Since this light irradiation is performed through the electrodes, at least one of the electrodes must be translucent. To make the electrode translucent, the electrode itself may be transparent, or a slit for taking in light may be provided.

The storage layer is configured as a composite layer including an electrical insulating layer. That is, as the composite layer structure of the memory holding layer, two electric insulating layers were laminated, and fine conductive particles were arranged and distributed in an island shape between the two electric insulating layers. A semiconductive thin film between the electric insulating layers, or an insulating film having a smaller band gap than the electric insulating layer, or a semiconductor for information detection. A stack of layers can be given.

Each of the electrodes in the pair of electrodes functions as a single electrode.

(Operation) Next, the operation of the present invention will be described.

The functions of the information storage element of the present invention are to input and store information by light, to read stored information contents, and to erase stored contents. Hereinafter, these will be sequentially described.

First, the input and storage of information by light will be described. The input of information is roughly classified into a method of sweeping a light beam and a method of projecting an optical image. The former is an effective method for both one-dimensional and two-dimensional forms, and the latter is more suitable as an input method for a two-dimensional information storage element.

In the case of sweeping the light beam, one of the information storage elements is used.
A relatively high voltage is applied between the pair of electrodes, and the information storage element is swept by a light beam. When the information storage element is in a two-dimensional form, the sweep includes a main sweep (linear or circular) and a sub-sweep in a direction orthogonal to the main sweep.
Alternatively, it is performed by a swirling sweep.

The light beam is intensity or wavelength-modulated according to the information to be stored, and is input to the information storage element as optical information.

Or keep the light beam intensity constant,
The voltage applied to the pair of electrodes may be intensity-modulated with the information signal in accordance with the sweep by the light beam.

In the case of a method of projecting an optical image, the above-described relatively high voltage may be applied between a pair of electrodes, and the optical image may be projected by focusing on the photoelectric conversion layer.

Now, as described above, in a state where light information is input to the information storage element, considering a portion of the photoelectric conversion layer that is irradiated with light, the photoelectric conversion layer is in a state where light is not irradiated. In the high impedance state, the voltage applied to the pair of electrodes is applied to both the photoelectric conversion layer and the storage holding layer in the high impedance state. However, when light is applied to the photoelectric conversion layer, the impedance is reduced in this portion. In addition, when the photoelectric conversion layer is configured as an aggregate of photodiodes, additional impedance is added together with the decrease in impedance. A voltage is generated, and eventually, in this portion, a higher voltage is applied in the thickness direction of the memory holding layer than in other portions (portions not irradiated with light).

Due to the action of the high voltage, charges are accumulated in a portion of the storage layer overlapping the photoelectric conversion layer irradiated with the light, for example, by charge injection or the like. The amount of accumulated charge is
This corresponds to the degree of photoelectric conversion in the photoelectric conversion layer, and the degree of photoelectric conversion corresponds to optical information. Therefore, the electric charge accumulated in the memory holding layer corresponds to the optical information irradiated to the position.

In this way, the optical information is stored as stored charges in the storage holding layer of the information storage element. By releasing the voltage applied to the pair of electrodes after the input of the optical information in this way, the distribution of the accumulated charges corresponding to the optical information is semi-permanently stored and saved. Note that a conductive path for preventing electrification can be provided between the pair of electrodes for safe storage of stored contents.

As is apparent from the above description, the magnitude of the voltage applied between the pair of electrodes is determined when light irradiation is not performed.
The size is set such that there is no charge accumulation in the storage holding layer, and sufficient charge accumulation occurs when light irradiation is performed.
Also, when the intensity of the light beam is fixed and the applied voltage is modulated in intensity by the light beam sweep type input, charge accumulation does not occur in the absence of information, so that the accumulated charge changes according to the information. Determine the voltage fluctuation region.

Next, the reading of the stored optical information content will be described. In this case, a light beam having a constant intensity is swept to the information storage element (in the two-dimensional information storage element, main sweep and sub sweep, Alternatively, a swirling sweep may be performed. Thus, the content of the optical information is read out as a current signal flowing between the pair of electrodes.

At a certain moment, when a specific portion of the photoelectric conversion layer is irradiated with a light beam for reading, carriers are generated in the photoconductive layer. If optical information is stored in the storage layer as stored charge at this site, the carrier moves by interacting with the partial charge formed by the stored charge,
This is taken out as a current signal. This current signal changes according to the stored charge. Therefore, the information content stored in the storage layer can be read out as a time-series current signal by sweeping the light beam. This signal may be converted to a voltage signal and read as needed.

In the case of reading, a weak voltage may be applied between a pair of electrodes.

Next, the erasure of the optical information stored in the information storage element is performed by the following method.

That is, a relatively high voltage is applied to a pair of electrodes of the information storage element in a direction opposite to that of input and storage, and in this state, uniform light irradiation is performed on the photoelectric conversion layer.
In this case, the charge stored in the storage layer is canceled by the charge of the opposite polarity, and the storage information element returns to the state before the storage of the optical information. , Can be memorized.

(Example) Hereinafter, a description will be given of a specific example with reference to the drawings.

FIG. 1 (I) is an explanatory view showing one embodiment of the information storage element of the present invention.

In the figure, reference numeral 10 is a transparent substrate, reference numeral 20 is a transparent electrode film,
Reference numeral 21 is a metal electrode for extraction, reference numeral 30 is a photoelectric conversion layer,
Reference numeral 40 indicates a storage layer, and reference numeral 50 indicates an electrode.

Although the transparent substrate can be made of plastic, glass, or the like, in this embodiment, it is made of a glass plate.

The transparent electrode film 20 has a film shape and is formed so as to cover one surface of the photoelectric conversion layer 30, and forms one of a pair of electrodes together with the metal electrode 21. The other of the pair of electrodes is an electrode 50. This electrode 50 is also in the form of a film, and is formed so as to cover one surface of the memory holding layer 40.

As a material of the transparent electrode film 20, SnO ₂ , ITO, ZnO or the like can be used. In the present embodiment, the transparent electrode film 20 is formed of SnO ₂ .

The photoelectric conversion layer 30 is a layer made of a photoconductive substance, and a known photoconductive substance can be appropriately used as a material. In the present embodiment, the photoelectric conversion layer 30 is made of amorphous silicon.

The memory holding layer 40 has a configuration in which two insulating films 41 and 42 are stacked. In this embodiment, the insulating film 41 is an SiO ₂ layer thin enough to allow a tunnel current to flow.
Reference numeral 42 denotes a silicon nitride layer having a thickness of several hundreds of square meters.

The electrode 50 is a metal electrode and may be formed of a metal thin film made of aluminum, nickel, or the like. In this embodiment, the electrode 50 is formed of an aluminum thin film.

The input and storage of the optical information to the information storage element will be described with reference to FIG.

The input of the optical information may be either the light beam sweeping method or the optical image projection method described above. Here, the light beam sweeping method will be described as an example.

As shown in FIG. 1 (II), the metal electrode 21 and the electrode 50 are connected to a power supply 100, and the metal electrode 21 and the electrode 50 are connected between the transparent electrode film 20 and the electrode 50.
Apply a voltage of ~ 30 volts. At this time, the side of the electrode 50 is set to the plus side as shown in the figure.

In this manner, the information storage element is irradiated and swept from the transparent substrate 10 side with the light beam SL whose intensity is modulated according to the information content. In FIG. 1 (II), the light beam SL
Considering the part illuminated by the optical signal L at home,
The optical signal L passes through the substrate 10 and the transparent electrode film 20 and enters the photoelectric conversion layer 30 to convert the portion indicated by the symbol P, which is hatched by a broken line, into a conductor. Thereby, the photoelectric conversion layer 30
Is in a low impedance state,
Most of the voltage applied by the power supply 100 is
It will take 0. As a result, electrons pass through the insulating film 41 made of SiO ₂ of the memory holding layer 40 by a tunnel effect, are injected into the insulating film 42 made of SiNx, and are accumulated in the same film 42. Since the amount of stored electricity corresponds to the light intensity of the optical signal L, the input optical information is converted into a stored state of electrons and stored in the storage holding layer 40.

When the input of the optical information is completed, the voltage applied between the transparent electrode film 20 and the electrode 50 is released. With this configuration, the optical information input to the information storage element is semi-permanently stored as an electrical state (charge accumulation) in the storage layer. In this case, it is preferable to provide a conductive path between the electrodes 21 and 50 for preventing electrification, as described above.

Next, reading of the optical information content stored as described above will be described with reference to FIGS. 1 (III) and (IV).

At the time of reading, a current detecting element (not shown) is connected between the metal electrode 21 and the electrode 50, and the reading light beam LA
Then, the information storage element is illuminated and swept from the substrate 10 side. At this time, a voltage (about several volts) that does not cause writing can be applied between the electrodes 21 and 50 if necessary.

Now, in FIG. 1 (III), reference numeral q of the memory holding layer 40
It is assumed that information is stored in a portion indicated by, and no information is stored around the portion.

At this time, the equivalent circuit in the vicinity of the part is shown in FIG.
It becomes as shown in.

The capacitance C indicates a capacitance at a nearby position other than the portion q. The capacity Cq indicates the capacity of the storage holding layer 40 in the part q, and corresponds to the stored information.

The parallel circuit of the capacitance Cd and the photodiode D has a partial q
Represents a photoelectric conversion layer 30 that is in contact with.

In this case, the photodiode D is equivalently generated by a surface barrier induced on the surface of the photoelectric conversion layer by the electric charge in the storage layer.

The light beam LA for reading has a constant light intensity, and when the photoelectric conversion layer 30 is swept, the irradiated portion is brought into a low impedance state, but in portions other than the portion q, charge is stored in the storage holding layer 40. In these parts, the impedance change does not cause a large electrical change in these parts.

However, when the impedance change occurs in the portion in contact with the portion q, the charge of the electrons stored in the portion q causes the movement of the charge in the photoelectric conversion layer 30, and this is detected by the current detecting element as a current change. You. Since the current detected in this manner changes according to the amount of charge stored in the storage layer 40, the stored optical information content is eventually changed according to the sweep of the reading light beam LA. They can be read out sequentially.

In order to erase the optical information content stored in the information storage element, between the metal electrode 21 and the electrode 50, the side of the metal electrode 21 is positive, that is, in a direction opposite to that at the time of inputting the optical information. , 20 to 30 V, and uniform light irradiation may be performed from the substrate 10 side of the information storage element.

In the above embodiment, the amorphous silicon layer used as the photoelectric conversion layer 30 has very large dark resistance and good photoelectric characteristics. Moreover, the diffusion length of minority carriers is 1 μm or less.

Therefore, in the above embodiment, 5 cm square, that is, 2 cm
About 10 ⁸ bits of information can be stored in an area of 5 cm ² .

In the above embodiment, the substrate 10 and the transparent electrode film 20 are
Both are transparent, so that optical information can be input, read,
At the time of erasing, photoelectric conversion could be generated in the photoelectric conversion layer 30 by light irradiation from the substrate 10 side.

However, other than a glass plate, a light-shielding metal substrate or a plastic substrate with poor light transmission can be used as the substrate.

In this case, the storage layer is made of a transparent material, and the electrode provided in contact with the storage layer is a transparent electrode or a metal thin-film electrode provided with a slit. , The input, storage, reading, and erasing of optical information may be performed while irradiating the photoelectric conversion layer with light.

Next, a modified example of the photoelectric conversion layer will be described with reference to FIG. In FIG. 2, reference numeral 40A indicates a general storage holding layer, and specific examples thereof include the storage holding layer 40 shown in FIG. 1, each example shown in FIG. 3, or another embodiment described later. Examples include those having a semiconductor layer in the examples.

The photoelectric conversion layer 30A shown in FIG. 2 (I) is formed by stacking a high-concentration impurity layer 31 and a low-concentration impurity layer 32, and the photoelectric conversion layer 30B shown in FIG. Concentration impurity layer 31
And 33 sandwich the low concentration impurity layer 32.
The high-concentration impurity layers 31 and 33 are for ensuring good ohmic contact between the transparent conductive film 20 and the storage layer 40A and the photoelectric conversion layers 30A and 30B, respectively.

Examples of the high-concentration impurity layers 31 and 33 include, for example, an amorphous silicon layer to which an N-type impurity such as phosphorus is added, an amorphous silicon layer to which a P-type impurity such as boron is added, and an impurity as the low-concentration impurity layer 32. An amorphous silicon layer which is not added can be given.

A photoelectric conversion layer 30A composed of a high-concentration impurity layer 31 made of amorphous silicon to which an N-type impurity is added and a low-concentration impurity layer 32 made of an amorphous silicon layer to which no impurity is added is used in the embodiment shown in FIG. Considering the information storage element used in place of 30, even in such an element, when optical information is input, a negative charge corresponding to the optical information content is accumulated in the storage holding layer 40. The charge induces positive charges (holes) at the interface between the low-concentration impurity layer 32 and the storage holding layer 40. Since the holes and the accumulated negative charges are exposed by the insulating film 41 made of SiO ₂ , the optical information content is stored as an equivalent PIN photoelectric conversion element, and the read information is read. When the light beam is irradiated, the output voltage of the equivalent photoelectric conversion element is applied to the capacity of the storage holding layer 40, so that a current corresponding to the stored content can be detected.

FIG. 3 shows various configuration examples of the memory holding layer.
In the figure, reference numeral 300 generally indicates a photoelectric conversion layer, and includes the photoelectric conversion layer 30 in FIG. 1, the photoelectric conversion layer 30A in FIG. 2, and others.

The memory holding layer 40C shown in FIG.
And an insulating film 41 are laminated. The insulating film 41 is, for example, SiO ₂ or SiNx, and has a function of increasing the detection sensitivity at the time of reading.

The memory holding layer 40D shown in FIG. 3 (II) has a structure in which conductive particles 45 are sandwiched between insulating layers 43 and 44, and the memory holding layer 40E shown in FIG. The layers 43 and 44 have a configuration in which an insulating film 46 having a semiconductive or relatively small band gap is sandwiched. The insulating layers 43 and 44 can be formed of, for example, SiO ₂ , and the insulating film 46 can be, for example, a SiNx film. In these cases, electric charges corresponding to the optical information are accumulated in the conductive particles and the insulating film.

In the embodiment described above, when reading out the stored optical information content, an electric change of the photoelectric conversion layer due to the electric charge accumulated in the storage holding layer was detected as a current change.

However, in the present invention, reading in another form is also possible, and an embodiment thereof will be described below.

In FIG. 4, reference numerals 20 and 21 denote a transparent electrode film and a metal electrode as in FIG.
One of the paired electrodes is configured.

The photoelectric conversion layer 30B is of the same type as that described with reference to FIG. 2 (II), and has a configuration in which the low-concentration impurity layer 32 is sandwiched between the high-concentration impurity layers 31 and 33. High concentration impurity layer 3
According to 1,33, the ohmic contact with the layer with which they come into contact is improved. Instead of the photoelectric conversion layer 30B, the photoelectric conversion layer 30 shown in FIG. 1 and the photoelectric conversion layer 30A shown in FIG. 2 (I) can be used.

In the embodiment shown in FIG. 4, the material of the photoelectric conversion layer 30B is amorphous silicon,
Numerals 1 and 33 contain a large amount of N-type impurities, and the low-concentration impurity layer 33 is provided so thin that the resistance in the plane direction does not become extremely low.

In the embodiment just described, the function of the photoelectric conversion layer 30B only needs to be reduced by light irradiation.

In FIG. 4, reference numeral 40F denotes a memory holding layer. In the memory holding layer 40F, the insulating film 47 is a layer for storing an amount of electric charge according to the content of optical information, and is, for example, a thin film of SiNx (having a thickness of about several hundreds of mm). The film 48 is a layer thin enough to allow a current to flow due to the tunnel effect, and is, for example, a SiO ₂ thin film. Hereinafter, for the sake of specificity, the insulating film 47 is a SiNx layer, and the insulating film 48 is a SiNx layer.
Let it be a layer of O ₂ .

Reference numeral 49 indicates a semiconductor layer. Reference numeral 51 denotes a metal electrode.

The semiconductor layer 49 has a dual character, and on the one hand, constitutes a part of the storage layer, and on the other hand, together with the metal electrode 51, constitutes the other of the pair of electrodes.

 Here, the semiconductor layer 49 is assumed to be P-type.

When inputting and storing optical information, a relatively high voltage (20 to 30 V) is applied between the metal electrodes 21 and 51, and the side of the electrode 51 is made positive.

When information is input by light from the side of the transparent electrode film 20 in this way, electrons are extracted from the insulating film 47 to the semiconductor layer 49 in the portion irradiated with light. Then, only the portion written by the light irradiation has relatively accumulated positive charges compared to the surroundings. Therefore, when an appropriate negative voltage is applied to the electrode 51, a negative charge is induced at the boundary between the semiconductor layer 49 and the insulating layer 48 by the equivalent accumulated positive charge of the portion irradiated with light, and together with the accumulated positive charge, A depletion state or a PN junction state due to the inversion layer is formed.

Therefore, when irradiation sweeping is performed with a reading light beam,
A voltage is generated only in the portion where the positive charges are accumulated, and the memory holding layer 40
A change in current output between the electrodes 21 and 51 can be detected through the capacitor constituted by F, and the stored information content can be read.

The case of erasure is the same as that of the embodiment shown in FIG.

In each of the embodiments described above, the photoelectric conversion layer has a continuous and uniform structure in a direction orthogonal to the thickness direction. However, when a material having a very small diffusion length of minority carriers, such as silicon single crystal, is used as the material of the photoelectric conversion layer, it is necessary to separate each pixel portion of the photoelectric conversion layer from each other in order to secure recording density. is there. One embodiment in such a case is shown in FIG.

In FIG. 5, reference numerals 21 and 51 indicate metal electrodes as in FIG.

Reference numeral 20A indicates an N ⁺ type silicon substrate. This board 20A
Together with the metal electrode 21 constitute one of a pair of electrodes.

Reference numeral 50A indicates a transparent electrode film. This transparent electrode film 5
0A forms the other of the pair of electrodes together with the electrode 51.

Reference numeral 60 denotes an insulating mesh for separation. Code 31A
Indicates a photoelectric conversion layer. The photoelectric conversion layer 31A is a layer made of N-type silicon, and is provided in a state of being taken in the insulating mesh 60, thereby separating each pixel.

SiO ₂ layers shown with reference numeral 41A has a thickness of 20-30 Å, with a layer 42A of silicon nitride having a thickness of 200～5000A,
It constitutes a memory holding layer.

In the case of this embodiment, the input of optical information, storage, reading, and light irradiation in the case of erasing are all performed on the transparent conductive film 50A side,
That is, the processing is performed from the lower side of FIG.

When inputting optical information while applying a relatively high voltage of 20 to 30 V between the metal electrodes 21 and 51 so that the side of the electrode 21 is positive, a negative charge corresponding to the optical information is nitrided. Although stored in the silicon layer 42A, this negative charge depletes the area of the N-type silicon layer serving as the photoelectric conversion layer 31A without inverting. Therefore, by irradiating the reading light beam, the stored contents can be read as a current signal between the metal electrodes 21 and 51.

In the case of this embodiment, because of the configuration of the insulating mesh 60,
Although microfabrication technology is required for fabrication, microfabrication is performed only once, so that difficulty in production does not actually pose a problem.

When the information storage element of the present invention is actually used, as shown in FIG. 6, the edge detection elements 110, 111, 120, and 121 can be provided around the information storage element 1000.

The end detecting element 110 and the like may be anything as long as an optical signal can be detected. For example, a pin photodiode or a structure in which a photoconductive layer is sandwiched between an electrode film and a transparent electrode film is preferable.

In this manner, for example, when the AA 'portion of FIG. 6 (I) is swept up and down by a light beam for reading, FIG.
Since a signal like I) can be obtained,
It can be used to detect the start or end of reading,
By sweeping the BB 'portion of FIG.
Since a signal as shown in FIG. 2 is obtained, the start point and the end point of the sweep for each line can be easily detected.

(Effects of the Invention) As described above, according to the present invention, a novel information storage element can be provided.

Since the information storage element of the present invention is configured as described above, the information storage element of the present invention has a very simple structure, Cost and compact,
Since there is no need to transfer the input information to the storage unit, a complicated transfer circuit is not required.

In addition, the information storage element of the present invention can freely store and erase optical information. By applying this to an optical disc, it is easy to rewrite information that has been conventionally difficult in an optical disc. And it can be realized reliably.

Since the information storage element of the present invention can input, store, read, and erase information by light, it can be suitably implemented as an electronic film for an electronic camera in addition to the optical disk. The information storage element of the present invention is generally formed on a substrate as in the embodiment shown in FIG. But,
Since the substrate can also serve as one of a pair of electrodes, an independent substrate is not necessarily required, and thus the substrate itself is not an essential requirement of the present invention. .

[Brief description of the drawings]

FIG. 1 is a diagram for explaining one embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing two examples of the configuration of the photoelectric conversion layer, FIG. 3 is a diagram showing three examples of the configuration of the storage layer, FIG. 4 is a diagram showing another embodiment of the present invention, and FIG. FIG. 6 is a view showing another embodiment of the present invention, and FIG. 6 is a view for explaining a preferable example of practical use of the information storage element of the present invention. 10: a transparent substrate, 20: a transparent electrode film, 21: a metal electrode (which constitutes one of a pair of electrodes together with the transparent electrode film 20), 30: a photoelectric conversion layer, 40: a memory holding layer, 50 …… Electrode

Continuation of the front page (72) Inventor Shunsuke Fujita 1-3-6 Nakamagome, Ota-ku, Tokyo Examiner in Ricoh Company Ltd. Jun Miyajima (56) References JP-A-62-183093 (JP, A)

Claims (1)

(57) [Claims] The information can be electrically stored by inputting information by light, and the stored information content can be read out as a time-series electrical signal by sweeping with a reading light beam.
An information storage element capable of erasing the stored optical information content and returning to the state before storage, comprising: a photoelectric conversion layer for photoelectrically converting an optical input; and a photoelectric conversion layer provided in contact with the photoelectric conversion layer; A storage layer for storing the photoelectric conversion state as an electrical state, and a pair of transparent electrodes provided to sandwich the photoelectric conversion layer and the storage layer. The information storage element, wherein the storage holding layer is configured as a composite layer including an electric insulating layer.