JP2866909B2 - Information storage element and information storage method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an information storage element and an information storage method.

[Prior Art] The inventors have previously proposed an information storage element in JP-A-63-34797.

[Problem to be Solved by the Invention] In the information storage element, the electric capacitance C of the entire element other than the portion where light irradiation for reading is performed at the time of reading information exists. This electric capacity C is relatively large in the information storage element, and can be a negative factor when the information storage element is enlarged. For example, since the electric capacity C is for the entire element, the larger the area of the information storage element is, the larger the capacitance is. Then, when the electric capacity C increases, the quickness of response at the time of storing and reading information decreases.

Further, the inventors have proposed an optical image information-to-electric signal conversion element in Japanese Patent Application Laid-Open No. 62-139481.

This optical image information-to-electric signal conversion element is, as the name implies, an element for converting an optical image into an electric signal,
According to the technical content disclosed in the above-mentioned publication, information conversion involves simultaneous irradiation of optical image information and conversion to an electrical signal, and the information storage capability of the optical image information-to-electric signal conversion element itself is a problem. And not. However, the element does not have information storage ability at all. Considering a very short time, for example, on the order of msec, the element has the storage ability within this short time, and therefore, the optical image information-to-electrical signal conversion element also uses this as a so-called temporary element. It can be used as a memory and can be called an information storage element in this sense. When the optical image information-to-electrical signal conversion element is considered as an information storage element, there is still a problem due to the electric capacitance C described above.

Further, in the case of the information storage element disclosed in Japanese Patent Application Laid-Open No. 63-34797, reading of information is possible at any time. However, when new information is stored in the information storage element in which information is stored, the same applies. In the information storage method disclosed in Japanese Patent Application Laid-Open Publication No. H10-157, an erasing procedure is required in advance, and it is necessary to temporarily return the information storage element to an initial state without information storage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to firstly solve the above-mentioned problem of electric capacity and reduce the speed of response in information storage and reading. Secondly, the present invention provides an information storage element having a large area without any problem. Secondly, the information storage element as described above is provided with a new information storage device without performing a procedure for previously erasing previously stored information. Another object of the present invention is to provide a new information storage method capable of storing value information.

[Means for Solving the Problems] Hereinafter, the present invention will be described.

The information storage element according to the present invention is capable of inputting and storing information by light and reading out the stored information as a time-series electric signal by sweeping with a reading light beam. And an information storage element capable of erasing stored information contents and returning to the state before storage. "

These information storage elements have "a first layer, a second layer in contact with the first layer, and a pair of electrodes provided in contact with the first and second layers, respectively". .

In the element of claim 1, one of the first and second layers has a function as a photoelectric conversion layer for photoelectrically converting light input, and the other layer has the above-mentioned photoelectric conversion state. It has a function as a storage holding layer for storing as an electrical state.

Further, in the element of the second aspect, the first and the second
Has a function of a photoelectric conversion layer for photoelectrically converting light input and a function of a storage holding layer for storing the photoelectric conversion state as an electrical state.

The “pair of electrodes” is provided so as not to substantially oppose each other with the first and second layers interposed therebetween.

Further, the information storage method of the present invention provides the information storage element according to claim 1 with "sweep of a light beam of a constant intensity, and changing the polarity of a voltage applied to a pair of electrodes in accordance with the sweep of the light beam. Invert according to the binary information to be stored and store the binary information. "

In the device of the first aspect, all of the structures disclosed in JP-A-63-34797 can be used as the first and second layers.

Further, all the photoelectric conversion structures such as photodiodes, photoconductors, and photocapacitors described in JP-A-62-139481 can be used as the first and second layers in the device of claim 2. . In this case, the first and second layers each perform any of the functions of the photoelectric conversion layer and the storage holding layer according to the combination of the respective layer configurations or the respective states of writing, reading, and erasing, Alternatively, the functions of the photoelectric conversion layer and the information storage layer are performed together.

[Function] Information storage element disclosed in JP-A-63-34797, JP-A-62-139
In the optical image information-to-electrical signal conversion element disclosed in Japanese Patent Publication No. 481, the electric capacitance C of the entire element, which is a problem, is such that a pair of electrodes sandwiches two layers having the functions of a photoelectric conversion layer and a storage layer. From where they are opposed to each other, they become quite large.

Therefore, in the information storage element of the first and second aspects, the pair of electrodes are provided so as not to substantially oppose each other across the first and second layers. "Substantially no opposition" means that even if there is a portion where the electrode pair actually opposes the first and second layers, the electric capacitance formed by the opposing area is sufficient to store and read information. Means that it is so small that it does not pose a problem for the response at the time.

In the case where binary information is stored in the information storage element according to claim 1, "a light beam having a constant intensity is swept, and the polarity of a voltage applied to a pair of electrodes in accordance with the sweep of the light beam is defined as: Invert according to the binary information to be stored,
When the storage of the value information is performed, the presence or absence of charge storage or the polarity distribution of the stored charge occurs in the storage holding layer according to the layer structure, which is caused by the information storage element before that. Irrespective of the state of

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

In FIG. 1 showing one example of the information storage element of claim 1, reference numeral 10 denotes a light-transmitting substrate. On one surface of the substrate 10, a photoelectric conversion layer 30 and a storage layer 40 are laminated as shown in the figure, and further, an electrode 20 is provided on the exposed surface of the photoelectric conversion layer 30, and a surface of the storage layer 40 is provided. Is provided with an electrode 50. The electrodes 20, 50 need not be translucent. In the present specification, when a member such as a substrate is referred to as “translucent”, this means that the member is transparent or substantially transparent, that is, the member is used at the wavelength used. Is such that the light does not cause any problem in terms of the intended use. "

The photoelectric conversion layer 30 is a layer made of a photoconductive material such as amorphous silicon. The storage layer 40 is a two-layer insulating film.
For example, the insulating layer 41 is an SiO ₂ layer thin enough to allow a tunnel current to flow, and the insulating layer 42 is several hundred
Is a silicon nitride layer having a thickness of

Light L for storing, reading, and erasing information is emitted from the substrate 10 side. When the information storage element is swept by the light L, the sweep is performed in a direction orthogonal to the drawing of FIG.

The light L is irradiated in the left-right direction of FIG. 1 with a width enough to irradiate the electrodes 20 and 50 simultaneously.

In this case, the overlapping portion of the light L and the electrode 50 becomes the actual storage area, and therefore, it is desirable to increase the area of the overlapping portion.

When a voltage is applied between the electrodes 20 and 50 to irradiate the light L, a low impedance or low impedance is generated in the photoelectric conversion layer 30 and an additional voltage is generated. To generate an electric field. By utilizing the action of the electric field, information can be stored, read, and erased.

At this time, the electrode 20 may be provided between the photoelectric conversion layer 30 and the substrate 10, as shown in FIG. In addition, in order to reduce a leakage current that may be generated mainly on the side surface of the edge of the storage layer 40 when the light L is irradiated, the electrode 50 is separated from the storage layer 40 as shown in FIG. 4 (III), the one insulating film 41 of the memory holding layer 40 is formed larger than the other insulating film 42, or
These methods shown in FIGS. 4 (II) and (III) may be combined.

For the purpose of preventing photoelectric conversion at the edge of the photoelectric conversion layer 30, as shown in FIG. 4 (IV), light shielding means 91 and 92 may be provided at the edge, or as shown in FIG. As shown in ()), it is also effective to provide an insulating film 80 at the laminated end of each layer.

In the portion where the light L is not irradiated, the photoelectric conversion layer 30 is in a high impedance state, so that the electric capacity between the electrodes 20 and 50 is small.
Can be reduced.

When comparing the embodiment described above with the information storage element disclosed in JP-A-63-34797, the following advantages are obtained in addition to the above-mentioned electric capacity. That is, in the case of the information storage element of the above embodiment,
Since a light-transmissive electrode that requires a technique for low-resistance and uniform film formation is not required, production is easy accordingly.

FIG. 2 shows another embodiment of the present invention.
Those which are not likely to be confused are denoted by the same reference numerals as in FIG.

In this embodiment, a photoelectric conversion layer 30 and a storage holding layer 40 are provided on one surface of a substrate 11 as in the embodiment of FIG. , Electrodes 20 and 51 are provided. In this example,
Irradiation of light L for reading and erasing is performed from the side where the photoelectric conversion layer 30 and the memory holding layer 40 are stacked. For this reason, the substrate 11 and the electrode 20 are not required to have a light-transmitting property.
51 must be translucent. Note that the electrode 20 may be provided between the photoelectric conversion layer 30 and the substrate 11.

When the information storage element is swept by the light L, the sweep is performed in a direction orthogonal to the drawing of FIG.

The light L is radiated in the left-right direction in FIG. 2 with a width sufficient to irradiate the electrodes 20 and 51 simultaneously. Also in this embodiment, the overlapping portion of the light L and the electrode 51 becomes the actual storage area, and therefore, it is desirable that the area of the overlapping portion be large.

In order to prevent leakage current from the side surface of the edge of the storage layer and to prevent photoelectric conversion at the edge of the photoelectric conversion unit,
The effectiveness of the method shown in each figure is the same as that of the embodiment shown in FIG.

In this embodiment, of course, the capacitance C can be reduced. Compared with the embodiment shown in FIG. 1, since the substrate 11 does not need to have a light-transmitting property, the choice of the substrate material is wider.

FIG. 3 also shows an embodiment of the first aspect of the present invention. In this embodiment, the electrodes 21 and 51 are formed separately from each other on the substrate 11, the storage layer 40 is stacked on the electrode 51, and the photoelectric conversion layer 30 is formed on the storage layer 40 and the electrode 21. The structure is provided.

In this example, irradiation of light L for storage / read / erase is performed from the photoelectric conversion layer 30 side. For this reason, the substrate 11 and the electrodes 21 and 51 are not required to have translucency.

When the information storage element is swept by the light L, the sweep is performed in a direction orthogonal to the drawing of FIG.

The light L is irradiated in the left-right direction of FIG. 3 with a width enough to irradiate the electrodes 21 and 51 simultaneously. Since the overlapping portion of the light L and the electrode 51 becomes the actual storage area, it is desirable to increase the area of this overlapping portion.

In order to prevent leakage current from the side surface of the edge of the storage layer and to prevent photoelectric conversion at the edge of the photoelectric conversion unit,
The effectiveness of the method shown in each figure is the same as that of the embodiment shown in FIGS.

In this embodiment, of course, the capacitance C can be reduced. Compared with the embodiment shown in FIG. 1, since the substrate 11 does not need to have a light-transmitting property, the choice of the substrate material is wider.

Regarding the photoelectric conversion layer and the storage layer in the three embodiments described above, all the photoelectric conversion layers and storage layers disclosed in JP-A-63-34794 can be used.

Further, as described above, all the photoelectric conversion structures such as photoconductors and photocapacitors disclosed in JP-A-62-139481 can be used as the first and second layers of the invention of claim 2. Comes. In this case, the first
And the second layer performs the function of one or both of the photoelectric conversion layer and the storage holding layer, depending on the combination of the respective layer configurations and the respective states of storage / read / erase. Also,
In this case, the time from information storage to reading is several milliseconds
In short, the erasing of the stored contents is performed with the passage of time or performed by a new information writing operation.

Therefore, in the embodiment shown in FIGS. 1 to 3, the photoelectric conversion layer and the memory holding layer are replaced by the above-mentioned "photoelectric conversion structure portion", whereby the embodiment of claim 2 is obtained.

The embodiment shown in FIGS. 1 to 3 is a one-dimensional information storage element, and irradiates a light image one-dimensionally or sweeps a light beam in a direction perpendicular to these drawings. These elements are two-dimensionally arranged, that is, arranged in the horizontal direction in FIGS. 1 to 3, and the light beam is swept two-dimensionally. Needless to say, storage or the like may be performed.

The method of storing information in the information storage element according to claim 1 is basically the method described in Japanese Patent Application Laid-Open No. 63-34794. That is, in the example of FIG. 1, while applying a constant voltage between the electrodes 20 and 50, the light beam modulated according to the information to be stored is swept, so that a portion where photoelectric conversion is caused is generated. Charges are stored in the corresponding storage layer, and information is stored by the presence or absence or change of the charge storage amount.

For this reason, when storing new information in an element in which information has already been stored, once in the case of the above storage method, once,
An erasing operation of removing the electric charge accumulated in the storage holding layer and returning the information storage element to an initial state was required.

Japanese Patent Application Laid-Open No. 63-34794 also discloses another method of modulating the voltage applied to a pair of electrodes according to the information to be stored while sweeping a light beam of constant intensity. The same applies to this case.

According to the third aspect of the present invention, the information to be stored is “1” “0”
In the case of binary information as described above, the voltage applied between the electrodes is polarity-modulated by the information while sweeping a constant intensity light beam to the information storage element.

FIG. 5 shows an embodiment of the third aspect of the present invention.
Reference numeral 100 indicates an information storage element according to the first aspect of the present invention.
Specific examples of this information storage element 100 are shown in FIGS.
This is described with reference to the drawing. Reference numerals 20a and 50a indicate electrodes provided in contact with the first and second layers of the information storage element. Through the polarity modulation means 200 between these electrodes,
An AC voltage is applied from an AC power supply 300, and a binary information signal is input to the polarity modulation means 200 while sweeping the information storage element 100 with a light beam LB having a constant intensity.

According to the input signal “1” or “0”, the electrodes 20a,
The polarity of the voltage applied during 50a is inverted. At this time, since the portion of the photoelectric conversion layer irradiated with the light beam LB is in a low impedance state, charge injection occurs in the storage holding layer in contact with the photoelectric conversion layer portion, and the charge is injected according to the binary information. As a result, the presence or absence of accumulated charges or the polarity of the accumulated charges is positive or negative.

Since this state is forcibly generated in accordance with the polarity of the applied voltage, it can be realized irrespective of the previous storage state. Therefore, so-called overwriting of information is possible. Incidentally, the method of claim 3 can be applied to all of the information storage elements disclosed in Japanese Patent Application Laid-Open No. 63-34794 unless the problem of the responsiveness caused by the capacitance C is considered.

[Effects of the Invention] As described above, according to the present invention, a novel information storage element and information storage method can be provided.

When the information storage element performs the storage and readout of information in time series as described above, the response of storage and readout is fast because the electric capacity of the entire element other than the part where the storage and readout operation is performed is small, and the operation of the information storage element is fast. Speeding up becomes possible. In addition, the information storage method allows so-called overwriting, so that the means and time for erasing the stored information can be omitted, and the applicable range of the element can be expanded.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining one embodiment of the invention of claim 1, FIG. 2 is a diagram for explaining another embodiment of the invention of claim 1, and FIG. FIG. 4 is a diagram for explaining another embodiment of the first invention, FIG. 4 is a diagram for explaining a modification of the embodiment of the first invention, and FIG. 5 is an embodiment of the third invention. It is a figure for explaining an example. 10 ... substrate, 20,50 ... electrode, 30 ... photoelectric conversion layer, 40 ...
… Memory retention layer

Continuation of the front page (51) Int.Cl. ⁶ identification symbol FI H04N 5/335 H01L 31 / 10Z (56) References JP-A-63-34797 (JP, A) JP-A-62-139481 (JP, A) JP-A-2-262761 (JP, A) JP-A-2-29763 (JP, A) JP-A-2-29354 (JP, A) JP-B-54-22060 (JP, B2)

Claims (3)

(57) [Claims] An information can be input and stored by light, and the stored information can be swept by a light beam for reading.
Can be read out as a time-series electrical signal, and
An information storage element capable of erasing stored information content and returning to a state before storage; a first layer, a second layer in contact with the first layer, and a first layer and a second layer. A pair of electrodes provided in contact with each other; one of the first and second layers has a function as a photoelectric conversion layer for performing photoelectric conversion of a light input, and the other has a function of converting the photoelectric conversion state into an electrical state. An information storage element having a function as a storage holding layer for storing a target state; wherein the pair of electrodes do not substantially face each other across the first and second layers. 2. Information can be input and stored by light, and the stored information content can be swept by a reading light beam.
Can be read out as a time-series electrical signal, and
An information storage element capable of erasing stored information content and returning to a state before storage; a first layer, a second layer in contact with the first layer, and a first layer and a second layer. A pair of electrodes provided in contact with each other; the first and second layers function as a photoelectric conversion layer for photoelectrically converting a light input and storage for storing the photoelectric conversion state as an electrical state. An information storage element having both functions as a holding layer; and the pair of electrodes do not substantially oppose each other across the first and second layers. 3. A storage device according to claim 1, wherein a light beam having a constant intensity is swept over the storage element, and the polarity of the voltage applied to the pair of electrodes according to the binary information to be stored in accordance with the sweep of the light beam. Storing the binary information by inverting the binary information.