JPH03263633A - Device and method for recording/reproducing/erasing - Google Patents

Abstract

PURPOSE:To reduce time required for erasing and to facilitate high-speed response with respect to the erasing of a wide range by providing a recording medium having a substrate electrode, a photoconductive thin film and a recording area where charge can be accumulated and a probe electrode. CONSTITUTION:The recording medium 14 consisting of a photoconductive thin film layer 10 formed on the substrate electrode 9 and a recording layer 13 where the charge can be accumulated, a light irradiation mechanism 16 which irradiates the medium 14 and the probe electrode 5 are provided. That means, by using a photoconductive thin film structure 10 for the supporting body of the recording area 12 where the charge can be accumulated and irradiating it with light, the conductivity of the thin film 10 is temporarily enhanced., Besides, by discharging the accumulated charge 15 through the thin film 10 and executing the erasing, an erasing mechanism which can simultaneously execute access for many bits without using a probe 5 is obtained. Thus, many bits can be simultaneously erased and reproducibility with respect to the erasing of the large quantity of data is enhanced. Besides, the high-speed response of the erasing operation is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording/reproducing device having a high-density recording capacity and an erasing function, and a recording/reproducing/erasing method.

More specifically, recording is performed by accumulating charges on the photoconductive layer, the amount of charge is detected as a current value or voltage value using a probe electrode, and the recorded information is reproduced. The present invention relates to a recording/reproducing device and a recording/reproducing/erasing method in which accumulated charges are discharged and erased by irradiating the photoconductive layer with light.

[Prior Art] In recent years, the uses of memory elements and memory systems are as follows:
It forms the core of the electronics industry, covering a wide range of products such as computers and related equipment, video discs, and digital audio discs. Generally speaking, the performance required of a memory system is 1) large capacity and small volume, 2) fast response speed for recording and playback, 3) low error rate, 4) low power consumption, and 5) high productivity and low price. Examples include cheap. Traditionally, magnetic memories and semiconductor memories have been the mainstream, but with the recent advances in laser technology, optical memory devices using inexpensive, high-density recording media have appeared. However, as the use of computers for home use and the information industry centering on images progress in the future, it is desired to realize memory devices or methods with even larger capacity and smaller volume.

On the other hand, in recent years, a scanning tunneling microscope (hereinafter abbreviated as STM) that can directly observe the electronic structure of surface atoms of a conductor has been developed (G, B1nn1g et al.).

Phys, Rev. Lett, 49 (1982)
57), it has become possible to measure real space images of both single crystal and amorphous materials with extremely high resolution (nanometers or less). STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal probe and a conductive substance and the probe is brought close to a distance of about 1 nm. This current is very sensitive to changes in the distance between the two, and by scanning the probe while keeping the tunneling current constant, it is possible to draw the surface structure in real space. Analysis using STM is limited to conductive materials, but it is also beginning to be applied to structural analysis of thin insulating films formed on the surfaces of conductive materials. Furthermore, since such devices and means use a method of detecting minute currents, they also have the advantage of being able to perform observations without damaging the medium and with low power. It is also possible to operate in the atmosphere.

For this reason, wide-ranging applications of STM are expected, and in particular, efforts are being made to put STM into practical use as a reproducing device that reads out information written in a sample with high resolution. For example, Kuwait et al. at Stanford University used an STM probe to inject charges into the interface of an insulator layer by applying a voltage ("recording"), and detecting such charges by a tunnel current flowing through the probe ( "Regeneration") method (C
.

F., Kuwait, U.S. Pat. No. 4,575,822).

Using such a method, it is possible to easily realize a memory device with extremely high density.

Specifically, the following methods and procedures are used. For example, a recording medium including a silicon oxide film layer formed on a conductive silicon semiconductor substrate doped with impurities and a silicon nitride film layer formed on the silicon oxide film layer is suitable for the invention.

That is, a probe electrode is brought into contact with the silicon nitride film layer,
By applying a voltage between the probe and the substrate, a desired voltage is applied to the insulating layer, and as a result, electrons tunnel through the insulating layer and charges are accumulated at the interface in the insulating layer. 6
(see figure). After that, the probe is removed from the insulation layer surface,
The tunneled electrons remain trapped at the insulating layer interface. To read out the accumulated information represented by the trapped electrons, bring the probe close enough to the silicon nitride layer and the trapped electrons, and simultaneously apply a voltage between the substrate and the probe to create a tunneling current. , change the distance between the probe and the insulator surface.

Normally, the tip bias when reading data is of opposite polarity to the tip bias when recording data.

The measured tunneling current indicates the presence or absence of accumulated charge at the insulator layer interface. At this time, the storage area for 1 bit of data becomes as small as 10-'gm2 in surface area. As a result, the volume of a large capacity memory device of, for example, 100 Mbytes can be reduced to the order of 1 cm'.

In the patent specification, Kuwait et al. state that "disturbances" on the surface of the recording medium formed by physical probes, focused laser beams, electron beams, adhesion of fine particles, etc. are not limited to charge accumulation. It has been shown that information recorded by "physical irregularities or changes in electronic state" can be easily read using tunneling current, but in practical terms, recording density, recording reproducibility, and simplicity are important. For these reasons, there are high expectations for recording using charge accumulation.

[Problems to be Solved by the Invention] However, a problem with the above recording/reproducing method is that it is not easy to erase recorded information. That is, in the erasing process, as in the recording process, it is necessary to bring the probe closer and access each bit one by one. For this reason, the time required for erasure increases in proportion to the amount of erasure, and it is difficult to respond quickly to erasure over a wide range. Furthermore,
It is necessary to apply a bias voltage of opposite polarity to the accumulated charge. In addition, in such situations, voltage values, media,
High controllability is required, including the distance between the probes. Deviation from the optimum conditions causes insufficient erasing or new accumulation of charges of opposite polarity. Therefore, an erasing mechanism and method that can access multiple bits simultaneously without using a probe is desired.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a recording/reproducing apparatus and method that overcomes the above-mentioned drawbacks of the prior art and facilitates erasing in recording/reproducing technology using charge accumulation that has a remarkable recording density.

[Means and actions for solving the problem] The above purpose is to
This is achieved by the following invention.

That is, the present invention provides a recording/reproducing apparatus comprising a recording medium having at least a base electrode and a photoconductive thin film and a recording area capable of accumulating charge, and a probe electrode for detecting the accumulation of charge. It is.

Further, the present invention is characterized by comprising a recording medium comprising at least a photoconductive thin film layer formed on a base electrode and a recording layer capable of accumulating charges, a light irradiation mechanism for the recording medium, and a probe electrode. This is a recording/erasing device.

Further, the present invention is characterized by comprising a recording medium comprising at least a photoconductive thin film layer formed on a base electrode and a recording layer capable of accumulating charges, a light irradiation mechanism for the recording medium, and a probe electrode. This is a recording, playback, and erasing device.

Furthermore, the present invention uses a probe electrode and a recording medium that has a base electrode and a photoconductive thin film and has a recording area capable of accumulating charges, and applies a voltage between the base electrode and the probe electrode. ,
This is a recording method characterized by recording by injecting charges into a desired recording area.

Furthermore, the present invention uses the recording medium and the probe electrode to apply a voltage between the base electrode and the probe electrode to inject a charge into the recording area, and then performs the recording using the probe electrode. This reproducing method is characterized in that recording is reproduced by detecting the amount of charge in an area.

Furthermore, the present invention uses the recording medium and the probe electrode to perform photoconductive conduction by irradiating a recording area into which charges have been injected by applying a voltage between the base electrode and the probe electrode. This erasing method is characterized by temporarily increasing the conductivity of a magnetic thin film and discharging accumulated charges through the thin film to erase records.

The present invention uses a photoconductive thin film structure as a support for a recording area capable of accumulating charges, and by irradiating the thin film with light, the conductivity of the thin film is temporarily increased and accumulated charges are transferred through the thin film. The present invention provides an erasing mechanism and method that can access multiple bits simultaneously without using a probe by performing erasing by discharging. Details of the invention are described below.

The operating principle of recording and reproducing is to perform recording by injecting carriers (electrons or holes) from a probe electrode into a charge storage region to cause a change in the electronic state or charge state of the region, and to search for such change. It uses needle electrodes to detect changes in current or voltage and reproduce recorded information.

The material for forming the charge storage region may be any material as long as it has a sufficient level density that can be occupied by injected carriers. Such levels do not need to be continuously distributed, and may be trapping levels such as surface or interface levels or impurity levels, and can also be applied to semiconductors and insulators. Moreover, not only inorganic materials but also organic materials can be used. However, materials with high level density are desired in the application of the present invention. Specifically, Au, Ag, Aj! Suitable materials include common conductors such as metals and alloys such as , Cr, and Pt.

Note that it is desirable that the charge storage regions are physically separated. As a result, the spread of charge during recording or storage is restricted, improving recording density, which was previously determined by the size of charge spread, and also significantly improving characteristics against information loss caused by charge diffusion over time. be able to.

Conventionally known techniques can be applied to fabricate a charge storage region consisting of mutually isolated microstructures on the photo-S conductive thin film structure. For example, microelectrodes of nanometer size or less can be easily formed using photolithography technology, which is widely used in semiconductor technology. Also,
By selecting materials, it is possible to employ a method for forming microstructures that does not require buttering.

For example, materials that exhibit an island-like structure when grown on a substrate, such as a deposited Au film (thickness: 10 nm or less), do not require a patterning process and are therefore very suitable for application of the present invention. Alternatively, materials in which molecules or molecular aggregates are arranged in columns or clusters, such as bacteriorhodopsin membranes or inorganic ultrafine particle membranes, generally have high electrical conductivity within molecules or within aggregates, and have high electrical conductivity between molecules or between boundaries. exhibits low electrical conductivity. Therefore, microstructures that are electrically isolated from each other can be easily formed without requiring a patterning process. Furthermore, such materials have high controllability and reproducibility of the size of microstructures, and are extremely suitable for the present invention.

The form of the photoconductive thin film sandwiched between the charge storage region and the base electrode described above is thin enough to allow tunneling current to flow.
It also needs to be uniform. Specifically, the film thickness is desired to be at least 1100 nm or less. More preferably, if the film thickness is 30 nm or less and 0.3 layer m or more, sufficient tunnel current can flow without shorting between the electrodes. Note that the material constituting the thin film and the method of forming the thin film are not limited in any way by the present invention. For example, Si, Ga, and As are typical photoconductive materials.
Alternatively, in addition to inorganic semiconductor materials such as CdSe, CdS, and ZnS, it is possible to apply photoconductive organic compounds, which have a wide variety of types and have a high degree of freedom in material design. Further, the object of the present invention can be achieved by conventionally known thin film forming means such as ordinary vapor deposition, molecular beam epitaxy, sputtering, and coating.

However, in a preferred embodiment of the present invention, such a thin film is constituted by a monomolecular film or a monomolecular cumulative film comprising organic molecules that have both hydrophilic sites and hydrophobic sites and exhibit photoconductivity. Such a monomolecular film or a monomolecular cumulative film has a high degree of order, and is extremely advantageous for application of the present invention in that a uniform, defect-free ultra-thin film can be easily formed. Specifically, the organic molecules include conventionally known organic dye molecules having both a hydrophilic site and a hydrophobic site. Suitable dyes include, for example, cyanine dyes, merocyanine dyes, phthalocyanine dyes, triphenylmethane dyes, azulene dyes, and the like. Furthermore, biomaterials such as chromoproteins such as chlorophyll, rhodamine, and cytochromes can also be applied.

Furthermore, the Langmuir-Prodgett method (abbreviated as LB method) can be cited as a suitable method for forming such an organic film layer. The LB method may be either a vertical dipping method or a horizontal deposition method. In order to increase the yield of tunnel current, it is sometimes required that the film thickness be several nanometers or less and be uniform, but such a configuration can be easily realized using the LB method.

In the present invention, the base electrode may be a conductive bulk (e.g., a metal plate or a semiconductor substrate doped with impurities), or a conductive thin film (e.g., a metal vapor deposited film) formed on a substrate as a support. This can be easily achieved using conventionally known techniques. Furthermore, such a substrate may be made of any material such as metal, glass, ceramics, or plastic material, and biomaterials with extremely low heat resistance may also be used. Such a substrate can have any shape. Although it is preferable to have a flat plate shape, it is not limited to a flat plate shape at all. That is, the LB method has the advantage that a film can be formed in accordance with any shape of the surface of the substrate.

[Example] The present invention will be specifically explained below using Examples.

Mitaninyu The present invention will be explained based on FIG.

After cleaning, the glass substrate 8 (manufactured by Corning Co., Ltd. #
7059) as a support, a base electrode 9/
A recording medium 14 having a laminated structure consisting of a photoconductive thin film 10 and an insulating thin film 11 was formed.

In such a recording medium, a photoconductive thin film 10 and an insulating thin film 1
The interface level existing at the boundary 12 with 1 functions as a charge accumulation region. Furthermore, for the photoconductive thin film 10 and the insulating thin film 11, monomolecular cumulative films produced by the LB method were used. Details of the method for forming the recording medium are as follows.

First, on the glass substrate 8 described above, 5 layers of Cr were deposited as an undercoat layer by vacuum evaporation using a resistance heating method, and then 30 nm of Au was deposited to form the base electrode 9.

Next, a dye monomolecular film was accumulated using the LB method to form a photoconductive layer 10. That is, an azulene dye derivative (specifically, squarylium bis-6-octyl azulene) is dissolved in a benzene solvent at a concentration of 1 mg/mf, and then spread on an aqueous phase consisting of pure water at a water temperature of 17°C. A monomolecular film was formed on top. After waiting for the benzene solvent to be removed by evaporation and increasing the surface pressure to 25 mN/m, the substrate on which the base electrode was formed was moved across the water surface at a speed of 5 mm/m while keeping the surface pressure constant. Soak gently at min. Subsequently, the film was gently pulled up at 5 mm/min to produce a two-layer Y-type monomolecular cumulative film. This operation was repeated as appropriate to form a monomolecular cumulative film of 2.4.6.8 layers of azulene dye derivative (film thickness per IN, 1.5
nm) was obtained.

Furthermore, an insulating monomolecular cumulative film 11 is laminated using araxic acid molecules, and a charge storage region 1 is formed at the interface with the photoconductive layer.
2 was formed. The accumulation of the araxic acid film was performed by the LB method similarly to the azulene dye film described above, and at this time, the water temperature was 17° C. and the surface pressure was 25 mN/m. However, chloroform was used as the developing solvent, and the cumulative speed was 10 mm/m.
in, and the calendar number was 2 layers (film thickness, 5.5 layers m).

For the recording medium 14 manufactured as described above, STM
When recording/reproducing was attempted using this, the results shown in Table 1 below were obtained. That is, as a recording operation, charge injection is carried out by applying a pulse voltage of 5 cm and 200 ns between the probe 5 and the base electrode 9 with the probe electrode 5 of the STM sufficiently close to the recording medium. Ta. Next, after the probe was once moved away from the recording site, the probe was brought close to the recording medium again as a reproduction operation and scanned in a direction parallel to the surface of the recording medium. As a result, it was confirmed that the tunnel current flowing between the base electrode and the probe increased in the region 15 where charge was accumulated first. Specifically, it has been revealed that when the bias voltage during reproduction is set to 100 mV, the tunnel current increases from twice to several tens of times in the region where the recording operation (pulse voltage application) is performed. Regarding the recording medium having two layers of monomolecular cumulative films, there was a tendency for recorded information to disappear over time (for example, by being left day and night).

Next, as an erasing operation, the above-mentioned recording medium was irradiated with light 16 having a center wavelength of about 650 nm from above. After this operation, when we brought the probe close again and observed the charge accumulation, it was confirmed that the previously accumulated charge had disappeared in the area irradiated with light, indicating that information had been erased. It became clear. The above results are also shown in Table 1.

Note that even if the above operation was repeated, the probe could be brought close to the recording surface without destroying the recording layer, and recording, reproduction, and erasing could be easily performed.

Table 1 Cumulative number of monomolecular film layers Recording/reproducing characteristics Erasing characteristics○
△ 0 0 0 0 ◎ ◎ In the same manner as in Example 1, a glass substrate 8 (#
7059) A recording medium having a laminated structure consisting of base electrode 9/photoconductive thin film 10/metal thin film 17 was formed thereon. An outline of the structure is shown in Figure 2.

As the photoconductive thin film 10, a monomolecular cumulative film of a phthalocyanine derivative (specifically, t-butyl/copper phthalocyanine) was used. Details of the method for producing such a monomolecular cumulative film are as follows.

Powdered phthalocyanine derivative at a concentration of 0.2 mg/mj
! It was dissolved in a chloroform solution and developed on an aqueous phase at a water temperature of 20°C to form a monomolecular film on the water surface. After waiting for the solvent to evaporate and remove, the surface pressure of the monomolecular film was increased to 20 mN/m, and then, while the surface pressure was kept constant, the substrate on which the base electrode was deposited was moved at a speed of 1.0 mm in the direction across the water surface. Two layers of Y-type monolayers were accumulated on such substrates by gently dipping for 5 mm and then gently pulling for 7 minutes. Accumulate operation 4
By repeating this process several times, an eight-layer monomolecular cumulative film was formed on the substrate.

On the other hand, Au was used for the metal thin film, which was vacuum evaporated using the usual resistance heating method (substrate temperature: room temperature, growth rate: 0.2 layer m/m).
Deposition on the photoconductive thin film 10 was carried out by s). However, at this time, the film thickness was as thin as 5 layers (as a result of control,
An island-shaped metal microstructure 17 was obtained as a metal thin film.

A boundary 18 exists between the microstructures, and the microstructures that are electrically isolated from each other function as charge storage regions. As mentioned above, by physically dividing the charge storage area, the spread of the charge during recording or storage is restricted, and the recording density, which was conventionally limited by the charge oxidation size, can be improved. Further, it is possible to significantly improve characteristics against information loss caused by charge diffusion over time.

Example 1
Recording and playback using STM was attempted in the same manner as above. As a result, the probe could be easily brought close to the recording surface without destroying the recording medium or the recording area, and recording could be performed more easily. When the probe was once moved away from the recorded area and the recorded area was recorded and reproduced again, it was possible to easily perform the reproduction. Furthermore, as in Example 1, it was confirmed that accumulated charges could be erased by light irradiation.

When the recording medium was observed using a scanning electron microscope, the size of each recording region (Au island electrode) was approximately 30 nm or less in diameter, and the smallest recording region was several nanometers in diameter. Ta. Approximately 10-'pm in terms of area
'', it can be seen that the recording density is improved by more than an order of magnitude compared to the recording/reproducing device by Kuwait et al., described above, despite the simpler method of forming the recording medium.

Of the 11 recording media of Example 1, the recording medium with a monomolecular cumulative film history number of 4 was subjected to recording/reproduction using the STM shown in the block diagram shown in FIG. 4 and by the light shown in FIG. 3. I deleted it. The details are as follows.

The recording medium 14 described above was fixed on the XY stage 32. The XY stage is moved approximately 0.1 pm by the coarse movement mechanism 31.
It can move horizontally up to 2mm with an accuracy of . After selecting an arbitrary area on the recording medium, the probe electrode 5 was brought roughly close to the recording medium 14 using the coarse movement mechanism 28 in the Z direction. Furthermore, using the servo circuit 25, the probe is brought close to the surface of the recording medium to a distance of 1 nm or less, and under such conditions, a pulse voltage of 5 V and 200 ns is applied to the probe electrode to inject charge into the recording layer 13. This was a recording operation.

Next, after moving the probe away from the recording site, the probe was brought close to the recording medium again as a reproduction operation and scanned in a direction parallel to the surface of the recording medium, and the value of the tunneling current flowing through the probe at this time was recorded. I read out the data. As a result, it was confirmed that the tunnel current flowing between the base electrode and the probe increased in the region 15 (FIG. 3) where charge was accumulated first. Specifically, when the bias voltage during reproduction was set to 100 mV, it was confirmed that the tunnel current increased by about one order of magnitude at the recording site (the position where the pulse voltage was applied).

Next, an erasing operation was performed. Specifically, about 4 cr is placed on the recording medium that remains fixed on the STM's XY stage.
Light 22 from a red LED 20 installed above was irradiated. At this time, L is set so that the entire recording medium is uniformly irradiated.
A milky white scattering plate (70% transmittance) 2 between the ED and the recording medium
] has been established. After this operation, the light irradiation device was removed, the probe 5 was brought close again, and the charge accumulation on the recording medium was observed, and it was confirmed that the previously accumulated charge had disappeared. In other words, it has become clear that already recorded information is erased by light irradiation.

By repeating the above operations, the probe could be brought close to the recording surface without destroying the recording layer, and recording, reproduction, and erasing could be easily performed.

Example 1 Recording and erasing of data was attempted on the recording medium produced in Example 2 in the same manner as in Example 3. A block diagram of the apparatus used is shown in FIG. The difference from Embodiment 3 is that the light irradiation 36 uses the output light of a semiconductor laser 34 (center wavelength ~ 65 pm), which is passed through a collimator 35 and narrowed down to a beam diameter of about 1 pm.
0 nm, output approximately 4 mW). By irradiating from diagonally above, light irradiation could be performed without removing the probe or the like. As for the recording operation, as in Example 1, the probe could be easily brought close to the recording surface without destroying the recording medium or the recording area, and charge could be easily accumulated by applying a voltage ( (confirmed by playback operation). Furthermore, when light irradiation was performed using the above-mentioned apparatus, it was found that the accumulated charge disappeared, and recording and erasing could be performed easily even in such an apparatus.

In this example, the irradiation area was limited by the spot shape, that is, the beam diameter, but with the light source fixed,
By moving the XY stage 32 on which the recording medium 14 is placed in the horizontal direction, it is easy to scan the light irradiation area and irradiate a wide range of light. in particular,
This purpose can be achieved using the STM horizontal coarse movement mechanism 31. In other words, the STM coarse motion and coarse motion drive systems installed horizontally are not limited to the linear actuator shown in this embodiment, but generally have a resolution on the order of 0.1 gm or less.
It has high precision and is ideal as a mechanism for moving the recording medium relatively and scanning the light beam. Further, since there is no need to separately provide a scanning mechanism, when a recording device and an erasing device are installed together, it is possible to easily realize the mechanism and the entire system without complicating or increasing the size.

However, in cases where it is necessary to perform 37M recording and optical erasing simultaneously and asynchronously, it is necessary to provide an optical scanning mechanism independent of the coarse movement mechanism for STM, and specifically, to use a conventionally known mirror. The object of the present invention can be achieved by using a light beam scanning system or the like. The scanning mechanism and method do not limit the present invention in any way.

[Effects of the Invention] According to the present invention, it has a simple erasing mechanism and has a high density (
It is possible to provide a recording/reproducing device capable of recording data of io-' to 10-6 μm2/bit). In addition, it is possible to erase multiple bits simultaneously, improving reproducibility when erasing large amounts of data, and enabling high-speed response to erasing operations.

Further, the recording/reproducing/erasing device of the present invention does not require complicated patterns or matrix circuits that are normally used in semiconductor memories, and is therefore suitable for downsizing not only the recording medium but the entire device.

Furthermore, since it is possible to use inexpensive organic materials for the recording medium and the manufacturing process is simple, it has a significant economic effect.

[Brief explanation of drawings]

FIG. 1 shows the recording and recording method of the present invention using a recording medium having an insulating thin film/photoconductive thin film interface as a recording area and having a photo-erasing mechanism.
A schematic diagram of a reproducing/erasing device; FIG. 2 is a schematic cross-sectional diagram of a recording medium used in the present invention in which a grain-shaped upper fine electrode is used as a recording region; FIG. 3 is a diagram of erasing by irradiating light from an LED. A schematic diagram of the recording/reproducing/erasing device of the present invention, FIG. 4 is a block diagram of the STM used as the recording/reproducing device, and FIG. 5 is a block diagram of the recording/reproducing device including an erasing device using a laser beam. , FIG. 6 is a schematic diagram of a conventional device for recording and reproducing by accumulating charges at the interface of an insulating film of a heterostructure. Figure 4 23 Ficroconipiuta 2!

Claims (16)

[Claims] (1) A recording/reproducing device comprising a recording medium having at least a base electrode and a photoconductive thin film and a recording area capable of accumulating charge, and a probe electrode. (2) The recording/reproducing device according to (1), wherein the charge storage regions are composed of mutually isolated fine structures. (3) The recording/reproducing apparatus according to (1), further comprising a mechanism for controlling a three-dimensional relative distance between the recording area and the probe. (4) The recording/reproducing apparatus according to claim 1, further comprising a mechanism for applying a bias voltage between the base electrode and the probe. (5) Claim (3) further comprising a mechanism for detecting and controlling the distance between the electrode and the probe or between the recording area and the probe from the magnitude of the current flowing between the base electrode and the probe when a bias voltage is applied. ) or the recording/playback device described in (4). (6) Claim (1) wherein the photoconductive thin film is made of an organic material.
) The recording/playback device described in . (7) The recording/reproducing device according to (6), wherein the organic thin film has a thickness of 30 nm or less. (8) The recording/reproduction according to claim (6) or (7), wherein the organic thin film is constituted by a monomolecular film or a monomolecular cumulative film of an organic compound having at least a hydrophilic site and a hydrophobic site. Device. (9) The recording/reproducing device according to (2), wherein the recording area is made of a vapor-deposited metal thin film exhibiting an island-like structure. (10) The recording/reproducing device according to (2), wherein the recording area is made of a polycrystalline or microcrystalline medium having a grain structure. (11) A recording medium comprising at least a photoconductive thin film layer formed on a base electrode and a recording layer capable of accumulating charge, a light irradiation mechanism for the recording medium, and a probe electrode. Recording/erasing device. (12) A recording medium comprising at least a photoconductive thin film layer formed on a base electrode and a recording layer capable of accumulating charge, a light irradiation mechanism for the recording medium, and a probe electrode. Recording/playback/erasing device. (13) Using a probe electrode and a recording medium that has at least a base electrode and a photoconductive thin film and a recording area capable of accumulating charges, a voltage is applied between the base electrode and the probe electrode to perform desired recording. A recording method characterized by recording by injecting charge into an area. (14) Using a probe electrode and a recording medium that has at least a base electrode and a photoconductive thin film and a recording area capable of accumulating charges, charge is generated by applying a voltage between the base electrode and the probe electrode. A reproducing method characterized in that recording is reproduced by detecting the amount of charge in the injected recording region using a probe electrode. (15) Using a probe electrode and a recording medium that has at least a base electrode and a photoconductive thin film and has a recording area capable of accumulating charges, charges are generated by applying a voltage between the base electrode and the probe electrode. Erasing is characterized by temporarily increasing the conductivity of the photoconductive thin film by irradiating the recording area injected with light, and discharging the accumulated charge through the thin film to erase the record. Method. (16) Using a probe electrode and a recording medium that has at least a base electrode and a photoconductive thin film and a recording area capable of accumulating charges, a voltage is applied between the base electrode and the probe electrode to perform desired recording. Recording is performed by injecting a charge into the area, reproduction is performed by detecting the amount of charge using a probe, and the conductivity of the photoconductive thin film is temporarily increased by irradiation with light. A recording/reproducing/erasing method characterized by erasing by discharging accumulated charges through such a thin film.