JPH10283685A - Method for recording and reproducing information and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable recording and reproducing in a high S/N ratio even at a low DC voltage by constituting the electrode layer of a recording medium and the electroconductive part of a recording and reproducing probe in combination of their different work functions and using either of them to be of its smaller work function at the recording time or to be of its larger work function at the reproducing time as a positive voltage respectively. SOLUTION: The recording medium 13 is formed by applying the thin film of a specific organic compound capable of emitting light with an impressed voltage on an electroconductive substrate 11 in a printing method, etc. The electroconductive probe 14 is covered with an electroconductive coat having a different material in work function from the material of the electrode substrate 11. At the time of recording, the smaller work function, for example, the electrode substrate 11 is regarded as the positive electrode, and the pulse voltage of a waveheight value of lower than the voltage of emitting light of the recording medium 13 is impressed upon the recording medium 13 to write information thereon. At the time of reproducing, the larger work function, for example, the electroconductive probe is regarded as the positive electrode, a DC voltage is impressed upon the recording medium 13 to perform the reproducing. An impressed DC voltage value at this time is set lower than a half of the voltage value required for light emission of the recording medium 13, thus enabling detection of a large current in a recording part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and apparatus for recording and reproducing information using a recording medium made of a material which emits light when a voltage is applied.

[0002]

2. Description of the Related Art In recent years, memory materials are used at the center of the electronics industry such as computers and related equipment, video disks, digital audio disks, and the like, and information recording and reproduction are applied to various products.
At present and in the future, memories will be required to have (1) high density and large recording capacity, (2) fast response time for recording and reproduction, and (3) memory.
The specifications are high productivity and low price, and (4) low power consumption. Recently, a scanning tunneling microscope (S) that can directly observe the electronic structure of surface atoms of a conductor
TM) was developed [G. Binnig et al, P
hys. Rev .. Lett. , 49, 57 (198
2)], which has a feature that the resolution in the in-plane direction is about 1 ° or less and that it can observe a real space image of the sample surface in a non-destructive manner, so that it is expected to be widely applied. For example, from the viewpoint of the memory technology described above, it is possible to perform high-density recording and reproduction of information in a molecular order (nm) or less (nm) to an atomic order (several Å). Actually, a method of changing the surface state of an appropriate recording layer using a high energy electromagnetic wave such as an electron beam or an ion beam, or a high energy electromagnetic wave such as an X-ray, or an energy beam such as visible light or ultraviolet light, and recording and reproducing by an STM. Also, there has been proposed a method of recording and reproducing information using an STM using a thin film layer made of a material having a memory effect on switching characteristics of voltage and current as a recording layer.

Further, an atomic force microscope (AFM) has been developed as a means for detecting an atomic force acting between a sample and a probe having a small tip diameter and observing the uneven shape of the sample surface [G. Binnig et al, Phys. Rev ..
Lett. , 56, 930 (1986)], enabling direct observation of the surface shape even when the observation sample is not only a conductor but also an insulator. Since the resolution by AFM is 1 nm or less in the in-plane direction of the sample, fine irregularities are formed at intervals of, for example, about 10 nm on the surface of the sample, and are read out by using the AFM to obtain a high resolution close to 10 ¹² bits / cm ^2. It is also possible to make a density memory.

Further, there has been disclosed an apparatus for observing the surface state of a sample more strictly by simultaneously measuring the conductivity information of the sample by the STM and the unevenness information in the sample surface by the AFM (Japanese Unexamined Patent Application Publication No. Hei. 277903, hereinafter referred to as AFM / STM). This apparatus uses a conductive probe (probe electrode) to detect the displacement of a cantilever caused by an atomic force generated between the probe and the sample surface when the probe approaches the sample surface. Detection (AF
M image), and a device that simultaneously applies a voltage between the probe and the sample to detect a current flowing between the two (STM image). Therefore, for example, while observing the unevenness of the minute portion of the sample with the AFM image, the conductivity information of the minute portion can be simultaneously obtained by the STM image. In addition, there is a proposal of a method and an apparatus for capturing molecules on a recording layer by applying a voltage pulse, selectively recording data bits, and reproducing and erasing the data bits (Japanese Patent Laid-Open No. 1-196551). Gazette).

[0005]

In the above-mentioned recording / reproducing method, for example, when reproducing recorded information, it is necessary to apply a DC voltage to the recording medium. It is preferable to apply as low a DC voltage as possible to prevent damage to the recording medium and the like. Further, in order to reliably reproduce the recorded information, the difference between the output signal from the recorded portion and the output signal from the non-recorded portion (including the background) can be further increased to further improve the S / N ratio. desired.

In order to solve the above-mentioned problems, the present invention increases the difference between the output signal from the recording portion and the output signal from the non-recording portion even when a low DC voltage is applied, thereby increasing S It is an object of the present invention to provide an information recording / reproducing method and a recording / reproducing apparatus capable of further improving the / N ratio.

[0007]

In order to solve the above-mentioned problems, the present invention is characterized in that an information recording / reproducing method and a recording / reproducing apparatus are configured as follows. That is, in the information recording / reproducing method of the present invention, a recording medium in which a recording medium layer made of an organic compound emitting light by voltage application is formed on an electrode layer, and a probe having a conductive portion in the recording medium layer are brought close to each other. In the method of recording / reproducing information for recording / reproducing, the electrode layer of the recording medium and the conductive portion of the probe are formed of different combinations of work functions, and one of the work functions having a smaller work function is set as a positive voltage and the recording is performed. Recording is performed by applying a pulse voltage at an arbitrary position on the medium, and the recorded information is reproduced by using one of the larger work functions as a positive voltage. Further, the information recording / reproducing apparatus of the present invention brings a recording medium in which a recording medium layer made of an organic compound which emits light by voltage application on an electrode layer and a probe having a conductive portion close to the recording medium layer close to each other. In an information recording / reproducing apparatus for recording / reproducing information, the electrode layer of the recording medium and the conductive portion of the probe are configured by different combinations of work functions. Further, the information recording method and apparatus of the present invention is characterized in that the organic compound includes a polymer compound. Further, in the information recording / reproducing method or apparatus according to the present invention, the information recording / reproducing method is preferably such that a layer having a high hole-transporting property is interposed between the electrode layer and the probe conductive portion in a portion having a large work function. It is characterized by. Further, the information recording / reproducing method or apparatus of the present invention is characterized in that a layer having a high electron transporting ability is interposed by bonding to a portion having a small work function of either the electrode layer or the probe conductive portion. Features. Further, the information recording and reproducing method or apparatus of the present invention is a method for bonding to a portion having a large work function of any one of the electrode layer or the probe conductive portion, intervening a layer having a high hole transporting ability, It is characterized in that a layer having a high electron transporting ability is interposed by being joined to a portion having a small work function of either the electrode layer or the probe conductive portion.

[0008]

According to the present invention, as described above, the electrode layer of the recording medium and the conductive portion of the probe are constituted by combinations having different work functions, and one of the work functions having the smaller work function is determined by the positive voltage. By applying a pulse voltage at an arbitrary position on the recording medium to perform recording, and by performing the reproduction of the recorded information as a positive voltage of one of the larger work functions, when reproducing the recorded information, The recorded signal can be reproduced without crosstalk between the output signal from the non-recorded portion (including the background) and the output signal from the recorded portion, and the S / N ratio can be improved. . According to the configuration of the present invention, the DC voltage for reproducing the recorded information is set to a low voltage such as 2 V by applying a low voltage that is half or less of a voltage value necessary for light emission of the recording medium. , The recorded information can be reproduced, and the power consumption of the system can be reduced.

Next, the contents of the present invention will be described in more detail with reference to the drawings. FIG. 1a is an example showing the recording / reproducing method of the present invention. Reference numeral 10 denotes an insulating substrate such as a glass / quartz / undoped silicon wafer. Reference numeral 11 denotes an electrode substrate for directly forming the recording medium 13 thereon. The substrate may be made of any material as long as its surface is conductive and smooth. Metals such as silver, copper, palladium, aluminum, indium, tungsten, tin, lead or alloys thereof; furthermore, graphite or silicide, or even conductive oxides such as ITO, n- or p-doped silicon, etc. Materials. A lead electrode 12 made of the same conductive material as described above is formed on a part of the substrate 11 so that a voltage can be applied to the recording medium 13 as described later. 1 above
As a manufacturing method of 1 and 12, a vacuum evaporation method, a sputtering method, a printing method, or the like can be used. In addition, the surface of the substrate 11 is provided with hydrophobicity or hydrophilicity as required evenly. The method is not particularly limited, but it is preferable to select an optimal method according to the type of the conductive substrate 11 listed above. In the case of imparting hydrophobicity, for example, for a noble metal or metal oxide material, the substrate surface is washed by an appropriate method, and then an amphiphilic substance such as a fatty acid or a derivative thereof is obtained by a Langmuir-Blodgett (LB) method described later. It is achieved by laminating. Especially for gold,
It is also possible to react with a hydrocarbon compound having a thiol group or an amino group at the terminal. When silicon is used, the above LB is used after cleaning the substrate surface by an appropriate method.
There is a method of treating with an amphiphilic substance or a solution containing hydrofluoric acid or the same salt by a method, or treating with a silane coupling agent after the washing. In the case of imparting hydrophilicity,
Ozone ashing, chromic acid mixed solution immersion, etc. are performed.

On the substrate 11, an organic compound which emits light when a voltage is applied as a recording medium 13 is applied as a thin film. Originally, the material of the recording medium 13 is not particularly limited as long as it is an organic compound that emits light when a voltage is applied, but the thin layer breaks at the end face of the electrode shape, or It is preferable to use a polymer compound so that defects such as pinholes do not easily occur in the thin film. For example, [J. Ch
em. Soc. Chem. Commun. , 101
4,1988], and various polymer compounds soluble in a solvent [Appl. Phys. Lett. , 58 , 19
82 (1991), Macromol. Chem. Ph
ys. , 195 , 1933 (1994)]. The coating method is a printing method, a spin coating method, a casting method using a solution or a mixed solution of the material,
Dipping method, bar coating method, roll coating method, LB
Method or the like can be used. The LB method is characterized in that the obtained accumulated film has high uniformity, and that the film thickness can be controlled on the order of one molecule. Further, the material density per unit area is high and uniform. The conditions are mild, a known method or apparatus can be used, and no special modification is required. The thickness of the recording medium 13 is preferably 1 nm to 1 μm, more preferably 1 to 500 nm. In addition, a portion where the thin film is unnecessary such as the drawer portion 12 is subjected to processing such as wiping with a solvent.

In FIG. 1a, a conductive probe 14 is shown.
Forms a conductive coating 15 by a method such as vapor deposition and sputtering. The conductive coating 15 is formed of a material having a work function different from the work function of the material used for the electrode substrate 11. That is, ITO, Pt, A
When a material having a large work function such as u is used, it is preferable to use a material having a small work function, such as Al, Mg, or Ag, alone or as a mixture. Further, when the material having a small work function is used for the electrode substrate, it is preferable to use the material having a large work function as the conductive material covering the probe. Next, the conductive probe 14 is brought close to the surface of the recording medium 13. The proximity method scans a metal probe (probe electrode) while monitoring a tunnel current flowing between the probe and a conductive substance, and can draw a surface structure in a real space. (STM, G. Binnig et al, 1 supra.
982), an atomic force microscope (AFM, Binnig et al., 1986, supra) for observing the shape of the sample surface by detecting the atomic force acting between the sample and the probe, and a composite device (AFM / STM) The direct application of the principle such as that described in Japanese Patent Application Laid-Open No. 3-277903) can provide a positional resolution on the order of nanometers.

Subsequently, a pulse voltage is applied to an arbitrary position on the recording medium 13 through the conductive probe 14.
At this time, for example, when the work function of the electrode 11 is larger than the work function of the conductive probe 14, a voltage is applied to the recording medium 13 with the smaller work function as +. The voltage value may be, for example, a peak value that is equal to or half the emission voltage of the recording medium 13. With the above operation, the voltage application portion becomes conductive in a range of about 10 nm or less in diameter of the tip of the probe, and information is written (recording, 16 in FIG. 1). Subsequently, the probe 13 is scanned on the sample surface in the x and y directions, and the same voltage is applied. in this way,
After the application of the pulse voltage is performed in an appropriate region, a DC voltage is applied to the recording medium 13 by setting the larger work function of the material of the electrode 11 and the conductive portion of the conductive probe 14 to +. The area is rescanned while detecting the output current. The DC applied voltage value at that time may be half or less of the voltage value required for light emission of the recording medium 13. At this time, a large current is detected in the portion where the pulse voltage is applied, but a small current is detected in other recording medium portions, and the portion where information is recorded as described above, that is, the portion 16 shown in FIG. Can be detected with a good S / N ratio, and reproduction can be performed.

Next, a recording / reproducing apparatus using a recording medium manufactured by the manufacturing method of the present invention will be described with reference to the block diagram of FIG. The tip of the probe 54 is provided with a conductive coating 56. The origin position of the probe 54 is determined by the probe displacement detecting means 5.
6 is set. In order to set the range of the atomic force to be measured, the amount of displacement of the probe 54 from the origin estimated from the known spring constant of the cantilever 55 is set.
The amount of displacement at this time corresponds to the atomic force acting between the probe 54 and the recording medium 53. Next, when the measurement is started with the distance between the recording medium 53 and the probe 54 approached, an atomic force is generated between the tip of the probe 54 and the surface of the recording medium 53, and this force causes the entire cantilever 55 to be displaced by bending. . That is, when the recording medium 53 is scanned in the xy directions, an output signal from the probe displacement detecting means 56 (for example, an “optical lever” method) and a feedback signal applied to the piezoelectric actuator 58 are recorded in accordance with the scanning signal. A surface unevenness image (AFM image) is displayed on the display device 510 through the computer 511 based on these signals. This signal is fed back to the servo control means 57. Servo control means 57
In, a drive voltage is applied to a piezoelectric actuator 58 that can be driven in a three-dimensional direction so as to maintain the set displacement amount of the probe, and a feedback operation is performed.

The actual recording / reproduction is performed as follows.
First, the probe 54 scans the xy plane of the recording medium 53.
The computer 51 synchronizes with the AFM signal obtained at this time.
1 to output a pulse application signal at an arbitrary position on the recording medium 53 through a voltage application power supply 512,
Record the information on 4. When reproducing the recorded information, the probe 54 and the conductive substrate 52 are supplied from the voltage application power supply 512.
The area where the recording operation has been performed is scanned while applying a bias DC voltage in between, and the current in the local portion (recording bit) where information has been recorded by the above-described recording operation is detected by the current detecting means 59 through the probe 54. The detected current value is reconstructed by the computer 511 in accordance with the position information of the probe 54, and the minute output is appropriately cut off and displayed on the display device 510 simultaneously with the AFM image.

In the recording medium 13 according to the present invention, for example, when the electrode 21 has a larger work function than the conductive portion 25 of the probe 24, as shown in FIG.
It is also possible to provide a hole transport layer 27 containing a hole transport material between. When the electrode 21 has a smaller work function than the conductive part 25 of the probe 24, FIG.
As described above, a hole transport layer 27 containing a hole transport material can be provided between the recording medium 23 and the probe 24. Further, for example, when the electrode 31 has a large work function as compared with the conductive portion 35 of the probe 34, the electron transport layer 37 containing an electron transport material between the recording medium 33 and the probe 34 as shown in FIG. It is also possible to provide. When the electrode 31 has a smaller work function than the conductive portion 35 of the probe 34, a hole containing an electron transport material is provided between the electrode 31 and the recording medium 33 as shown in FIG. It is also possible to provide a transport layer 37. Further, for example, the electrode 41
Has a larger work function than the conductive portion 45 of the probe 44, a hole transport layer 47 containing a hole transport material is provided between the recording medium 43 and the electrode 41 as shown in FIG. An electron transport layer 48 containing an electron transport material can be provided between the recording medium 43 and the probe 44.
When the electrode 41 has a smaller work function than the conductive portion 45 of the probe 44, the electron transport containing an electron transport material between the electrode 41 and the recording medium 43 as shown in FIG. A hole transport layer 47 containing a hole transport material between the recording medium 43 and the probe 44 at the same time.
It is also possible to provide.

As the above-mentioned electron transporting material or hole transporting material, known materials can be used and are not particularly limited. Examples of the hole transporting material include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives and the like. Can be Examples of the electron transporting material include oxadiazole derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives, fluorenone derivatives, Examples include diphenyldicyanoethylene and its derivatives, diphenoquinone derivatives, and metal complexes of 8-hydroxyquinoline and its derivatives. These may be used alone or as a mixture of two or more. The hole transporting layer 18 and the electron transporting layer 19 are formed by using a solution or a mixed solution of the layer material, by a printing method, a spin coating method, a casting method, a dipping method, a bar coating method, a roll coating method, an LB method or the like. It can be formed using.

[0017]

EXAMPLES Examples of the present invention will be described below, but they do not limit the scope of the present invention in any way. Embodiment 1 FIG. 1 shows the basic configuration of Embodiment 1 of the present invention. The substrate used in this example was prepared according to the following recipe. An undoped silicon wafer having a thickness of 0.5 mm was used as the substrate 10, and Au / Cr was pattern-deposited on the substrate 10 at a thickness of 1000 ° to form electrodes 11 and lead portions 12. Next, the substrate 10 was washed with UV-O ₃ (60 ° C., 3
(0 min), the substrate was mounted on a substrate drive mechanism of an LB film forming apparatus such that the electrode surface was perpendicular to the water surface, and immediately immersed in a pure water phase. Then, octadecylamine (0.3m
g / ml) was dissolved in chloroform, developed on the water surface, compressed to a surface pressure of 20 mN / m, and allowed to stand for 5 minutes while maintaining the surface pressure. Next, the substrate driving mechanism 33 is operated, and the substrate 30 mounted on the
mm / min. As a result, octadecylamine was transferred to the substrate with one layer of hydrophobic group on the outside, and the outermost surface of the substrate could be made hydrophobic.

Next, a solvent-soluble precursor of poly (p-phenylenevinylene) was used [M. Era et al Che
m. Lett. , 1097 (1988)], and 10 layers were accumulated on the substrate 30. Subsequently, the substrate 30 was heated at 200 ° C. for 2 hours under reduced pressure to obtain a poly (p-phenylenevinylene) thin film as a final product.

Next, the substrate with the thin film formed in this embodiment was mounted as a recording medium 53 on the apparatus according to the present invention (FIG. 5). Next, a probe 54 on which Al was vapor-deposited at 500 ° as a conductive coating was brought close to the recording medium 53, and the surface in a 10 μm square area was scanned to evaluate the state of the unevenness. there were. Next, while scanning the probe 54, a voltage pulse shown in FIG.
And recording was performed. After returning the probe 54 to the scanning origin, this time the probe 54 is applied with a DC voltage of 1 V between the recording medium 53 and the probe 54 so as to be on the recording medium side +. Scanning is performed again on the surface 53, the detected current value is reconstructed as an image by the computer 511 together with the position information of the probe 54, and a cut-off of 10 nA (actual measurement value) or less of the detected current value is performed. A current (actual value) of at least 150 nA was observed only in the position where the pulse was applied as described above in a region having a diameter of about 10 nm. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

Second Embodiment A second embodiment of the present invention will be described with reference to FIG. First, a substrate used in this example was prepared with the following recipe. An undoped silicon wafer having a thickness of 0.5 mm was used as the substrate 10, and Al was added to the substrate 10.
The electrode 11 and the lead-out part 12 were formed by pattern evaporation with a thickness of 00 °. Next, the outermost surface of the substrate 10 was hydrophobized according to the prescription described in Example 1. Next, poly (p-
A solvent-soluble precursor of phenylene vinylene) was accumulated in 10 layers on the substrate according to the recipe described in Example 1, and a heat treatment was performed to obtain a poly (p-phenylene vinylene) thin film as a final product. Next, the recording medium 5 is added to the apparatus according to the present invention (FIG. 5).
As No. 3, the substrate with a thin film prepared in this example was mounted.
Next, a probe 54 in which Au was deposited as a conductive coating to a thickness of 500 ° was brought close to the recording medium 53, and the surface in a 10 μm square area was scanned to evaluate the unevenness. Was 1 nm or less.

Next, while scanning the probe 54, a voltage pulse shown in FIG. 6 was applied so that the recording medium 53 side became +, and recording was performed. After returning the probe 54 to the scanning origin, this time the probe 54 is placed between the recording medium 53 and the probe 54.
While applying a DC voltage of 1 V so that the probe 5
4 is rescanned on the surface of the recording medium 53, and the detected current value is reconstructed as an image by the computer 511 together with the position information of the probe 54. As a result, the same result as in the first embodiment can be obtained. Was. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[Embodiment 3] In Embodiment 3, first,
The substrate used in this example was prepared according to the recipe described in Example 1. Next, polyisobutyl methacrylate and N, N'-
Bis (3-methylphenyl) -1,1'-biphenyl-
4-4′-Diamine (TPD) was mixed and dissolved in chloroform at a molar ratio of 1: 1 and 20 layers were accumulated on the substrate by the LB film forming apparatus used in Example 1. Next, 10 solvent-soluble precursors of poly (p-phenylenevinylene) were accumulated on the substrate according to the recipe described in Example 1, and a heat treatment was performed to obtain a poly (p-phenylenevinylene) thin film as a final product. FIG. 2A is a schematic configuration diagram of the substrate and the recording medium in the present embodiment. Thereafter, the recording medium was mounted on the apparatus described in Example 1, and the recording / reproducing operation was performed by the same method as described in Example 1. As a result, the same result as in Example 1 was obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[Embodiment 4] In Embodiment 4, first,
The substrate used in this example was prepared according to the recipe described in Example 2. Next, 10 solvent-soluble precursors of poly (p-phenylenevinylene) were accumulated on the substrate according to the prescription described in Example 1, and a heat treatment was performed to obtain a poly (p-phenylenevinylene) thin film as a final product. Next, according to the formulation described in Example 3, polyisobutyl methacrylate and N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,
4′-Diamine (TPD) was mixed and 20 μm was deposited on the poly (p-phenylenevinylene) thin film substrate already accumulated above.
Layer superposition was accumulated. FIG. 2B is a schematic view of the configuration of the substrate and the recording medium in this embodiment. Thereafter, the recording medium was mounted on the apparatus described in Example 2, and the recording and reproducing operation was performed by the same method as described in Example 2. As a result, the same results as in Example 2 could be obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[Embodiment 5] In Embodiment 5, first,
The substrate used in this example was prepared according to the recipe described in Example 1. Next, 10 solvent-soluble precursors of poly (p-phenylenevinylene) were accumulated on the substrate according to the prescription described in Example 1, and a heat treatment was performed to obtain a poly (p-phenylenevinylene) thin film as a final product. Next, polyisobutyl methacrylate and 2- (4-biphenylyl) -5- (4-t
-Butylphenyl) -1,3,4-oxadiazole (PBD) was mixed and dissolved in chloroform at a molar ratio of 1: 1 and 20 layers were superposed on the thin film by the LB film forming apparatus used in Example 1. Cumulative. FIG. 3A is a schematic view of the configuration of the substrate and the recording medium in this embodiment. Thereafter, the recording medium was mounted on the apparatus described in Example 1, and the recording / reproducing operation was performed by the same method as described in Example 1. As a result, the same result as in Example 1 was obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[Embodiment 6] In Embodiment 6, first,
The substrate used in this example was prepared according to the recipe described in Example 2. Next, polyisobutyl methacrylate and 2- (4-biphenylyl) -5- (4-t
-Butylphenyl) -1,3,4-oxadiazole (PBD) was mixed, and 20 layers were accumulated on the substrate. Next, 10 layers of a solvent-soluble precursor of poly (p-phenylenevinylene) were accumulated on the substrate according to the formulation described in Example 1,
After the heat treatment, a poly (p-phenylenevinylene) thin film was obtained as a final product. FIG. 3B is a schematic diagram of the configuration of the substrate and the recording medium in this embodiment. Hereinafter, the recording medium was mounted on the device described in the second embodiment, and the recording / reproducing operation was performed in the same manner as in the second embodiment.
The same result as was obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and the reproducing operation was performed over time after the first reproduction.
There was no particular change in the playback state. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and the reproducing operation was performed over time after the first reproduction.
There was no particular change in the playback state.

[Embodiment 7] In Embodiment 7, first,
The substrate used in this example was prepared according to the recipe described in Example 1. Next, the polyisobutyl methacrylate and N, N'-bis (3-methylphenyl)-
1,1′-biphenyl-4,4′-diamine (TPD)
And 20 layers were accumulated on the substrate. Next, 10 solvent-soluble precursors of poly (p-phenylenevinylene) were accumulated on the substrate according to the recipe described in Example 1, and a heat treatment was performed to obtain a poly (p-phenylenevinylene) thin film as a final product. Next, polyisobutyl methacrylate and 2- (4-biphenylyl)-
5- (4-t-butylphenyl) -1,3,4-oxadiazole (PBD) was mixed, and 20 layers were superposed and accumulated on the thin film. FIG. 4A is a schematic view of the configuration of the substrate and the recording medium in this embodiment. Thereafter, the recording medium was mounted on the apparatus described in Example 1, and the recording / reproducing operation was performed by the same method as described in Example 1. As a result, the same result as in Example 1 was obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[Embodiment 8] In the embodiment 8, first,
The substrate used in this example was prepared according to the recipe described in Example 2. Next, polyisobutyl methacrylate and 2- (4-biphenylyl) -5- (4-t
-Butylphenyl) -1,3,4-oxadiazole (PBD) was mixed, and 20 layers were accumulated on the substrate. Next, 10 solvent-soluble precursors of poly (p-phenylenevinylene) were accumulated on the substrate according to the recipe described in Example 1, and a heat treatment was performed to obtain a poly (p-phenylenevinylene) thin film as a final product. Next, polyisobutyl methacrylate and N, N'-bis (3
-Methylphenyl) -1,1'-biphenyl-4,4 '
-Diamine (TPD) was mixed, and 20 layers were superposed and accumulated on the thin film. FIG. 4B is a schematic view of the configuration of the substrate and the recording medium in this embodiment. Thereafter, the recording medium was mounted on the apparatus described in Example 2, and the recording and reproducing operation was performed by the same method as described in Example 2. As a result, the same results as in Example 2 could be obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[Embodiment 9] In Embodiment 9, first,
The substrate used in this example was prepared according to the recipe described in Example 1. In this example, a recording medium was prepared using another organic compound. A substrate prepared according to the same formulation as in Example 1 [I.
Watanabe, et al. ICSM 1988,
[Santa Fe], 10 layers of polyhexylthiophene LB films were produced as recording media.
Thereafter, the recording medium was mounted on the apparatus described in Example 1, and the recording / reproducing operation was performed by the same method as described in Example 1. As a result, the same result as in Example 1 was obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

Example 10 In Example 10, first, a substrate used in this example was prepared according to the recipe described in Example 2. Next, based on the prescription described in Example 9, 10 layers of polyhexylthiophene LB film were produced as a recording medium. Thereafter, the recording medium was mounted on the apparatus described in Example 2, and the recording and reproducing operation was performed by the same method as described in Example 2. As a result, the same results as in Example 2 could be obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[Embodiment 11] The basic configuration of Embodiment 11 is as follows.
This was shown in FIG. 1, and the substrate was prepared according to the following recipe. An undoped silicon wafer having a thickness of 0.5 mm was used as the substrate 10, and Cr was pattern-deposited on the substrate 10 to a thickness of 1000 ° to form the electrodes 11 and the lead portions 12. Next, the substrate 10 is subjected to UV-O ₃ cleaning (60 ° C.,
(30 minutes), the substrate was mounted on a substrate driving mechanism of an LB film forming apparatus so that the electrode surface was perpendicular to the water surface, and immediately immersed in a pure water phase. Then octadecylamine (0.3m
g / ml) was dissolved in chloroform, developed on the water surface, compressed to a surface pressure of 20 mN / m, and allowed to stand for 5 minutes while maintaining the surface pressure. Next, the substrate driving mechanism 3
3 is operated, and the substrate 30 mounted on the mechanism is moved at a speed of 10 m.
m / min. As a result, octadecylamine was transferred to the substrate with one layer of hydrophobic group on the outside, and the outermost surface of the substrate could be made hydrophobic.

Next, 10 solvent-soluble precursors of poly (p-phenylenevinylene) were accumulated on the substrate in accordance with the recipe described in Example 1, and after heating, a poly (p-phenylenevinylene) thin film was obtained as a final product. Obtained. Next, Example 1
The substrate with the thin film prepared in this example was mounted as a recording medium on the apparatus used in the above. Next, as a conductive coating, 5
00Å The deposited probe is brought close to the recording medium and
When the surface of the area was scanned to evaluate the unevenness, the unevenness was 0.5 nm or less in the scanning range. When the recording / reproducing operation was continuously performed in the same manner as in the first embodiment,
The same result as in Example 1 was obtained. Further, the recording medium recorded by the above method is stored at normal temperature and normal pressure,
When the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

Example 12 In Example 12, first, a substrate used in this example was prepared according to the recipe described in Example 1. Next, a methanol-soluble derivative of polyphenylenevinylene was prepared [Y-E Kimetal, Apl. P
hys. Lett. , 69 , 599 (1996)], and the substrate was spin-coated at 70 °. Subsequently, the substrate was heated at 100 ° C. for 1 hour to completely dry the methanol. Next, the substrate with the thin film formed in this example was mounted on the device used in Example 1 as a recording medium, and the same evaluation as in Example 1 was performed. When the unevenness of the recording medium was evaluated by a probe on which Al was deposited at 500 [deg.] As a conductive coating, the unevenness was 3 in the scanning range.
nm or less in other embodiments in terms of smoothness.
Inferior to B film. Subsequently, the recording / reproducing operation was performed in the same manner as in Example 1. As a result, the same result as in Example 1 could be obtained. Further, the recording medium on which recording was performed by the above method was stored at normal temperature and normal pressure, and when the reproducing operation was performed with the passage of time from the first reproduction, no particular change was observed in the reproduction state.

[0033]

As described above, according to the present invention, the electrode layer of the recording medium and the conductive portion of the probe are constituted by combinations having different work functions, and one of the work functions having the smaller work function is defined as a positive voltage. When a pulse voltage is applied at an arbitrary position on the recording medium to perform recording, and the recorded information is reproduced by using one of the work functions having a larger work function as a positive voltage, the reproduction of the recorded information is performed. A method for reproducing a recording signal without crosstalk between an output signal from a non-recording part (including a background) and an output signal from a recording part, and a recording / reproducing method and recording / reproduction of information having a higher S / N ratio. The device can be realized. Further, according to the configuration of the present invention, the DC in reproducing the recorded information is reduced.
The voltage is applied by applying a low voltage equal to or less than half the voltage value required for light emission of the recording medium, for example, by applying a low voltage such as 2V.
The recorded information can be reproduced, and the power consumption of the system can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a substrate and a recording medium used in the present invention.

FIG. 2 is a schematic diagram showing a configuration of a substrate and a recording medium used in the present invention.

FIG. 3 is a schematic diagram showing a configuration of a substrate and a recording medium used in the present invention.

FIG. 4 is a schematic diagram showing a configuration of a substrate and a recording medium used in the present invention.

FIG. 5 is a block diagram of a recording / reproducing apparatus used in the present invention.

FIG. 6 is a waveform diagram of a pulse voltage applied to a recording medium to record information on the recording medium.

[Explanation of symbols]

 10, 20, 30, 40, 50 ... insulating substrate 11, 21, 31, 41, 51 ... conductive substrate 12, 22, 23, 42 ... lead-out portion 13, 23, 33, 43, 53 ... recording medium 14, 24, 34, 44, 54 ... probe 55 ... cantilever 15, 25, 35, 45 ... conductive coating 16, 26, 36, 46, 52 ... recording part 27, 47 ... hole transport layer 37, 48 ... electron transport Layer 56: Probe displacement detection means 57: Servo control means 58: Piezoelectric actuator 59: Current detection means 510: Display device 511: Computer 512: Voltage application power supply

Claims (10)

[Claims] 1. A recording medium in which a recording medium layer made of an organic compound which emits light upon application of a voltage is formed on an electrode layer, and a probe having a conductive portion is brought close to the recording medium layer for recording and reproducing information. In the recording / reproducing method, the electrode layer of the recording medium and the conductive part of the probe are formed of a combination having different work functions, and a pulse having a smaller work function is set as a positive voltage at an arbitrary position on the recording medium as a positive voltage. An information recording / reproducing method, comprising: performing recording by applying a voltage; and reproducing the recorded information by using one of the work functions having a larger work function as a positive voltage. 2. The information recording / reproducing method according to claim 1, wherein said organic compound includes a polymer compound. 3. The semiconductor device according to claim 1, wherein a layer having a high hole-transporting ability is interposed between the electrode layer and the conductive portion of the probe in a portion having a large work function. Item 4. A method for recording and reproducing information according to Item 2. 4. The semiconductor device according to claim 1, wherein a portion having a small work function is bonded to one of the electrode layer and the probe conductive portion, and a layer having a high electron transport ability is interposed. 2. A method for recording and reproducing information according to item 2. 5. The electrode layer or the probe conductive portion is bonded to a portion having a large work function of either the electrode layer or the probe conductive portion, and a layer having a high hole transport ability is interposed therebetween. 3. The information recording / reproducing method according to claim 1, wherein a layer having a high electron transporting ability is interposed by bonding to a portion having a small work function. 6. A recording medium in which a recording medium layer made of an organic compound which emits light by application of a voltage is formed on an electrode layer, and a probe having a conductive portion is brought close to the recording medium layer for recording and reproducing information. An information recording / reproducing apparatus, wherein the electrode layer of the recording medium and the conductive portion of the probe are constituted by combinations having different work functions. 7. The information recording / reproducing apparatus according to claim 6, wherein said organic compound includes a polymer compound. 8. The semiconductor device according to claim 6, wherein a layer having a high hole transporting ability is interposed between the electrode layer and the portion having a large work function of one of the probe conductive portions. Item 8. An information recording / reproducing apparatus according to Item 7. 9. The semiconductor device according to claim 6, wherein one of the electrode layer and the probe conductive portion is joined to a portion having a small work function, and a layer having a high electron transport ability is interposed. 8. The information recording / reproducing apparatus according to 7. 10. The electrode layer or the probe conductive portion is joined to a portion having a large work function of one of the electrode layer and the probe conductive portion, and a layer having a high hole transport ability is interposed therebetween. 8. The information recording / reproducing apparatus according to claim 6, wherein a layer having a high electron transporting ability is interposed by being joined to a portion having a small work function.