JPH02149954A - Recording/playback device and method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an information recording/reproducing device.

(Prior Art) In recent years, the use of memory materials has become the core of the electronics industry, such as computers and related equipment, video disks, digital audio disks, etc.
The development of these materials is also progressing very actively. The performance required of memory materials varies depending on the application, but in terms of numbers, they are: ■High density and large storage capacity; ■Fast response speed for recording and playback; ■Low power consumption; ■High productivity and price. is cheap, etc.

Until now, semiconductor memory and magnetic memory were mainly made of magnetic materials and semiconductors, but with the recent advances in laser technology, inexpensive and high-density optical memory using organic thin films such as organic dyes and photopolymers has been developed. recording media have appeared.

On the other hand, recently, a scanning tunneling microscope (hereinafter abbreviated as STM) that can directly observe the electronic structure of surface atoms of a conductor has been developed.
ica Physica Acta.

55, 726 (1982)] It has become possible to measure real space images with high resolution regardless of whether they are single crystal or amorphous, and it also has the advantage of being able to observe with low power without damaging the medium due to current. Furthermore, it is expected to have a wide range of applications because it can operate in the atmosphere and can be used with various materials.

STM involves applying a voltage between a metal tip and a conductive material.
It takes advantage of the fact that a tunnel current flows when brought close to a distance of about 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 and at the same time draw various information about the total electron cloud of surface atoms. Information can also be read. Analysis using STM is limited to conductive samples, but it is beginning to be applied to the structural analysis of extremely thin monomolecular films formed on the surface of conductive materials, using the differences in the states of individual organic molecules. Application as a reproduction technology for high-density recording is also considered.

For example, devices using STM include an organic rectifying element (US Pat. No. 3,953,874) and an organic memory element (US Pat. No. 3,953,874).
833894). Although device characteristics have been investigated through these series of studies, the characteristics are still insufficient for practical use.

Meanwhile, a proposal for a molecular electronic device in which a single organic molecule has functions such as a logic element or a memory element was announced, and a Langmuir-Blodgett film (hereinafter referred to as LB film), which is considered to be one of the construction technologies for molecular electronic devices, was announced. Research on (abbreviated) is also becoming more active. The LB film arranges organic molecules in an orderly manner.
The film thickness can be controlled in units of molecular length by laminating one molecular layer at a time, and the M? #Can form a film.

Many attempts have been made to use the LB film as an insulating film to create devices that take full advantage of this feature. For example, tunnel junction devices with metal-insulator-metal (MIM) structures [G, L, Larkins et al., Th1
n 5 solid filns, 99. (1983)
] and metal-insulator-semiconductor (MIS) structures with light-emitting elements [
G.G., Roberts et al., El.
electronics Letters.

20, 489 (1984)] or switching elements [N.

J,Thoa+as at al,, Electro
nics Letters, 20°838 (198
4) Furthermore, JP-A-63-161552 and JP-A-63-161 regarding high-density recording in combination with STM
There are 553. Although device characteristics have been investigated through a series of these studies, variations in characteristics between devices, reproducibility and stability such as changes over time, and practical characteristics are still insufficient and remain unresolved problems.

[Problem to be solved by the invention]

An object of the present invention is to provide a recording/reproducing apparatus and a recording/reproducing method using a high-density recording medium having excellent voltage/current switching characteristics and memory properties.

[Means for Solving the Problems] The present invention is a recording/reproducing device having a light source, a probe electrode, and a recording medium comprising a monomolecular film of a charge transfer complex.

The recording medium of this recording/reproducing device is disposed between the probe electrode and a counter electrode disposed opposite to the probe electrode, and the recording medium is formed by the Langmuir-Blodgett method. Included in the present invention.

The planar charge transfer complex is composed of a metal, a metal ion, and an organic electron acceptor, the probe electrode has an XY scanning drive device, and the relative position of the probe electrode and the recording medium is finely moved in three dimensions. The present invention also includes means for controlling.

Furthermore, the present invention provides a method for recording information by applying a voltage exceeding a threshold voltage that causes a memory effect to the recording medium according to the information using a probe electrode while irradiating the recording medium with light from a light source. , applying a voltage to the probe electrode and scanning the probe electrode along the recording medium while keeping the distance between the recording medium and the probe electrode constant;
It also includes a method of reproducing information by detecting a change in the value of current flowing through a probe electrode, and a method of erasing information recorded on a recording medium by applying excavation energy.

The present invention relates to a recording/reproducing apparatus having a light source, a probe electrode, a recording medium having an electric memory effect, a write/read voltage applying means for applying a voltage to the recording medium from the probe electrode, and an erasing means, and a recording medium having an electric memory effect. The recording method is characterized by applying a voltage exceeding a threshold voltage that causes an electrical memory effect from the probe electrode while irradiating the area with light.

The reading method is characterized by using STM, applying voltage to the probe while keeping the distance between the probe and electrode constant, and measuring changes in the amount of current flowing.

Furthermore, in the erasure method, recorded information can be easily erased by applying vibrational energy to the recording medium by irradiating it with light or the like.

The material used for the recording medium may be any material passed through an amphiphilic LB film containing a charge transfer complex of a metal and an organic electron acceptor, such as n-octadecyltetracyanoquinodimethane copper complex (ODTCNQ/Cu ), n-dodecyltetracyanoquinodimethane copper complex (DDTCNQ/Cu)
, n-octadecyltetracyanoquinodimethane silver complex (
ODTCNQ/Ag), n-dodecyltetracyanoquinodimethane silver complex (DDTCNQ/Ag), and substituted products thereof.

The electrode material may be any material as long as it forms a film with excellent conductivity and smoothness, and examples thereof include Au/Pd, Pt, n''''-3i, and the like.

The light source may be anything that emits light with a wavelength between visible light and infrared light; for example, various light sources such as xenon lamps, helium-neon lasers, argon lasers, semiconductor lasers, and carbon dioxide lasers may be used. Can be used. It is also possible to change the applied voltage that allows recording by varying the light intensity.

FIG. 1 is a block diagram showing a recording apparatus of the present invention. In FIG. 1, 5 is a probe current amplifier, and 6 is a servo circuit that controls a fine movement mechanism 7 using a piezoelectric element so that the probe current is constant. Reference numeral 8 denotes a power source for applying a pulse voltage for recording/erasing between the probe electrode 2 and the electrode 3.

Since the probe current changes rapidly when the pulse voltage is applied, the servo circuit 6 controls the HOLD circuit to be turned on so that the output voltage remains constant during that time.

9 is an X for controlling the movement of the XY force direction probe electrode 2.
This is a Y scan drive circuit. 10 and 1■ are 10
The distance between the probe electrode 2 and the recording medium 1 is coarsely controlled so that a probe current of about -'A is obtained.

All of these functions are centrally controlled by the microcomputer 12. Further, 13 represents a display device.

Furthermore, examples of mechanical performance in movement control using piezoelectric elements are shown below.

Z direction fine movement control range: 0.1nm y lnmZ
Directional coarse movement control range: lOnm ~IOma+XY
Directional scanning range: 0.1 nm to Inm Measurement, control tolerance: <0.1 nm The present invention will be described below with reference to Examples.

Example 1 A recording/reproducing apparatus shown in FIG. 1 was used. As the probe electrode 2, a platinum/rhodium probe electrode was used. This probe electrode 2 is used to control the distance m<z> from the surface of the recording layer +01, and is controlled by a piezoelectric element to keep the current constant. (Z) is controlled by fine movement. Furthermore, the fine movement control mechanism 7 maintains the distance Z constant and moves the in-plane (
It is designed to allow fine movement control in the X, Y) directions as well. However, these are all conventionally known techniques. Further, the probe electrode 2 can directly perform recording, reproduction, and erasing. Further, the recording medium is placed on a high-precision XY stage 14 and can be moved to any position.

Next, octadecyltetracyanoquinodimethane/copper complex (
The method for forming a film of ODTCNQ/Cu) will be described. ODT using acetonitrile (ACN) as a solvent
A solution of CNQ/Cu with a concentration of 4*10-'M was prepared. This solution was developed in an aqueous phase of pure water at 20°C,
The surface pressure was increased to 20 mN/IB to form a monomolecular film on the water surface. Gold/palladium (Au/Pd), which had been immersed in the water phase in advance while keeping the surface pressure constant, was
A glass substrate deposited with a thickness of 0.0 mm was gently pulled across the water surface at a speed of 5 mm/win.
A CNQ/Cu monolayer was deposited on an Au/Pd evaporated glass substrate. This was designated as recording medium 1.

Next, a recording/reproducing/erasing experiment using a recording medium 1 having one layer of ODTCNQ/Cu-LB film will be described. The recording medium 1 was placed on the xY stage 14, and the position of the probe electrode 2 was determined and fixed visually. A voltage of 3 cm was applied between the A u / P d electrode 3 and the probe, and the distance Z between the probe electrode 2 and the surface of the recording layer 101 was adjusted while monitoring the current. Probe electric J
When a voltage of +300 mV was applied to Ji2, the measured current value was less than 1 pA. When the voltage application was stopped, the recording medium was irradiated with a xenon lamp, and a voltage of +5 V was applied to the probe electrode 2 again, recording was performed, and the probe transitioned to an ON state in which electricity flows well. After stopping light irradiation and voltage application, set the probe voltage i2 to ÷3000]V again at the same position.
When a voltage of 5 nA was applied and recording/reproduction was performed, a current of 5 nA flowed and the ON state was preserved, indicating that the recording was preserved. The voltage application was stopped and the recording site was irradiated with an argon laser to give vibrational energy. When a voltage of +300[11 V was applied to the probe voltage 8i2 again at the same position and recording/reproduction was performed, a transition occurred to an OFF state with a current value of 1 p^ or less, and it was confirmed that the recording had been erased.

Example 2 As in Example 1, the recording and reproducing apparatus shown in FIG. 1 was used.

Dodecyltetracyanoquinodimethane/copper complex (DD
The method for forming a film of TCNQ/Cu) will be described.

D D T C using acetonitrile (ACN) as a solvent
A solution of NQ/Cu with a concentration of 4*10''M was prepared. This solution was developed in an aqueous phase of pure water at 20° C., the surface pressure was increased to 20111 N/[11], and a monomolecular film was formed on the water surface. Gold/palladium (Au/Pd), which had been immersed in the water phase in advance while keeping the surface pressure constant, was
Gently lift the glass substrate deposited to a thickness of 0.00 mm across the water surface at a speed of 5 mm/min.
T CN Q / Cu monolayer A u / P d
A film was formed on a vapor-deposited glass substrate. This was designated as recording medium 1.

Next, a recording/reproducing/erasing experiment using a recording medium 1 in which one layer of DDTCNQ/Cu-LB films was accumulated will be described.

The recording medium 1 was placed on the XY stage 14, and the position of the probe electrode 2 was determined and fixed visually. A u /
A voltage of 3 V was applied between the Pd electrode 3 and the probe, and the distance gz between the probe electrode 2 and the surface of the recording layer 101 was adjusted while monitoring the current. +300m to probe electrode 2
When a voltage of V was applied, the measured current value was 1 pA or less. When the voltage application was stopped, the recording medium 1 was irradiated with a xenon lamp, and a voltage of +5 V was applied to the probe electrode 2 again to perform recording, the probe electrode 2 transitioned to an ON state in which electricity flows well. When light irradiation and voltage application were stopped, a voltage of +300 mV was again applied to the probe electrode 8i2 at the same position, and recording and reproduction was performed, a current of 5 nA flowed and the ON state was preserved, indicating that the recording was preserved. The voltage application was stopped and the recording site was irradiated with an argon laser to give vibrational energy. Probe electrode 2 again at the same position
When a voltage of +300 mV was applied to and played back, it was confirmed that the current value was 1 pA or less and the data shifted to the OFF state, and that the recording had been erased.

Example 3 As in Example 1, the recording and reproducing apparatus shown in FIG. 1 was used.

Octade°siltetracyanoquinodimethane/silver complex (O
DTCNQ/Ag)'s production method is described below. 0DTcN using acetonitrile (ACN) as a solvent
A 4*10-6M solution of Q/Ag was prepared. This solution was developed in an aqueous phase of pure water at 20°C, and the surface pressure was adjusted to 1
The pressure was increased to 5+nN/m to form a monomolecular film on the water surface.

While keeping the surface pressure constant, a glass substrate on which gold/palladium (Au/Pd), which had been previously immersed in the water phase, had been vapor-deposited to a thickness of 300 mm, was gently moved across the water surface for 5 minutes.
Pull at a speed of mm/min, OD T CN Q
A single molecule of 11% of A/Ag was deposited on an Au/Pd vapor-deposited glass substrate. This was designated as recording medium 1.

Next, a recording/reproducing/erasing experiment using recording medium 1 in which one layer of 0DTCNQ/Ag-LB film was accumulated will be described.

The recording medium 1 was placed on the XY stage 14, and the position of the probe electrode 2 was determined and fixed visually. Au/Pd′
A voltage of 3 V was applied between the quasi-Vi3 and the probe, and the distance Z between the probe electrode 2 and the surface of the recording layer 101 was adjusted while monitoring the current. Probe electrode, +300m to pole 2
When a voltage of V was applied, the measured current value was 1 pA or less. When the voltage application was stopped, the recording medium 1 was irradiated with a helium-neon laser, and a voltage of +3 V was applied to the probe electrode 2 again to perform recording, the probe electrode 2 transitioned to an ON state in which electricity flows well. After stopping the light irradiation and voltage application, a voltage of -300 mV was applied to the probe electrode 2 again at the same position, and when recording and reproducing were performed, a current of 5 nA flowed.
It was found that the N state was saved and the records were saved.

The voltage application was stopped and the recording site was irradiated with a carbon dioxide laser to provide vibrational energy. When a voltage of +300 mV was again applied to the probe electrode 2 at the same position and recording/reproduction was performed, a transition occurred to an OFF state with a current value of 1ρ8 or less, and it was confirmed that the recording had been erased.

Example 4 As in Example 1, the recording and reproducing apparatus shown in FIG. 1 was used.

Octadecyltetracyanoquinodimethane/Sfi forceps (
The method for forming a film of ODTCNQ/Ag) will be described. A solution of 0DTcNQ/Ag at a concentration of 4*Io-'M was prepared using acetonitrile (ACN) as a solvent. This 78 liquid was developed into an aqueous phase of pure water at 20°C, and the surface pressure was adjusted to 15111N/[
11 to form a monomolecular film on the water surface. The sample was previously immersed in the aqueous phase while keeping the surface pressure constant.
”-3i board gently at 5 mm/m in the direction across the water surface.
A monomolecular film of oorcNQ/Ag was formed on the n''-5i substrate by pulling the film at a speed of 1.5 in. This was designated as recording medium 1.

Next, a recording/reproducing/erasing experiment using the recording medium 1 in which one layer of ODTCNQ/Ag-LBM was accumulated will be described. The recording medium 1 was placed on the XY stage 14, and the position of the probe electrode 2 was determined and fixed visually. A voltage of 3 V was applied between the electrode (n-3i) 3 and the probe, and the distance SZ between the probe electrode 2 and the surface of the recording layer 101 was adjusted while monitoring the current. When a voltage of +300 mV was applied to the probe electrode 2, the measured current value was 1p8 or less. Stop applying voltage and turn off the helium
The recording medium 1 was irradiated with a neon laser, a voltage of +3 V was applied to the probe electrode 2 again, and recording was performed, resulting in a transition to an ON state in which electricity flows well. Stop light irradiation and voltage application and apply +300 to probe electrode 2 at the same position again.
When a voltage of +nV was applied and recording/reproduction was performed, the result was 5nA.
It was found that the current flowed, the ON state was preserved, and the record was preserved.

The voltage application was stopped and the recording site was irradiated with a carbon dioxide laser to provide vibrational energy. When a voltage of +300 mV was again applied to the probe electrode 2 at the same position and recording and reproduction was performed, the current value changed to ip8 and the state shifted to the OFF state below, confirming that the recording was erased.

(Effects of the invention) 1) Since a monomolecular film is formed by the LB method, the molecular order is superior compared to chemical adsorption methods, etc., and a high-density film can be obtained, making it suitable for ultra-high-density recording media. I'm passing through.

2) Since recording is performed without performing light irradiation, writing errors during reproduction can be prevented.

3) Since vibration energy must be applied when erasing records, storage stability is compromised.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the recording/reproducing apparatus of the present invention. 15; light source +01: Recording layer

Claims (1)

[Scope of Claims] 1) A recording/reproducing device having a recording medium made of a monomolecular film of a charge transfer complex, a light source, and a probe electrode. 2) The monomolecular film is arranged to face the probe electrode and the probe electrode. 3) The recording/reproducing device according to claim 1, wherein the monomolecular film is formed by a Langmuir-Blodgett method; 4) the charge transfer complex; 5) The recording/reproducing device according to claim 1, wherein the recording/reproducing device comprises a metal or a metal ion and an organic electron acceptor. 5) The recording/reproducing device according to claim 1, further comprising an XY scanning drive device for the probe electrode. 6) The probe electrode 7) The recording/reproducing apparatus according to claim 1, further comprising means for finely controlling the relative position of the recording medium in three dimensions.7) While irradiating the recording medium with light from a light source, the recording medium is A method of recording information by applying a voltage that exceeds a threshold voltage that causes a memory effect using a probe electrode. 8) While applying a voltage to the probe electrode and keeping the distance between the recording medium and the probe electrode constant. A method of reproducing information by scanning a probe electrode along a recording medium and detecting a change in the value of a current flowing through the probe electrode 9) Applying vibrational energy to the information recorded on the recording medium according to claim 1. How to erase by