JPH0435066A - Organic compound semiconductor electric element and manufacture thereof - Google Patents

Abstract

PURPOSE:To facilitate manufacture with reversible switching action by a method wherein an organic compound semiconductor layer is a thin film made of a diacetylene derivative compound in an electric element having the organic compound layer between the upper electrode and the lower electrode. CONSTITUTION:After a thin film made of a diacetylene derivative compound resulting from solid phase polymerization by vacuum vapor-deposition is deposited on the upper electrode, the upper electrode is formed on this thin film. That is, aluminum is vacuum-deposited on one surface of a substrate to form an electrode substrate with the lower electrode. This is followed by vapor deposition of nonacosa 10, 12 diine acid of powdery state, and then by irradiation with ultraviolet rays from a high-tension mercury-vapor lamp. Further, the top face of this poly(nonacosa 10, 12 diine acid) thin film is turned into the upper electrode by Al vacuum deposition. This way provides an electric element having an organic compound semiconductor layer within a pair of upper and lower electrodes.

Description

[Detailed description of the invention] It is used for switching elements and memory elements.

[Prior Art] As is well known, research into organic semiconductors has been remarkable, starting with the discovery of the superconductivity of (SN)x and the high conductivity of doped polyacetylene.

On the other hand, recently, due to the application of voltage or the incidence of pulsed light,
U.S. Pat. No. 4,371,883 (P.
OLember et al.) disclose an electronic device using the above-mentioned organic semiconductor, that is, a current-controlled switching device using a charge transfer complex thin film (shown in FIG. 4). 1 in the figure is a switching element. This device has a structure in which a lower electrode 3, a charge transfer complex layer (organic compound semiconductor layer) 4, and an upper electrode 5 are sequentially laminated on a substrate 2''. Here, the charge transfer complex layer 4 is made of polycrystalline Cu-TCNQ (copper-tetracyanoquinodimethane). Note that 6 and 7 in the figure are the lower electrodes 3 and 3, respectively. ”
This is a lead wire connected to the two-part electrode 5 via a joint 8. That is, the switching element having the above structure is a two-terminal element in which a pair of electrodes 3.degree. 5 is provided on the charge transfer complex layer 4.

This electric element is manufactured, for example, as follows.

First, a substrate made of a donor material such as Cu or Ag is immersed in a solution in which a neutral acceptor molecule such as TCNQ (tetracyanoquinodimethane) is dissolved in a solvent such as acetonitrile. At this time, a redox reaction occurs to form a metal salt with the ion radical of the acceptor molecule. When the crystals have grown to an appropriate thickness (several μm) through this reaction, the substrate is taken out from the solvent, the solvent is removed by vacuum drying, and then an 8Ω or Cr upper electrode is formed by vacuum evaporation or the like.

FIG. 5 shows a circuit incorporating the above switching element. This cord 1 includes a power source 11, an ammeter 12, a voltmeter 13,
and a load resistor 14 are connected. Using a circuit with such a configuration, the current-voltage of the switching element 1 (
v-r) characteristics are as shown in FIG. The figure shows that when the applied voltage reaches the threshold voltage Vlh, it shifts from point A to point B along the load line and changes discontinuously. Even if the voltage is subsequently lowered, the electrical conductivity remains high. Therefore, the electric element has characteristics as a memory switching element.

Regarding the above switching mechanism, the charge transfer complex layer 4
By applying an electric field in the direction of the stack axis, neutral TCNQ is produced in an amount corresponding to the applied voltage. Therefore, it is thought that the equilibrium state shown in the following formula (1) is established, a mixed atomic chain state is generated, and as a result, a state of high electrical conductivity is created. On the other hand, regarding this memory property, it is thought that it is necessary to take into account the displacement of ions or molecules, but the reality is that there are many unknown points.

[Cu + (TCNQ”') Co
. → Cu 0[Cu+ (TCNQ''): 1
n-8+ (TCQN').

(1) Such switching characteristics and memory characteristics are phenomena observed in some organic compound semiconductors. in general,
Organic compound semiconductors have been found to exhibit unique electronic behavior that is not seen in inorganic semiconductors, such as Si semiconductors, and a wide range of research is currently underway, with great expectations for future developments. ing.

[Problems to be Solved by the Invention] By the way, the above-mentioned charge transfer complex electric device is an electric current control type electric device that exhibits a negative resistance that changes from a high resistance state to a low resistance state when the applied voltage reaches a threshold value. Because it is an electric element, the current increases rapidly when it changes to a low resistance state as shown in Figure 6, which can cause thermal damage to the electric element, and the applied voltage must be removed or Even if an erasable operation such as applying a current pulse of the opposite polarity is performed, a phenomenon occurs in which the low resistance state does not return to the high resistance state, making it difficult to realize reversible switching operation. there were.

Furthermore, the above-mentioned method for producing the electric element is a wet method, which not only requires careful attention to the solvent, but also poses problems in that it is difficult to establish production conditions.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly reliable organic compound semiconductor electric device that can perform a reversible switching operation, is easy to manufacture, and a method for manufacturing the same.

[Means for Solving the Problems] The first invention of the present application is an electric element having an organic compound semiconductor layer between an upper electrode and a lower electrode, in which the organic compound semiconductor layer is a thin film made of a diacetylene derivative compound. This is a characteristic organic compound semiconductor electric device.

The second invention of the present application is a method for manufacturing an electric device having an organic compound semiconductor layer between an upper electrode and a lower electrode, in which a thin film made of a diacetylene dielectric compound solid-phase polymerized by vacuum evaporation is formed on the lower electrode. After that, an upper electrode is formed on this thin film.

Examples of the substrate according to the present invention include a crystallized glass plate having a coefficient of thermal expansion comparable to that of the material of the lower electrode, or a synthetic resin substrate such as a polyimide plate or a polyethylene plate.

Examples of the material for the lower electrode according to the present invention include gold, copper, chromium, and ITO (indium tin oxide). The lower electrode can be formed by vacuum evaporation, electroless plating, or sputtering.

Examples of the material for the upper electrode according to the present invention include aluminum.

Examples of the organic compound semiconductor layer according to the present invention include a single film or a mixed film of a diacetylene derivative compound or a polydiacetylene derivative compound.

In the method of the present invention, a thin film made of a solid-phase polymerized diacetylene dielectric compound is obtained by performing at least one treatment such as ultraviolet rays, X-ray electron beams, γ-ray irradiation, or heating.

The above polydiacetylene is a general term for conjugated polymers in which diacetylene compounds having various side chains (R-CC-CC-R'R, R' are side chain substituents) undergo homopolymerization in a certain molecular arrangement state. be. The noteworthy features are (1) crystalline polymer, (2) homopolymerizable polymer (topochemical polymerization)
, (3)-dimensional π-electron system polymer.

This polydiacetylene has been intensively studied, including the relationship between the geometric conditions of the monomer crystal and polymerization reactivity, the dynamics of polymerization reactivity, and the properties of reaction intermediates. In addition, since it can be obtained in a nearly perfect crystalline state, it has become a research target in the field of optical physics as a model material for -dimensional conjugated polymers. The physical properties of polydiacetylene are due to the delocalized π electrons on the long quasi-order main chain structure. however,
The conductivity of single crystal polydiacetylene is 1o-10 to 1O
It has a low value of -15S/cm and is a semiconductor or an insulator.

Furthermore, thermal analysis results show that the thermal decomposition temperature of polydiacetylene in a single crystal state is about 210'C or higher.

The reason why polydiacetylene is attracting attention as a functional material is the presence of π electrons that exhibit delocalized behavior on the long quasi-order main chain structure mentioned above, and another reason is the vacuum evaporation method, L
The reason lies in the diversity of film forming methods such as the B method and the casting method.

[Function] In the present invention, the electric element preferably has the following characteristics. That is, the organic compound semiconductor layer has a characteristic that the electrical resistance value of the organic compound semiconductor layer changes from a high resistance state to a low resistance state when the voltage applied between the two-part electrode and the lower electrode exceeds a first threshold; Furthermore, applying a voltage having a polarity opposite to that of the voltage applied to change from a high resistance state to a low resistance state,
When a second threshold value applied between the upper electrode and the lower electrode is exceeded, the resistance value changes from a low resistance state to a high resistance state. More preferably, the electric resistance value of the organic compound semiconductor layer changes from a high resistance state to a low resistance state when the voltage applied between the upper electrode and the lower electrode exceeds a first threshold; A voltage with a polarity opposite to that of the voltage applied to change from a high resistance state to a low resistance state is applied, and when the second threshold value applied between the upper electrode and the lower electrode is exceeded, the resistance increases. The characteristic that the value changes from a low resistance state to a high resistance state can be repeated. Specifically, the electric element according to the present invention behaves as shown in FIG. That is, the initial state is a high resistance state, but the negative threshold value ■.

When it exceeds , it changes to a low resistance state. However, if the resistance state essentially changes from a high resistance state to a low resistance state, the problem of thermal damage will not disappear, but since only a constant current flows at a constant voltage after switching, it is necessary to use an external resistor of an appropriate value. When used, good repeatability can be obtained without excessive current flowing.

Further, this electric element has a retention characteristic in a low resistance state after transitioning from an initial high resistance state. In other words,
Even if the voltage applied to the electric element is removed, it maintains a low resistance state. To erase this low resistance state, a voltage of the opposite polarity to the applied voltage that changed from the high resistance state to the low resistance state is applied, thereby returning the low resistance state to the initial high resistance state.

By combining the write operation (change from high resistance state to low resistance state) and erase (change from low resistance state to high resistance state) described above, the electric element has reversible switching characteristics. become.

Embodiments of the present invention will be described below with reference to the drawings.

[Example 1] First, aluminum (AΩ) was vacuum-deposited on one surface of a polycarbonate substrate to a thickness of [iloon] to form an electrode substrate on which a lower electrode was formed. However, the electrode substrate and A
, and the distance from the Q sputtering power source was 4 cm. Continuing,
Powdered Nonacosa 10.12 diyic acid (Doguchi Kagaku Kenkyusho) was vacuum-deposited so that 1 μg/cm 2 was deposited in 1 hour. Next, ultraviolet rays were irradiated for 20 seconds using an 80 W/am high-pressure mercury lamp (Ushio). Furthermore, AΩ was vacuum-deposited to a thickness of 600 nm on the upper surface of this poly(nonacosa 10.12 diyic acid) thin film to form an upper electrode. In this way, an electric element having an organic compound semiconductor layer between a pair of upper and lower electrodes was obtained.

The organic compound semiconductor electric device manufactured in this way has powdered Nonacosa 10.
12 Diynic acid is vacuum-deposited and an organic compound semiconductor layer obtained by irradiation with ultraviolet rays is provided.
Reversible switching characteristics can be obtained.

In fact, the V--characteristic measured in a circuit in which the above electric element is arranged with a series resistor shown in FIG. 3 is as shown in FIG. 1. That is, even when a voltage was applied with the upper electrode side of the electric element being positive, the electric element did not switch. However, after this, when the upper electrode was made negative and a voltage was applied, the initial high resistance state changed to a low resistance state at the negative threshold value V L h l. Here, the resistance value in the high resistance state is
At V+b+, it was about 450Ω, and the resistance value in the low resistance state after switching was 19Ω. Furthermore, even if a voltage is applied to this electric element again, it remains in a low resistance state, so this low resistance state is maintained even if the voltage applied to the electric element is removed, and this electric element remains in a low resistance state. It was discovered that it has memory properties.

After that, a polarity opposite to the polarity of the voltage applied to switch the electric element to a low resistance state is applied, that is, a voltage is applied with the upper electrode positive, and a positive threshold value V+h2 is reached. At that time, the electrical element reached its initial high resistance state. From now on, if a similar operation is performed, that is, applying a voltage between V + h r with the upper electrode negative, then reversing the polarity and applying a voltage between V + h 2, the V-I characteristic will change. Obtained repeatedly.

As described above, we succeeded in reversibly creating a high-resistance state and a low-resistance state by changing the polarity and magnitude of voltage application. From this result, it has become clear that the electric element can freely change between the two values of the memory state and the erased state (initial state) because the writing and erasing operations can be performed by applying voltages and controlling them. Note that in order to read the stored information in this electric element, current detection may be performed by applying a voltage so that the upper electrode of the electric element in the memory state (low resistance state) becomes negative.

[Example 2] First, 600 nm% of chromium was applied to one surface of a glass substrate.
Subsequently, gold was vacuum-deposited to a thickness of 200 nm to produce an electrode substrate on which a lower electrode was formed. Next, 1 c of powdered 5,7-dozocadiine 1, 12 diol bis(ethyl carbamate) (Doguchi Kagaku Kenkyusho) was added in 2 hours.
Vacuum deposition was carried out to deposit 0.6 μg/m2. Next, a high-pressure mercury lamp (Ushio) of 80 W/cm was used to
Ultraviolet rays were irradiated for 0 seconds.

Furthermore, AΩ
was vacuum-deposited to a thickness of 600 nm to form an upper electrode. In this way, an electric element having an organic compound semiconductor layer between a pair of upper and lower electrodes was obtained.

In fact, the VI characteristics measured in the same manner as in "Example 1 of the electric device" are as shown in FIG.

Further, its behavior is similar to that in the first embodiment. That is, even when voltage was applied with the upper electrode side of the electric element being positive, the electric element did not switch. However, after this, if the upper electrode is made negative and a voltage is applied, the negative threshold value V + h
At +, the initial state of high resistance changed to a low resistance state. Here, the resistance value in the high resistance state is approximately 80 KΩ at V l h l, and the resistance value in the low resistance state after switching is 0. It was IKΩ. Furthermore, even if a voltage is applied to this electric element again, it remains in a low resistance state, so this low resistance state is maintained even if the voltage applied to the electric element is removed, and this electric element remains in a low resistance state. It turns out that it has memory properties.

After that, a polarity opposite to the polarity of the voltage applied to switch the electric element to a low resistance state is applied, that is, a voltage is applied with the upper electrode positive, and a positive threshold value V L h is applied. 2, the electrical element has reached its initial high resistance state. From now on, if a similar operation is performed, that is, applying a voltage of V + h + with the upper electrode negative, then reversing the polarity and applying a voltage of V + h2, the V-I characteristic will change. Obtained repeatedly.

[Effects of the Invention] As detailed above, according to the present invention, when the applied voltage exceeds a negative threshold, the high resistance state changes to the low resistance state and this state is maintained, and the high resistance state changes to the low resistance state. When a voltage with the polarity opposite to that of the applied voltage that caused the state is applied and the positive threshold is exceeded, the low resistance state returns to the initial high resistance state, so electrical control is required. As a result, it is possible to provide a highly reliable organic compound semiconductor electric device that can reversibly change between two values, a memory state and an erased state, and that is easy to manufacture and a method for manufacturing the same.

[Brief explanation of the drawing]

FIG. 1 is a ■I characteristic diagram of an electronic device according to Example 1 of the present invention, FIG. 2 is a V-1 characteristic diagram of an electronic device according to Example 2 of the present invention, and FIG. 3 is a characteristic diagram of a conventional electronic device. Incorporated circuit diagram, 4th
The figure is a sectional view of a conventional electronic element, FIG. 5 is a circuit diagram incorporating a conventional switching element, and FIG. 6 is a 1I characteristic diagram of this switching element. DESCRIPTION OF SYMBOLS 1... Electrode substrate, 2... Upper electrode, 3... Organic compound semiconductor layer, 4... Electronic element. Applicant's agent Patent attorney Atsushi Tsuboi

Claims (3)

[Claims] (1) An electric element having an organic compound semiconductor layer between an upper electrode and a lower electrode, wherein the organic compound semiconductor layer is a thin film made of a diacetylene derivative compound. (2) The voltage applied between the upper electrode and the lower electrode is the first
The electrical resistance value of the organic compound semiconductor layer changes from a high resistance state to a low resistance state when the threshold value is exceeded. The resistance value changes from a low resistance state to a high resistance state when a voltage with opposite polarity is applied and a second threshold value applied between the upper electrode and the lower electrode is exceeded. The organic compound semiconductor electric device according to claim 1. (3) In a method for manufacturing an electric device having an organic compound semiconductor layer between an upper electrode and a lower electrode, a thin film made of a diacetylene dielectric compound solid-phase polymerized by vacuum evaporation is formed on the lower electrode, and then this A method for manufacturing an organic compound semiconductor electric device, comprising forming an upper electrode on a thin film.