JP5453628B2 - Non-conductive nanowire and manufacturing method thereof - Google Patents

Description

The present invention relates to a non-conductive nanowire that is an organic Mott insulator, a manufacturing method thereof, and the like. More specifically, the present invention relates to a non-conductive nanowire that is a fine organic Mott insulator, in which an electrolytic crystal growth method is applied to manufacture of a non-conductive nanowire, a manufacturing method thereof, a transistor using the same, and the like.

As a method for growing a single crystal, many methods such as a liquid phase epitaxial (LPE) method, a molecular beam epitaxial (MBE) method, a chemical transport (CVT) method, and a chemical vapor deposition (CVD) method have been proposed. By using these methods, a relatively large single crystal or thin film can be obtained. In addition, a method for growing a crystal by an electrolytic method, which is a crystal growth method using an electrolysis reaction, is known (for example, published in Experimental Chemistry Course 12 Substances, 4th Edition, pages 40 to 45, Maruzen). . In addition, it has been known so far that a Mott insulator having a visible size can be obtained by an electrolytic method (for example, “Chemistry of Organic Conductors” by Gunji Saito, page 149 published by Maruzen).

JP-A-6-321686 discloses a metal atom characterized by growing a single crystal of the compound on the cathode side by an electrolysis method in an organic solvent in which a metal organic acid salt and a carbon cluster are dissolved. A method for producing doped carbon cluster compounds is described.

In the case of manufacturing molecular nanowires, it has been known to use molecular vapor deposition or molecular beam methods in ultra-high vacuum. In addition, methods for producing molecular nanowires by arranging dendrimers and closed shell molecules and methods for producing carbon nanotubes have been known.

The present inventors have developed a novel method for producing conductive nanowires. And the novel electroconductive nanowire using the organic compound manufactured with the manufacturing method is indicated by the following patent document 1 (WO03 / 076332 gazette). This conductive nanowire has a relatively high conductivity.

WO03 / 076332 Publication

However, the conventional method for producing a single crystal is intended to obtain as large a crystal as possible, not a nanoscale crystal. Moreover, since there was no attempt to obtain non-conductive nanowires, there was no motivation to obtain non-conductive nanowires. Also, conventional molecular vapor deposition and molecular beam methods in ultra-high vacuum could not produce non-conductive nanowires that are Mott insulators. Furthermore, there was no motivation to obtain a transistor using non-conductive nanowires. Moreover, although the manufacturing apparatus and manufacturing method of electroconductive nanowire are described in WO03 / 076332, the manufacturing method regarding nonelectroconductive nanowire is not described. Moreover, a method for producing non-conductive nanowires that are organic Mott insulators is not disclosed.

Accordingly, an object of the present invention is to provide a non-conductive nanowire that is an organic Mott insulator, a manufacturing method thereof, and a transistor using the non-conductive nanowire.

In the present invention, basically, when a raw material that becomes an organic Mott insulator is used, a non-conductive organic Mott insulator is formed by an electrolytic method that satisfies predetermined conditions such as an electrode shape and an applied voltage. This is based on the knowledge that nanowires can be manufactured. This method is based on the knowledge that non-conductive nanowires, which are fine organic Mott insulators, can be obtained effectively. In addition, since a transistor made of conductive nanowires is turned on without applying a gate voltage, there is a problem in terms of power consumption. However, a transistor using nonconductive nanowires according to the present invention has a problem. Since the transistor is turned off in a normal state where no voltage is applied to the gate electrode, a transistor having suitable transistor characteristics can be provided.

FIG. 1 is a schematic view of an electrolysis cell. FIG. 2 is a schematic view (top view) of the electrolysis cell. FIG. 3 is a diagram illustrating an example of an electrode on a substrate. FIG. 4 is a diagram showing an example of electrodes on the substrate. FIG. 5 is a diagram showing an example of electrodes on the substrate. FIG. 6 is a schematic view of an electrode. FIG. 7 is a schematic view of the protrusion (A in FIG. 6 and the like). FIG. 8 is a schematic configuration diagram of the transistor of the present invention. FIG. 8A is a front view of the transistor according to the first embodiment of the present invention. FIG. 8B is a cross-sectional view taken along the line II of FIG. FIG. 9 is a schematic configuration diagram of a transistor of the present invention according to another embodiment different from the above. FIG. 9A is a front view of a transistor according to the second embodiment of the present invention. FIG. 9B is a cross-sectional view taken along the line II of FIG. FIG. 10 is a schematic configuration diagram of a transistor of the present invention according to another embodiment different from the above. FIG. 10A is a front view of a transistor according to the third embodiment of the present invention. FIG. 10B is a cross-sectional view taken along the line II of FIG. FIG. 11 is a schematic configuration diagram of a transistor of the present invention according to another embodiment different from the above. FIG. 11A is a front view of a transistor according to the third embodiment of the present invention. FIG. 11B is a cross-sectional view taken along the line AB of FIG. FIG. 12 is a diagram illustrating an example of protrusions of the source electrode and the drain electrode. FIG. 12 (A) shows the tip portions parallel to each other, FIG. 12 (B) shows that the tip portion of the projection portion has a shape that becomes thinner, and FIG. 12 (C) shows the shape. FIG. 12D shows a shape having a plurality of comb-shaped protrusions at the tip portion. FIG. 13 is an SEM photograph replacing the drawing of the nonconductive nanowire obtained in Example 1. FIG. 14 is an SEM photograph replacing the drawing of the nonconductive nanowire obtained in Example 2. FIG. 15 is an SEM photograph replacing the drawing of the non-conductive nanowire obtained in Example 3. FIG. 16 is an SEM photograph replacing the drawing of the nonconductive nanowire obtained in Example 4. FIG. 17 is a SEM photograph replacing the drawing of the nonconductive nanowire obtained in Example 5.

1. Non-conductive nanowire The non-conductive nanowire of the present invention (also referred to simply as nanowire) has a width of 1 to 1 μm for a constituent molecule, a length of 1 nm to 500 μm, and is an organic Mott insulator. It is a conductive nanowire. That is, the non-conductive nanowire of the present invention is a non-conductive nanowire having poor conductivity but containing an organic substance such as phthalocyanine as a constituent molecule. When the width of the nanowire is not uniform, for example, the maximum width may be set as the width of the nanowire. In this specification, the nanowire is a linear or curved wire shape in which molecules are regularly arranged, one width molecule to 1 μm, two length molecules or more (for example, 1 nm to 500 μm in length). , Refers to a substance in the shape of a block. In this specification, the non-conductive nanowire means a non-conductive nanowire alone or a group of a plurality of nanowires (a state like a bundled aggregate crystal), or a nanowire existing between electrodes. Means the entire wire.

Non-conductive nanowires include needle crystals. Specific examples include one having a width of 1 to 1 μm for a constituent molecule, 100 nm to 1 μm, or 1 nm to 200 nm, and more preferably 10 nm to 200 nm. A relatively long nanowire is preferable because the electrodes can be connected independently. However, as will be described later, a plurality of short nanowires may be connected to connect the electrodes. The length of the nanowire may be 1 to 500 μm or 1 nm to 500 μm, but may be 10 nm to 50 μm, 10 nm to 5 μm, or 100 nm to 500 nm. Examples of the length of the nanowire that is a needle-like crystal include 10 nm to 100 μm, or 50 nm to 500 nm. In the non-conductive nanowire of the present invention, the ratio (l / s) between the major axis l and the minor axis s is preferably 1 or more, more preferably 2 or more and 100 or less, or 5 or more and 30 or less.

Among non-conductive nanowires, those having a diameter (width) of 1 nm to 100 nm and a length of 10 nm to 100 μm are preferably 60% by weight or more, more preferably 80% by weight or more, and 90% by weight or more. If it is more preferable, it is more preferable if it is 95 weight% or more, and it is especially preferable if it is 99 weight% or more. In order to produce such a ratio of nonconductive nanowires, it is preferable to apply an alternating voltage between the microelectrodes.

The non-conductive nanowire is preferably a non-conductive nanowire formed by repeating a unit in which molecules constituting the non-conductive nanowire are regularly arranged in a row to 100 rows, and the molecule is in a row to 50 rows. More preferably, the number of molecules is more preferably 1 to 20 rows, and the number of molecules may be 1, 2, 3, 4, or 5 rows. The non-conducting nanowires of needle-like crystals may be straight or may be curved to some extent. In addition, although it is preferable that it is a single crystal as a nonelectroconductive nanowire, it may contain the impurity. The shape of the non-conductive nanowire is not particularly limited as long as molecules are regularly or irregularly aligned, including linear, columnar, cylindrical, and block shapes. The non-conductive nanowire is preferably grown on the substrate, more preferably grown on the electrode and around the electrode, and particularly preferably grown between the electrodes, particularly between the gap portions.

The conductivity of the non-conductive nanowire may be controlled according to the required non-conductive nanowire or the like. However, in the present invention, an organic Mott insulator is basically used. cm ⁻¹ or less. The conductivity of the non-conductive nanowire is ¹ S · cm ⁻¹ or less, and may be ¹ × ^{10 −10} S · cm ⁻¹ or more and 1 S · cm ⁻¹ or less, and ¹ × 10 ⁻⁸ S · cm ⁻¹ or more and ¹ × 10 ⁻² or less. S · ^{cm -1} may be ^below or at 1x10 -5 S · ^{cm -1} or more ^1x10 -3 S · ^{cm -1} or less. As the non-conductive nanowire, a non-conductive nanowire having mott characteristics is preferable.

The conductivity may be measured by a known method. For example, since the non-conductive nanowire connects two electrodes, the conductivity of the non-conductive nanowire existing between the electrodes in that state may be measured.

The raw material of the non-conductive nanowire may be basically a raw material that becomes an organic Mott insulator. Specific examples include TTF derivatives, BEDT-TTF derivatives, and non-conductive nanowires that contain organic compound crystals. Examples of the organic compound crystal include a single crystal of an organic compound complex or a single crystal of an organic compound. As crystals of organic compounds, K · TCNQ, Rb · TCNQ, TMPD · TCNQ, BEDT-TTF · TCNQ, BEDT-TTF · F ₂ TCNQ, BEDT-TTF ₂ AuCl ₂ , BEDT-TTF ₂ BrICl, BEDT-TTF ₂ ICl ₂ , BEDT-TTF ₂ Cu ₂ (CN) ₃ , or [M (Pc) L ₂ ] neutral radical crystal (M represents a metal (metal), L represents an axial ligand, and Pc represents phthalocyanine) )) Or a single crystal of an organic compound complex. Examples of M in the formula include Co, Ni, Cu, Fe, Sn, Mn, Ru, Cr, Pb, Pt, Al, and V, preferably cobalt (Co) and copper (Cu). L includes CN, Cl, O, OH, and NH ₃ , preferably CN or Cl. TCNQ is an abbreviation for 7,7,8,8-tetracyanoquinodimethane, and TMPD is an abbreviation for N, N, N ′, N′-tetramethylparaphenylenediamine. Yes, TTF is an abbreviation for tetrathiafulvalene.

Specific examples of [M (Pc) L ₂ ] neutral radical crystals include [Co (Pc) (CN) ₂ ] · 2CH ₃ OH crystals, [Co (Pc) (CN) ₂ ] · 2CHBr ₃ crystals, [Co (Pc) (CN) ₂ ] · 2CH ₂ Cl ₂ crystal, [Co (Pc) (CN) ₂ ] · 2CHCl ₃ crystal, [Co (Pc) (CN) ₂ ] · CH ₃ CN crystal, [Co (Pc ) (CN) ₂ ] · 2 (CH ₃ ) ₂ SO crystal, [Co (Pc) (CN) ₂ ] · 2H ₂ O crystal, [Co (Pc) Cl ₂ ] · 2 (CH ₃ ) ₂ CO crystal, [Co (Pc) (CN) ₂ ] · 2 (CH ₃ ) ₂ CO crystal, [Co (Pc) (CN) ₂ ] · CH ₃ CH ₂ OH crystal, or [Co (Pc) Cl ₂ ] · CH ₃ CH ₂ OH crystals are exemplified.

2. Manufacturing method of non-conductive nanowire The manufacturing method of the non-conductive nanowire of the present invention basically uses an electrolytic solution containing a raw material for organic Mott insulator, and the distance between the closest parts is 1 nm to 100 μm. Including a step of producing a non-conductive nanowire by applying either or both of a DC voltage or an AC voltage having a maximum potential difference of 10 mV to 20 V from two electrodes to the two electrodes. It is a manufacturing method of nanowire. In particular, by applying an alternating voltage to the two electrodes, a non-conductive nanowire having a width of 1 nm to 1 μm and a length of 1 nm to 500 μm is selectively grown between the two electrodes. be able to. With conventional molecular vapor deposition and molecular beam methods in ultra-high vacuum, it was not possible to manufacture non-conductive nanowires that are Mott insulators. However, in the present invention, one electron is extracted per molecule from the closed-shell molecule HOMO, and a state where all of the nanowires become SOMO can be created, and an organic Mott insulator nanowire can be produced. In the present invention, molecules that have become SOMO by electrolysis are self-assembled by charge resonance or charge transfer interaction, and non-conductive nanowires that are organic Mott insulators can be grown.

2.1. Electrolyzer FIG. 1 is a schematic view of an electrolyzer for producing the non-conductive nanowire of the present invention. The electrolysis apparatus of the present invention has two electrodes (4) and an electrolysis cell (1). Further, a voltage control device (not shown) for controlling the voltage applied to the two electrodes and / or a current control device (not shown) for controlling the current supplied to the two electrodes may be provided. Good. The electrolytic apparatus of the present invention holds an electrolytic solution containing molecules constituting non-conductive nanowires in an electrolytic cell, and applies a voltage to the two electrodes in a state where the electrolytic solution and the two electrodes are in contact with each other. By doing (or supplying current), non-conductive nanowires are manufactured.

The electrolysis device may further include a reference electrode for measuring the potential of the electrode, a potential measurement device, a gate electrode for functioning as an FET, and a control computer. The electrolytic cell (1) includes an electrolytic solution holding unit that holds an electrolytic solution (solution) and a substrate insertion unit that inserts a substrate.

FIG. 2 is a conceptual diagram showing a substrate insertion portion of the electrolytic cell. FIG. 2a shows that an insulator is provided around the board insertion part, and FIG. 2b shows that the copper wire (2) is connected to the board by a conducting wire (7) such as a gold wire. In FIG. 2b, the connecting portions are connected by a conductive paste such as silver paste. For example, as shown in FIG. 2a, the substrate insertion portion of the electrolytic cell is preferably provided with, for example, a clay-like insulator (6). This serves to protect the electrode while holding the substrate. As such an insulator, putty is preferable.

The substrate of the present invention is preferably one on which at least two electrodes can be mounted. Examples of the material of the substrate include a glass substrate, a silicon substrate, and a plastic substrate, but are not particularly limited as long as they are suitable as a substrate for photolithography or electron beam lithography. The shape of the substrate is preferably a rectangular parallelepiped. The length of the substrate is preferably from 0.1 mm to 10 cm, more preferably from 1 mm to 5 cm, even more preferably from 1 cm to 4 cm, and particularly preferably from 2 cm to 3 cm. The substrate is preferably used after being cleaned so as not to contain impurities.

As an electrode in the present invention, an electrode including two electrodes provided on a substrate and facing (or arranged in parallel) is preferable. FIG. 3 is a schematic view showing an electrode having an insulating portion in which two opposing electrodes are covered with an insulator. 3a shows a front view and FIG. 3b shows a cross-sectional view. FIG. 4 is a schematic diagram showing an electrode having an insulating portion other than the surface closest to each other among the electrode surfaces. 4a shows a front view and FIG. 4b shows a cross-sectional view. FIG. 5 shows an electrode having opposing protrusions. 5a shows a front view and FIG. 5b shows a cross-sectional view. The electrode shown in FIG. 5 preferably has an insulating portion other than the opposing protruding portion. By providing such an insulating portion, it is possible to select a portion where non-conductive nanowires grow.

3a and 3b, a gate electrode (16) provided on the substrate (5) and two opposing electrodes (4) provided on an insulating layer (15) covering the gate electrode. ) Is preferable because it can function as an FET field-effect transistor after the electrodes are connected by nanowires.

Examples of the material of the electrode provided on the substrate include gold, platinum, copper, graphite, and other conductive materials. Of these, platinum is preferable, but it is particularly limited if it is suitable for lithography. It is not something.

It is preferable that at least two electrodes are formed on the substrate. The electrolytic cell may be an electrode that plays one role among the electrodes. Further, a gate electrode or a reference electrode may be further provided, or an electrode for measuring physical properties such as an electrolytic solution may be further provided.

FIG. 6 is a schematic diagram showing the shapes of two electrodes. FIG. 6a is a schematic diagram showing two electrodes having protrusions at the tips of which the electrodes are bent (opposed) toward the other electrode. FIG. 6b is a schematic view of two electrodes facing each other (aligned in parallel). FIG. 6c is a schematic diagram showing two electrodes having protrusions facing (opposing) toward the other electrode in the middle of each electrode. As the electrode, those described in FIGS. 6a, 6b, and 6c can be used as appropriate, but an electrode having a shape as shown in FIG. 6a or 6c is preferable. This is because such a shape can effectively generate non-conductive nanowires between the opposing protrusions. Furthermore, it is preferable to cover the portion other than the opposing protruding portion (or its tip) with an insulator. By doing so, it is possible to control the portion where the nanowire grows.

The electrode spacing (11) is preferably 1 nm to 100 μm, more preferably 1 nm to 1 μm, and even more preferably 1 nm to 200 nm, but is particularly limited as long as it is suitable for the desired nanowire length. It is not something. The width of the electrode is preferably 0.5 nm to 1 cm, more preferably 0.5 nm to 200 nm or 1 mm to 3 mm. The length of the electrode is preferably 1 nm to 25 mm.

FIG. 7 is a conceptual diagram for explaining the shape of the protruding portions of the electrodes facing each other. FIG. 7a is a diagram showing the tip portions of the two opposing protrusions parallel to each other. FIG. 7 b is a diagram showing a shape in which the protruding portions facing each other have a tapered shape. FIG. 7c is a diagram showing an example in which the tips of the opposing protrusions are narrowed stepwise. Further, as the shape of the protrusions, there are those described in FIGS. 7a, 7b, and 7c, and each of the protrusions has a comb-shaped tip having a plurality of thin protrusions. Also good.

The electrode is preferably immersed in an electrolyte solution, preferably 20% or more of the electrode volume is immersed, more preferably 50% or more is immersed, and particularly preferably 80% or more is immersed. . It is also preferable to perform electrolysis on the substrate by dropping an electrolytic solution between the electrodes.

In the present invention, the electrode is preferably formed on the substrate. Examples of the method for forming the electrode on the substrate include, but are not limited to, a mask vapor deposition method, a photolithography method, an electron beam lithography method, and a combination of these methods.

In the mask vapor deposition method, a mask in which a shape to be an electrode is hollowed is placed on a substrate, and a metal film is deposited thereon. Thereafter, the mask is removed from the substrate. In this way, a metal film is deposited only on the electrode portion, and a microelectrode can be formed.

In electrode preparation by photolithography, a metal film forming process for forming a metal film on a substrate, a resist layer forming process for forming a resist layer on the metal film deposited in the metal film forming process, and a resist layer forming process A resist process for exposing the resist layer formed in a desired pattern, a developing process for developing the exposed resist layer, and an etching process for etching the metal film using the resist layer remaining after the development as a mask. The resist for forming the resist layer is not particularly limited as long as it is a so-called photoresist.

In electrode preparation by electron beam lithography, a metal film forming process for forming a metal film on a substrate, a resist layer forming process for forming a resist layer on the metal film deposited in the metal film forming process, and a resist layer forming process The resist layer formed in the process is irradiated with an electron beam in a desired pattern, a development process in which the resist layer irradiated with the electron beam is developed, and a metal film is formed using the resist layer remaining in the development as a mask. An etching step of etching. The resist for forming the resist layer is not particularly limited as long as it is a so-called electron beam resist.

2.2. Voltage controller The voltage applied to the electrode is preferably controlled by a voltage controller connected to the electrode. It is more preferable that there is a reference electrode in the electrolytic cell, the potential difference between the electrodes can be measured, and the voltage applied to the electrodes can be controlled according to the measurement result. It may be a current control device that controls the current supplied to the electrodes together with or instead of the voltage control device.

2.3. Electrolyte In the manufacturing method of the nonelectroconductive nanowire of this invention, it is preferable to carry out using an electrolysis apparatus. When manufacturing non-conductive nanowires, it is preferable to use a solution (electrolyte) containing a raw material for organic Mott insulator. Non-conductive nanowires can be manufactured by an electrolytic method in which a voltage is applied to an electrolytic solution in which a substance that becomes non-conductive nanowires is dissolved.

Examples of the raw material of the organic Mott insulator in the electrolytic solution containing the raw material of the organic Mott insulator include a raw material containing a constituent molecule of the target organic Mott insulator crystal. [M (Pc) L ₂ ] (M represents a metal, L represents an axial ligand, and Pc represents phthalocyanine) as a raw material for an organic Mott insulator (potassium salt, sodium salt) Etc.). Examples of M include Co, Ni, Cu, Fe, Sn, Mn, Ru, Cr, Pb, Pt, Al, and V. Examples of L include CN, Cl, O, OH, and NH ₃ .

Solvents that dissolve the non-conductive nanowires include water and organic solvents, among which alcohols such as methanol, ethanol, propanol; chloromethane, dichloromethane, trichloroethane, bromomethane, dibromomethane. Halogenated alkanes such as tribromomethane and tetrachloropropane; acetonitrile, acetone, benzene, halogenated benzene, 1-chloronaphthalene, dimethyl sulfoxide, N, N-dimethylformamide, tetrahydrofuran, nitrobenzene, pyridine and the like are preferable, dimethyl sulfoxide, Acetonitrile, acetone, ethanol and methanol are more preferred, and dichloromethane and methanol are still more preferred. These may be used alone or in combination of two or more. Examples of the ratio of water or organic solvent include, but are not particularly limited to, those obtained by saturating a substance that becomes a non-conductive nanowire. Note that this solvent may be a raw material constituting the organic Mott insulator. The solvent when the non-conductive nanowire is [M (Pc) L ₂ ] neutral radical is preferably water or an organic solvent, such as water, alcohols, acetone, acetonitrile, benzonitrile solution of crown ether, dimethyl sulfoxide, N, N-dimethylformamide , chloroform, bromoform, dichloromethane, and a mixed solvent of two or more of these are more preferable. Acetone, acetonitrile, ethanol, methanol, dichloromethane, excess benzonitrile solution of dibenzo18-crown-6, bromoform and acetonitrile Of these, a mixed solvent of bromoform and acetone, a mixed solvent of chloroform and acetonitrile, dimethyl sulfoxide, and N, N-dimethylformamide are particularly preferable. By using such a combination of raw material and solvent, a nonconductive nanowire can be obtained effectively.

2.4. Manufacturing Process The non-conductive nanowire manufacturing method of the present invention basically manufactures a non-conductive nanowire by putting an electrolytic solution in the electrolytic cell and applying a voltage to the electrode or passing a current. Is. The current passed through the electrode may be a direct current or an alternating current. The current passed through the electrode is preferably 1 nA to 1 mA, more preferably 100 nA to 10 μA. The potential difference between the electrodes is preferably 10 mV to 20 V, more preferably 0.1 V to 5 V, and particularly preferably 0.1 V to 3 V. The applied voltage is preferably an alternating voltage, a frequency of 1 mHz to 1 kHz is preferable, and 500 mHz to 10 Hz is more preferable. In the case of an AC voltage, examples of the waveform include a sine wave, a square wave, and a sawtooth wave. A sine wave and a square wave are preferable, and a square wave is particularly preferable. The amplitude of the AC voltage is preferably 10 mV to 20 V, more preferably 100 mV to 5 V, and particularly preferably 0.1 V to 3 V. The time for applying the voltage is, for example, 10 days or less, preferably 0.01 seconds to 10 days, more preferably 1 second to 2 days, but the size of the nonconductive nanowire to be obtained. Depending on the type, voltage to be applied, voltage to be applied, etc., an appropriate time may be set, and it may be 1 minute to 10 hours, or 10 minutes to 1 hour. The temperature of the electrolytic solution is preferably −30 ° C. to 200 ° C., more preferably −30 ° C. to 120 ° C., and particularly preferably 15 ° C. to 30 ° C. There is no particular limitation as long as it is not solidified.

3. Transistor The transistor of the present invention will be specifically described with reference to the drawings. FIG. 8 is a schematic configuration diagram of the transistor of the present invention. FIG. 8A is a front view of the transistor according to the first embodiment of the present invention. FIG. 8B is a cross-sectional view taken along the line II of FIG. As shown in FIG. 8B, the transistor 21 of this embodiment is a transistor in which the source electrode 22 and the drain electrode 23 are connected by a nonconductive nanowire 24. The transistor 21 has a structure in which an insulating layer 25 is provided between the source electrode 22 and the drain electrode 23 and the gate electrode 26. The transistor of this embodiment is mounted in the order of the gate electrode 26; the insulating layer 25; and the source electrode 22, the drain electrode 23, and the nonconductive nanowire 24.

In the transistor of this embodiment, as shown in FIG. 8B, the width of the gate electrode 26 and the width of the insulating layer 25 are substantially the same. Such a transistor is preferable because it can be manufactured by using a substrate in which a gate electrode and an insulating layer are integrated as a substrate and connecting the source electrode and the drain electrode with a non-conductive nanowire by electrolysis.

FIG. 9 is a schematic configuration diagram of a transistor of the present invention according to another embodiment. FIG. 9A is a front view of a transistor according to the second embodiment of the present invention. FIG. 9B is a cross-sectional view taken along the line II of FIG. As shown in FIG. 9B, the transistor 21 in this embodiment is a transistor in which the source electrode 22 and the drain electrode 23 are connected by a nonconductive nanowire 24. The transistor 21 has a structure in which the source electrode 22 and the drain electrode 23 include a gate electrode 26 with an insulating layer 25 interposed therebetween. In the transistor of this embodiment, the gate electrode 26 is buried in the insulating layer 25, and at least two surfaces of the gate electrode are covered with the insulating layer. The width of the gate electrode 26 is narrower than that between the outermost portions of the source electrode 22 and the drain electrode 23. That is, the gate electrode 26 exists below the source electrode 22 and the drain electrode 23, but the gate electrode 26 does not protrude from the source electrode 22 and the drain electrode 23. In FIG. 9B, the transistor is formed over the substrate 7, but the substrate is an optional element and may be omitted.

FIG. 10 is a schematic configuration diagram of a transistor of the present invention according to another embodiment. FIG. 10A is a front view of a transistor according to the third embodiment of the present invention. FIG. 10B is a cross-sectional view taken along the line II of FIG. As shown in FIG. 10B, the transistor 21 of this embodiment is a transistor in which the source electrode 22 and the drain electrode 23 are connected by a nonconductive nanowire 24. The transistor 21 has a structure in which the source electrode 22 and the drain electrode 23 include a gate electrode 26 with an insulating layer 25 interposed therebetween. In the transistor of this mode, the source electrode 22, the drain electrode, and the gate electrode 26 are buried in the insulating layer 25, and at least two surfaces of the gate electrode are covered with the insulating layer. Further, the width of the gate electrode is narrower than the width of the combined portion of the source electrode and the drain electrode. In FIG. 10B, the transistor is formed over the substrate 7, but the substrate is an optional element and may be omitted.

FIG. 11 is a schematic configuration diagram of a transistor of the present invention according to another embodiment different from the above. FIG. 11A is a front view of a transistor according to the fourth embodiment of the present invention. FIG. 11B is a cross-sectional view taken along the line AB of FIG. As shown in FIG. 11B, the transistor 21 of this embodiment is a transistor in which the source electrode 22 and the drain electrode 23 are connected by a nonconductive nanowire 24. The transistor 21 has a structure in which the source electrode 22 and the drain electrode 22 include a gate electrode 26 with an insulating layer 25 interposed therebetween. In the transistor of this embodiment, the gate electrode 26 and the insulating layer 25 cover the nonconductive nanowire 24. Further, the width of the gate electrode is the same as or narrower than the width of the combined portion of the source electrode and the drain electrode. In FIG. 11B, the transistor is formed over the substrate 27; however, the substrate is an optional element and may be omitted.

The materials of the source electrode, gate electrode, and drain electrode constituting the transistor may be the same or different. Examples of the material for these electrodes include conductive materials such as gold, platinum, copper, and graphite. Among these, gold or platinum is more preferable, but it is not particularly limited.

As shown in FIGS. 8 to 11, the source electrode 22 and the drain electrode 23 are preferably configured as two electrodes facing each other. A part of two opposing electrodes may be covered with an insulating layer, or a face other than the face closest to each other may be covered with an insulating layer. As shown in FIGS. 8A and 9A, the source electrode and the drain electrode have protrusions (convex portions) in the middle or at the tip thereof toward the other electrode. Is preferred. FIG. 12 is a diagram illustrating an example of protrusions of the source electrode 22 and the drain electrode 23. FIG. 12 (A) shows that the tip portions are parallel to each other, FIG. 12 (B) shows that the tip portion of the projection portion has a shape that becomes thinner, and FIG. 12 (C) FIG. 12 (D) shows a shape having a plurality of comb-shaped protrusions at the distal end portion. In the figure, 24a indicates a non-conductive nanowire that connects the source electrode 22 and the drain electrode 23, and 24b indicates that the source electrode 22 and the drain electrode 23 cannot be connected due to insufficient growth. Among these protrusions, the protrusions shown in FIGS. 12B to 12D are preferable, and the protrusion shown in FIG. 12D is particularly preferable. In the protrusion portion of FIG. 12A, since crystals grow from the entire parallel electrode surface, the crystal growth is insufficient and the source electrode 22 and the drain electrode 23 cannot be connected, or the transistor characteristics are difficult to control. Become more. On the other hand, in the protrusions of FIGS. 12B and 12C, the crystal grows from the portion where the width is narrow, so that the source electrode 22 and the drain electrode 23 can be effectively connected. On the other hand, the protrusion in FIG. 12D has a plurality of, preferably 2 to 10, and more preferably 3 to 7, comb-like protrusions. Even if the growth is not sufficient, the source electrode 22 and the drain electrode 23 can be connected. For example, as shown in FIG. 12D, the plurality of protrusions may be provided with protrusions having the same length in parallel, or protrusions having different lengths may be provided in parallel. The nanowire is preferably grown from the tips of a plurality of protrusions and connects the electrodes. As shown in FIG. 12D, the interval between the plurality of protrusions is an equal interval. However, the interval may be narrower as it approaches the center. Further, a plurality of protrusions may be provided at the tip as shown in FIGS. 12B and 12C. The width of the electrode is preferably 0.5 nm to 1 cm, more preferably 0.5 nm to 200 nm or 1 mm to 3 mm. The length of the electrode is preferably 1 nm to 25 mm.

The distance between the source electrode and the drain electrode (distance between the closest portions) is 1 nm to 100 μm, more preferably 1 nm to 1 μm, and even more preferably 1 nm to 200 nm. There is no particular limitation as long as it is suitable. This interval may be appropriately adjusted according to the physical properties of the nanowire.

Nanowires exist between the source electrode and the drain electrode, and connect the source electrode and the drain electrode. Only one nanowire may exist between the source electrode and the drain electrode, or a plurality of nanowires may exist. Further, several nanowires may be connected between the source electrode and the drain electrode alone, or the source electrode and the drain electrode may be connected in a state where a plurality of nanowires are connected.

Examples of the insulating layer include known insulating layers such as a silicon dioxide film and a metal oxide film. The thickness of the insulating layer is 0.1 nm to 5 mm.

These transistors are normally turned on when no voltage is applied to the gate electrode, and a current flows when a voltage is applied between the source electrode 22 and the drain electrode 23. However, when a voltage higher than a threshold is applied to the gate electrode, these transistors are turned off. Thus, no current flows even when a voltage is applied between the source electrode 22 and the drain electrode 23.

The transistor of the present invention may be basically manufactured according to the method disclosed in WO03 / 076332. Specifically, by conducting electrolysis with the above-described electrolysis apparatus, non-conductive nanowires are grown between the electrodes, and the electrodes are connected to each other, whereby a transistor can be manufactured.

[Production Example 1: Production of Electrolytic Cell] The electrolytic cell shown in FIG. 1 was produced using a commercially available reagent bottle. As shown in FIG. 2b, the copper wire and the upper part of the electrode were connected by a gold wire. The electrolyte holding part used the conductor part of the reagent bottle, and the board insertion part was used by modifying the cap part of the reagent bottle. Putty was put on the board insertion part. The diameter of the reagent bottle was 23 mm.

[Production Example 2: Production of Electrode with 20 μm Interval] An electrode used for the non-conductive nanowire growth method was produced on a glass substrate. A glass substrate of 25 × 10 mm was prepared, and platinum was deposited on the substrate. A photoresist agent S1818 (manufactured by Shipley Far East Co., Ltd.) was spin-coated on a platinum-deposited substrate. The spin coater was rotated at 5000 rpm for 90 seconds. A coating film was formed by drying at 110 ° C. for 2 minutes. The substrate coated with the photoresist was exposed through a mask in the form of an electrode using a mercury lamp light source mask aligner. Development was performed for 60 seconds using MicroPosit DeveloperPer MF319 (manufactured by Shipley Far East Co., Ltd.). At this time, the unexposed portion was completely dissolved. Subsequently, washing was performed using pure water. Then, it etched using the dry etching apparatus (Samco Co., Ltd. RIE-10NR). Thereafter, the mask was removed from the substrate by dipping in a stripping solution. In this way, a platinum electrode was formed on the silicon substrate with an oxide film. The width of each electrode was 1 mm, the length of each electrode was 2.0 cm to 2.3 cm, and the distance between the electrodes was 20 μm.

[Production Example 3: Production of Electrode with 20 μm Interval] An electrode used for the non-conductive nanowire growth method was produced on a silicon substrate with an oxide film. A silicon substrate with an oxide film of 30 × 10 mm was prepared, and platinum was deposited on the substrate. A photoresist agent S1818 (manufactured by Shipley Far East Co., Ltd.) was spin-coated on a platinum-deposited substrate. The spin coater was rotated at 5000 rpm for 90 seconds. A coating film was formed by drying at 110 ° C. for 2 minutes. The substrate coated with the photoresist was exposed through a mask in the form of an electrode using a mercury lamp light source mask aligner. Development was performed for 60 seconds using MicroPosit DeveloperPer MF319 (manufactured by Shipley Far East Co., Ltd.). At this time, the unexposed portion was completely dissolved. Subsequently, washing was performed using pure water. Then, it etched using the dry etching apparatus (Samco Co., Ltd. RIE-10NR). Thereafter, the mask was removed from the substrate by dipping in a stripping solution. In this way, a platinum electrode was formed on the silicon substrate with an oxide film. The width of each electrode was 1 mm, the length of each electrode was 2.0 cm to 2.3 cm, and the distance between the electrodes was 20 μm.

[Production Example 4: Production of Nano-Spacing Electrode] An electrode used in the production method of non-conductive nanowires was produced on a silicon substrate with an oxide film. A 30 × 10 mm silicon substrate with an oxide film was prepared, and ZEP52A (manufactured by Zeon Corporation) was applied as an electron beam resist using a spin coater. After drying, the tip portion was exposed with an electron beam lithography apparatus ELS-7700 (Elionix). After the exposure, the electron beam resist was developed. After development, 5 nm of titanium was vapor-deposited with a sputtering apparatus, and then 100 nm of gold was vapor-deposited. After removing the electron beam resist, photoresist S1818 (manufactured by Shipley Far East Co., Ltd.) was applied, dried, exposed and developed, titanium was again deposited by 5 nm, and gold was deposited by 100 nm. The photoresist agent was stripped by dipping in a stripping solution. In this way, an electrode was created.

When 5 mg of K · [Co (Pc) (CN) ₂ ] and 14 ml of methanol were added to the container and dissolved, a saturated electrolyte solution with undissolved residue was obtained. This electrolytic solution was filtered using a syringe filter (pore diameter 200 nm) and added to the electrolytic solution holding part. The electrode substrate of Production Example 2 was inserted into the substrate insertion portion, and the electrode substrate was fixed in place using a putty. A gold wire was passed between the upper part of the electrode and the copper wire of the electrolytic cell and fixed with silver paste. After the substrate holder was combined with the electrolyte holder, a power source and a digital multimeter were connected to the copper wire. An AC voltage of 2.5 V and 2.0 kHz was applied to the electrode and allowed to stand for 2 minutes. The temperature of the solution at this time was 23 ° C. The non-conductive nanowires thus obtained were columnar with a length of 100 nm to 1 μm and a width of 50 nm to 500 nm. An SEM photograph of the non-conductive nanowire obtained at this time is shown in FIG.

A non-conductive nanowire was obtained in the same manner as in Example 1 except that the electrode substrate was made in Production Example 3 and the electrolysis period was 3 minutes. The non-conductive nanowires thus obtained were columnar with a length of 500 nm to 2 μm and a width of 50 nm to 200 nm. The SEM photograph of the non-conductive nanowire obtained at this time is shown in FIG.

A nonconductive nanowire was obtained in the same manner as in Example 2 except that the electrolysis period was 10 minutes. The non-conductive nanowires thus obtained were needle-shaped having a length of 300 μm to 5 μm and a width of 50 nm to 300 nm. An SEM photograph of the non-conductive nanowire obtained at this time is shown in FIG.

A nonconductive nanowire was obtained in the same manner as in Example 2 except that the applied AC voltage was 3.0 V and the electrolysis period was 5 minutes. The non-conductive nanowires thus obtained were columnar with a length of 100 nm to 1 μm and a width of 50 nm to 500 nm. An SEM photograph of the non-conductive nanowire obtained at this time is shown in FIG.

A non-conductive nanowire was obtained in the same manner as in Example 1 except that the electrode substrate was made in Production Example 4, the electrolysis period was 5 minutes, and the applied voltage was 2.5 V. The non-conductive nanowires thus obtained were columnar with a length of 100 nm to 2 μm and a width of 50 nm to 500 nm. An SEM photograph of the non-conductive nanowire obtained at this time is shown in FIG.

DESCRIPTION OF SYMBOLS 1 Electrolysis cell 2 Copper wire 3 Substrate insertion part 4 Electrode 5 Substrate 6 Insulator 7 Gold 8 Silver paste 11 Space | interval 12 Protrusion part

Claims (11)

The width is 50 nm to 1 μm,
The length is 100 nm to 5 μm,
A non-conductive nanowire that is an organic Mott insulator containing crystals of an organic compound,
The organic Mott insulator is made of [M (Pc) L ₂ ] neutral radical crystal (M represents a metal, L represents an axial ligand, and Pc represents phthalocyanine).
The [M (Pc) L ₂ ] neutral radical crystals are [Co (Pc) (CN) ₂ ] · 2CHBr ₃ crystals, [Co (Pc) (CN) ₂ ] · 2CH ₂ Cl ₂ crystals, [Co (P Pc) (CN) ₂ ] · 2CHCl ₃ crystal, [Co (Pc) (CN) ₂ ] · CH ₃ CN crystal, [Co (Pc) (CN) ₂ ] · 2 (CH ₃ ) ₂ SO crystal, [Co (Pc) (CN) ₂ ] · 2H ₂ O crystal, [Co (Pc) (CN) ₂ ] · 2 (CH ₃ ) ₂ CO crystal, or [Co (Pc) (CN) ₂ ] · CH ₃ CH ₂ Non-conductive nanowires that are OH crystals. The nonconductive nanowire according to claim 1, wherein the conductivity is 1 S · cm ⁻¹ or less. Using electrolyte containing raw material for organic Mott insulator,
By applying either or both of a DC voltage and an AC voltage with a maximum potential difference of 10 mV to 20 V from two electrodes having a distance of 20 μm to 100 μm closest to each other, the non-conductive nano Including the process of manufacturing the wire,
The organic Mott insulator is made of [M (Pc) L ₂ ] neutral radical crystal (M represents a metal, L represents an axial ligand, and Pc represents phthalocyanine).
The [M (Pc) L ₂ ] neutral radical crystals are [Co (Pc) (CN) ₂ ] · 2CHBr ₃ crystals, [Co (Pc) (CN) ₂ ] · 2CH ₂ Cl ₂ crystals, [Co (P Pc) (CN) ₂ ] · 2CHCl ₃ crystal, [Co (Pc) (CN) ₂ ] · CH ₃ CN crystal, [Co (Pc) (CN) ₂ ] · 2 (CH ₃ ) ₂ SO crystal, [Co (Pc) (CN) ₂ ] · 2H ₂ O crystal, [Co (Pc) (CN) ₂ ] · 2 (CH ₃ ) ₂ CO crystal, or [Co (Pc) (CN) ₂ ] · CH ₃ CH ₂ The manufacturing method of the nonelectroconductive nanowire which is an organic Mott insulator which is OH crystal. By applying an alternating voltage to the two electrodes,
The method for producing a nonconductive nanowire according to claim 3, wherein a nonconductive nanowire having a width of 50 nm to 1 µm and a length of 100 nm to 5 µm is produced between the two electrodes. A source electrode, a drain electrode and a gate electrode;
The source electrode and the drain electrode are connected by a non-conductive nanowire that is an organic Mott insulator containing an organic compound crystal,
The organic Mott insulator is made of [M (Pc) L ₂ ] neutral radical crystal (M represents a metal, L represents an axial ligand, and Pc represents phthalocyanine).
The [M (Pc) L ₂ ] neutral radical crystals are [Co (Pc) (CN) ₂ ] · 2CHBr ₃ crystals, [Co (Pc) (CN) ₂ ] · 2CH ₂ Cl ₂ crystals, [Co (P Pc) (CN) ₂ ] · 2CHCl ₃ crystal, [Co (Pc) (CN) ₂ ] · CH ₃ CN crystal, [Co (Pc) (CN) ₂ ] · 2 (CH ₃ ) ₂ SO crystal, [Co (Pc) (CN) ₂ ] · 2H ₂ O crystal, [Co (Pc) (CN) ₂ ] · 2 (CH ₃ ) ₂ CO crystal, or [Co (Pc) (CN) ₂ ] · CH ₃ CH ₂ Transistors that are OH crystals.   6. The transistor according to claim 5, further comprising an insulating layer between the source and drain electrodes and the gate electrode.   The transistor according to claim 5, wherein the distance between the closest portions of the source electrode and the drain electrode is 20 μm to 100 μm.   The transistor according to claim 5, wherein the non-conductive nanowire has a width of 50 nm to 1 μm and a length of 100 nm to 5 μm. The transistor according to claim 5, wherein the conductivity of the non-conductive nanowire is 1 S · cm ⁻¹ or less. The source electrode and the drain electrode each have a protrusion,
The transistor according to claim 5, wherein the protrusion has a plurality of comb-shaped protrusions at a tip portion.   The transistor according to claim 5, wherein the non-conductive nanowire is made of a single crystal of an organic compound complex or a single crystal of an organic compound.

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