Tunneling molecular junction structure and construction method and application thereof

Abstract

The invention relates to the technical field of electronic devices, and provides a tunneling molecular junction structure and a construction method and application thereof.The tunneling molecular junction structure comprises a first electrode, a second electrode and a self-assembly monomolecular layer, the first electrode and the second electrode are oppositely arranged, and the self-assembly monomolecular layer is arranged between the first electrode and the second electrode. The second electrode comprises a silicon substrate and a gold film layer arranged on the surface of the silicon substrate, the gold film layer is located between the silicon substrate and the self-assembly monomolecular layer, and the material of the first electrode comprises gallium indium liquid metal. The asymmetric tunneling molecular junction structure provided by the invention has an obvious rectification characteristic, and effective combination of a metal electrode and a silicon semiconductor is realized.

Description

Technical Field

[0001] The present application belongs to the technical field of electronic devices, and in particular relates to a tunneling molecular junction structure and a construction method and application thereof. Background Art

[0002] As the electronic industry technology develops rapidly towards miniaturization and integration, the integration of chips is getting higher and higher. However, in the process of development, it also faces many challenges in physical laws, such as Moore's Law cannot further guide the process development of silicon-based electronics. Molecular electronics creatively uses single molecules or single-layer molecular films as components of devices and applies them to the field of tunneling, breaking the bottleneck of miniaturization technology of traditional silicon-based devices and developing rapidly in related fields.

[0003] In order to realize the application of molecules in electronic circuits, it is necessary to stably fix the molecules in the electronic circuits to form an anchoring connection between organic molecules and solid metals. In the development of molecular electronics, since the concept of molecular diodes was proposed in 1974, many functional molecular devices have been confirmed and prepared, and a series of methods for constructing molecular-scale tunneling molecular junction structures have also been derived, such as scanning tunneling microscope splitting technology, mechanically controllable splitting technology, atomic force microscope splitting method, micro-nano processing technology, etc., which can realize the connection between single molecules and electrodes. At the same time, the electrical measurement technology of single-layer molecular films has also developed rapidly, which is of great value to the construction of molecular tunneling junctions and the study of the physical and chemical properties of molecules themselves.

[0004] In the existing electrode-molecule-electrode system, metal electrodes such as gold, silver, and platinum are relatively common metal electrodes. However, these metal electrodes have limitations in specific systems, such as process incompatibility with existing silicon-based semiconductor technology, poor versatility of conductive optical devices, and cost factors of precious metals. Therefore, exploring new electrode materials and realizing large-scale application of molecular tunneling junction devices are of great significance to the industrial application of molecular devices. Summary of the invention

[0005] The purpose of the present application is to provide a tunneling molecular junction structure and a construction method thereof, aiming to solve the problem of compatible phase difference between metal electrodes and semiconductor silicon.

[0006] Another object of the present application is to provide a tunneling molecular device containing the tunneling molecular junction structure, aiming to solve the problems of high cost and poor versatility of existing conductive optical devices.

[0007] Another object of the present application is to provide a method for testing the electrical properties of a tunneling molecular junction structure, aiming to solve the problem of how to measure the current density of a large-area molecular junction.

[0008] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0009] In a first aspect, the present application provides a tunneling molecular junction structure, comprising a first electrode and a second electrode arranged opposite to each other, and a thiol-containing self-assembled monolayer arranged between the first electrode and the second electrode, the second electrode comprising a silicon substrate and a gold film layer arranged on the surface of the silicon substrate, the gold film layer being located between the silicon substrate and the self-assembled monolayer, and the material of the first electrode comprising gallium-indium liquid metal.

[0010] In a second aspect, the present application provides a method for constructing a tunneling molecular junction structure, comprising the following steps:

[0011] Providing a silicon substrate, and depositing a gold film layer on the surface of the silicon substrate to obtain a second electrode;

[0012] Molecules containing thiol functional groups are self-assembled to form a self-assembled monolayer on the surface of the gold film layer;

[0013] A gallium-indium liquid metal first electrode is arranged on the surface of the self-assembled monolayer to form the tunneling molecular junction structure of the present application.

[0014] In a third aspect, the present application provides a tunneling molecular device, including the tunneling molecular junction structure of the present application and / or the tunneling molecular junction structure constructed by the construction method of the tunneling molecular junction structure of the present application.

[0015] In a fourth aspect, the present application provides a method for testing the electrical properties of the tunneling molecular junction structure, comprising the following steps:

[0016] Connect one end of the electrode lead to the first electrode, and connect the other end of the electrode lead to the second electrode to form a closed loop;

[0017] Apply voltage to the closed loop, obtain a signal of current varying with voltage, and collect multiple current-voltage curves;

[0018] The data of the current-voltage curve are calculated to obtain the electrical properties of the tunneling molecular junction structure.

[0019] The tunneling molecular junction structure provided in the first aspect of the present application uses gallium-indium liquid metal as the first electrode, a silicon substrate provided with a gold film layer as the second electrode, and molecules containing mercapto functional groups as molecular conductors, thereby forming a gallium-indium liquid metal-molecule-gold / silicon doped electrode asymmetric tunneling molecular junction structure. The current-voltage curve of the asymmetric tunneling molecular junction structure has obvious rectification characteristics, realizes the effective combination of the metal electrode and the silicon semiconductor, and obtains a molecular diode device based on a molecular wire containing mercapto functional groups.

[0020] The second aspect of the present application provides a method for constructing a tunneling molecular junction structure. First, a gold film layer is deposited on the surface of a silicon substrate. Then, a self-assembled monolayer containing a thiol group is prepared in the form of self-assembly on the surface of the gold film layer. Then, a gallium-indium liquid metal electrode is formed on the surface of the self-assembled monolayer. The presence of the gold film layer makes the transmission of electronic current in the metal semiconductor junction depend on the energy barrier of the electrons, namely the Schottky barrier. At the same time, gold atoms will diffuse to the silicon surface of the substrate, which is conducive to the formation of gold doping and deep traps. This makes it possible for the molecular junction based on the thiol-containing molecular system to produce special electrical properties, thereby effectively constructing an asymmetric tunneling molecular junction structure of gallium-indium liquid metal-molecule-gold / silicon doped electrode.

[0021] The tunneling molecular device provided in the third aspect of the present application contains an asymmetric tunneling molecular junction structure constructed in the present application, which realizes the effective combination of metal electrodes and silicon-based semiconductors and improves the versatility of conductive optical devices.

[0022] The electrical performance testing method provided in the fourth aspect of the present application can obtain the current density distribution characteristics of a large-area molecular junction containing a gallium-indium liquid metal electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 is a schematic diagram of a current closed loop formed by a tunneling molecular junction structure provided in an embodiment of the present application;

[0025] Figure 2 It is a one-dimensional curve of voltage-current density and a two-dimensional distribution thermodynamic diagram provided in the embodiments of the present application.

[0026] Among them, the reference numerals in the figure are:

[0027] 1. First electrode, 2. Self-assembled monolayer, 3. Second electrode. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0030] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0031] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0032] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0033] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0034] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0035] The term "EGaIn" stands for gallium indium liquid metal.

[0036] A first aspect of an embodiment of the present application provides a tunneling molecular junction structure, comprising a first electrode and a second electrode arranged opposite to each other, and a thiol-containing self-assembled monolayer arranged between the first electrode and the second electrode, the second electrode comprising a silicon substrate and a gold film layer arranged on the surface of the silicon substrate, the gold film layer being located between the silicon substrate and the self-assembled monolayer, and the material of the first electrode comprising gallium-indium liquid metal.

[0037] The tunneling molecular junction structure provided in the first aspect of the embodiment of the present application uses gallium-indium liquid metal as the first electrode, a silicon substrate provided with a gold film layer as the second electrode, and molecules containing mercapto functional groups as molecular conductors, thereby forming a gallium-indium liquid metal-molecule-gold / silicon doped electrode asymmetric tunneling molecular junction structure. The current-voltage curve of the asymmetric tunneling molecular junction structure has obvious rectification characteristics, realizes the effective combination of the metal electrode and the silicon semiconductor, and obtains a molecular diode device based on a molecular wire containing mercapto functional groups.

[0038] Using the asymmetric tunneling molecular junction structure provided in the embodiment of the present application, one end of the electrode lead is connected to the silicon substrate, and the other end is connected to the gallium indium liquid metal, and a current is passed to form a closed loop, as shown in the schematic diagram. Figure 1 As shown. By adjusting the voltage and current in the closed loop, the voltage-current density signal of the gallium-indium alloy-molecule-gold / silicon tunnel junction formed in this process is collected, and then a large number of collected voltage and current density curves are analyzed, and finally the current density distribution of the large-area molecular junction of the liquid gallium-indium alloy and the electrical properties of the whole system, such as conductivity range, rectification ratio, etc., are obtained. The stable conductivity and consistent chemical interaction between the thiol-containing molecules and the electrodes successfully demonstrate the potential for reliable molecular connection, thereby providing the feasibility of constructing large-area molecular junctions with gold-silicon doped electrodes. At the same time, the current density distribution and circuit characteristics of the large-area molecular junction obtained in the closed circuit can also indicate that there is a stable chemical interaction between the thiol-containing molecules and the electrodes, and the corresponding molecular junction is also stable and reliable.

[0039] In some embodiments, the chemical formula of the material of the self-assembled monolayer is CH3(CH2) n SH, n is 9 to 16.

[0040] The material of the self-assembled monolayer provided in the embodiment of the present application is a monothiol alkyl molecule, and the end containing the thiol group can form a stable coupling with the gold atoms in the gold film layer, while the coupling form formed by the end without the thiol group and the gallium indium liquid metal is different from the coupling form of the thiol group / gold atom. At the same time, since the molecule has a higher HOMO-LUMO (HOMO: highest occupied molecular orbital; LUMO: lowest unoccupied molecular orbital) gap, the molecular junction interface barrier formed by the self-assembled monolayer arranged between the first electrode and the second electrode has asymmetry, so that the formed gallium indium liquid metal-molecule-gold / silicon doped electrode asymmetric tunneling molecular junction structure has a higher rectification characteristic.

[0041] There is a certain correlation between the molecular chain length of the material contained in the self-assembled monolayer and the current density of the formed asymmetric tunneling molecular junction. Based on this, within the molecular length range of the material of the self-assembled monolayer provided in the embodiment of the present application, the constructed gallium indium liquid metal-monothiol alkyl molecule-gold / silicon doped electrode asymmetric tunneling molecular junction has a higher rectification ratio and current density.

[0042] In some embodiments, the chemical formula of the material of the self-assembled monolayer is CH3(CH2) n SH, n is 9 to 13. Specifically, n may be 9, 10, 11, 12 or 13.

[0043] In some embodiments, the material of the self-assembled monolayer includes at least one of 1-thiodecane, 1-dodecyl mercaptan, and 1-tetradecyl mercaptan.

[0044] The embodiments of the present application use 1-thiodecane, 1-dodecyl mercaptan or 1-tetradecyl mercaptan as a molecular conductor to form a rectangular potential barrier between the gold silicon doped electrode and the gallium indium liquid metal electrode. Due to the different potential barrier heights at the molecular junction interface, the asymmetric tunneling molecular junction formed has an obvious rectifying effect.

[0045] In some embodiments, the contact surface between the first electrode and the self-assembled monolayer is circular, and the diameter of the contact surface is ≤50 μm.

[0046] The current density is determined by the ratio of the current to the contact area. The larger the contact area, the larger the conductive channel formed, and the greater the current. In order to obtain a stable and high current density, the embodiment of the present application controls the diameter of the contact surface between the first electrode and the self-assembled monolayer to be ≤50μm, so that the constructed gold-silicon doped electrode produces a stable and reliable molecular junction and obtains a current density close to the order of magnitude of a pure gold electrode.

[0047] In some embodiments, the diameter of the contact surface between the first electrode and the self-assembled monolayer is 12.5 μm to 50 μm. Specifically, the diameter of the contact surface between the first electrode and the self-assembled monolayer can be 12.5 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or within the range of any of the above values.

[0048] In some embodiments, the first electrode is in a cone shape, the tip of the cone faces the self-assembled monolayer molecular layer, and the diameter of the tip of the cone is 12.5 μm to 37.5 μm.

[0049] It should be understood that the first electrode is in the shape of a cone with a thin tip and a thick base, and the cross section of the cone tip is circular.

[0050] Considering the current density of the asymmetric tunneling molecular junction structure constructed by the present application and the ductility of the gallium-indium liquid metal provided by the present application, the embodiment of the present application designs the first electrode into a cone, that is, a cone with a thin tip and a thick root, so that the first electrode has an appropriate contact area with the self-assembled monolayer molecular layer, so that a stable current signal and a higher current density can be obtained. Specifically, the diameter of the conical tip of the embodiment of the present application can be 12.5μm, 15μm, 20μm, 25μm, 30μm, 37.5μm or within the range of any of the above values.

[0051] In some embodiments, the thickness of the gold film layer is 20nm to 200nm. The gold atoms contained in the gold film disposed on the surface of the silicon substrate can diffuse to the surface of the silicon substrate to form gold doping and deep traps. When a tunneling molecular junction with a gold-silicon doped electrode as the second electrode is constructed, the transmission of the electron current in the metal / semiconductor junction depends on the energy barrier of the electron, i.e., the Schottky barrier, so that the molecular junction with the thiol-containing molecular system produces special electrochemical properties, such as rectification properties.

[0052] In some embodiments, the thickness of the gold film layer is 50 nm to 100 nm. Within the thickness range of the gold film layer provided in the embodiments of the present application, gold atoms in the gold film layer can diffuse into the silicon substrate to form gold doping and deep traps, which is conducive to constructing a molecular tunneling junction with mercapto-containing molecules as molecular conductors.

[0053] In some specific embodiments, the thickness of the gold film layer is 20 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 200 nm, or any range thereof.

[0054] In some embodiments, the thickness of the silicon substrate is 400 μm to 600 μm. Specifically, the thickness of the silicon substrate may be 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, or any range thereof.

[0055] In some embodiments, the purity of the gallium-indium liquid metal is ≥99.99%, wherein the mass content of gallium is 70-80wt% and the mass content of indium is 20-30wt%.

[0056] In some embodiments, in the gallium-indium liquid metal, the mass content of gallium is 75.5 wt %, and the mass content of indium is 24.5 wt %.

[0057] A second aspect of the present application provides a method for constructing a tunneling molecular junction structure, comprising the following steps:

[0058] Step S10, providing a silicon substrate, and depositing a gold film layer on the surface of the silicon substrate to obtain a second electrode;

[0059] Step S20, forming a self-assembled monolayer on the surface of the gold film layer by self-assembling the molecules containing the thiol functional group;

[0060] Step S30: disposing a first gallium-indium liquid metal electrode on the surface of the self-assembled monolayer to form the tunneling molecular junction structure of the present application.

[0061] The second aspect of the embodiment of the present application provides a method for constructing a tunneling molecular junction structure. First, a gold film layer is deposited on the surface of a silicon substrate. Then, a self-assembled monolayer containing a thiol group is prepared in the form of self-assembly on the surface of the gold film layer. Then, a gallium-indium liquid metal electrode is formed on the surface of the self-assembled monolayer. The presence of the gold film layer makes the transmission of electronic current in the metal semiconductor junction depend on the energy barrier of the electrons, namely the Schottky barrier. At the same time, gold atoms will diffuse to the silicon surface of the substrate, which is conducive to the formation of gold doping and deep traps. This makes it possible for the molecular junction based on the thiol-containing molecular system to produce special electrical properties, thereby effectively constructing an asymmetric tunneling molecular junction structure of gallium-indium liquid metal-molecule-gold / silicon doped electrode.

[0062] In some embodiments, in step S10, a person skilled in the art may deposit a gold film layer on the surface of a silicon substrate using conventional or well-known techniques in the art, such as magnetron sputtering. To ensure that the gold atoms and -SH in the self-assembled monolayer form an effective and stable coupling, the gold film layer on the surface of the silicon substrate provided in the embodiment of the present application has a high surface flatness and good cleanliness.

[0063] In some embodiments, in step S10, the size of the second electrode includes but is not limited to 1 cm×1 cm, or 1.5 cm×1.5 cm, or 2 cm×2 cm.

[0064] In some embodiments, in step S20, the step of forming a self-assembled monolayer on the surface of the gold film layer by self-assembling the molecules containing thiol functional groups comprises:

[0065] Step S210, providing a molecular solution containing a thiol functional group;

[0066] Step S220: immersing the second electrode in the molecular solution to form a self-assembled monolayer on the surface of the gold film layer.

[0067] In some embodiments, in step S210, the concentration of the molecular solution is 5 mmol to 20 mmol. Specifically, the concentration of the molecular solution may include but is not limited to 5 mmol, 8 mmol, 10 mmol, 15 mmol, 18 mmol, and 20 mmol.

[0068] In some embodiments, in step S210, the solvent of the molecular solution may include but is not limited to methanol and ethanol.

[0069] In some embodiments, in step S220, the second electrode is immersed in the molecular solution for 3 to 24 hours. Specifically, the immersion time may include but is not limited to 3 hours, 5 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, and 24 hours.

[0070] In some embodiments, in step S30, the gold film layer is dried before forming the first electrode on the surface of the self-assembled monolayer, and the drying method can be drying with an inert gas.

[0071] In some embodiments, in step S30, the step of providing a first electrode of gallium-indium liquid metal on the surface of the self-assembled monolayer includes:

[0072] Step S310, using a microneedle to suck liquid gallium-indium alloy, using mechanical force to slowly squeeze the liquid metal out of the needle tube, and repeatedly stretching the liquid metal to form a conical first electrode, and the diameter of the tip of the first electrode is 12.5 μm to 37.5 μm, which can be called a liquid metal needle tip electrode;

[0073] Step S320, using a micromanipulator for precise control, gradually bringing the prepared needle tip electrode close to the surface of the self-assembled monolayer, until the gallium indium liquid metal forms an appropriate contact area with the self-assembled monolayer, thereby forming the tunneling molecular junction structure of the present application.

[0074] In some specific embodiments, in step S310, the specification of the microneedle tube is 10 μL to 20 μL.

[0075] In some specific embodiments, in step S320 , the moving distance of the needle tip electrode is 50 μm to 100 μm per step.

[0076] A third aspect of an embodiment of the present application provides a molecular tunneling device, including the tunneling molecular junction structure of the present application and / or a tunneling molecular junction structure constructed by the construction method of the tunneling molecular junction structure of the present application.

[0077] The tunneling molecular device provided in the third aspect of the embodiment of the present application contains an asymmetric tunneling molecular junction structure constructed in the present application, which realizes the effective combination of metal electrodes and silicon-based semiconductors and improves the versatility of conductive optical devices.

[0078] A fourth aspect of the present application provides a method for measuring large-area molecular conductivity of a tunneling molecular junction structure, comprising the following steps:

[0079] Step S1, connecting one end of the electrode lead to the first electrode, and connecting the other end of the electrode lead to the second electrode to form a closed loop;

[0080] Step S2, applying voltage to the closed loop, obtaining a signal of current varying with voltage, and collecting a plurality of current-voltage curves;

[0081] Step S3: Calculate the data of the current-voltage curve to obtain the electrical properties of the tunneling molecular junction structure.

[0082] According to the large-area molecular conductivity testing method provided in the embodiment of the present application, the current signal of the asymmetric tunneling molecular junction structure provided in the embodiment of the present application can be obtained, indicating that the gold-silicon doped electrode can produce a stable and reliable molecular junction, and there is a stable and high interaction force between the self-assembled monolayer and the first electrode and the second electrode.

[0083] In some embodiments, in step S1, one end of the electrode lead is connected to the silicon substrate, and the other end is connected to the first electrode of the gallium indium liquid metal, and a current is passed to form a closed loop, as shown in the schematic diagram. Figure 1 shown.

[0084] In some embodiments, in step S3, all collected current-voltage curves are imported into Origin software, a two-dimensional distribution histogram of current density and voltage is drawn, and the tunnel molecular junction current density and rectification ratio are calculated.

[0085] The following describes the invention in conjunction with specific embodiments.

[0086] Example 1

[0087] This embodiment provides a tunneling molecular junction structure and a construction method thereof.

[0088] A method for constructing a tunneling molecular junction structure (gallium indium liquid metal-1-tetradecyl mercaptan-gold / silicon doped electrode asymmetric tunneling molecular junction structure) comprises the following steps:

[0089] Step A1, preparing a molecular solution: dissolving 1-tetradecyl mercaptan (purchased from Aladdin) in a methanol solution to prepare a molecular solution with a concentration of 10 mmol.

[0090] Step A2, provide a silicon substrate, and use magnetron sputtering to deposit a gold target onto the flat surface of the silicon substrate to form a gold film layer with a thickness of 100 nm. The gold film layer has high surface flatness and good cleanliness, and then cut into a specification of 1 cm×1 cm to obtain a second electrode.

[0091] Step A3, immerse the second electrode in 10 mL of the molecular solution, and after immersion for 12 hours, a self-assembled monolayer is formed on the surface of the gold film layer. Then, the silicon substrate is taken out with tweezers, the gold film surface is rinsed with ethanol, and blown dry with inert gas for standby use.

[0092] Step A4, use a 10uL microneedle to inhale liquid gallium-indium alloy, use mechanical force to slowly squeeze the liquid metal out of the needle, and form a conical first electrode by repeatedly stretching the liquid metal, and the diameter of the tip of the first electrode is 25μm; use a micromanipulator to bring the prepared conical first electrode close to the surface of the self-assembled monolayer, and wait for the gallium-indium liquid metal to form an appropriate contact area with the self-assembled monolayer (the diameter of the contact area is 40μm), forming a gallium-indium liquid metal-1-tetradecylthiol-gold / silicon-doped electrode asymmetric tunneling molecular junction.

[0093] Example 2

[0094] This embodiment provides a tunneling molecular junction structure and a construction method thereof.

[0095] A method for constructing a tunneling molecular junction structure (gallium-indium liquid metal-1-dodecyl mercaptan-gold / silicon doped electrode asymmetric tunneling molecular junction structure) is the same as that in Example 1, except that 1-tetradecyl mercaptan in step A1 is replaced by 1-dodecyl mercaptan.

[0096] Example 3

[0097] This embodiment provides a tunneling molecular junction structure and a construction method thereof.

[0098] A method for constructing a tunneling molecular junction structure (gallium-indium liquid metal-1-thiodecane-gold / silicon-doped electrode asymmetric tunneling molecular junction structure) is the same as that in Example 1, except that 1-tetradecyl mercaptan in step A1 is replaced by 1-thiodecane.

[0099] The electrical properties of the asymmetric tunneling molecular junction structures constructed in Examples 1-3 were tested, and the testing process was as follows:

[0100] The probes are connected to the second electrode and the first electrode of the asymmetric tunneling molecular junction structure to form a test loop, and a step voltage is applied to the test loop to obtain the current signal in the test loop. The parameters of the electrical test are as follows: scanning range: 0 to 1V, 1V to -1V, -1 to 1V scanning direction, the current threshold is 0.1A, and the current measurement gear is AUTO.

[0101] Using the above test parameters, when the instrument scan is stable and there is no obvious noise or short circuit, the current density-voltage scanning curve is collected, and the data is saved using the host computer software. Eventually, hundreds of such molecular junction current characteristic curves are obtained.

[0102] The original Txt data of thousands of voltage-current density curves collected were imported into the Origin software, and the one-dimensional curves of the voltage-current density of all curves and the two-dimensional distribution thermodynamic map were drawn; the current density values ​​at the +1V and -1V positions were obtained, and the rectification ratio of the tunneling molecular junction was obtained.

[0103] The test results of the asymmetric tunneling molecular junction constructed in Example 1 are as follows: Figure 2 The test results of the asymmetric tunneling molecular junctions constructed in Examples 2 to 3 are similar to those in Example 1. The current density is different due to the different molecular chain lengths of the materials of the self-assembled monolayer. Specifically, the test results are shown in Table 1 below. It can be seen from Table 1 that under the voltage condition of -1V or +1V, the current density decreases with the decrease of the molecular chain length in the molecular conductor.

[0104] Table 1

[0105]

[0106] Note: Rectification ratio = current density (+1V) / current density (-1V).

[0107] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A tunneling molecular junction structure, characterized in that: It includes a first electrode and a second electrode arranged opposite to each other, and a self-assembled monolayer containing a thiol group arranged between the first electrode and the second electrode, the second electrode includes a silicon substrate and a gold film layer arranged on the surface of the silicon substrate, the gold film layer is located between the silicon substrate and the self-assembled monolayer, and the material of the first electrode includes gallium-indium liquid metal.

2. The tunneling molecular junction structure according to claim 1, characterized in that: The chemical formula of the material of the self-assembled monolayer is CH3(CH2) n SH, n is 9 to 16.

3. The tunneling molecular junction structure according to claim 2, characterized in that: The material of the self-assembled monomolecular layer includes at least one of 1-thiodecane, 1-dodecyl mercaptan and 1-tetradecyl mercaptan.

4. The tunneling molecular junction structure according to claim 1, characterized in that: The contact surface between the first electrode and the self-assembled monolayer is circular, and the diameter of the contact surface is ≤50 μm.

5. The tunneling molecular junction structure according to claim 4, characterized in that: The diameter of the contact surface between the first electrode and the self-assembled monolayer is 12.5 μm to 50 μm.

6. The tunneling molecular junction structure according to any one of claims 1 to 5, characterized in that: The first electrode is in a cone shape, the tip of the cone faces the self-assembled monolayer molecular layer, and the diameter of the tip of the cone is 12.5 μm to 37.5 μm.

7. The tunneling molecular junction structure according to any one of claims 1 to 5, characterized in that: The thickness of the gold film layer is 20nm to 200nm; and / or The thickness of the silicon substrate is 400 μm to 600 μm.

8. A method for constructing a tunneling molecular junction structure, characterized in that: The following steps are involved: Providing a silicon substrate, and depositing a gold film layer on the surface of the silicon substrate to obtain a second electrode; Molecules containing thiol functional groups are self-assembled to form a self-assembled monolayer on the surface of the gold film layer; A gallium-indium liquid metal first electrode is arranged on the surface of the self-assembled monolayer to form the tunneling molecular junction structure as claimed in any one of claims 1 to 7.

9. The method for constructing a tunneling molecular junction structure according to claim 8, characterized in that: The step of forming a self-assembled monolayer on the surface of the gold film layer by self-assembling molecules containing thiol functional groups comprises: Providing a solution of molecules containing thiol functional groups; The second electrode is immersed in the molecular solution to form a self-assembled monolayer on the surface of the gold film layer.

10. A tunneling molecular device, characterized in that: A tunneling molecular junction structure comprising the tunneling molecular junction structure as described in any one of claims 1 to 7 and / or a tunneling molecular junction structure constructed by the construction method of the tunneling molecular junction structure as described in any one of claims 8 to 9.

11. A method for testing the electrical properties of a tunneling molecular junction structure according to any one of claims 1 to 7, characterized in that: The following steps are involved: Connecting one end of the electrode lead to the first electrode, and connecting the other end of the electrode lead to the second electrode to form a closed loop; Applying voltage to the closed loop, obtaining a signal of current varying with voltage, and collecting a plurality of current-voltage curves; The data of the current-voltage curve are calculated to obtain the electrical properties of the tunneling molecular junction structure.

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