A discontinuous metal film with tunneling effect, a tunneling electrode chip and a preparation method thereof

Abstract

The present invention provides a discontinuous metal film with a tunneling effect, a tunneling electrode chip, and a method for preparing the same. A large-area uniform discontinuous metal film is in situ grown on a glass substrate by magnetron sputtering deposition, constructing a charge tunneling structure with a random nanoarray. The discontinuous metal film comprises a substrate and a nanogap film disposed on the substrate. The nanogap film comprises a number of randomly distributed nanoislands and a number of nanogaps. A nanogap is formed between any two adjacent nanoislands, and the nanogap is <10 nm. The thickness of the nanogap film is <100 nm. The tunneling electrode chip achieves atomic-level thickness control through high-precision thin film deposition, significantly improving the uniformity of multiple batches of devices and increasing the yield by more than 50% compared to traditional methods. This breaks through the expensive micro-nano processing limitations faced by traditional tunneling devices, has the ability to sensitively respond to different small molecule media, and can present molecular information as transient conductivity information.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic devices, and in particular to a discontinuous metal film with a tunneling effect, a tunneling electrode chip and a preparation method thereof. Background Art

[0002] Tunneling electrodes, which refer to electrodes with a gap of less than 10 nm, have advantages such as good mechanical properties, tunable size, ease of modification, and ease of integration. They have been widely used in research fields such as DNA sequencing, protein conformational analysis, biomolecular interactions, enzyme kinetics, and single-molecule sensing. The efficient and controllable fabrication of sub-10 nm gap electrodes has long been a bottleneck in micro-nanofabrication and even single-molecule sensing. To date, traditional tunneling electrode preparation methods include: broken junction technology, electromigration, and photolithography. However, all of these technologies also have numerous problems, such as cumbersome processing steps, high processing costs, and limited controllability of gap size. This leads to poor reproducibility in electrode preparation, which is not conducive to large-scale production.

[0003] Conventional microneedle tunneling electrodes typically rely on a complex process chain involving glass tube drawing, carbon calcination, chemical etching, vacuum gold plating, and feedback regulation. This results in low device consistency and success rates. Furthermore, the multi-step wet etching and metal deposition process can easily introduce interface contamination, significantly reducing the quantum transmission efficiency of the tunneling junction. This severely restricts the device's large-scale production and application expansion.

[0004] At the same time, existing tunneling electrodes are typically designed to construct only a single electron tunneling pathway, detecting and analyzing trace molecules in a sample solution by monitoring current changes in this pathway. This tunneling electrode structure is commonly used in sensing, but its functional limitations make it difficult to meet the needs of multifunctional integrated devices such as light detection, molecular sensing, and nonlinear optical response. This is because these fields typically require a high-density array of tunneling pathways to achieve simultaneous detection and response to the tunneling effect in a large number of tunneling pathways.

[0005] Therefore, there is an urgent need to develop a new type of integrated tunneling electrode chip. The ideal solution should have the following characteristics: (1) integrated high-density electron tunneling channel array; (2) maintain miniaturized device size; (3) have a controllable fabrication process and low cost advantages; (4) produce a stable and measurable tunneling effect; (5) achieve accurate detection and response of multi-path tunneling effects. This breakthrough chip design will provide key basic device support for cutting-edge fields such as optoelectronic fusion devices and multifunctional sensors. Summary of the Invention

[0006] In response to the problems existing in the prior art, the present invention provides a discontinuous metal film with tunneling effect, a tunneling electrode chip and a preparation method thereof. A large-area uniform discontinuous metal film is in-situ grown on a glass substrate by magnetron sputtering deposition, and a charge tunneling structure with a random nanoarray is constructed. The discontinuous metal film includes a substrate and a nanogap film provided on the substrate. The nanogap film includes a number of randomly distributed nanoislands and a number of nanogaps. A nanogap is formed between any two adjacent nanoislands, and the nanogap is <10nm; the thickness of the nanogap film is <100nm. The tunneling electrode chip achieves atomic-level thickness control through high-precision thin film deposition, significantly improving the uniformity of multiple batches of devices, and the yield is increased by more than 50% compared with traditional methods. It breaks through the expensive cost limitation of micro-nano processing faced by traditional tunneling devices, has the ability to sensitively respond to different small molecule media, and can present molecular information in the form of transient conductivity information.

[0007] On the one hand, the present invention provides a discontinuous metal film with a tunneling effect, comprising a substrate and a nanogap film disposed on the substrate; the nanogap film comprises randomly distributed nanoislands, with a nanogap formed between any two adjacent nanoislands; and the number of the nanoislands and nanogaps is more than one.

[0008] The tunneling effect is a unique phenomenon in quantum mechanics, whereby microscopic particles (such as electrons) can penetrate energy barriers considered insurmountable in classical physics. It is a direct manifestation of the wave-particle duality of quantum mechanics. Detecting the tunneling current generated by the tunneling effect has applications in a wide range of fields, including surface atomic-level imaging, nanoelectronic devices, the semiconductor industry, quantum computing, chemical and biological sensing, and fundamental physics research. Detecting tunneling currents not only advances nanotechnology and quantum information, but also plays an irreplaceable role in industrial storage, biomedicine, and other fields.

[0009] The discontinuous metal film with tunneling effect provided by the present invention is different from the existing tunneling electrode which only contains a single electron tunneling path. Instead, it has countless nanogaps in the film, thereby forming multiple electron tunneling paths and constructing a high-density integrated tunneling junction array.

[0010] In some embodiments, based on the discontinuous metal film provided by the present invention, the comprehensive tunneling effect generated by each electron tunneling path can be detected macroscopically through electrodes, thereby obtaining a macroscopic judgment of the sample to be tested, which can be used for real-time monitoring of gas-liquid or solid-liquid interface reactions, such as identification, redox reaction, catalysis, etc.

[0011] The nano-islands refer to metal materials that are discontinuously distributed in a metal film. They are named nano-islands because of their island-like appearance. The nano-gaps between the nano-islands are electron tunneling paths.

[0012] In some embodiments, numerous nano-islands are distributed in the discontinuous metal film, and nano-gaps are provided between each nano-island.

[0013] The discontinuous metal film of the present invention has a large, uniform distribution of sub-10nm gaps across its substrate. Electrons have a certain probability of crossing these gaps, generating a tunneling current. The tunneling current-voltage relationship no longer conforms to Ohm's law, resulting in a typical nonlinear IV curve. This is related to the electron transport characteristics of the tunneling mechanism. When a pair of electrodes are conducting, electrons are transported through a continuous conductor, which conforms to Ohm's law, with the IV response being a sloping straight line. Therefore, the discontinuous metal film provided by the present invention can effectively stimulate localized surface plasmon resonance (LSPR) and quantum tunneling effects, resulting in excellent optical and electrical properties. This lays an experimental foundation for the development of multifunctional integrated devices with capabilities such as light detection, molecular sensing, and nonlinear optical response.

[0014] Furthermore, the distance of the nanogap is sub-10 nm; and / or the thickness of the nanogap film does not exceed 100 nm.

[0015] In order to produce the tunneling effect, the discontinuous metal film cannot be fully conductive, nor can it be non-conductive. If it is fully conductive, it is equivalent to the entire discontinuous metal film being completely conductive, and its IV curve is linear, and the tunneling current cannot be detected; if it is non-conductive, the current cannot be detected either.

[0016] The discontinuous metal film prepared by the present invention can maintain the nanogaps between each nanoisland at a specific value, such as within the sub-10nm range, thereby meeting the requirements for quantum tunneling detection, such as 3-10nm, 5-10nm, 3-30nm, or 5-20nm, etc. The nanogaps can also be controlled as much as possible within a more precise size range through precise control of the preparation method.

[0017] In theory, the smaller the nanogap for quantum tunneling detection, the better. However, a gap that is too small will limit the adjustment range. If the gap is too small, it may even cause the entire film to be fully conductive, making it impossible to detect the tunneling current. It may also cause surface atomic migration or oxidation, affecting the device life. Of course, the nanogap cannot be too large. If it is too large, it may directly cause the entire film to be non-conductive and the tunneling current cannot be detected. Therefore, the nanogap needs to strike a balance between tunneling probability, current conduction, signal-to-noise ratio, stability and process feasibility. The nanogap of the discontinuous metal film prepared by the present invention is preferably controlled within the range of 3-10nm.

[0018] In order for discontinuous metal films to meet the requirements of tunneling detection, their thickness must be maintained within a specific range. If the film is too thin, not only will production become more difficult, but uneven nanoisland thickness may also occur. Furthermore, if the film is too thin, the nanogap may become too thin, causing the electrode to become disconnected and, electrically, no current signal generated. Therefore, the thickness of the discontinuous metal film must be sub-100nm to maintain optimal tunneling effects while maintaining a low manufacturing cost and high yield.

[0019] In some embodiments, the preferred thickness of the discontinuous metal film may be 3-20 nm, more preferably 5-10 nm, 3-30 nm, or 5-8 nm. The most preferred thickness of the discontinuous metal film is 5-6 nm.

[0020] In some embodiments, the total coverage of the nanogaps in the discontinuous metal film is 26.64% to 46.45% based on the area of ​​the substrate. The coverage of the nanogaps in the present invention is obtained by analyzing the SEM images of the discontinuous film using ImageJ software and calculating the ratio of the area of ​​the nanogaps to the area of ​​the substrate. When the coverage of the nanogaps is too high, it means that the gap area is larger, the energy barrier that electrons need to cross is higher, and it is more difficult to generate tunneling current. Therefore, the preferred nanogap coverage is 26.64% to 46.45%, and the tunneling effect can be detected.

[0021] In some embodiments, the size of the nano-islands is 100-500 nm.

[0022] Furthermore, the material of the substrate is selected from one or more of silicon dioxide, glass, silicon, silicon nitride and sapphire; and / or the material of the nanogap film is selected from one or more of gold, silver, aluminum and copper.

[0023] It is understood that silicon dioxide, glass, silicon, silicon nitride and sapphire can all be used to prepare the substrate, and gold, silver, aluminum and copper can all be used to prepare the nanogap film, so that any combination can be used to prepare a discontinuous metal film.

[0024] In some embodiments, the substrate is preferably made of glass. This is because glass has high light transmittance, with excellent transmittance in the visible light range (typically >90%), does not interfere with the optical properties of the metal film, and has high surface flatness and smoothness, as well as good chemical stability, thermal stability, and mechanical strength.

[0025] In some embodiments, the nanogap film is made of gold. When gold is used as the material, the discontinuous metal film formed can maintain structural stability and oxidation resistance for a long time at room temperature due to its chemical inertness, high reduction potential, and stable electronic structure.

[0026] Furthermore, an adhesion layer is provided between the nanogap film and the substrate, which can make the film and the substrate adhere more firmly and have more stable performance.

[0027] Furthermore, the material of the adhesion layer is selected from one or more of chromium, titanium, and titanium tungsten.

[0028] It is understandable that chromium, titanium, and titanium tungsten can all be used to prepare the adhesion layer, thereby improving the firmness between the discontinuous metal film and the substrate.

[0029] In some embodiments, the material of the adhesion layer is preferably chromium, because chromium has good adhesion, film-forming properties and stability. The prepared adhesion layer has better adhesion effect and can effectively prevent the discontinuous metal film from diffusing to the substrate, avoiding interface degradation; at the same time, it also has suitable conductive properties, which helps to improve detection accuracy and stability when used for tunneling detection.

[0030] In some embodiments, the adhesion layer has a thickness of 0.8-1.2 nm.

[0031] In order to perform tunneling effect detection better and more accurately, the conductivity of the discontinuous metal film prepared by the present invention must be maintained within an appropriate range. Too high conductivity will lead to full conduction, while too low conductivity may directly lead to no conduction. Neither full conduction nor no conduction can be used for tunneling effect detection.

[0032] In some embodiments, the conductivity of the discontinuous metal film is 0.1-1000 nS, which can be used to respond to the tunneling effect.

[0033] When used in optical inspection, discontinuous metal films also need to have good transmittance, for example, a transmittance of at least 60%. Of course, the appropriate transmittance can be selected based on the specific application requirements of the discontinuous metal film in different fields. The transmittance of the discontinuous metal film prepared by the present invention is 66.33% to 70.25%, which meets the requirements of the optical inspection field.

[0034] In addition, the discontinuous metal film of the present invention has excellent stability and can be stably stored in a dry environment at room temperature. The loss of conductivity after storage is very small, which meets the requirements of the field of micro-nano photonic devices.

[0035] On the other hand, the present invention provides a method for preparing a discontinuous metal film with a tunneling effect, the method comprising the following steps: depositing a nanogap film on a substrate surface by a magnetron sputtering method to obtain the discontinuous metal film.

[0036] The tunneling electrode device fabricated in this invention addresses the limitations of traditional tunneling electrode fabrication processes by providing an innovative solution, resulting in an integrated tunneling junction array. Through innovative planar device architecture, ultrathin gold films are deposited directly on a glass substrate using magnetron sputtering technology, combined with nanoscale patterning techniques to construct a large-scale, sub-10nm gap array.

[0037] By replacing traditional microneedle-based three-dimensional molding with a planar sputtering process, high-precision thin-film deposition achieves atomic-level thickness control, effectively eliminating structural errors caused by mechanical deformation. Furthermore, the all-dry process avoids batch fluctuations associated with chemical etching, significantly improving the uniformity of devices within a single batch, and increasing the yield by over 50% compared to traditional methods. Furthermore, centimeter-scale planar electrodes enable the integration of high-density tunneling junction arrays, broadening the application range of planar tunneling electrodes. This innovative fabrication strategy not only significantly reduces process complexity and production costs, but also lays a reliable manufacturing foundation for the large-scale application of quantum tunneling devices in fields such as biosensing and nanoelectronics.

[0038] The magnetron sputtering method is a physical vapor deposition (PVD) technique whose core principle is to bombard the target surface with high-energy ions, causing target atoms to escape and deposit on the substrate to form a thin film. This study compared different methods for preparing ultrathin nanogap films and found that magnetron sputtering can more precisely control the size and coverage of the tunneling nanogap, as well as the thickness of the discontinuous metal film, resulting in a higher yield of the finished product at a lower cost.

[0039] The present invention deposits a large-area uniform ultra-thin nano-gap film on a substrate at one time by a magnetron sputtering method. The preparation process is simple and the cost is low, breaking through the technical bottlenecks of traditional metal nano-gap processing such as high cost and complicated operation.

[0040] Furthermore, in the magnetron sputtering method, the deposition time is 10-30 seconds. This should be neither too long nor too short. If it is too long, the film will become connected, resulting in a fully conductive appearance. If it is too short, the film will be too thin and the gaps will be too large, resulting in a disconnected appearance. Neither of these situations can be used for tunneling effect detection.

[0041] In some methods, the deposition rate of magnetron sputtering is 1.74 Å / s. The deposition rate is an important parameter affecting the performance of discontinuous thin films.

[0042] In some embodiments, the starting power of magnetron sputtering is 40-60 Ws, and the atmosphere pressure is: nitrogen pressure is 0.05-0.09 mPa, argon pressure is 0.03-0.07 mPa, and air pressure is 0.30-0.8 mPa. Specifically, the starting power is 50 W, and the atmosphere pressure is: nitrogen pressure is 0.07 mPa, argon pressure is 0.05 mPa, and air pressure is 0.55 mPa.

[0043] In some methods, the substrate must be pretreated before magnetron sputtering. This pretreatment involves washing, such as ultrasonic cleaning, to remove organic or inorganic matter from the substrate surface. The solvent used for washing is selected from one or more of acetone, isopropyl alcohol, and ethanol. After washing, the substrate must be dried before magnetron sputtering can be used to prepare a discontinuous metal film with tunneling effect.

[0044] In some embodiments, the adhesion layer is also deposited by magnetron sputtering.

[0045] In some methods, magnetron sputtering includes the following steps: placing a target material in the chamber of a magnetron sputtering device, evacuating the chamber, and ionizing an inert gas (argon) by applying an electric field. The generated ions bombard the target material, and the bombarded plasma plume is deposited on the substrate.

[0046] In some methods, during deposition, the pressure is 1.6E-6 MPa, the starting power is 40-60 W, the deposition time is set to 10-30 seconds, and the turntable speed is set to 10-30 rpm; the atmosphere is: nitrogen pressure = 0.05-0.09 mPa, argon = 0.03-0.07 mPa, and air = 0.30-0.8 mPa. Specifically, the pressure is 1.6E-6 MPa, the starting power is 50 W, the deposition time is set to 20 seconds, and the turntable speed is set to 20 rpm; the atmosphere is: nitrogen pressure = 0.07 mPa, argon = 0.05 mPa, and air = 0.55 mPa.

[0047] On the other hand, the present invention provides a tunneling electrode chip, which includes the discontinuous metal film as described above; and also includes a continuous conductive layer provided on the discontinuous metal film, and an electrode pair provided on the continuous conductive layer.

[0048] Furthermore, the material of the continuous conductive layer is selected from one or more of gold, silver, aluminum, and copper; and / or the material of the electrode pair is selected from one or more of gold, silver, aluminum, and copper.

[0049] In some embodiments, the conductive layer has a thickness of 80-100 nm.

[0050] In some embodiments, the electrode chip is prepared by placing a mask on a discontinuous metal film and depositing the film by magnetron sputtering. The mask is typically lattice-shaped with a hollowed-out grid. Thus, a conductive layer is formed on the discontinuous metal film in the hollowed-out areas of each grid, while areas separated by the mask cannot form a conductive layer.

[0051] The conductive layer is discontinuous due to the use of a mask, with the connected conductive layers interrupted by the mask. Therefore, the discontinuous metal film cannot fully conduct through the conductive layer, thus enabling detection or response to the tunneling effect. The electrode pairs are positioned on either side of the interruption in the mask. The distance the conductive layer is interrupted corresponds to the spacing between the electrode pairs, preventing the discontinuous metal film from being fully conductive. In other words, the spacing between the electrode pairs described in the present invention refers to the distance between the two pairs of electrodes that is interrupted by the mask and prevents conduction.

[0052] In some embodiments, the spacing between the electrode pairs is 30~100μm. The present invention explores the influence of the distance between the electrode pairs on the electrical characteristics of the device and finds that when the electrode distance is in the range of 30~100 μm, it can be used to detect the tunneling effect generated by the discontinuous metal film; when the spacing between the electrode pairs is greater than 100 μm, the prepared electrode chip cannot achieve conductivity and cannot be used for tunneling effect detection; and when the spacing between the electrode pairs is less than 30μm, because the conductive layer is too close, the discontinuous metal film is completely conductive, and only a linear IV curve can be detected, which cannot be used for tunneling effect detection. In other words, the width of the partition in the mask needs to be in the range of 30~100 μm.

[0053] The magnetron sputtering method includes the following steps: placing a target material in a cavity of a magnetron sputtering device, evacuating the cavity, and ionizing an inert gas (argon) by applying an electric field. The generated ions bombard the target material, and the bombarded plasma plume is deposited on a substrate.

[0054] In some embodiments, during deposition, the pressure is 1.6E-6 MPa, the starting power is 40-60 W, the deposition time is set to 10-30 seconds, and the turntable speed is set to 10-30 rpm; the atmosphere is: nitrogen pressure is 0.05-0.09 mPa, argon is 0.03-0.07 mPa, and air is 0.30-0.8 mPa. Preferably, during deposition, the pressure is 1.6E-6 MPa, the starting power is 50 W, the deposition time is set to 20 seconds, and the turntable speed is set to 20 rpm; the atmosphere is: nitrogen pressure is 0.07 mPa, argon is 0.05 mPa, and air is 0.55 mPa.

[0055] On the other hand, the present invention provides a method for molecular medium sensing detection, which uses the discontinuous metal film as described above, or the tunneling electrode chip as described above for detection; the detection method includes: dripping a solution onto the surface of the discontinuous metal film or the tunneling electrode chip, and being captured by the nanogap under the drive of an electrostatic field, and detecting the IV curve.

[0056] Existing tunneling electrodes typically feature only a single electron tunneling pathway between electrodes, enabling analysis of small molecules in sample solutions by detecting changes in current generated within this tunneling pathway. However, in the identification and detection of solid-liquid and gas-liquid interfacial reactions, catalysis, and diffusion effects, traditional microneedle devices can struggle to effectively capture interfacial reactions due to structural limitations and limited contact area. Planar, large-area contact surfaces, on the other hand, offer more comprehensive interface coverage, improving detection sensitivity and accuracy.

[0057] The present invention expands the traditional microneedle single-point tunneling device to a multi-point tunneling chip on a plane, which has more tunneling arrays and active sites, which is conducive to improving tunneling efficiency. In addition, this tunneling chip also has advantages in specific application scenarios. It is easy to integrate with microfluidic systems or other analytical technologies and is suitable for real-time monitoring of complex reaction environments.

[0058] For the detection of samples with a large number of unknown small molecule mediators, especially small molecule mediators at the solid-liquid interface, the detection device provided by the present invention integrates multiple electron tunneling pathways and can accurately detect the comprehensive tunneling effect generated by passing through each electron tunneling pathway at the same time through electrodes, thereby achieving a sensitive response to small molecule mediators as a whole.

[0059] It should be noted that when testing with the discontinuous metal film or tunneling electrode chip provided by the present invention, a nonlinear IV curve is obtained, rather than a linear line. This is because the tunneling effect occurs, causing the relationship between current and voltage to no longer conform to Ohm's law, resulting in a nonlinear IV curve. In contrast, if the tunneling effect were absent, under normal conduction conditions, the IV curve detected by the electrode would be a linear line. Without the tunneling effect, the conductivity would remain unchanged.

[0060] Different molecular media lead to different tunneling barriers, which in turn cause conductivity variations. When different molecular media are filled into a nanogap, due to their varying dielectric constants, electrons must overcome different potential barriers to cross the gap, resulting in varying conductivity. Consequently, different nonlinear IV curves are obtained when testing different samples. Therefore, the shape of these nonlinear IV curves can be used to determine the different tunneling effects occurring across the nanogaps of discontinuous metal films, thereby assessing the overall state of the molecular media within the sample.

[0061] In some embodiments, the molecule used for detection is one or more of n-hexane, carbon tetrachloride, formamide, dimethyl sulfoxide, and the like.

[0062] In another aspect, the present invention provides use of the discontinuous thin film or the tunneling electrode chip described above in a photodetection device, a molecular sensor device, or a photoresponsive device.

[0063] In some embodiments, the photodetection device includes an imaging device, a single electron transistor, a photoconductive antenna, a terahertz wave emitter, and a detector.

[0064] In some embodiments, the molecular sensing device includes ultrasensitive interfacial catalysis, biomolecule detection, and stress sensing for wearable devices.

[0065] In some embodiments, the photoresponsive device comprises a high-efficiency catalytic electrode or a supercapacitor.

[0066] The present invention has the following beneficial effects:

[0067] 1) A novel device with tunneling effect is provided. The device has the appearance of a thin film or chip and comprises randomly distributed nanoislands, two adjacent nanoislands and a nanogap between them, thus realizing a large-area uniformly distributed nanogap structure. This structure can effectively stimulate the localized surface plasmon resonance effect (LSPR) and quantum tunneling effect, thereby exhibiting excellent optical and electrical properties.

[0068] 2) It provides a new preparation method that can form a discontinuous metal film with multiple tunneling nanogaps on a substrate. Through high-precision thin film deposition, atomic-level thickness control is achieved, which significantly improves the uniformity of multiple batches of devices and increases the yield by more than 50% compared with traditional methods.

[0069] 3) Compared with the traditional chemical solvent growth method, by controlling the experimental parameters of the deposition process such as atmosphere, deposition rate, pressure, and power, a large-area, highly uniform, discontinuous metal film with controllable nanogap size and film thickness is deposited on the substrate through magnetron sputtering deposition, constructing a charge tunneling structure with an integrated nanoarray.

[0070] 4) The discontinuous metal film preparation method of the present invention is conducive to batch preparation, is simpler and lowers the cost, and to a certain extent breaks through the technical bottlenecks of traditional nanogap electrode processing, such as high cost and complicated operation.

[0071] 5) When the discontinuous metal film of the present invention is used for molecular medium detection, its IV curve shows typical nonlinear characteristics. The IV curve measured by cyclic voltammetry is consistent with the fitting result of the classical tunneling model.

[0072] 6) The prepared discontinuous metal film with tunneling effect maintains structural stability for a long time under room temperature drying conditions and has excellent anti-oxidation properties.

[0073] 7) It has important application value in the fields of electronic devices, nanotechnology, and biomarker analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 These are the physical picture and SEM picture of the discontinuous metal film with tunneling effect in Example 1.

[0075] Figure 2 Schematic diagram of the structure of the tunneling electrode chip in Example 2.

[0076] Figure 3 The following are actual pictures of the tunneling electrode chip in Example 2 undergoing masking, deposition, laser cutting, and wire bonding; (1) is a picture after masking; (2) is a picture after sputtering deposition of the conductive layer; (3) is a picture of a separate tunneling electrode chip after laser cutting; and (4) is a microscope photo of the wire-bonded electrode chip.

[0077] Figure 4 This is the IV curve of the tunneling electrode chip in Example 3 in air.

[0078] Figure 5 The IV curves of the tunneling electrode chip in Example 3 responding to different media.

[0079] Figure 6 This is an SEM image of the discontinuous metal film prepared by the chemical solvent growth method (hydrothermal synthesis method) in Example 4.

[0080] Figure 7 This is a fully conductive and linear IV curve formed in Example 5 with a deposition time of 40 seconds.

[0081] Figure 8 These are the actual pictures of substrate / Au and substrate / Cr / Au after heat treatment and soaking in ethanol solution overnight; A is substrate / Au (without adhesion layer) and B is substrate / Cr / Au (with adhesion layer). DETAILED DESCRIPTION

[0082] To describe the present invention in more detail, the technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. These descriptions are merely intended to illustrate how the present invention is implemented and are not intended to limit the specific scope of the present invention. The scope of the present invention is defined in the claims.

[0083] The magnetron sputtering deposition in the following examples was performed using a PRO Line PVD 75 multifunctional sputtering, electron beam, and thermal evaporation thin film deposition system purchased from Kurt J. Lesker, USA. During sputtering deposition, the turntable speed was 20 rpm and the temperature was room temperature.

[0084] The Cr target used in the examples had a size of φ76.2 × 3 mm (diameter and thickness), a purity of 99.99%, and was purchased from Zhongnuo New Materials (Beijing) Technology Co., Ltd. The Au target used in the examples had a size of φ50.8 × 3 mm, a purity of 99.999%, and was purchased from Kurt J. Lesker, Inc., USA. The Ag target had a size of φ76.2 × 3 mm, a purity of 99.999%, and was purchased from Kurt J. Lesker, Inc., USA. The Al target had a size of φ76.2 × 3 mm, a purity of 99.999%, and was purchased from Kurt J. Lesker, Inc., USA. The substrate glass sheet used in the examples had a size of φ150 × 1 mm.

[0085] Example 1: Preparation of a discontinuous metal film with tunneling effect

[0086] The specific preparation method of the discontinuous metal film with tunneling effect provided in this embodiment is as follows:

[0087] 1) Deposit a Cr layer about 1 nm thick on the substrate surface as an adhesion layer using a magnetron sputtering deposition device. The specific steps are as follows:

[0088] Loading: Place the Cr target (purity of 99.999%) in the corresponding chamber of the magnetron sputtering equipment, fix the substrate on the turntable with tape, and hang it vertically with the front side facing down on the electron gun in the middle of the chamber.

[0089] Vacuum: Click PC Pump to vacuum the cavity and make the pressure inside the cavity reach 1.6E-6MPa.

[0090] Parameter settings: Select the corresponding working end, click Switch to switch, and open the working end cover of the Cr target. Set the starting power to 50W, the deposition time to 5s, and the turntable speed to 20 rpm.

[0091] Sputtering deposition: Click Substrate Shutter to begin the process. A high-voltage electric field is applied to ionize the inert gas (argon), generating high-energy ions. These ions collide with the target, sputtering Cr atoms that are deposited on the substrate surface, forming a uniform film. The atmospheric pressure is: nitrogen pressure = 0.07mPa, argon = 0.05mPa, and air = 0.55mPa.

[0092] Post-processing: After the deposition is completed, the substrate with the adhesion layer deposited is removed from the chamber and subjected to subsequent treatment or processing.

[0093] The substrate is a glass sheet, which has been pretreated as follows: ultrasonically cleaning the glass sheet (15 cm*15 cm) with acetone and isopropyl alcohol for 5 minutes to remove impurities adsorbed on its surface, and then rinsing it with deionized water and drying it with nitrogen.

[0094] 2) Use magnetron sputtering deposition equipment to in-situ deposit nanogap film on the adhesion layer. The specific operation steps are as follows

[0095] Loading: Place the Au target in the corresponding cavity. Fix the substrate after the adhesion layer is deposited in step 1) on the turntable with tape and hang it vertically with the front side facing down on the electron gun in the middle of the cavity.

[0096] Vacuum: Click PC Pump to vacuum the cavity and make the pressure inside the cavity reach 1.6E-6MPa.

[0097] Parameter settings: Select the corresponding working end, click Switch to switch, and open the working end cover of the Au target. Set the starting power to 50W, the deposition time to 20s, and the turntable speed to 20rpm.

[0098] Sputtering deposition: Click Substrate Shutter to begin dusting. A high-voltage electric field is applied to ionize the inert gas (argon), generating high-energy ions. These ions impact the target, sputtering Au atoms that are deposited on the surface of the adhesion layer, forming a nanogap film. This nanogap film consists of randomly distributed nanoislands. Two adjacent nanoislands and the nanogap between them form a pair of tunneling junctions, resulting in a discontinuous film with a tunneling effect. The atmosphere pressure is: nitrogen pressure = 0.07mPa, argon = 0.05mPa, and air = 0.55mPa.

[0099] Post-processing: After the deposition is completed, the substrate with the nano-gap film deposited is removed from the chamber to obtain a discontinuous metal film.

[0100] The obtained discontinuous film was photographed and scanned by electron microscope. The actual picture and SEM picture are shown in Figure 1 .

[0101] from Figure 1 The middle left image shows a transparent discontinuous metal film. The discontinuous film is composed of randomly distributed, independent nanoislands with well-defined boundaries. There are channels (nanogaps) between adjacent nanoislands, and a tunnel junction is formed between two adjacent nanoislands and the nanogap between them.

[0102] from Figure 1 As can be seen from the SEM image, Nano Measurer software was used to analyze the width of the nanogap between two adjacent nano-island structures in the SEM image, and the average nanogap was 5 nm. Image J software was used to analyze the SEM image and calculate the coverage of the nanogap, which is the area of ​​the nanogap divided by the area of ​​the substrate. The calculated coverage of the nanogap is 21.69%.

[0103] Example 2: Preparation of tunneling electrode chip

[0104] The structure of the tunneling electrode chip provided in this embodiment is as follows Figure 2 As shown, the tunneling electrode chip includes, from bottom to top, a substrate 4, an adhesion layer 3, a discontinuous metal film 2, and a conductive layer 1. Depositing a continuous conductive layer on the surface of the discontinuous metal film obtained in Example 1 and providing an electrode pair on the continuous conductive layer to form a tunneling electrode chip includes the following:

[0105] 1) Mask: The size of the mask is 7*7cm, which contains 105 small structural units (each structural unit is hollowed out in the middle, used to form a conductive layer on the surface of the discontinuous metal film, and the non-hollowed-out area in the mask can act as a barrier, so that a conductive layer cannot be formed on the surface of the discontinuous metal film at that location). The smallest structural unit is a rectangular structure of 0.3*0.4 cm. The mask (the shortest distance between two adjacent rectangular structures (the partition part 5 of the mask) is 30 µm) is attached to the surface of the discontinuous metal film obtained in Example 1 with tape, and then the sample is placed in the sputtering chamber. After the mask is attached, Figure 3 (1) (The black color in the picture is the color of the metal turntable below, and the film is actually transparent).

[0106] 2) Sputtering deposition: Then, a continuous gold film of about 10 nm thick is deposited on the mask surface for 120 s as a conductive layer, and an electrode pair is formed at both ends. The operation method is similar to the method of depositing a non-continuous thin film in step 2) of Example 1. After the sputtering is completed, the mask is removed, and the actual object is shown in FIG. Figure 3 Chinese (2).

[0107] 3) Laser cutting: The laser cutting system is used to cut the result of step 2) into individual tunneling electrode chips for subsequent testing. Figure 3 Chinese (3).

[0108] 4) Wire bonding: Use a wire bonding machine to weld 30µm aluminum wire to both ends of the electrode pair, and the other end of the aluminum wire is connected to the PCB pad. Figure 3 (4) in the figure, and connect the working electrode and reference / counter electrode of the microcurrent instrument through pin headers and Dupont wires.

[0109] Example 3: Performance Study of Tunneling Electrode Chip

[0110] This example studies the performance of the tunneling electrode chip prepared in Example 2:

[0111] 1. Consistency Study

[0112] Using the same method as in Example 1, tunneling electrode chips were obtained by using the same method as in steps 1) to 4) for discontinuous metal films prepared from five different batches. The conductivity and transmittance of the electrode chips from different batches were studied to investigate the consistency of the magnetron sputtering method. The results are shown in Table 1.

[0113] The conductivity test method is: collect the IV curve by cyclic voltammetry and calculate it by the formula G=ΔI / ΔU.

[0114] Transmittance testing: Tunneling electrode chips (substrate size: φ150 × 1 mm) deposited with a continuous conductive layer and electrode pairs were cut into segments measuring 10 * 10 * 1 mm. Transmittance was tested at room temperature using a Thermo Scientific Evolution 220 series UV spectrophotometer. Each sample was scanned three times and the average value was obtained.

[0115] Table 1 Statistics of average conductivity and transmittance of 5 different batches

[0116]

[0117] As shown in Table 1, the conductivity of the electrode chips from all five batches was within the theoretical tunneling conductivity range (0.1-1000 nS), with an RSD of 25.2% (since 0.1-1000 nS falls within the tunneling conductivity range, the RSD is relatively large). The RSD of the transmittance was 2.26%, less than 10%, indicating that the electrode chips prepared in this example had good consistency. This method can achieve good reproducibility and is suitable for large-scale production of discontinuous thin films and electrode chips.

[0118] In addition, in order to detect the tunneling effect, the conductivity must be maintained in the range of 0.1-1000nS. The reason is that if the conductivity is too high, the electrodes will be completely conductive, and a linear IV curve will be directly detected, and the tunneling effect cannot be detected. When the conductivity is too low, it will be difficult for the two electrodes to be conductive, and the tunneling effect cannot be detected. Therefore, the tunneling electrode chip prepared in this embodiment can maintain the conductivity in the range of 0.1-1000nS, which can be used to successfully detect the tunneling effect.

[0119] 2. IV performance

[0120] The IV curve of the tunneling electrode chip No. 1 in Table 1 was tested by cyclic voltammetry. The results are shown in Fig. Figure 4 The test conditions are as follows: voltage 1V, Scan Rate (V / s) = 0.1.

[0121] from Figure 4 It can be seen that the IV curve of the tunneling electrode chip shows typical nonlinear characteristics, indicating that the tunneling electrode chip prepared in this embodiment can produce a significant tunneling effect and can detect or respond to tunneling current. The research results have laid an experimental foundation for the development of multifunctional integrated devices with light detection, molecular sensing and nonlinear optical response. The relevant technical parameters (nanogap size, metal film thickness, conductivity, transmittance, etc.) meet the core requirements of the field of micro-nano photonic devices for high sensitivity, wide spectrum response and low power consumption operation.

[0122] 3. Stability study

[0123] The tunneling electrode chip was stored at room temperature for 15 days, with conductivity measured every five days. After storage, the loss and ratio were calculated. Loss is calculated as: conductivity on day N - conductivity on day 0; the ratio is calculated as: conductivity on day N / conductivity on day 0. Table 2 shows the change in conductivity during the 15-day storage period.

[0124] Table 2. Changes in conductivity of samples after 15-day storage

[0125]

[0126] As shown in Table 2, after 15 days of storage, the conductivity loss of the electrode chip is 1.8 nS, and the ratio (storage 15 / 0 days) is 40%, which also shows that the tunneling electrode chip has good repeatability and reliability, which is conducive to large-scale production and commercial application.

[0127] 4. Small molecule media sensing detection

[0128] The tunneling electrode chip prepared in this example was used to test the IV curves in sample solutions and air. The sample solutions were 100% formamide, dimethyl sulfoxide, n-hexane, and carbon tetrachloride solutions, respectively. 10 μL of each sample solution was added dropwise to the tunneling electrode chip. A 6V voltage was applied to the control terminal of the microcurrent instrument, and the signal-to-noise ratio was set to 0.3 rat / s. The IV curves of different media were tested using cyclic voltammetry ( Figure 5 ).

[0129] according to Figure 5It can be seen that the difference in dielectric constants of different small molecules leads to differences in the potential barriers that electrons need to overcome to cross the gap, causing different changes in conductivity. The nonlinear IV curves obtained in turn are also different. The small molecule media in the sample solution can be inferred from the different IV curves obtained.

[0130] Example 4: Comparison of different preparation methods for discontinuous metal films with tunneling effect

[0131] This example uses the following two methods to prepare discontinuous metal thin films: 1. Magnetron sputtering (according to Example 1); 2. Chemical solvent growth method (hydrothermal synthesis). The chemical solvent growth method uses sodium citrate as both a reducing agent and a stabilizer. The specific steps are as follows: First, add 500 mL of HAuCl4 (1 mM) to a round-bottom flask (1 L) and heat to boiling with vigorous stirring. Then, immediately add 50 mL of sodium citrate (38.8 mM), at which point the color changes from light yellow to maroon. Continue heating for 10 minutes. Remove the heating mantle and continue stirring for 15 minutes, at which point the color changes to purple-red, yielding gold nanoparticles. Finally, cool the prepared gold nanoparticles to room temperature and store at 4°C until ready for use. For use, add 500 µL of gold nanoparticles dropwise to the surface of a cleaned glass slide, incubate overnight at room temperature, and air-dry to form a glass slide sample loaded with gold nanoparticles.

[0132] The SEM images of the discontinuous metal films prepared by the first method (Example 1) and the second method (hydrothermal synthesis method) are shown in FIG. Figure 1 B and Figure 6 As shown. Figure 6 The discontinuous metal film prepared by the second method (hydrothermal synthesis) exhibits significant gold nanoparticle agglomeration, indicating poor dispersion and uniformity. Furthermore, due to the poor uniformity, the nanogaps within the discontinuous metal film produced by the second method vary in size, ranging from very small to very large. This results in an extremely low yield (only approximately 1.2%), making it impossible to accurately detect or respond to tunneling current signals, making it difficult to apply in industry. The yield rate is determined by the presence of a nonlinear IV curve, indicating the ability to produce a tunneling effect. Furthermore, films with a thickness less than 100nm, nanogaps 3-10nm, a nanogap coverage of 21.64-46.45%, a conductivity of 0.1-1000nS, and a transmittance of 66.33-70.25 are considered acceptable.

[0133] The discontinuous metal film prepared by the method provided in Product Example 1 has very good uniformity, stable performance, and a yield rate of 30%, which is more than 50% higher than that of traditional methods.

[0134] Example 5: Effect of different deposition times on the preparation of discontinuous metal films

[0135] This example uses the method provided in Example 1 to prepare discontinuous metal films. Using magnetron sputtering with an Au target, the deposition times were 5, 10, 20, 30, and 40 seconds, respectively. All other conditions remained the same as in Example 1. Five discontinuous metal films were produced, and the nanogap size, nanogap coverage, film thickness, particle morphology, IV characteristics, and yield of two films were measured. The nanogap size and nanogap coverage were measured as described in Example 1. Film thickness was measured by atomic force microscopy (AFM) imaging using the staircase method and then analyzed and calculated. Particle morphology was measured by scanning electron microscopy (SEM) imaging. IV characteristics were measured as described in Example 3. Yield was measured as described in Example 4. Each test was repeated three or more times, and the average value was calculated. Specific performance parameter test results are shown in Table 3.

[0136] Table 3. Effect of different deposition times on the preparation of discontinuous metal films

[0137]

[0138] As can be seen from Table 3, when magnetron sputtering Au target, the change of deposition time will directly affect the performance of the prepared discontinuous metal film. When the deposition time is 5s, due to the short deposition time, the prepared discontinuous metal film is very thin, the uniformity of the nano-gap size decreases, and the IV curve is parallel, indicating that the film is not conductive and cannot be used for tunneling effect detection. Its yield rate is basically 0%. When the deposition time is 40s, due to the long deposition time, the prepared discontinuous metal film is thicker, the nano-islands are interwoven into a silk screen, and the IV curve is linear (see Figure 7 ), with a very high conductivity of 0.03 s. The electrical properties demonstrate full conduction, corresponding to an ohmic conduction mechanism, indicating that the film is fully conductive, making the tunneling effect undetectable and the yield rate essentially 0%. Therefore, the deposition time must be controlled between 10 and 30 seconds to prepare a discontinuous metal film that can be used to detect or respond to the tunneling effect. A time of 20 seconds is optimal, as the resulting discontinuous metal film has smaller nanogaps and better consistency, a moderate film thickness, and a higher yield, making it suitable for accurate detection or response to the tunneling effect.

[0139] Example 6: Necessity of Adhesion Layer

[0140] This example used the method provided in Example 1 to prepare discontinuous metal films. The results were compared without the adhesion layer. Two discontinuous metal films were produced. The nanogap size, nanogap coverage, film thickness, film uniformity, particle morphology, adhesion strength, IV characteristics, and yield of the two films were measured. The testing methods are as described in Example 5. Each test was repeated three or more times, and the average values ​​were calculated. The specific performance parameter test results are shown in Table 4.

[0141] Table 4. Effect of adhesion layer on the preparation of discontinuous metal films

[0142]

[0143] Table 4 shows that when no adhesion layer is provided in the prepared discontinuous metal film, its adhesion is poor. (Poor adhesion means that the results of repeated use in subsequent application tests are inconsistent, and the gold film is easily corroded after multiple immersions, which destroys the microstructure and affects stability.) Although nonlinear IV curves can be detected and the tunneling effect can be responded to, the yield rate is low, making it difficult to produce a discontinuous metal film that fully meets the requirements. Therefore, the provision of an adhesion layer is very necessary.

[0144] In this example, the two discontinuous metal films were heat treated at 500°C for 30 min and then immersed in ethanol solution overnight and photographed. Figure 8 , where A is the case without an adhesion layer, and B is the case with an adhesion layer.

[0145] from Figure 8 As can be seen, after heat treatment and overnight immersion in ethanol, the film without the adhesion layer dissolves and fades significantly, limiting its application performance. In contrast, the film with the adhesion layer retains a vibrant purple-red color. These results demonstrate that the Cr layer inhibits the diffusion of Au atoms, significantly improving thermal stability and adhesion.

[0146] Example 7: Target material screening

[0147] This example uses the method provided in Example 1 to prepare discontinuous metal films, using Au, Ag, and Al as targets, respectively. All other parameters were consistent with the preparation method in Example 1. Three discontinuous metal films were produced, and their oxidizability, corrosion resistance, work function, contact resistance, and yield were tested. Each test was repeated three or more times, and the average value was taken. The specific performance parameter test results are shown in Table 5.

[0148] Table 5. Effect of different target materials on the preparation of discontinuous metal films

[0149]

[0150] As can be seen from Table 5, Au, Ag, and Al targets can all be used to prepare discontinuous metal films, but there are certain differences in the preparation effects. Among them, Au target is the most preferred for the following reasons:

[0151] 1. Au hardly oxidizes at room temperature (inert metal), while Al and Ag oxidize in air at room temperature to form Al2O3 and Ag2S insulating layers, resulting in fluctuations in surface roughness and increased contact resistance, affecting the tunneling current and device stability.

[0152] 2. The high work function of Au can form a higher tunneling barrier, and the tunneling probability and sensitivity can be optimized by adjusting the barrier thickness (discontinuous gap).

[0153] 3. Au films can be stored stably at room temperature without significant diffusion or structural changes, whereas Ag and Al are more sensitive to temperature and humidity, and are soluble in acidic or alkaline solutions. These factors contribute to a higher yield when using Au targets.

[0154] Example 8: Screening of Adhesion Layer

[0155] This example uses the method provided in Example 1 to prepare discontinuous metal films. The adhesion layers are made of chromium, titanium, and titanium tungsten, respectively. All other aspects of the preparation method are consistent with those of Example 1. Three discontinuous metal films were produced, and their adhesion, adhesion mechanism, contact resistance, cost, and application scenarios were analyzed and evaluated. Subsequently, the thermal stability and yield of tunneling devices containing different adhesion layers were tested. The testing method is described in Example 5, and the thermal treatment stability testing method is described in Example 6. Each test was repeated three or more times, and the average value was taken. The specific performance parameter test results are shown in Table 6.

[0156] Table 6. Effects of different adhesion layers on the preparation of discontinuous metal films

[0157]

[0158] As can be seen from Table 6, chromium, titanium, and titanium tungsten targets can all be used to prepare the adhesion layer of discontinuous metal films, but there are certain differences in the preparation effects. Among them, the most preferred is the chromium target. The reason for selection is that all three materials have low contact resistance and good thermal stability. However, the chromium material adheres through a physical mechanism, which largely avoids the interference caused by chemical bonding. In addition, its cost is also lower, and it is most suitable for the processing of rigid substrates. It also has good adhesion and a higher processing yield, and performs best in this tunnel chip processing.

[0159] Example 9: Screening of substrate materials

[0160] This example uses the method provided in Example 1 to prepare discontinuous metal films. Three substrate materials were compared: 1. quartz wafer, 2. glass wafer, and 3. high-resistivity silicon. Discontinuous metal films were prepared using identical magnetron sputtering parameters. By comparing the conductivity, thermal stability, resistivity, and cost of the three substrates, and testing the IV curves and yield of the films deposited on different substrates, it was found that glass wafer was the optimal substrate. The testing method is described in Example 5. Each test was repeated three or more times, and the average value was calculated. Specific performance parameter test results are shown in Table 7.

[0161] Table 7. Effect of different substrates on the preparation of discontinuous metal films

[0162]

[0163] As can be seen from Table 7, in addition to high-resistance silicon, quartz and glass can be used as substrates. However, the effects of different substrate materials on the preparation of nonlinear metal films vary. Glass is the most preferred substrate for the following reasons:

[0164] 1. In order to prevent the substrate from interfering with the tunneling current in the gold film, a completely insulating substrate should be selected. Since high-resistance silicon refers to a semiconductor material with a resistivity significantly higher than that of conventional doped silicon crystals, its resistance value is in the MΩ level, and the IV curve is nonlinear, it is not completely insulating, so it is excluded.

[0165] 2. Secondly, quartz glass has excellent insulation properties, high resistivity, and good thermal stability, with an IV value of a straight line (no current). However, the price of quartz sheets is 10 times higher than that of glass sheets, but their yield rate is not higher than that of glass. Moreover, the performance of glass fully meets the process requirements, and the yield rate has reached the level of quartz sheets, making it more suitable for mass production and commercialization. Therefore, from the perspective of cost and yield, glass sheets are the preferred substrate material.

[0166] Example 10: Distance between electrode pairs

[0167] This embodiment adopts the method provided in embodiment 2 to prepare the tunneling electrode chip, wherein the distance between the electrode pairs, that is, the separation portion 5 of the mask (see Figure 3 The widths of (3) and (4), i.e., the shortest distances between two adjacent rectangular structures (i.e., the electrode pair distances), are 30µm, 50µm, 100µm, 300µm, 500µm, and 1000µm, respectively. Six sets of tunneling electrode chips were thus prepared, and their conductivity was tested respectively, as shown in Table 8.

[0168] Table 8. Statistics of spacing between different electrode pairs

[0169]

[0170] As shown in Table 8, research has found that when the distance is ≤100 µm, the conductivity can be maintained in the 0.1-1000 nS range, allowing subsequent tunneling between the electrode pairs. However, when the distance is greater than 100 µm, the conductivity is too low, resulting in no conduction between the electrode pairs and no detection of tunneling current. Therefore, the distance between the electrode pairs must be kept within 100 µm. Therefore, the optimal minimum distance is 30-100 µm, with a 30 µm mask being the most preferred for subsequent testing.

[0171] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A method for preparing a discontinuous metal film with tunneling effect, characterized in that: The discontinuous metal film includes a substrate and a nanogap film disposed on the substrate; the nanogap film includes randomly distributed nano-islands, with a nanogap formed between any two adjacent nano-islands; an adhesion layer is disposed between the nanogap film and the substrate; the adhesion layer is made of chromium; The preparation method comprises the following steps: (1) Depositing a Cr layer with a thickness of about 1 nm on the substrate surface as an adhesion layer by magnetron sputtering deposition equipment; (2) In situ deposition of nanogap films on the adhesion layer using magnetron sputtering deposition equipment; In the magnetron sputtering method, the deposition time is 20 s to obtain the discontinuous metal film; The yield rate of the discontinuous metal film prepared by the method reaches 30%; The yield rate detection method is as follows: if a nonlinear IV curve is present, it is judged to be capable of generating a tunneling effect, and the film thickness is less than 100 nm, the nanogap is 3-10 nm, the nanogap coverage is 21.64-46.45%, the conductivity is 0.1-1000 nS, and the transmittance is 66.33-70.25%, then it is judged to be a good product.

2. Use of an adhesion layer in improving the yield of a discontinuous metal film having a tunneling effect, characterized in that: The adhesion layer is made of chromium; the discontinuous metal film includes a substrate and a nanogap film disposed on the substrate; the nanogap film includes randomly distributed nanoislands, with a nanogap formed between any two adjacent nanoislands; an adhesion layer is disposed between the nanogap film and the substrate; and the method for preparing the discontinuous metal film includes the following steps: (1) Depositing a Cr layer with a thickness of about 1 nm on the substrate surface as an adhesion layer by magnetron sputtering deposition equipment; (2) in situ depositing a nanogap film on the adhesion layer using a magnetron sputtering deposition device for 20 s to obtain the discontinuous metal film; The yield rate of the discontinuous metal film prepared by the method reaches 30%; The yield rate detection method is as follows: if a nonlinear IV curve is present, it is judged to be capable of generating a tunneling effect, and the film thickness is less than 100 nm, the nanogap is 3-10 nm, the nanogap coverage is 21.64-46.45%, the conductivity is 0.1-1000 nS, and the transmittance is 66.33-70.25%, then it is judged to be a good product.

3. A method for preparing a discontinuous metal film with tunneling effect, characterized in that: The discontinuous metal film includes a substrate and a nanogap film disposed on the substrate; the nanogap film includes randomly distributed nano-islands, with a nanogap formed between any two adjacent nano-islands; an adhesion layer is disposed between the nanogap film and the substrate; the adhesion layer is made of chromium; The preparation method comprises the following steps: (1) Depositing a Cr layer with a thickness of about 1 nm on the substrate surface as an adhesion layer by magnetron sputtering deposition equipment; (2) A nanogap film is in situ deposited on the adhesion layer using a magnetron sputtering deposition device, with a deposition time of 10 to 30 seconds to obtain the discontinuous metal film.

4. A discontinuous metal film with tunneling effect, comprising a substrate, characterized in that: The present invention also includes a nanogap film disposed on the substrate; the nanogap film comprises randomly distributed nanoislands, with a nanogap formed between any two adjacent nanoislands; the number of the nanoislands and the number of nanogaps is greater than one; the distance between the nanogaps is less than 10 nm; and / or the thickness of the nanogap film does not exceed 100 nm; an adhesion layer is disposed between the nanogap film and the substrate; the adhesion layer is made of chromium; and the film is prepared by the method described in claim 3.

5. The discontinuous metal film according to claim 4, wherein: The material of the substrate is selected from one or more of silicon dioxide, glass, silicon, silicon nitride and sapphire; and / or the material of the nano-gap film is selected from one or more of gold, silver, aluminum and copper.

6. A tunneling electrode chip, characterized in that: It comprises the discontinuous metal film as claimed in claim 4 or 5; it also comprises a continuous conductive layer provided on the discontinuous metal film, and an electrode pair provided on the continuous conductive layer.

7. The tunneling electrode chip according to claim 6, characterized in that: The material of the continuous conductive layer is selected from one or more of gold, silver, aluminum, and copper; and / or the material of the electrode pair is selected from one or more of gold, silver, aluminum, and copper; and / or the spacing between the electrode pairs is 30-100 μm.

8. A method for molecular media sensing detection, characterized in that: The detection is performed using the discontinuous metal film as described in claim 4 or 5, or the tunneling electrode chip as described in claim 6 or 7; the detection method comprises: dripping a solution onto the surface of the discontinuous metal film or the tunneling electrode chip, and being captured by the nanogap under the drive of an electrostatic field, and detecting an IV curve.

9. Use of the discontinuous metal film according to claim 4 or 5 or the tunneling electrode chip according to claim 6 or 7 in photoelectric detection devices, molecular sensor devices and photoresponsive devices.

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