CN113793789B - Side anode vacuum channel nanometer gap triode and preparation method thereof - Google Patents

Abstract

The invention discloses a side anode vacuum channel nanometer gap triode and a preparation method thereof, wherein the nanometer gap triode comprises a cathode, an anode, a grid electrode and an oxide insulating layer; the nanogap means that the distance between the anode and the gate electrode is maintained within 300 nm; the nanometer gap triode is characterized in that the device has similar electrical characteristics to a traditional field effect transistor, electrons are transported in a ballistic transport or tunneling mode inside a vacuum channel, and the driving voltage is smaller than the first ionization potential of molecules because the vacuum channel is smaller than/close to the average free path of the electrons in the air, so that the device can work normally without strict vacuum encapsulation. The structure is intended to break through the technical bottleneck of the traditional electric vacuum device, and is combined with the existing semiconductor processing technology to obtain a miniaturized and integrated vacuum nano electronic device so as to obtain the technical advantages of high frequency, quick response and no need of strict vacuum packaging, and has higher application potential in novel electronic components.

Description

A side anode vacuum channel nanogap transistor and its preparation method

Technical field

The invention relates to a side anode vacuum channel nanogap transistor and a preparation method, and belongs to the field of new vacuum micro-nano structures and field emission devices.

Background technique

Vacuum electronic devices have technical advantages such as high power, bandwidth and high frequency, and are widely used in technical fields such as communications, radar, navigation and imaging. However, due to complex mechanical processing and other reasons, traditional vacuum electronic systems are often bulky and bloated, making it difficult to achieve miniaturization, lightweight and integration. The development of nanotechnology, whether it is advanced processing technology or the emergence of new nanomaterials, provides the possibility to break through the bottleneck of traditional vacuum electronic devices. In recent years, the emergence of nanogap structures has injected new vitality into vacuum nanoelectronic devices.

The nanogap is an electron transport channel in the vacuum. The average size of the gap is smaller than the mean free path of electrons in the medium or vacuum. The electrons are not interfered by scattering and other factors inside the nanogap. On the other hand, the transport mode of electrons in the nanogap satisfies field electron emission, that is, when the voltage applied between the anodes is very large, the width of the potential barrier on the cathode surface decreases, and free electrons can penetrate through the quantum barrier. effect, released from the cathode. The nanogap vacuum triode will take into account the wide frequency band, high operating frequency, and fast response of field emission electronic devices, and will be integrated with solid-state devices to reduce the size and power consumption of the device and realize the innovation of vacuum electronic technology.

Contents of the invention

New transistors based on nanogap channel structures can be widely used in vacuum nanoelectronic devices, optoelectronic devices and other fields. With the rapid development of science and technology, the performance and requirements of devices are constantly improving, so effective and suitable preparation processes have to be developed. , explore the electrical properties and internal transport mechanism of the nanogap structure, broaden its application fields, and build new highly integrated device structures on this basis to meet the requirements of the times.

The present invention adopts the following technical solutions to solve the above technical problems:

The invention provides a vacuum side anode channel nanogap transistor structure, which is characterized in that: on an insulating base material, conductive materials are used to make cathodes and grids on the same straight line, and 300 nanometers are maintained between the cathodes and the grid. Within the gap, an anode electrode is arranged on one side of the gap area in a direction perpendicular to the straight line between the cathode and the gate. When a modulation voltage higher than the cathode is applied to the gate, adjusting the gate modulation voltage can cause the cathode to emit electrons; setting a voltage higher than the cathode on the anode and adjusting the anode voltage can make the electrons emitted by the cathode partially or All are hit to the anode, thereby forming a nanogap device triode structure with controllable current.

As a further technical solution of the present invention, in order to enable more electrons emitted by the cathode to be utilized by the anode under the action of the anode voltage, the cathode can be made into a tip structure, which can increase the field enhancement factor of the cathode and enhance the electron emission probability of the cathode. This makes it easier for electrons to be emitted from the cathode, and the electrons emitted from the cathode can more easily reach the anode under the action of the anode voltage.

As a further technical solution of the present invention, the cathode and the gate are in the shape of a pair of tips, which is more conducive for electrons to reach the anode under the action of the anode voltage.

As a further technical solution of the present invention, the anode is characterized by: according to the shape of the cathode and the grid, the end can be made into a flat, round, pointed cone, or a combination thereof, which can improve the field enhancement of the cathode. Factor, enhances the electron emission probability of the cathode, making it easier for electrons to be emitted from the cathode, and the electrons emitted from the cathode can more easily reach the anode under the action of the anode voltage.

As a further technical solution of the present invention, other features of the spatial structure of the cathode, gate and anode are: the shape of the gap between the electrodes is V or Y-shaped, which can be processed by etching processes such as focused ion beam etching. It is prepared without the need for a photolithography mask (mask-free) to simplify the manufacturing process.

As a further technical solution of the present invention, the spatial structure of the cathode, grid and anode is characterized by: a backup anode is provided on the other side of the anode of the cathode and the grid, and the gap between the four electrodes is The shape is X-shaped. On the one hand, the backup anode can enhance the surface electric field intensity of the entire cathode and gate area and reduce the turn-on voltage. On the other hand, it can improve the efficiency of the anode in collecting electrons, thereby increasing the current density.

As a further technical solution of the present invention, the electrodes and gaps can be produced through traditional semiconductor manufacturing processes such as coating, etching, electron beam lithography, and focused ion beam to produce patterned conductive electrode structures of cathodes, gates, and anodes. Its characteristics are: using technology to ensure that the gap between the cathode and the gate is within 300 nanometers.

As a further technical solution of the present invention, the gap area between the cathode, the gate electrode and the anode is characterized by using wet method, dry method, focused ion beam etching, etc. to remove the gap and nearby base materials. , thereby ensuring that electrons can be emitted directly from the cathode to the anode without colliding with the substrate, reducing the interaction between electrons and the substrate surface, reducing phonon scattering and charge conduction on the substrate surface.

As a further technical solution of the present invention, the materials used for the cathode, gate and anode are specifically semiconductor or metal materials, which can be prepared through thin film deposition and other processes; they can also be low-dimensional nanomaterials, which can be made by transfer or screen It is prepared by printing or growth processes to reduce the work function of the cathode emitting material and improve the electron emission performance of the cathode.

As a further technical solution of the present invention, the semiconductor materials include silicon, germanium, silicon carbide, gallium nitride, zinc oxide, gallium arsenide, etc., and the metal materials include gold, silver, copper, aluminum, iron, tungsten, Platinum, etc. and their alloys, the low-dimensional nanomaterials include graphene, carbon nanotubes, molybdenum disulfide, tungsten disulfide, zinc oxide nanowires, etc.

As a further technical solution of the present invention, the specific material of the insulating substrate is a high dielectric constant material.

As a further technical solution of the present invention, the high dielectric constant materials include silicon dioxide, aluminum oxide, hafnium oxide, boron nitride, etc. The use of atomic layer deposition to prepare the oxide insulating layer can reduce the thickness of the insulating layer. At the same time, its insulation performance is ensured. Materials with high dielectric constant can effectively reduce the leakage current of the bottom insulation layer.

As a further technical solution of the present invention, the cathode and the grid are at a certain angle (more than 90 degrees) and are not completely opposite to each other in the same straight line, so that the electrons emitted from the edge of the cathode are easily collected by the anode, improving the collection of electrons. efficiency.

As a further technical solution of the present invention, the cathode and the grid are opposite each other in the same straight line, but are not vertically opposite to the anode (the anode is tilted at an angle of less than 90 degrees relative to the central axis between the cathode and the grid), so that the emitted light is emitted from the edge of the cathode. The electrons that go out are easily collected by the anode, improving the electron collection efficiency.

As a further technical solution of the present invention, the anode is closer to the cathode, that is, the distance between the anode and the cathode should be smaller than the distance between the anode and the gate, so that the electrons emitted by the cathode are more easily collected by the anode instead of being collected by the gate. intercepted.

As a further technical solution of the present invention, a method for preparing a vacuum channel nanogap triode structure includes the following steps:

Step 1: Ultrasonically clean the silicon wafer with acetone, isopropyl alcohol and deionized water in sequence, and blow dry the surface with nitrogen; deposit an oxide insulating layer on the polished surface by magnetron sputtering;

Step 2: Spin-coat the photoresist, and use electron beam lithography to expose the preset pattern area on the sample surface;

Step 3: After developing the mixed solution of isopropyl alcohol and methyl isobutyl ketone, use chemical vapor deposition or electron beam evaporation and other thin film deposition processes to prepare semiconductor or metal thin films as cathodes, anodes and gates respectively;

Step 4: Peel off the prepared sample in acetone and ultrasonically clean it in isopropyl alcohol and deionized water respectively;

Step 5: Use etching processes such as wet or dry methods or focused ion beam etching to remove the nanogaps and nearby base materials. After the process preparation is completed, use a scanning electron microscope to observe and evaluate;

If the cathode, anode and gate are low-dimensional nanomaterials such as graphene and carbon nanotubes, the nanomaterial film is prepared on the upper surface of the insulating layer by wet transfer, screen printing or growth, and then electron beam lithography is used. Or the nanogap channel is prepared by focused ion beam etching and other processes. Finally, the prepared samples are cleaned in isopropyl alcohol and deionized water respectively. After the process preparation is completed, a scanning electron microscope is used for observation and evaluation.

Compared with the existing technology, the present invention adopts the above technical solution and has the following technical effects:

1) Compared with the traditional back gate and side gate structures, the V-shaped, Y-shaped or X-shaped vacuum channel structure provided by the present invention can effectively enhance the surface electric field intensity of the entire cathode and gate areas, thereby Improve the electron emission efficiency and reduce the turn-on voltage; on the other hand, it improves the efficiency of the anode to collect electrons, thereby increasing the current density and current density;

2) The present invention uses atomic layer deposition to prepare the oxide insulating layer, which can reduce the thickness of the insulating layer while ensuring its insulating performance. High dielectric constant aluminum oxide or hafnium oxide materials can effectively reduce the leakage current of the bottom insulating layer;

3) In the present invention, focused ion beam etching can be used to prepare the vacuum channel between the cathode and the anode with a size of less than 50 nanometers. At this scale, electrons can be transported by ballistic transport or tunneling, breaking through the traditional electric vacuum. The technical bottleneck of devices requiring strict packaging has broadened the vacuum requirements and application scope of vacuum electronic devices;

4) The present invention compresses the size of the vacuum device to 300 nanometers, and the device processing technology requirements are similar to the traditional semiconductor technology, which improves the complex mechanical processing and assembly required by traditional electric vacuum devices. More importantly, it provides the possibility for miniaturization and integration of vacuum components, integrated circuits and vacuum electronic systems in the future.

5) Compared with traditional back-gate or side-gate nanogap transistors, the triode structure of the present invention can effectively enhance the surface electric field intensity of the entire cathode and gate regions, thereby improving the electron emission efficiency and reducing the turn-on voltage; On the other hand, the efficiency of the anode in collecting electrons is improved, thereby increasing the current density as well as the current density.

Description of the drawings

Figure 1 shows a schematic structural diagram of a traditional back gate and side gate nanogap transistor.

Figure 2 is a schematic diagram of the preparation process of the vacuum channel nanogap transistor in the present invention.

Figure 3 is a top view of the basic structure of the vacuum channel nanogap transistor in the present invention.

Figure 4 is a top view of a V-shaped vacuum channel nanogap transistor in the present invention.

Figure 5 is a top view of a Y-shaped vacuum channel nanogap transistor in the present invention.

Figure 6 is a top view of an expanded nanogap structure in the present invention with an X-shaped vacuum channel nanogap transistor.

Figure 7 is a top view of a nanogap transistor in which the channel between the cathode and the anode has a V-shaped structure in the present invention.

Figure 8 is a top view of the cathode morphology, including flat, round, pointed cone, and their combination shapes.

FIG. 9 is a top view of one structure of the vacuum channel nanogap transistor in the present invention.

FIG. 10 is a top view of one structure of the vacuum channel nanogap transistor in the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and cannot be construed as limitations of the present invention.

It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "the" and "the" used herein may also include the plural forms. It should be further understood that the word "comprising" used in the description of the present invention refers to the presence of stated features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components and/or groups thereof. It will be understood that when we refer to an element being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Additionally, "connected" or "coupled" as used herein may include wireless connections or couplings. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It can be understood by one of ordinary skill in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in general dictionaries are to be understood to have meanings consistent with their meaning in the context of the prior art, and are not to be taken in an idealized or overly formal sense unless defined as herein. explain.

Specific embodiments are introduced below with reference to example diagrams:

Example 1:

Figure 2 shows a schematic diagram of the preparation process of the vacuum channel nanogap transistor in the present invention. Take cathode 2, grid 3 and anode 5 as metal or semiconductor materials as an example: first, clean the silicon wafer ultrasonically with acetone, isopropyl alcohol and deionized water in sequence, blow dry its surface with nitrogen; use magnetron sputtering on the polished surface. The oxide insulating layer is deposited by radiation; the photoresist is spin-coated, and a preset pattern area is exposed on the sample surface using electron beam lithography; after development with a mixed solution of isopropyl alcohol and methyl isobutyl ketone, chemical vapor phase is used to Semiconductor or metal films are prepared by thin film deposition processes such as deposition or electron beam evaporation as cathode 2, gate electrode 3 and anode 5 respectively; the prepared samples are peeled off in acetone (lift-off process) and washed in isopropyl alcohol and deionizer respectively. Ultrasonic cleaning in ionized water; finally, etching processes such as wet or dry methods or focused ion beam etching are used to remove the nanogap 4 and the base material nearby. After the process preparation is completed, a scanning electron microscope is used for observation and evaluation.

If the cathode 2, gate 3 and anode 5 are low-dimensional nanomaterials such as graphene or carbon nanotubes, a nanomaterial film is prepared on the upper surface of the insulating base material 1 by wet transfer, screen printing or growth. , the nanogap 4 is prepared using processes such as electron beam lithography or focused ion beam etching. Finally, the prepared samples are cleaned in isopropyl alcohol and deionized water respectively. After the process preparation is completed, a scanning electron microscope is used for observation and evaluation.

Example 2:

Figure 3 is a top view of the basic structure of the vacuum channel nanogap transistor in the present invention. It is characterized in that: on the insulating base material 1, conductive materials are used to make the cathode 2 and the gate 3 on the same straight line. The cathode is connected to the anode and the gate electrode. A gap 4 within 300 nanometers is maintained between the gate electrodes, and an anode 5 is arranged on one side of the gap area in a direction perpendicular to the straight line between the cathode and the gate electrode. When a modulation voltage 6 higher than that of the cathode is applied to the gate, adjusting the gate modulation voltage can cause the cathode to emit electrons; setting a voltage 7 higher than the cathode on the anode, and adjusting the anode voltage can cause the electrons emitted by the cathode to emit electrons under the action of the anode voltage. Part or all of it is driven onto the anode, thereby forming a nanogap device triode structure in which the current can be controlled. Anode 5 is closer to cathode 2, that is, the distance between anode 5 and cathode 2 should be smaller than the distance between anode 5 and grid 3, so that the electrons emitted by the cathode are more easily collected by the anode rather than intercepted by grid 3. .

Example 3:

Figure 4 is a top view of a V-shaped vacuum channel nanogap transistor in the present invention. On the insulating base material 1, conductive materials are used to make the cathode 2 and the grid 3 on the same straight line. The cathode is connected to the anode and the grid. A V-shaped gap 4 within 300 nanometers is maintained between them, and an anode 5 is arranged on one side of the gap area in a direction perpendicular to the straight line between the cathode and the gate. When a modulation voltage 6 higher than that of the cathode is applied to the gate, adjusting the gate modulation voltage can cause the cathode to emit electrons; setting a voltage 7 higher than the cathode on the anode, and adjusting the anode voltage can cause the electrons emitted by the cathode to emit electrons under the action of the anode voltage. Part or all of it is driven onto the anode, thereby forming a nanogap device triode structure in which the current can be controlled. The anode 5 is closer to the cathode 2, that is, the distance between the anode 5 and the cathode 2 should be smaller than the distance between the anode 5 and the grid 3, so that the electrons emitted by the cathode are more easily collected by the anode rather than intercepted by the grid.

Example 4:

Figure 5 is a top view of a Y-shaped vacuum channel nanogap transistor in the present invention. On the insulating base material 1, conductive materials are used to make the cathode 2 and the grid 3 on the same straight line. The cathode, the anode, and the grid are A Y-shaped gap 4 within 300 nanometers is maintained between them, and an anode 5 is arranged on one side of the gap area in a direction perpendicular to the straight line between the cathode and the gate. When a modulation voltage 6 higher than that of the cathode is applied to the gate, adjusting the gate modulation voltage can cause the cathode to emit electrons; setting a voltage 7 higher than the cathode on the anode, and adjusting the anode voltage can cause the electrons emitted by the cathode to emit electrons under the action of the anode voltage. Part or all of it is driven onto the anode, thereby forming a nanogap device triode structure in which the current can be controlled. The anode 5 is closer to the cathode 2, that is, the distance between the anode 5 and the cathode 2 should be smaller than the distance between the anode 5 and the grid 3, so that the electrons emitted by the cathode are more easily collected by the anode rather than intercepted by the grid.

Example 5:

Figure 6 is a top view of an expanded nanogap structure in the present invention with an X-shaped vacuum channel nanogap triode. On the insulating base material 1, conductive materials are used to make the cathode 2 and the gate 3 on the same straight line. An X-shaped gap 4 within 300 nanometers is maintained between the cathode and the gate. An anode 5 is located on one side of the gap area in a direction perpendicular to the straight line between the cathode and the gate; a backup is provided on the other side of the anode 5. Anode 8, the gap between the four electrodes presents an The anode voltage can cause some or all of the electrons emitted by the cathode to hit the anode under the action of the anode voltage, thereby forming a nanogap device triode structure with controllable current. Anode 5 and backup anode 8 are closer to cathode 2, that is, the distance between anode 5 and backup anode 8 and cathode 2 should be smaller than the distance between anode 5 and backup anode 8 and grid 3, making it easier for the cathode to emit electrons. collected by the anode rather than intercepted by the gate.

Example 6:

Figure 7 is a top view of the nanogap transistor in which the channel between the cathode and the anode has a V-shaped structure in the present invention. It is characterized in that: on the insulating base material 1, conductive materials are used to make the cathode 2 and the gate on the same straight line. 3. The gaps between the cathode and the anode, the cathode and the grid all have a V-shaped structure; an anode 5 is set on one side of the gap area in a direction perpendicular to the straight line between the cathode and the grid. When a modulation voltage 6 higher than that of the cathode is applied to the gate, adjusting the gate modulation voltage can cause the cathode to emit electrons; setting a voltage 7 higher than the cathode on the anode, and adjusting the anode voltage can cause the electrons emitted by the cathode to emit electrons under the action of the anode voltage. Part or all of it is driven onto the anode, thereby forming a nanogap device triode structure in which the current can be controlled.

Example 7:

Figure 8 is a top view of the cathode morphology, including flat, round, pointed cone, and their combination shapes.

Example 8:

Figure 9 is a top view of the vacuum channel nanogap transistor in the present invention. On the insulating base material 1, the cathode 2 and the gate 3 face each other at an angle greater than 90 degrees, so that the electrons 9 emitted from the edge of the cathode can easily It is collected by the anode 5 to improve the collection efficiency of electrons.

Example 9:

Figure 10 is a top view of the vacuum channel nanogap transistor in the present invention. On the insulating base material 1, the cathode 2 and the gate 3 are opposite to each other in the same straight line, but are not vertically opposite to the anode 5 (the anode is opposite to the cathode-gate). The inclination of the central axis is less than 90 degrees), so that the electrons 9 emitted from the edge of the cathode are easily collected by the anode 5, thereby improving the electron collection efficiency.

Claims (14)

1. A side anode vacuum channel nanometer gap triode structure is characterized in that: on an insulating base material (1), a cathode (2) and a grid electrode (3) on the same straight line are made of conductive materials, a gap (4) within 300 nanometers is kept between the cathode (2) and the grid electrode (3), and an anode (5) is arranged on one side of the gap (4) area in the direction perpendicular to the connecting line of the cathode (2) and the grid electrode (3); when the grid electrode (3) is applied with a modulation voltage (6) higher than the cathode electrode (2), the cathode electrode (2) can emit electrons by adjusting the modulation voltage of the grid electrode (3); the voltage (7) higher than the voltage (2) of the cathode (2) is arranged on the anode (5), and the voltage of the anode (5) is adjusted, so that electrons emitted by the cathode (2) can be partially or completely beaten on the anode (5) under the action of the voltage of the anode (5), and a triode structure of the nano-gap device with controllable current is formed.

2. The side anode vacuum channel nanogap triode structure according to claim 1, wherein: in order to enable more electrons emitted by the cathode (2) to be utilized by the anode (5) under the voltage of the anode (5), the cathode (2) adopts a tip structure, so that electrons emitted by the cathode (2) can more easily reach the anode (5) under the voltage of the anode (5).

3. The side anode vacuum channel nanogap triode structure according to claim 1, wherein: the cathode (2) and the grid (3) are made into a pair of circular or conical tip shapes, which is more beneficial for electrons to reach the anode (5) under the voltage action of the anode (5).

4. The side anode vacuum channel nanogap triode structure according to claim 1, wherein: the end of the anode (5) may be shaped flat, rounded, tapered, and combinations thereof, depending on the shape of the cathode (2) and the grid (3), to further facilitate electrons reaching the anode (5) between the cathode (2) and the grid (3).

5. The side anode vacuum channel nanogap triode structure according to claim 1, wherein: the shape of the gap (4) among the cathode (2), the grid (3) and the anode (5) is V-shaped or Y-shaped, so that the manufacturing process is simplified.

6. The side anode vacuum channel nanogap triode structure according to claim 1, wherein: on the other side of the cathode (2) and the grid (3) where the anode (5) is provided, a backup anode (8) is provided, and the shape of the gap portion between the four electrodes is X-shaped.

7. A side anode vacuum channel nanogap triode structure according to any one of claims 1 to 6, wherein: in order to reduce the effect of electrons on the substrate surface, the gap (4) between the cathode (2), the grid (3) and the anode (5) and the nearby substrate materials are removed by adopting a wet method, a dry method or a focused ion beam etching method.

8. A side anode vacuum channel nanogap triode structure according to any one of claims 1 to 6, wherein: the cathode (2), the grid (3) and the anode (5) are made of semiconductor materials or metal materials by a thin film deposition process; or low-dimensional nano material, which is prepared by a growth, transfer or screen printing process, and the three electrodes are made of different materials.

9. The side anode vacuum channel nanogap triode structure according to claim 8, wherein: the semiconductor material is silicon, germanium, silicon carbide, gallium nitride, zinc oxide or gallium arsenide, the metal material is gold, silver, copper, aluminum, iron, tungsten, platinum or alloys thereof, and the low-dimensional nano material is graphene, carbon nano tube, molybdenum disulfide, tungsten disulfide or zinc oxide nano wire.

10. A side anode vacuum channel nanogap triode structure according to any one of claims 1 to 6, wherein: the material of the grid electrode (3) is an emission material with high work function so as to reduce electron emission of the grid electrode and reduce grid leakage current.

11. The side anode vacuum channel nanogap triode structure according to claim 1, wherein: the substrate material (1) is specifically made of a high dielectric constant material.

12. A side anode vacuum channel nanogap triode structure according to any one of claims 1 and 11, wherein: the substrate material (1) is silicon dioxide, aluminum oxide, hafnium oxide or boron nitride.

13. The side anode vacuum channel nanogap triode structure according to claim 1, wherein: the anode (5) is closer to the cathode (2), i.e. the distance between the anode (5) and the cathode (2) should be smaller than the distance between the anode (5) and the grid (3), so that electrons emitted by the cathode (2) are more easily collected by the anode (5) than are intercepted by the grid (3).

14. The method for preparing the side anode vacuum channel nanogap triode structure according to claim 1, which is characterized in that: the method comprises the following steps:

step 1: sequentially ultrasonically cleaning a silicon wafer by using acetone, isopropanol and deionized water, and blow-drying the surface of the silicon wafer by using nitrogen; depositing an oxide insulating layer on the polished surface by magnetron sputtering;

step 2: spin-coating photoresist, and exposing a preset pattern area on the surface of a sample by using an electron beam lithography method;

step 3: after the mixed solution of isopropanol and methyl isobutyl ketone is developed, preparing a semiconductor or metal film by utilizing a chemical vapor deposition or electron beam evaporation film deposition process, wherein the semiconductor or metal film is respectively used as a cathode (2), an anode (5) and a grid (3);

step 4: the prepared sample is put into acetone for stripping and respectively ultrasonically cleaned in isopropanol and deionized water;

step 5: removing the nano gap (4) and nearby substrate materials by utilizing a wet method, a dry method or a focused ion beam etching process, and observing and evaluating the nano gap by utilizing a scanning electron microscope after the process preparation is finished;

if the cathode (2), the anode (5) and the grid (3) are made of graphene or carbon nano-tube low-dimensional nano-materials, preparing a nano-material film on the upper surface of the insulating layer in a wet transfer, screen printing or growth mode, preparing a nano-gap channel by utilizing an electron beam lithography or focused ion beam etching process, and finally cleaning the prepared sample in isopropanol and deionized water respectively, wherein the process preparation is finished and is evaluated by utilizing a scanning electron microscope.