Electron source, electron gun and application of electron source

Abstract

The invention relates to an electron source, an electron gun and application of the electron source, the electron source comprises an optical fiber, a conductive connection layer and an electron emission layer, and the conductive connection layer is arranged on the outer surface of the optical fiber; the electron emission layer at least comprises an electron excitation layer electrically connected with the conductive connection layer, the electron emission layer is arranged on a laser emission path of the optical fiber, and laser emitted by the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons; the electron excitation layer contains a one-dimensional material, and the axial direction of the one-dimensional material in the electron excitation layer is the same as the emergent direction of laser, so that the emergent efficiency of electrons in the electron source and the stability of the electron source are effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of electron sources, and particularly to an electron source, an electron gun, and an application of the electron source. Background Art

[0002] An electron source is a device capable of emitting an electron beam. Electron sources are mainly classified into thermionic electron sources, field emission electron sources, and photoemission electron sources according to the excitation method. Traditional thermionic electron sources mainly select materials with metallic properties such as tungsten filaments and lanthanum hexaboride. When heated to thousands of degrees Celsius, electrons are thermally excited to escape from the surface of the material to form vacuum electrons. Traditional field emission electron sources mainly select metal tips such as tungsten. Under the action of a strong electric field applied from the outside, a tip discharge effect is generated. Traditional photoemission electron sources use a metal material as a photocathode, and a laser is used to irradiate and excite the photocathode material to generate electrons. However, the electron emission efficiency of the above traditional electron sources is relatively low and the stability is poor, and further improvement is needed. Summary of the Invention

[0003] Based on this, the present application provides an electron source, an electron gun, and an application of the electron source to improve the electron emission efficiency and the stability of the electron source.

[0004] In the first aspect of the present application, an electron source is provided. The electron source includes an optical fiber, a conductive connection layer, and an electron emission layer. The conductive connection layer is disposed on the outer surface of the optical fiber;

[0005] The electron emission layer at least includes an electron excitation layer electrically connected to the conductive connection layer. The electron emission layer is disposed on the laser emission path of the optical fiber, and the laser emitted from the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons;

[0006] The electron excitation layer contains one-dimensional materials, and the axial directions of the one-dimensional materials in the electron excitation layer are all the same as the emission direction of the laser.

[0007] In some embodiments, the diameter of the one-dimensional material is 1 nm to 20 nm, and the length of the one-dimensional material is 0.1 μm to 1 μm.

[0008] In some embodiments, the one-dimensional material includes one or more of nanotubes, nanowires, and nanobelts.

[0009] In some embodiments, the nanotube includes one or more of a carbon nanotube and a molybdenum disulfide nanotube.

[0010] In some embodiments, the nanowire includes one or more of a gold nanowire, a semiconductor nanowire, and a tellurium quantum wire.

[0011] In some embodiments, the nanobelt includes one or more of carbon nanobelts and molybdenum disulfide nanobelts.

[0012] In some embodiments, the laser wavelength in the optical fiber is 200 nm to 2000 nm, and the pulse power is 1 nW to 1 W.

[0013] In some embodiments, the electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on the side of the electron excitation layer close to the optical fiber; or,

[0014] The auxiliary layer is stacked on the side of the electron excitation layer away from the optical fiber.

[0015] In some embodiments, the thickness of the auxiliary layer is 0.1 nm to 100 nm, and the light transmittance of the auxiliary layer is ≥10%.

[0016] In some embodiments, the auxiliary layer has conductivity, and the auxiliary layer is electrically connected to the conductive connection layer.

[0017] In some embodiments, the material of the auxiliary layer includes one or more of graphene and conductive metals.

[0018] In some embodiments, the electron emission layer is located on one side in the length direction of the optical fiber.

[0019] In some embodiments, the optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a perforated optical fiber.

[0020] In a second aspect of the present application, an electron gun is provided. The electron gun includes a housing, a grid, an anode, and the electron source according to the first aspect of the present application. The electron source is fixed in the housing, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

[0021] In a third aspect of the present application, an application of the electron source according to the first aspect of the present application is provided. The application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, a free electron laser, and a display.

[0022] Compared with the traditional technology, the above-mentioned electron source, electron gun, and application of the electron source have at least the following beneficial effects:

[0023] The axial direction of the one-dimensional material in the above-mentioned electron emission layer is the same as the emission direction of the laser, enabling the electron source to achieve point emission and having the advantages of high resolution. When the above-mentioned electron source works, the laser is directly transmitted through the optical fiber, without involving a complex and unstable external spatial optical path, greatly improving the structural simplicity and operation convenience of the electron source, reducing the interference of the external space on the stability of the electron beam, and enabling the electron source to have ultra-high stability and integration; the one-dimensional material has an atomic-level diameter, strong interaction with the optical field and electric field, and high electron emission efficiency, making it very suitable for an ultrafast electron source with a narrow pulse width; moreover, the one-dimensional material has no dangling bonds, stable properties, high melting point, and is not easily damaged, and can be applied to scenarios with high-power excitation. Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of the electron source according to Embodiment 1 of the present application. Among them, 110a is an optical fiber; 1101a is a core; 1102a is a cladding; 121a is an electron excitation layer; 130a is a conductive connection layer.

[0025] Figure 2 is Figure 1 a cross-sectional view taken along the A-A direction in

[0026] Figure 3 It is a schematic structural diagram of the electron source according to Embodiment 2 of the present application. Among them, 110b is an optical fiber; 1101b is a core; 1102b is a cladding; 120b is an electron emission layer; 121b is an electron excitation layer; 122b is an auxiliary layer; 130b is a conductive connection layer.

[0027] Figure 4 is Figure 3 a cross-sectional view taken along the B-B direction in

[0028] Figure 5 It is a schematic internal structure diagram of an electron gun according to an embodiment of the present application. Among them, 100 is an electron source; 200 is a grid; 300 is an anode. Detailed Embodiments

[0029] To make the above objects, features, and advantages of the present application more obvious and understandable, the following detailed description of the specific embodiments of the present application is provided. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0030] In this application, terms such as "first aspect", "second aspect", "third aspect", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", etc. only serve the purpose of non-exhaustive enumerative description and should be understood not to constitute a closed limitation on quantity.

[0031] In this application, "optionally", "optional", "option" mean that it can be either present or absent, that is, it refers to any one of the two alternative options of "present" or "absent". If "optional" appears multiple times in a technical solution, and there is no special instruction, no contradiction or mutual restriction relationship, then each "optional" is independent of each other.

[0032] In this application, regarding numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0033] In this application, for technical features described in an open-ended manner, it includes closed technical solutions composed of the listed features, as well as open-ended technical solutions containing the listed features.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items. The meaning of the term "multiple" in this application is at least two, such as two, three, etc., unless otherwise specifically defined.

[0035] In this application, unless otherwise clearly specified and limited, terms such as "install", "connect", "join", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] Although traditional hot electron sources and traditional field emission electron sources can efficiently generate electrons, they lack effective modulation of physical parameters such as the energy, momentum, deflection state, and spatio-temporal distribution of electrons. Their operating modes and working environments mostly fall within the scope of electron beam applications with continuous time and Gaussian spatial distribution, making it difficult to meet the research requirements related to particle interactions and ultrafast time resolution in modern physics. In addition, hot electron emission requires a high working temperature and the cathode material is continuously consumed during operation and needs to be replaced regularly. Although traditional cold field emission electron sources can work at room temperature, they often require an ultra-high vacuum of about 10 -7 Pa, and the preparation of their cathode materials is difficult, costly, and requires regular high-temperature tip cleaning, resulting in high maintenance costs. Whether it is a hot electron source or a field emission electron source, the regulation of electron emission properties is limited, and it is impossible to balance coherence, pulsed nature, emission efficiency, and stability.

[0037] Optoelectronic sources have made improvements in aspects such as modulation methods, diversity of excitation principles, and integration, but there are still some problems. For example, traditional optoelectronic sources open optical windows on the side of the electron gun and focus free laser light on the surface of the metal tip to excite electrons. However, this method requires modification of the instrument itself and is sensitive to environmental factors such as vibrations, resulting in poor long-term stability. For electron emission on the surface of the fiber tip or the end face metal layer, since the distance between the metal bottom layer directly interacting with the laser and the metal surface layer where electron emission occurs is relatively far, the electrons generated by the action of the bottom layer are easily affected by lattice scattering during the process of passing through the metal layer, affecting the emission efficiency. Moreover, when the thickness of the metal layer is thinned, the melting point of the metal decreases, making it easy to be damaged, and the electron emission efficiency and stability are affected.

[0038] Based on this, an embodiment of the present application provides an electron source, which includes an optical fiber, a conductive connection layer, and an electron emission layer. The conductive connection layer is disposed on the outer surface of the optical fiber;

[0039] The electron emission layer at least includes an electron excitation layer electrically connected to the conductive connection layer. The electron emission layer is disposed on the laser emission path of the optical fiber, and the laser emitted by the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons;

[0040] The electron excitation layer contains one-dimensional materials, and the axial directions of the one-dimensional materials in the electron excitation layer are all the same as the laser emission direction.

[0041] The axial direction of the one-dimensional material in the above-mentioned electron excitation layer is the same as the laser emission direction, which enables the electron source to achieve point emission and has the advantages of high resolution. When the above-mentioned electron source works, the laser is directly transmitted through the optical fiber, without involving a complex and unstable external space optical path, greatly improving the structural simplicity and operation convenience of the electron source, reducing the interference of the external space on the electron beam stability, and making the electron source have ultra-high stability and integration; the one-dimensional material has an atomic-level diameter, and the back-incident electrons can be emitted into the vacuum without passing through in-body transmission, with high electron emission efficiency, and is very suitable for an ultrafast electron source with a narrow pulse width; moreover, the one-dimensional material has no dangling bonds, is stable in nature, has a high melting point, is not easily damaged, and can be applied to the scenario of high-power excitation. The above-mentioned electron source includes but is not limited to a large beam current electron source, an ultrafast electron source, or a highly coherent electron source.

[0042] It should be noted that the laser light output path of the optical fiber in this application refers to the path where the laser irradiates in the optical fiber. Taking a solid-core optical fiber as an example, the laser emission position of the solid-core optical fiber is at the end face of the fiber core, that is, the electron excitation layer can be arranged at the fiber core; taking a side-cut optical fiber as an example, the laser emission position of the side-cut optical fiber is on the side-cut side of the side-cut optical fiber, that is, the electron excitation layer can be arranged at the side-cut. It can be understood that in this application, the electron excitation layer can be directly in contact with the laser output surface of the optical fiber, or can be supported by other structural layers, that is, as long as the laser output from the optical fiber can irradiate on the electron excitation layer.

[0043] It should also be noted that the purpose of the electrically conductive connection layer being electrically connected to the electron excitation layer in this application is to connect the one-dimensional material in the electron excitation layer to the external circuit to form a complete circuit and realize charge replenishment and electric field control. As an implementation manner, the electrically conductive connection layer in this application can be directly connected to the electron excitation layer. In other implementation manners, the electrically conductive connection layer and the electron excitation layer can also be electrically connected through other conductive structures. For example, taking a solid-core optical fiber as an example, the electrically conductive connection layer is arranged on the side of the solid-core optical fiber, the electron excitation layer is arranged at the fiber core of the solid-core optical fiber, and the electrically conductive connection layer and the electron excitation layer are electrically connected, and there is no electrically conductive connection layer at the fiber core.

[0044] In some implementation manners, the one-dimensional material further includes doping elements. Optionally, the doping elements include one or more of alkali metal elements, alkaline earth metal elements, transition metal elements, rare earth elements, halogen elements, and light elements. Among them, the light elements include at least one of B, C, N, and O. The doping elements can improve the conductivity of the one-dimensional material, change the work function, and adjust the electron emission performance. For example, alkali metal elements and alkaline earth metal elements can improve the conductivity of the one-dimensional material, and at the same time can reduce the work function of the one-dimensional material to increase the emission beam current; elements such as B, C, N, O, F, and rare earth can create discrete energy levels to obtain an electron beam with a narrow energy.

[0045] In some embodiments, the diameter of the one-dimensional material is 1 nm to 20 nm, and the length of the one-dimensional material is 0.1 μm to 1 μm. When the diameter and length of the one-dimensional material are within the above ranges, the emission efficiency and stability of the electron source can be further improved. If the diameter of the one-dimensional material is too large, the field enhancement factor is small, and the interaction with light is weak. If the length of the one-dimensional material is too short, it exhibits the properties of a zero-dimensional material and is difficult to fabricate controllably; if the length of the one-dimensional material is too long, there will be large scattering and other losses during the light transmission process, and the interaction with the one-dimensional material is weakened. It can be understood that the diameter of the one-dimensional material includes but is not limited to: 1 nm, 3 nm, 5 nm, 7 nm, 10 nm, 13 nm, 15 nm, 17 nm, 20 nm; the length of the one-dimensional material includes but is not limited to: 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm.

[0046] In some embodiments, the one-dimensional material includes one or more of nanotubes, nanowires, and nanoribbons. Thereby, the emission efficiency and stability of the electron source can be further improved.

[0047] In some embodiments, the nanotubes include one or more of carbon nanotubes and molybdenum disulfide nanotubes. Thereby, the emission efficiency and stability of the electron source can be further improved.

[0048] In some embodiments, the nanowires include one or more of gold nanowires, semiconductor nanowires, and tellurium quantum wires (Te quantum wires). Thereby, the emission efficiency and stability of the electron source can be further improved. Optionally, the semiconductor nanowires include GaAs nanowires.

[0049] In some embodiments, the nanoribbons include one or more of carbon nanoribbons and molybdenum disulfide nanoribbons. Thereby, the emission efficiency and stability of the electron source can be further improved.

[0050] In some embodiments, the laser wavelength in the optical fiber is 200 nm to 2000 nm, and the pulse power is 1 nW to 1 W. Controlling the laser wavelength and pulse power within the above ranges can avoid the problem of melting caused by laser irradiation of the conductive metal and ensure that the auxiliary layer has the functions of support and conductivity. It can be understood that the laser wavelength in the optical fiber includes but is not limited to: 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, 2000 nm; the pulse power includes but is not limited to: 1 nW, 10 - 8 W, 10 -7 W, 10 -6 W, 10 -5 W, 10 -4 W, 10-3 W, 0.01W, 0.1W, 1W.

[0051] In some embodiments, the conductive connection layer is provided with electrodes. Optionally, the conductive connection layer may entirely cover the outer surface of the optical fiber or partially cover the outer surface of the optical fiber, and there is no conductive connection layer in the light output path of the laser. Further optionally, the thickness of the conductive connection layer is 0.1 nm to 100 nm.

[0052] In some embodiments, the material of the conductive connection layer includes one or more of metals, graphite, and low-dimensional materials. Metals include, for example, but are not limited to gold, and low-dimensional materials include at least one of zero-dimensional materials, one-dimensional materials, and two-dimensional materials. The zero-dimensional material can be, for example, a quantum dot, the one-dimensional material can be, for example, a carbon nanotube, and the two-dimensional material can be, for example, graphene.

[0053] In some embodiments, the electron source further includes an auxiliary layer, and the auxiliary layer is stacked on the side of the electron excitation layer close to the optical fiber; or,

[0054] The auxiliary layer is stacked on the side of the electron excitation layer away from the optical fiber.

[0055] In the above embodiments, when the electron excitation layer requires structural support, the auxiliary layer is used to provide structural support for the electron excitation layer, that is, the electron excitation layer is disposed on the auxiliary layer; or, when the electron excitation layer cannot be directly connected and conducted with the conductive connection layer, the conductive auxiliary layer is used to connect with the conductive connection layer, and the auxiliary layer is used to achieve electrical conduction between the electron excitation layer and the conductive connection layer.

[0056] In some embodiments, the one-dimensional materials in the electron excitation layer are arranged in a low-density manner. At this time, the electron energy dispersion emitted by the electron excitation layer is low, and the brightness of the electron source is high. Low density means that adjacent one-dimensional materials in the electron excitation layer do not contact and cannot achieve electron conduction.

[0057] In some embodiments, the one-dimensional materials in the electron excitation layer are arranged in a high-density manner. Thus, a large beam current electron source can be formed. High density means that adjacent one-dimensional materials in the electron excitation layer are in contact and can achieve electron conduction.

[0058] In some embodiments, low density refers to the number of one-dimensional materials per unit area. For example, a density less than 1 / nm 2 is low density, and greater than 1 / nm 2 is high density.

[0059] In some embodiments, the thickness of the auxiliary layer is 0.1 nm to 100 nm, and the light transmittance of the auxiliary layer is ≥10%. Thus, the laser emitted from the optical fiber can pass through the auxiliary layer to reach the electron excitation layer, thereby further improving the electron emission efficiency in the electron source and the stability of the electron source. It can be understood that the thickness of the auxiliary layer includes but is not limited to: 0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 5 nm, 10 nm, 30 nm, 50 nm, 70 nm, 90 nm, 100 nm; the light transmittance of the auxiliary layer includes but is not limited to: 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, etc.

[0060] In some embodiments, the thickness of the auxiliary layer is 0.5 nm to 10 nm, and the light transmittance of the auxiliary layer is ≥50%. Thus, the laser emitted from the optical fiber can pass through the auxiliary layer to reach the electron excitation layer, thereby further improving the electron emission efficiency in the electron source and the stability of the electron source.

[0061] In some embodiments, the auxiliary layer has conductivity and is electrically connected to the conductive connection layer. On the one hand, the auxiliary layer can be used as a conductive material to connect all the one-dimensional materials in the electron excitation layer to the external circuit, and on the other hand, it can improve the heat dissipation performance of the electron excitation layer.

[0062] In some embodiments, the material of the auxiliary layer includes one or more of graphene, conductive metal, and semiconductor thin film. In this application, the auxiliary layer can adopt a conductive metal, and by controlling the laser wavelength and pulse power in the optical fiber, the problem of laser irradiation causing melting of the conductive metal can be avoided, ensuring that the auxiliary layer has the functions of support and conductivity. Optionally, the laser wavelength is 200 nm to 2000 nm, and the pulse power is 1 nW to 1 W. Optionally, the conductive metal includes one or more of gold, silver, and copper.

[0063] In some embodiments, the electron excitation layer is located on one side in the length direction of the optical fiber. Thus, the laser emitted from the optical fiber can reach the electron excitation layer, thereby further improving the electron emission efficiency in the electron source and the stability of the electron source.

[0064] In some embodiments, the optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a perforated optical fiber. Optionally, the optical fiber is a solid-core optical fiber. Further optionally, the solid-core optical fiber includes a single-mode optical fiber, a multi-mode optical fiber, a polarization-maintaining optical fiber, or a multi-core optical fiber.

[0065] In some embodiments, the optical fiber is a solid-core optical fiber. In this embodiment, the one-dimensional material can be directly placed on the end face of the optical fiber, and the optical field and the one-dimensional material directly interact with each other with a high interaction intensity to achieve high-brightness electron emission. In addition, different diameters of micro-nano optical fibers can be drawn, enabling the interaction of light with different modes and intensities with the one-dimensional material to achieve precisely controlled electron emission parameters.

[0066] In some embodiments, the optical fiber is a tip optical fiber. In this embodiment, the electron emission layer is disposed on the tip optical fiber, and the tip geometric structure of the tip optical fiber can increase the field emission enhancement factor, thereby obtaining a higher-brightness electron source.

[0067] In some embodiments, the optical fiber is a side-cut optical fiber. In this embodiment, the electron emission layer is disposed on the side-cut surface of the side-cut optical fiber, and the evanescent wave leaking from the core interacts with the one-dimensional material in the electron excitation layer in the horizontal direction. In this embodiment, the one-dimensional material in the electron excitation layer obtains the edge state of the zero-dimensional material at the side-cut, forming a new electron emission structure, which can endow the electron source with functions such as high brightness, low energy dispersion, and narrow pulse width.

[0068] In some embodiments, the optical fiber is a porous optical fiber. The porous optical fiber in this embodiment is a type of optical fiber with microstructures or completely hollow, including photonic crystal fibers, anti-resonant fibers, or capillary fibers, etc. The one-dimensional material in the electron excitation layer can be disposed in the pores or pore walls of the porous optical fiber, enabling the laser to have a longer interaction distance with the one-dimensional material, thereby achieving large-beam-current and high-brightness electron emission.

[0069] It should be noted that this application does not make specific requirements and special limitations on the size of the optical fiber, and those skilled in the art can reasonably select the size of the optical fiber according to actual usage requirements.

[0070] In some embodiments, the electron excitation layer is formed by at least one of dry transfer, wet transfer, and direct growth.

[0071] In some embodiments, the electron excitation layer is prepared by dry transfer. The preparation method includes: transferring the one-dimensional material to the tape by mechanical peeling, and transferring the one-dimensional material to the laser output side of the optical fiber through the tape.

[0072] In some embodiments, the electron excitation layer is prepared by wet transfer. The preparation method includes: directly preparing the one-dimensional material in a solution and floating it on the liquid surface, and contacting the material on the liquid surface with the optical fiber and drying.

[0073] In some embodiments, the electron excitation layer is prepared by direct growth, and the preparation method includes: directly preparing the electron excitation layer on the laser emitting side of the optical fiber by at least one of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy, and liquid filling.

[0074] Another embodiment of the present application provides an electron gun, which includes a housing, a grid, an anode, and the above-mentioned electron source of the present application. The electron source is fixed in the housing, and a grid and an anode are sequentially arranged on the electron emitting side of the electron source. The grid in the above-mentioned electron gun is used to limit the shape of the electron beam, and the anode is used to accelerate the electrons. When electrons are excited and emitted from the electron source, they will interact with the electrostatic field established by the grid and the space charge of the electrons themselves, forming an electron beam with a certain shape and emitting from the anode for use.

[0075] Another embodiment of the present application provides an application of the above-mentioned electron source of the present application. The application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, a free electron laser, and a display.

[0076] In order to further illustrate the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments. For those not specified in the embodiments, the techniques or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0077] In the following embodiments, the conductive connection layer is in contact connection with the auxiliary layer or the electron excitation layer.

[0078] Example 1

[0079] Refer to Figure 1 - Figure 2 , the preparation method of the electron source includes the following steps:

[0080] (1) Remove the coating layer at the end of the single-mode solid optical fiber 110a and cut the cross-section of the optical fiber 110a to make it flat. Use a polymer ball to block one end of the fiber core 1101a, and the diameter of the polymer ball is between the diameter of the fiber core 1101a and the diameter of the cladding 1102a.

[0081] (2) Use the evaporation method to deposit titanium and gold on the optical fiber 110a in sequence, ensuring that titanium and gold are firmly deposited on the end face and the uncoated position at the end of the optical fiber 110a to form a conductive connection layer 130a with a thickness of 54 nm, where the thickness of the titanium layer is 4 nm and the thickness of the gold layer is 50 nm. Soak the end of the fiber core 1101a blocked by the polymer ball in acetone to dissolve the polymer ball and peel off the coating on the polymer ball, exposing the fiber core 1101a at the end face position of the optical fiber 110a.

[0082] (3) Use chemical vapor deposition to grow carbon nanotubes on the end face of the optical fiber 110a with the conductive connection layer 130a to form the electron excitation layer 121a made of carbon nanotubes. The carbon nanotubes are electrically connected to the conductive connection layer 130a. The diameter of the carbon nanotubes is 1 nm, the length of the carbon nanotubes is 0.1 μm, and the axial directions of the carbon nanotubes are all parallel to the axial direction of the optical fiber 110a, obtaining an electron source. Among them, the diameter of the core 1101a of the optical fiber 110a is 8.2 μm, and the diameter of the optical fiber 110a is 125 μm.

[0083] Example 2

[0084] Reference Figure 3 - Figure 4 , The preparation method of the electron source includes the following steps:

[0085] (1) Remove the coating layer at the end of the single-mode solid optical fiber 110b and cut the end face of the optical fiber 110b to make it flat. Use polymer beads to block one end of the core 1101b. The diameter of the polymer beads is between the diameter of the core 1101b and the diameter of the cladding 1102b.

[0086] (2) Use evaporation coating to deposit titanium and gold on the optical fiber 110b in sequence, ensuring that titanium and gold are firmly deposited on the end face and the uncoated position at the end of the optical fiber 110b in sequence to form a 54-nm-thick conductive connection layer 130b. Among them, the thickness of the titanium layer is 4 nm, and the thickness of the gold layer is 50 nm. Soak the end of the blocked core 1101b with acetone to dissolve the polymer beads and peel off the coating on the polymer beads, exposing the core 1101b at the end face position of the optical fiber 110b.

[0087] (3) Deposit and grow the auxiliary layer 122b made of gold on the end face of the optical fiber 110b with the conductive connection layer 130b. The thickness of the auxiliary layer 122b is 10 nm, and the auxiliary layer 122b is electrically connected to the conductive connection layer 130b. Then use chemical vapor deposition to grow carbon nanotubes on the surface of the auxiliary layer 122b to form the electron excitation layer 121b made of carbon nanotubes. The carbon nanotubes are electrically connected to the conductive connection layer 130b. The diameter of the carbon nanotubes is 1 nm, the length of the carbon nanotubes is 0.1 μm, and the axial directions of the carbon nanotubes are all parallel to the axial direction of the optical fiber 110b, obtaining an electron source. Among them, the diameter of the core 1101b of the optical fiber 110b is 8.2 μm, and the diameter of the optical fiber 110b is 125 μm. The electron excitation layer 121b and the auxiliary layer 122b constitute the electron emission layer 120b.

[0088] The preparation method of the electron source in this example is basically the same as that in Example 1, the difference being: step (3) is different.

[0089] Example 3

[0090] The preparation method of the electron source is basically the same as that of Example 2, except that: in step (3), the diameter of the carbon nanotubes is 10 nm.

[0091] Example 4

[0092] The preparation method of the electron source is basically the same as that of Example 2, except that: in step (3), the diameter of the carbon nanotubes is 20 nm.

[0093] Example 5

[0094] The preparation method of the electron source is basically the same as that of Example 2, except that: in step (3), the length of the carbon nanotubes is 1 μm.

[0095] Example 6

[0096] The preparation method of the electron source is basically the same as that of Example 2, except that: in step (3), the diameter of the carbon nanotubes is 0.5 nm.

[0097] Example 7

[0098] The preparation method of the electron source is basically the same as that of Example 2, except that: in step (3), the diameter of the carbon nanotubes is 21 nm.

[0099] Example 8

[0100] The preparation method of the electron source is basically the same as that of Example 1, except that: the carbon nanotubes in Example 1 are replaced by gold nanowires.

[0101] Comparative Example 1

[0102] An electron source is prepared according to the structure of Example 1, except that: the electron excitation layer in Example 1 is replaced by a gold layer with a thickness of 100 nm, and the gold layer is obtained by deposition.

[0103] As Figure 5 shown, the electron sources 100 prepared by the above examples and comparative examples are assembled into an electron gun, and the electron gun further includes a housing, a grid 200 and an anode 300, and the performance of the prepared electron gun is tested.

[0104] Performance test of the electron gun

[0105] (1) Stability

[0106] When the excitation power is 50% of the damage power, the vacuum degree is 2×10 -5 Pa, and the continuous emission current is 1 h. After removing the bad points, the difference between the maximum current and the minimum current and the average current are calculated, that is, the stability parameter = (maximum current - minimum current) / average current. The smaller the value of the stability parameter, the better the stability of the electron source of the electron gun.

[0107] (2) Lifetime

[0108] When the excitation power is 50% of the damage power, the vacuum degree is 2×10 -5 Pa. The time when the continuous emission current is emitted until the current decays to less than 10% of the initial value is defined as the lifetime.

[0109] (3) Operating vacuum degree

[0110] When the excitation power is 50% of the damage power, with a continuous emission current, gradually increase the operating vacuum degree of the electron gun until a rapid decay of the current occurs (the rapid decay is defined as the current decaying by more than 50% within 1 minute). The vacuum degree at this time is defined as the operating vacuum degree. The higher the operating vacuum degree, the higher the electron emission efficiency in the electron source of the electron gun.

[0111] Among them, the damage power refers to the laser power when the material is damaged under the irradiation of a 100 - fs pulsed laser. For example, the damage power of graphene is 0.25 J / cm 2 , and the damage threshold of gold is 0.1 J / cm 2 .

[0112] The test results are shown in Table 1.

[0113] Table 1

[0114]

[0115] It can be seen from Table 1 that compared with the electron gun of Comparative Example 1, the electron guns of Examples 1 - 8 have a higher operating vacuum degree, better stability, and longer lifetime, indicating that Examples 1 - 8 provided in this application effectively improve the electron emission efficiency and the stability of the electron source.

[0116] The technical features of the above - described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above - described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0117] The above - described embodiments only express several implementation manners of this application. Their descriptions are relatively specific and detailed, but they should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application patent should be subject to the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. An electron source, characterized in that, The electron source includes an optical fiber, a conductive connection layer, and an electron emission layer. The conductive connection layer is disposed on the outer surface of the optical fiber; The electron emission layer at least includes an electron excitation layer electrically connected to the conductive connection layer. The electron emission layer is disposed on the laser emission path of the optical fiber, and the laser emitted from the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons; The electron excitation layer contains one-dimensional materials, and the axial directions of the one-dimensional materials in the electron excitation layer are all the same as the emission direction of the laser.

2. The electron source according to claim 1, characterized in that, The diameter of the one-dimensional material is 1 nm to 20 nm, and the length of the one-dimensional material is 0.1 μm to 1 μm.

3. The electron source according to claim 1, wherein The one-dimensional material includes one or more of nanotubes, nanowires, and nanobelts; Optionally, the nanotubes include one or more of carbon nanotubes and molybdenum disulfide nanotubes; Optionally, the nanowires include one or more of gold nanowires, semiconductor nanowires, and tellurium quantum wires; Optionally, the nanobelts include one or more of carbon nanobelts and molybdenum disulfide nanobelts.

4. The electron source according to claim 1, characterized in that, The laser wavelength in the optical fiber is 200 nm to 2000 nm, and the pulse power is 1 nW to 1 W.

5. The electron source according to any one of claims 1 to 4, characterized in that, The electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on the side of the electron excitation layer close to the optical fiber; or, The auxiliary layer is stacked on the side of the electron excitation layer away from the optical fiber.

6. The electron source according to claim 5, wherein The thickness of the auxiliary layer is 0.1 nm to 100 nm, and the light transmittance of the auxiliary layer ≥ 10%.

7. The electron source according to claim 5, characterized in that, The auxiliary layer has conductivity, and the auxiliary layer is electrically connected to the conductive connection layer.

8. The electron source according to claim 5, characterized in that, The material of the auxiliary layer includes one or more of graphene and conductive metals.

9. The electron source according to any one of claims 1 to 4, characterized in that, The optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a perforated optical fiber.

10. An electron gun, characterized in that, The electron gun includes a housing, a grid, an anode, and the electron source according to any one of claims 1 to 9. The electron source is fixed in the housing, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

11. Use of the electron source according to any one of claims 1 to 9, characterized in that, The applications of the electron source include at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, a free electron laser, and a display.

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