Electron source and preparation method and application thereof

Abstract

The invention provides an electron source and a preparation method and application thereof. The electron source comprises an optical fiber, a conductive connection layer and an electron emission layer. The electron emission layer comprises an electron excitation layer electrically connected with the conductive connection layer, the electron excitation layer comprises a three-dimensional nanometer material, the electron excitation 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 three-dimensional nano material is used as the material of the electron emission layer, and has the characteristics of good stability, long service life and the like; the optical fiber can provide a stable excitation source with adjustable wavelength, polarization and optical mode, and can be suitable for different application scenes.

Description

Technical Field

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

[0002] An electron source is a device for generating vacuum electrons. Traditional electron sources are mainly classified into thermionic electron sources, field emission electron sources, and photoemission electron sources according to the excitation method. Thermionic electron sources mainly select metal materials. When heated to thousands of degrees Celsius, electrons are thermally excited to escape from the material surface to form vacuum electrons. Field emission electron sources mainly select metal tips. Under the action of a strong electric field applied externally, a tip discharge effect is generated. A photoemission electron source uses a metal material as a photocathode, and uses laser irradiation to excite the photocathode material to generate electrons.

[0003] However, the electron sources in the traditional technology cannot balance the emission efficiency and stability. How to provide an electron source with high electron emission efficiency and good stability has become an urgent technical problem to be solved at present. Summary of the Invention

[0004] Based on this, it is necessary to provide an electron source with high electron emission efficiency and good stability, a preparation method thereof, and an application thereof.

[0005] In a first aspect, 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;

[0006] The electron emission layer includes an electron excitation layer electrically connected to the conductive connection layer. The electron excitation layer includes a three-dimensional nanomaterial;

[0007] The electron excitation 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.

[0008] In some embodiments, the structure of the three-dimensional nanomaterial includes at least one of a conical three-dimensional nanomaterial, a star-shaped three-dimensional nanomaterial, and a rod-shaped three-dimensional nanomaterial. Optionally, the circumscribed sphere diameter of the three-dimensional nanomaterial is 1 nm to 10 μm.

[0009] In some embodiments, the structure of the three-dimensional nanomaterial includes a layered three-dimensional nanomaterial. Optionally, the thickness of the layered three-dimensional nanomaterial is 1 nm to 100 nm.

[0010] In some embodiments, the three-dimensional nanomaterial includes at least one of lanthanum hexaboride, diamond, and gallium arsenide.

[0011] In some embodiments, the electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on a side of the electron excitation layer close to the optical fiber; or,

[0012] the auxiliary layer is stacked on a side of the electron excitation layer away from the optical fiber.

[0013] In some embodiments, the auxiliary layer includes a transparent support layer, and the material of the transparent support layer includes at least one of polycarbonate propylene, boron nitride, mica, and diamond.

[0014] In some embodiments, the thickness of the transparent support layer is 0.1 nm to 100 nm, and the light transmittance is ≥10%.

[0015] In some embodiments, the auxiliary layer includes a conductive support layer, and the electron emission layer is electrically connected to the conductive connection layer through the conductive support layer.

[0016] In some embodiments, the material of the conductive support layer includes at least one of conductive metal and graphene.

[0017] In some embodiments, the thickness of the conductive support layer is 0.1 nm to 100 nm.

[0018] 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.

[0019] In a second aspect, the present application provides a method for preparing an electron source as described in the first aspect, and the preparation method includes:

[0020] An electron excitation layer composed of three-dimensional nanomaterials is formed on the laser emission path of the optical fiber, and a conductive connection layer electrically connected to the electron emission layer is formed on the outer surface of the optical fiber to prepare the electron source.

[0021] In a third aspect, the present application provides an electron gun, and the electron gun includes a housing, a grid, an anode, and an electron source as described in the first aspect;

[0022] 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.

[0023] In a fourth aspect, the present application provides an application of the electron source as described in the first aspect, and 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.

[0024] Compared with the traditional technology, the present application has at least the following beneficial effects:

[0025] This application uses three-dimensional nanomaterials as the material of the electron emission layer. The three-dimensional nanomaterials have small sizes and nanoscale tips, and can obtain strong optical field enhancement and electron emission under the condition of back incident laser. Moreover, the three-dimensional nanomaterials are integrated with optical fibers, and the optical fibers can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, which can be applied to different application scenarios without providing a complex optical path. The electron source of this application has the characteristics of stable emission, high service life, small volume, and high integration. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the electron source provided in Embodiment 1 of this application. Among them, 110a - solid-core optical fiber; 120a - electron excitation layer; 130a - conductive connection layer.

[0027] Figure 2 It is a schematic structural diagram of the electron source provided in Embodiment 2 of this application. Among them, 110b - solid-core optical fiber; 120b - electron excitation layer; 130b - conductive connection layer; 140b - conductive support layer.

[0028] Figure 3 It is a schematic structural diagram of the electron source provided in Embodiment 3 of this application. Among them, 110c - tip optical fiber; 120c - electron excitation layer; 130c - conductive connection layer.

[0029] Figure 4 It is a schematic structural diagram of the electron source provided in Embodiment 4 of this application. Among them, 110d - side-section optical fiber; 120d - electron excitation layer; 130d - conductive connection layer; 140d - conductive support layer.

[0030] Figure 5 It is a schematic internal structural diagram of the electron gun provided in an embodiment of this application. Among them, 100 - electron source; 200 - grid; 300 - anode. Detailed Embodiments

[0031] The following combines the embodiments and examples to further elaborate on this application in detail. These embodiments and examples are only used to illustrate this application and not to limit the scope of this application. The purpose of providing these embodiments and examples is to make the understanding of the disclosed content of this application more thorough and comprehensive. It should also be understood that this application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of this application, and the equivalent forms obtained also fall within the protection scope of this application. In addition, in the following description, a large number of specific details are given to provide a more comprehensive understanding of this application. It should be understood that this application can be implemented without one or more of these details.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0033] In this application, "optionally", "optional", and "option" mean either having or not having, that is, any one of the two alternative options of "having" or "not having". If the term "optional" appears multiple times in a technical solution, without special instructions and without contradictions or mutual restrictions, each "optional" is independent of each other.

[0034] In this application, in "the first aspect", "the second aspect", etc., the terms "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumerative description and should be understood not to constitute a closed limitation on quantity.

[0035] In this application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, as well as an open-ended technical solution containing the listed features.

[0036] In this application, regarding numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of the optional numerical values within the numerical interval is considered continuous and includes the two numerical endpoints of the numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" allows for a broad inclusion of quantitative intervals such as percentage intervals, ratio intervals, and ratio value intervals.

[0037] All documents mentioned in this application are incorporated herein by reference as if each document was individually incorporated by reference. Unless it conflicts with the inventive purpose and / or technical solution of this application, the cited documents involved in this application are cited in their entirety and for all purposes. When this application involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also incorporated by reference. When this application involves cited documents, the examples and preferred methods of the relevant technical features cited can also be incorporated into this application as references, but only to the extent that this application can be implemented. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or be amended adaptively according to the description of this application.

[0038] In the prior art, 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 material surface to form vacuum electrons. Field emission electron sources mainly select metal tips such as tungsten. Under the action of a strong electric field applied externally, a tip discharge effect is generated. Among them, the electron beam emitted by the thermionic electron source can work in a relatively poor vacuum environment, has good adaptability to the environment and good stability, but has a low brightness and poor coherence. The electron beam of the field emission electron source has a high brightness and good coherence, but has high requirements for the vacuum degree and is very sensitive to vibrations, etc. Whether it is a thermionic electron source or a field emission electron source, the regulation of electron emission properties is limited, and it is impossible to balance the emission efficiency and stability.

[0039] Optical emission electron sources use metal materials such as Au as the material of the electron emission layer, with a thickness of more than 50 nm, even reaching hundreds of nanometers. However, the inventors of this application have found that the electron emission layer of the metal material has a relatively large thickness, and the distance between the surface directly irradiated by the laser (the bottom layer of the electron emission layer) and the surface from which electrons are emitted (the surface layer of the electron emission layer) in the electron emission layer is relatively far (50 nm to hundreds of nanometers). During the process of electrons excited from the bottom layer passing through the electron emission layer, they are easily affected by metal lattice scattering, thereby affecting the emission efficiency. Moreover, the metal material is easily damaged under high-power laser irradiation, affecting the service life of the electron emission layer, and thus affecting the electron emission efficiency and stability. Some use the method of laser side incidence to excite electrons. Compared with laser back incidence, side incidence requires modification of the vacuum chamber, and the irradiation method has a high operation difficulty and problems such as unstable excitation conditions.

[0040] In addition, in traditional technologies, graphene is used as a saturable absorber. Graphene has broadband saturable absorption characteristics and a fast recovery time, and is used in Q-switching and mode-locking of lasers, or to adjust the laser spectrum using graphene for sensing detection. However, there are differences between graphene laser regulation and graphene electron emission. The graphene photoexcited electron source is based on the photoelectric effect, exciting and emitting electrons, while graphene laser regulation is based on the principle of light absorption to regulate the output parameters of the laser. Specifically, there are obvious differences between graphene laser regulation and graphene electron emission. Graphene electron emission is based on the photoelectric effect, while graphene laser regulation is based on the principle of light absorption. In laser regulation, the graphene saturable absorber mainly utilizes the situation where the light absorption rate (or transmittance) of graphene increases (or decreases) as the incident light power increases, and finally reaches the saturation threshold. Its main application is in lasers to generate laser pulses. For example, in the ring fiber resonator of a fiber laser, when the light power passing through the graphene saturable absorber exceeds its saturation absorption threshold during the circulation of light in the resonator, due to the saturable absorption effect, the light intensity in the cavity will instantaneously drop below the saturation absorption threshold, and this part of the dropped light energy is output in the form of pulses from the optical splitter of the cavity.

[0041] Based on this, it is necessary to provide an electron source that can balance the electron emission efficiency and stability.

[0042] In this application, a three-dimensional nanomaterial is used as the material of the electron excitation layer. The three-dimensional nanomaterial emits electrons through the photoelectric effect, multiphoton emission, and optical field emission under laser irradiation. Moreover, the three-dimensional nanomaterial has a nanoscale thickness or very sharp tips or edges, and has characteristics such as good stability, high service life, and strong interaction with light. In addition, in this application, the three-dimensional nanomaterial is directly integrated with the optical fiber, and the optical fiber can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, and can be applied to different application scenarios.

[0043] In the first aspect of this 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;

[0044] The electron emission layer includes an electron excitation layer electrically connected to the conductive connection layer, and the electron excitation layer includes a three-dimensional nanomaterial;

[0045] The electron excitation layer is disposed on the laser output path of the optical fiber, and the laser output 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.

[0046] This application uses three-dimensional nanomaterials as the materials for the electron excitation layer. The three-dimensional nanomaterials have small sizes and nanoscale tips, and can obtain strong light field enhancement and electron emission under the condition of back incident laser. Moreover, the three-dimensional nanomaterials are integrated with optical fibers, and the optical fibers can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, which can be applied to different application scenarios without the need to provide a complex optical path. The electron source of this application has the characteristics of stable emission, high service life, small size, and high integration.

[0047] It should be noted that in this application, the three-dimensional nanomaterials refer to materials whose sizes in at least one dimension are restricted to the nanoscale. The nanoscale refers to 1 nm to 100 nm, which can refer to the thickness of the material or the scale of a tip or edge of the three-dimensional material. The three-dimensional nanomaterials can emit electrons under the action of laser excitation.

[0048] It should be noted that in this application, the light output path of the optical fiber refers to the path of laser irradiation in the optical fiber. Taking a solid-core optical fiber as an example, the laser output position of the solid-core optical fiber is located at the end face of the fiber core, that is, the electron emission layer can be arranged at the fiber core; taking a side-cut optical fiber as an example, the laser output position of the side-cut optical fiber is located on the side-cut side of the side-cut optical fiber, that is, the electron emission layer can be arranged at the side-cut. It can be understood that in this application, the electron emission 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, the laser output from the optical fiber can irradiate on the electron emission layer.

[0049] It can be understood that in this application, the electron excitation layer can be formed by a single three-dimensional nanomaterial or a combination of multiple three-dimensional nanomaterials.

[0050] It should also be noted that the purpose of the electrical connection between the conductive connection layer and the electron emission layer in this application is to connect the low-dimensional material with the external circuit to form a complete circuit, realize the replenishment of charges and the control of the electric field, and can regulate the direction and convergence of electron emission through voltage. As an implementation manner, the conductive connection layer in this application can be directly connected to the electron emission layer. In other implementation manners, the conductive connection layer and the electron emission layer can also be electrically connected through other conductive structures. For example, taking a solid-core optical fiber as an example, the conductive connection layer is arranged on the side of the solid-core optical fiber, the electron emission layer is arranged at the fiber core of the solid-core optical fiber, and the conductive connection layer and the electron emission layer are electrically connected, and there is no conductive connection layer at the fiber core.

[0051] In some embodiments, the three-dimensional nanomaterials include doping elements. Optionally, the doping elements include at least one of alkali metals, alkaline earth metals, transition metals, rare earth elements, halogen elements, and light elements, where the light elements include at least one of B, C, N, and O.

[0052] This application improves the conductivity and electron emission performance of three-dimensional nanomaterials by doping elements into the three-dimensional nanomaterials. For example, alkali metals and alkaline earth metal elements can improve the conductivity of low-dimensional materials, and at the same time can reduce the work function of low-dimensional materials to enhance the emission beam current; elements such as B, C, N, O, F, and rare earths can create discrete energy levels to obtain an electron beam with a narrow energy range.

[0053] In some embodiments, the conductive connection layer is provided with an electrode for connecting to an external circuit. Optionally, the conductive connection layer can completely 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 on the light output path of the laser.

[0054] Further optionally, the thickness of the conductive connection layer is 10 nm to 1 μm, for example, it can be 10 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1 μm.

[0055] In some embodiments, the structure of the three-dimensional nanomaterial includes at least one of a conical three-dimensional nanomaterial, a star-shaped three-dimensional nanomaterial, and a rod-shaped three-dimensional nanomaterial. Optionally, the circumscribed sphere diameter of the three-dimensional nanomaterial is 1 nm to 10 μm, for example, it can be 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 1 μm, or 10 μm.

[0056] In some embodiments, the three-dimensional nanomaterial is a triangular pyramid, and the side length of the bottom surface of the triangular pyramid is 1 nm to 10 μm, and the height is 1 nm to 10 μm.

[0057] It can be understood that the structure of the three-dimensional nanomaterial in this application can be a polyhedron or an irregular structure. The irregular structure can be an integral structure or assembled from several three-dimensional nanostructures. That is, there are many optional materials and morphologies for the three-dimensional nanomaterial, which can obtain a large field enhancement factor, have low requirements for the excitation light power, and low requirements for the electric field.

[0058] In some embodiments, the structure of the three-dimensional nanomaterial includes a layered three-dimensional nanomaterial. Optionally, the thickness of the layered three-dimensional nanomaterial is 1 nm to 100 nm, for example, it can be 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.

[0059] In some embodiments, the three-dimensional nanomaterial includes at least one of lanthanum hexaboride, diamond, and gallium arsenide.

[0060] In some embodiments, the electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on a side of the electron excitation layer close to the optical fiber; or,

[0061] the auxiliary layer is stacked on a side of the electron excitation layer away from the optical fiber.

[0062] In some embodiments, the auxiliary layer is disposed on a side of the electron excitation layer away from the optical fiber, and the thickness of the auxiliary layer is 0.1 nm to 10 nm. For example, it may be 0.1 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm. In this application, the thickness of the auxiliary layer on the side of the electron excitation layer away from the optical fiber is controlled to avoid the auxiliary layer affecting the electron emission effect.

[0063] In some embodiments, the side of the electron excitation layer away from the optical fiber is the electron emission side.

[0064] In some embodiments, the auxiliary layer includes a transparent support layer, and the material of the transparent support layer includes at least one of polycarbonate propylene, boron nitride, mica, and diamond.

[0065] In some embodiments, the thickness of the transparent support layer is 0.1 nm to 100 nm. For example, it may be 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.

[0066] The light transmittance of the transparent support layer is ≥ 10%. For example, it may be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%.

[0067] In some embodiments, the auxiliary layer includes a conductive support layer, and the electron excitation layer is electrically connected to the conductive connection layer through the conductive support layer. Optionally, the conductive metal includes at least one of gold, silver, and copper.

[0068] In some embodiments, the conductive support layer is on the laser emission path of the optical fiber, and the wavelength of the laser is 200 nm to 2000 nm, and the pulse power is 1 nW to 1 W.

[0069] In this application, the auxiliary layer uses a conductive metal and controls the laser parameters, thereby avoiding the problem of melting caused by laser irradiation of the conductive metal and ensuring that the auxiliary layer has the functions of support and conductivity.

[0070] In some embodiments, the auxiliary layer is graphene. In this application, graphene is used as the auxiliary layer. Graphene not only has conductivity but also has good heat dissipation ability.

[0071] In some embodiments, the material of the conductive support layer includes at least one of a conductive metal and graphene.

[0072] In some embodiments, the thickness of the conductive support layer is 0.1 nm to 100 nm, and for example, it can be 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.

[0073] In some embodiments, the optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a porous optical fiber.

[0074] In some embodiments, the optical fiber is a tip optical fiber. In this application, the three-dimensional nanomaterial is disposed on the tip optical fiber. Due to the tip geometric structure of the tip optical fiber, the field emission enhancement factor is increased, and a higher-brightness electron source can be obtained. Further, at least one of a zero-dimensional material and a one-dimensional material is disposed on the three-dimensional nanomaterial, thereby realizing functions such as high brightness, low energy dispersion, and narrow pulse width.

[0075] In some embodiments, the optical fiber is a side-cut optical fiber. In this application, the three-dimensional nanomaterial is disposed on the side-cut surface of the side-cut optical fiber, and the evanescent wave leaking from the core interacts with the three-dimensional nanomaterial in the horizontal direction. An edge-state electron emission structure is obtained at the side-cut.

[0076] In some embodiments, the optical fiber is a porous optical fiber. The porous optical fiber in this application is a type of optical fiber with a microstructure or completely hollow, including photonic crystal fiber, anti-resonant fiber, or capillary fiber, etc. The three-dimensional nanomaterial can be disposed in the pores or on the pore walls of the porous optical fiber, such that the laser has a longer interaction distance with the low-dimensional material, thereby realizing high-brightness electron emission. Since the porous optical fiber itself has a special optical transmission mode, and different types or dimensions of materials can continue to be grown or transferred in the pores or on the pore walls where the three-dimensional nanomaterial has already grown or been filled to form a heterojunction, multi-functional electron emission can be realized.

[0077] In some embodiments, the optical fiber is a solid-core optical fiber. In this application, the three-dimensional nanomaterial is disposed at the core of the solid-core optical fiber, and the evanescent wave leaking from the core can interact with the three-dimensional nanomaterial surrounding the optical fiber. A longer interaction distance between light and the material can be realized in this system to achieve high-brightness electron emission. In addition, different diameters of micro-nano optical fibers can be drawn, and light with different modes and intensities can interact with the three-dimensional nanomaterial to achieve precisely regulated electron emission parameters. In addition, different types or dimensions of materials can continue to be grown or transferred on the three-dimensional nanomaterial that has been grown or transferred to form a heterojunction to achieve multi-functional electron emission.

[0078] It should be noted that this application does not make specific requirements or 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.

[0079] The second aspect of this application provides a method for preparing an electron source as described in the first aspect, and the preparation method includes:

[0080] An electron excitation layer composed of three-dimensional nanomaterials is formed on the laser emission path of the optical fiber, and a conductive connection layer electrically connected to the electron emission layer is formed on the outer surface of the optical fiber, and the electron source is prepared.

[0081] It should be noted that this application does not make specific requirements or special limitations on the formation method of the three-dimensional nanomaterials, and those skilled in the art can make reasonable selections according to the actual materials. For example, the three-dimensional nanomaterials can be formed by direct preparation or transfer methods. For example, it can be prepared by a liquid phase method or a magnetron sputtering method.

[0082] The third aspect of this application provides an electron gun, and the electron gun includes a housing, a grid, an anode, and an electron source as described in the first aspect;

[0083] 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.

[0084] It should be noted that in this application, the grid 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 being emitted from the anode for use.

[0085] In the fourth aspect, this application provides an application of the electron source as described in the first aspect, and is characterized in that 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.

[0086] Next, the implementation solutions of this application will be described in detail in conjunction with the embodiments. It should be understood that these embodiments are only used to illustrate this application and not to limit the scope of this application. For the experimental methods without specific conditions in the following embodiments, first refer to the guidance given in this application, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or refer to the experimental methods known in the art.

[0087] Among them, the conductive connection layer includes a titanium layer with a thickness of 5 nm and a gold layer with a thickness of 60 nm that are sequentially stacked from far away from the surface of the optical fiber.

[0088] Example 1

[0089] This example provides an electron source, such asFigure 1 As shown, it includes a solid-core optical fiber 110a, an electron excitation layer 120a, and a conductive connection layer 130a. The conductive connection layer 130a coats the side wall of the solid-core optical fiber 110a and forms an annular layer on one side of the laser output end face of the solid-core optical fiber 110a. The annular layer does not cover the core of the solid-core optical fiber 110a. On one side of the laser output end face of the solid-core optical fiber 110a, a lanthanum hexaboride nanosheet with a thickness of 50 nm is provided as the electron excitation layer 120a. The electron excitation layer 120a covers the core of the solid-core optical fiber 110a and is arranged on the annular layer and electrically connected to the conductive connection layer 130a.

[0090] This embodiment also provides a preparation method of the above electron source, including:

[0091] A lanthanum hexaboride nanosheet with a thickness of 50 nm is formed on a silicon wafer by magnetron sputtering. Then, a polycarbonate acrylate film is coated on the lanthanum hexaboride nanosheet, and after peeling, a polycarbonate acrylate film with a lanthanum hexaboride nanosheet is obtained.

[0092] A conductive connection layer 130a is evaporated on the solid-core optical fiber 110a to form an annular layer on the laser output side of the solid-core optical fiber 110a. Then, the polycarbonate acrylate film with a lanthanum hexaboride nanosheet is transferred to the laser output side of the solid-core optical fiber 110a, so that the polycarbonate acrylate film with a lanthanum hexaboride nanosheet is attached to the annular layer and covers the core of the solid-core optical fiber 110a. After heating and melting the polycarbonate acrylate, the residual polycarbonate acrylate film is removed by soaking in acetone to form an electron excitation layer 120a composed of lanthanum hexaboride nanosheets, and the electron source is prepared.

[0093] Example 2

[0094] This embodiment provides an electron source, as Figure 2 shown, including a solid-core optical fiber 110b, an electron excitation layer 120b, a conductive connection layer 130b, and a conductive support layer 140b. The conductive connection layer 130b coats the side wall of the solid-core optical fiber 110b and forms an annular layer on one side of the laser output end face of the solid-core optical fiber 110b. The annular layer does not cover the core of the solid-core optical fiber 110b. The conductive support layer 140b is arranged on the laser output side of the solid-core optical fiber 110b. The conductive support layer 140b is electrically connected to the conductive connection layer 130b. The material of the conductive support layer 140b is graphene with a thickness of 2 nm. The electron excitation layer 120b is arranged on the side of the conductive support layer 140b away from the solid-core optical fiber 110b. The electron excitation layer 120b is composed of a lanthanum hexaboride nanocone. The size of the lanthanum hexaboride nanocone is that the bottom side length is 100 nm and the height is 100 nm.

[0095] Example 3

[0096] This embodiment provides an electron source, asFigure 3 As shown, it includes a tip optical fiber 110c, an electron excitation layer 120c, and a conductive connection layer 130c. The electron excitation layer 120c is composed of a lanthanum hexaboride nanocone. The size of the lanthanum hexaboride nanocone is 10 μm in height. The lanthanum hexaboride nanocone is arranged at the tip of the tip optical fiber. The conductive connection layer 130c coats the side wall of the tip optical fiber 110c and is electrically connected to the lanthanum hexaboride nanocone.

[0097] Example 4

[0098] This example provides an electron source, such as Figure 4 As shown, it includes a side-sectioned optical fiber 110d, an electron excitation layer 120d, a conductive connection layer 130d, and a conductive support layer 140d. Among them, the electron excitation layer 120d is composed of four lanthanum hexaboride nanocones arranged on the conductive support layer 140d. The bottom side length of the lanthanum hexaboride nanocone is 10 μm, and the height is 10 μm. The conductive support layer 140d is arranged on the side section of the side-sectioned optical fiber 110d. The conductive support layer is graphene with a thickness of 2 nm. The conductive connection layer 130d coats the outer surface of the side-sectioned optical fiber 110d and is electrically connected to the conductive support layer 140d (the connection is not shown in the sectional view in the figure).

[0099] Comparative Example 1

[0100] An electron source is prepared according to the structure of Example 1, and the only difference is that the electron excitation layer in Example 1 is replaced with a gold layer with a thickness of 100 nm, and the gold layer is prepared by deposition.

[0101] Comparative Example 2

[0102] An electron source is prepared according to the structure of Comparative Example 1, and the only difference is that the electron excitation layer in Comparative Example 1 is replaced with a gold layer with a thickness of 1 nm.

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

[0104] Stability test: 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, calculate the difference between the maximum current and the minimum current and the average current, that is, the stability parameter = (maximum current - minimum current) / average current.

[0105] Lifetime test: When the excitation power is 50% of the damage power, the vacuum degree is 2×10 -5Pa, the continuous emission current, and the time until the current decays to less than 10% of the initial value is defined as the lifetime.

[0106] Working vacuum degree test: When the excitation power is 50% of the damage power, continuously emit current, and gradually increase the working environment vacuum degree of the electron gun until the current shows a rapid decay (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 working vacuum degree.

[0107] 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 .

[0108] The test results are shown in Table 1.

[0109] Table 1

[0110]

[0111] It can be seen from the above table that:

[0112] This application uses three-dimensional nanomaterials as the material of the electron excitation layer. The three-dimensional nanomaterials have a small size and nanoscale tips, and can obtain strong optical field enhancement and electron emission under the condition of back-incident laser. And the three-dimensional nanomaterials are integrated with optical fibers. The optical fibers can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, can be applied to different application scenarios, and do not require a complex optical path. The electron source of this application has the characteristics of stable emission, high service life, small volume, and high integration.

[0113] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of 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 described in this specification.

[0114] The above-described embodiments only represent several implementation manners of this application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. 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 the patent of this application should be subject to the appended 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 includes an electron excitation layer electrically connected to the conductive connection layer. The electron excitation layer includes three-dimensional nanomaterials; The electron excitation 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.

2. The electron source according to claim 1, characterized in that, The structure of the three-dimensional nanomaterials includes at least one of conical three-dimensional nanomaterials, star-shaped three-dimensional nanomaterials, and rod-shaped three-dimensional nanomaterials; The diameter of the circumscribed sphere of the three-dimensional nanomaterials is 1 nm to 10 μm.

3. The electron source according to claim 1, wherein The structure of the three-dimensional nanomaterials includes layered three-dimensional nanomaterials; The thickness of the layered three-dimensional nanomaterials is 1 nm to 100 nm.

4. The electron source according to claim 1, wherein The three-dimensional nanomaterials include at least one of lanthanum hexaboride, diamond, and gallium arsenide.

5. The electron source according to claim 1, wherein The electron emission layer further includes an auxiliary layer. 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, characterized in that, The auxiliary layer includes a transparent support layer. The material of the transparent support layer includes at least one of polycarbonate propylene, boron nitride, mica, and diamond; The thickness of the transparent support layer is 0.1 nm to 100 nm, and the light transmittance is ≥10%.

7. The electron source according to claim 5, characterized in that, The auxiliary layer includes a conductive support layer. The electron emission layer is electrically connected to the conductive connection layer through the conductive support layer; The material of the conductive support layer includes at least one of conductive metals and graphene; The thickness of the conductive support layer is 0.1 nm to 100 nm.

8. The electron source according to any one of claims 1-7, characterized in that, The optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a porous optical fiber.

9. A method for preparing the electron source according to any one of claims 1-8, characterized in that, The preparation method includes: Forming an electron excitation layer composed of three-dimensional nanomaterials on the laser emission path of the optical fiber, and forming a conductive connection layer electrically connected to the electron emission layer on the outer surface of the optical fiber to prepare the electron source.

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 1-8; 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 1-8, 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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