Electron source and method of making and using the same

Abstract

The application provides an electron source and a preparation method and application thereof. The electron source comprises an optical fiber, a conductive connecting layer and an electron emission layer. The electron emission layer comprises an electron excitation layer electrically connected with the conductive connecting layer. The electron excitation layer comprises a three-dimensional nanomaterial. The electron excitation layer is arranged on a laser emission path of the optical fiber. Laser emitted by the optical fiber can directly irradiate on the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons. The three-dimensional nanomaterial as the material of the electron emission layer has the characteristics of good stability and long service life. The optical fiber can provide a stable excitation source with adjustable wavelength, polarization and optical mode, and can be applied to different application scenarios.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electron sources, in particular to an electron source and a preparation method and application thereof. BACKGROUND

[0002] An electron source is a device for generating vacuum electrons. Traditional electron sources are mainly classified into thermal emission electron sources, field emission electron sources and light emission electron sources according to the excitation mode. The thermal emission electron source mainly selects metal materials, and when heated to several thousand degrees Celsius, electrons are excited by heat to escape from the surface of the material to form vacuum electrons. The field emission electron source mainly selects metal needle tips, and under the action of a strong electric field applied from outside, a sharp tip discharge effect is generated. The light emission electron source uses metal materials as a photocathode, and uses laser irradiation to excite the photocathode material to generate electrons.

[0003] However, the electron source in the prior art cannot balance the emission efficiency and stability. Therefore, how to provide an electron source with high electron emission efficiency and good stability has become an urgent technical problem to be solved. SUMMARY

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

[0005] In a first aspect, the present application provides an electron source, which comprises an optical fiber, a conductive connection layer and an electron emission layer, wherein the conductive connection layer is arranged on the outer surface of the optical fiber.

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

[0007] The electron excitation layer is arranged 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 comprises 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 comprises 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 comprises at least one of lanthanum hexaboride, diamond and gallium arsenide.

[0011] In some embodiments, the electron emission layer further comprises an auxiliary layer, the auxiliary layer is arranged on one side of the electron excitation layer close to the optical fiber; or,

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

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

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

[0015] In some embodiments, the auxiliary layer comprises 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, a material of the conductive support layer comprises at least one of a conductive metal and graphene.

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

[0018] In some embodiments, the optical fiber is a solid core optical fiber, a needle tip optical fiber, a side profile optical fiber or a hole optical fiber.

[0019] In a second aspect, the present application provides a preparation method of the electron source according to the first aspect, the preparation method comprising:

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

[0021] In a third aspect, the present application provides an electron gun, the electron gun comprising a shell, a grid, an anode and the electron source according to the first aspect.

[0022] The electron source is fixed in the shell, and the grid and the anode are arranged in sequence on an electron emission side of the electron source.

[0023] In a fourth aspect, the present application provides an application of the electron source according to the first aspect, the application of the electron source comprising at least one of an electron microscope, an electron beam exposure machine, an X-ray tube, a free electron laser and a display.

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

[0025] The application uses three-dimensional nanomaterial as the material of the electron emission layer. The three-dimensional nanomaterial has a small size and a nanoscale tip, and can obtain a strong light field enhancement and electron emission under the condition of laser back incidence. Moreover, the three-dimensional nanomaterial is integrated with an optical fiber. The optical fiber can provide a stable excitation source with adjustable wavelength, polarization and optical mode, can be suitable for different application scenarios, and does not need to provide a complex optical path. The electron source has the characteristics of stable emission, high service life, small volume and high integration. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 FIG. 1 is a structural schematic diagram of an electron source provided in Embodiment 1 of the application, wherein 110a is a solid core optical fiber; 120a is an electron excitation layer; and 130a is a conductive connection layer.

[0027] Figure 2 FIG. 2 is a structural schematic diagram of an electron source provided in Embodiment 2 of the application, wherein 110b is a solid core optical fiber; 120b is an electron excitation layer; 130b is a conductive connection layer; and 140b is a conductive support layer.

[0028] Figure 3 FIG. 3 is a structural schematic diagram of an electron source provided in Embodiment 3 of the application, wherein 110c is a needle tip optical fiber; 120c is an electron excitation layer; and 130c is a conductive connection layer.

[0029] Figure 4 FIG. 4 is a structural schematic diagram of an electron source provided in Embodiment 4 of the application, wherein 110d is a side-cut optical fiber; 120d is an electron excitation layer; 130d is a conductive connection layer; and 140d is a conductive support layer.

[0030] Figure 5 FIG. 5 is a schematic diagram of the internal structure of an electron gun provided in an embodiment of the application, wherein 100 is an electron source; 200 is a grid; and 300 is an anode. DETAILED DESCRIPTION

[0031] The application will be further described below in conjunction with embodiments and examples. These embodiments and examples are only used to illustrate the application and not to limit the scope of the application. The purpose of providing these embodiments and examples is to make the disclosure of the application more thoroughly and comprehensively understood. It should also be understood that the 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 spirit and scope of the application, and the equivalent forms obtained thereby also fall within the protection scope of the application. In addition, in the following description, a large number of specific details are given in order to provide a more complete understanding of the application. It should be understood that the 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 belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0033] In the present application, "optionally", "optional", "option" means optional, that is, selected from "have" or "no" two parallel schemes. If there are multiple "options" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "option" is independent.

[0034] In the present application, the terms "first", "second", etc. in the "first aspect", "second aspect" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or quantity, nor can it be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration description, and should be understood as not constituting a closed limitation on the quantity.

[0035] In the present application, the technical features described in an open manner include both closed technical solutions consisting of listed features and open technical solutions containing listed features.

[0036] In the present application, with respect to numerical intervals (i.e. numerical ranges), unless otherwise specified, the distribution of optional values within the numerical interval is considered to be continuous, and includes both numerical endpoints (i.e. minimum and maximum values) of the numerical interval, and every value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only points to the integers within the numerical interval, including the two endpoint integers of the numerical range and every integer between the two endpoints, it is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in the present application should be understood to include any and all sub-ranges included 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" is allowed to be broadly interpreted as a quantitative interval, including percentage interval, ratio interval, ratio interval, etc.

[0037] All the documents mentioned in the present application are incorporated by reference into the present application as if each document were individually incorporated. The cited documents are incorporated by reference in the entirety, for all purposes, unless and to the extent that a particular reference is inconsistent with the description of the present application and / or the technical solutions of the present application. When the present application refers to the cited documents, the definitions of the relevant technical features, terms, names, phrases, etc. in the cited documents are also incorporated by reference. When the present application refers to the cited documents, the examples and preferred modes of the relevant technical features are also incorporated by reference into the present application, as far as the present application can be implemented. It should be understood that when the cited content conflicts with the description in the present application, the present application is used as the reference or is modified according to the description in the present application.

[0038] In the conventional technology, the thermal emission electron source mainly selects materials with metallic properties such as tungsten wire and lanthanum hexaboride, and when heated to several thousand degrees Celsius, electrons are thermally excited to form a vacuum electron on the surface of the material. The field emission electron source mainly selects metal needle tips such as tungsten, and under the action of a strong electric field applied from outside, a sharp tip discharge effect is generated. Among them, the electron beam emitted by the thermal electron source can work in a poor vacuum environment, has good adaptability to the environment, and has good stability, but the brightness is low and the coherence is poor. The electron beam of the field emission electron source has high brightness and good coherence, but has high requirements for vacuum degree and is very sensitive to vibration. Whether it is a thermal emission electron source or a field emission electron source, the regulation of the electron emission property is limited, and the emission efficiency and stability cannot be considered.

[0039] The light emission electron source uses Au and other metal materials as the material of the electron emission layer, and the thickness is more than 50 nm, and even reaches several hundred nanometers. However, the present inventors have found that the thickness of the electron emission layer of the metal material is large, the distance between the side surface directly acted on by the laser (the bottom layer of the electron emission layer) and the side surface of the electron emission (the surface layer of the electron emission layer) is far (50 nm to several hundred nanometers), and the electrons excited from the bottom layer are easily affected by the metal lattice scattering during the process of passing through the electron emission layer, 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, thereby affecting the emission efficiency and stability of the electrons. Some use a laser side incidence method to excite electrons, compared with laser back incidence, side incidence needs to modify the vacuum cavity, and the irradiation method is difficult to operate, and there are problems such as unstable excitation conditions.

[0040] In addition, in the prior art, graphene is used as a saturable absorber. Graphene has wide-band saturable absorption characteristics and fast recovery time, and is used in Q-switching and mode-locking of lasers, or is used for sensing and detection by adjusting laser spectrum with graphene. However, graphene laser adjustment is different from graphene electron emission. Graphene light excitation electron source is based on photoelectric effect, and graphene laser adjustment is based on light absorption principle. Specifically, graphene laser adjustment is obviously different from graphene electron emission. Graphene electron emission is based on photoelectric effect, and graphene laser adjustment is based on light absorption principle. In laser adjustment, the graphene saturable absorber mainly uses the fact that the light absorption rate (or light transmission rate) of graphene increases (or decreases) with the increase of incident light power, and finally reaches a saturation threshold. It is mainly applied in lasers for generating laser pulses. For example, in the ring fiber resonant cavity of a fiber laser, when the light circulates in the resonant cavity, the light power passing through the graphene saturable absorber exceeds the saturable absorption threshold, and due to the saturable absorption effect, the light intensity in the cavity instantaneously falls below the saturable absorption threshold, and the part of the falling light energy is output from the cavity splitter in the form of a pulse.

[0041] Therefore, it is necessary to provide an electron source capable of balancing electron emission efficiency and stability.

[0042] The three-dimensional nanomaterial is used as the material of the electron excitation layer in the present application. The three-dimensional nanomaterial emits electrons through photoelectric effect, multi-photon emission and light field emission under laser irradiation. The three-dimensional nanomaterial has the characteristics of good stability, high service life and strong interaction with light due to its nanoscale thickness or very sharp tips or edges. In addition, the three-dimensional nanomaterial is directly integrated with an optical fiber in the present application. 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] The present application provides an electron source. The electron source includes an optical fiber, a conductive connection layer and an electron emission layer. The conductive connection layer is arranged 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. The electron excitation layer includes a three-dimensional nanomaterial.

[0045] The electron excitation layer is arranged 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.

[0046] The application adopts three-dimensional nanomaterials as the material of the electron excitation layer. The three-dimensional nanomaterials have small size and nanoscale tips, and can obtain strong light field enhancement and electron emission under the condition of laser back incidence. 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 has the characteristics of stable emission, high service life, small size and high integration.

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

[0048] It should be noted that the light path of the optical fiber in the application refers to the path of laser irradiation in the optical fiber. For example, the laser exit position of a solid core optical fiber is located at the core end face, that is, the electron emission layer can be arranged at the core; for example, the laser exit position of a side profile optical fiber is located at the side profile side of the side profile optical fiber, that is, the electron emission layer can be arranged at the side profile. It can be understood that the electron emission layer in the application can be directly in contact with the laser exit surface of the optical fiber, or can be supported by other structural layers, that is, the laser emitted by the optical fiber can irradiate the electron emission layer.

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

[0050] It should be further noted that the purpose of the electrically conductive connection layer being electrically connected to the electron emission layer in the application is to connect the low-dimensional material to the external circuit to form a complete loop, so as to realize the supplement of electric charge and the control of electric field. The direction and convergence of electron emission can be controlled by voltage. As an embodiment, the electrically conductive connection layer can be directly connected to the electron emission layer, and in other embodiments, the electrically conductive connection layer and the electron emission layer can be electrically connected through other conductive structures. For example, the electrically conductive connection layer is arranged on the side of the solid core optical fiber, the electron emission layer is arranged at the core of the solid core optical fiber, the electrically conductive connection layer is electrically connected to the electron emission layer, and the core does not have the electrically conductive connection layer.

[0051] In some embodiments, the three-dimensional nanomaterials include a doping element. Optionally, the doping element includes at least one of an alkali metal, an alkaline earth metal, a transition metal, a rare earth element, a halogen element and a light element, wherein the light element includes at least one of B, C, N and O.

[0052] The application improves the conductivity and electron emission performance of the three-dimensional nanomaterial by doping elements in the three-dimensional nanomaterial. For example, alkali metal and alkaline earth metal elements can improve the conductivity of the low-dimensional material, and can also reduce the work function of the low-dimensional material to improve the emission current; elements such as B, C, N, O, F and rare earth can create discrete energy levels to obtain a narrow-energy electron beam.

[0053] In some embodiments, the conductive connecting layer is provided with an electrode for connecting with an external circuit. Optionally, the conductive connecting layer can fully coat the outer surface of the optical fiber or can partially coat the outer surface of the optical fiber, and the conductive connecting layer is not present on the light emission path of the laser.

[0054] Further optionally, the thickness of the conductive connecting layer is 10 nm to 1 μm, for example, 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, 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 base side length 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 the application can be a polyhedron, or can be a special-shaped structure, which can be an integrated structure or formed by assembling several three-dimensional nanomaterials. That is, the three-dimensional nanomaterial has a large field enhancement factor and low requirements for excitation light power and electric field due to a large number of optional materials and forms.

[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, 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 comprises an auxiliary layer, which is arranged on the side of the electron excitation layer away from the optical fiber; or

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

[0062] In some embodiments, the auxiliary layer is arranged on the 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, 0.1 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm. The application controls the thickness of the auxiliary layer on the side of the electron excitation layer away from the optical fiber to avoid the influence of the auxiliary layer on 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 comprises a transparent support layer, and the material of the transparent support layer comprises at least one of polypropylene carbonate, 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, 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, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%.

[0067] In some embodiments, the auxiliary layer comprises 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 comprises at least one of gold, silver and copper.

[0068] In some embodiments, the conductive support layer is arranged 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 the application, the auxiliary layer adopts a conductive metal, and the laser parameters are controlled to avoid the problem of melting caused by laser irradiation of the conductive metal, thereby ensuring that the auxiliary layer has the functions of supporting and conducting electricity.

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

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

[0072] In some embodiments, the conductive support layer has a thickness of 0.1 nm to 100 nm, for example, 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 fiber, a tip fiber, a side profile fiber, or a hole fiber.

[0074] In some embodiments, the optical fiber is a tip fiber. The present application sets the three-dimensional nanomaterial on the tip fiber, and due to the tip geometry of the tip fiber, the field emission enhancement factor is improved, and a higher brightness electron source can be obtained. Further, at least one of the zero-dimensional material and the one-dimensional material is set on the three-dimensional nanomaterial, thereby realizing high brightness, low energy dispersion, and narrow pulse width functions.

[0075] In some embodiments, the optical fiber is a side profile fiber. The present application sets the three-dimensional nanomaterial on the side profile of the side profile fiber, and the evanescent wave leaked from the fiber core interacts with the three-dimensional nanomaterial in the horizontal direction. The edge state electron emission structure is obtained at the side profile.

[0076] In some embodiments, the optical fiber is a hole fiber. The hole fiber in the present application is a kind of optical fiber with microstructure or completely hollow, including photonic crystal fiber, anti-resonant fiber or capillary fiber, etc. The three-dimensional nanomaterial can be set in the pore or the pore wall of the hole fiber, so that the laser has a long interaction distance with the low-dimensional material, thereby realizing high-brightness electron emission. Because the hole fiber itself has a special light transmission mode, and different kinds or dimensions of materials can be further grown or transferred in the pore or the pore wall where the three-dimensional nanomaterial has been grown or filled, forming a heterojunction, multi-functional electron emission can be realized.

[0077] In some embodiments, the optical fiber is a solid core fiber. The three-dimensional nanomaterial of the present application is set at the fiber core of the solid core fiber, and the evanescent wave leaked from the fiber core can interact with the three-dimensional nanomaterial surrounding the optical fiber. In this system, a long light-material interaction distance can be realized to achieve high-brightness electron emission. In addition, different diameters of micro-nano optical fibers can be drawn, and different modes and intensities of light can be used to interact with the three-dimensional nanomaterial to realize precise parameter control of electron emission. In addition, different kinds or dimensions of materials can be further grown or transferred on the grown or transferred three-dimensional nanomaterial to form a heterojunction, thereby realizing multi-functional electron emission.

[0078] It should be noted that the size of the optical fiber is not specifically required and specially limited in the present application, and the size of the optical fiber can be reasonably selected by the person skilled in the art according to the actual use requirements.

[0079] The second aspect of the present application provides a preparation method of the electron source as described in the first aspect, and the preparation method comprises:

[0080] The electron excitation layer composed of the three-dimensional nanomaterial is formed on the laser emission path of the optical fiber, and the conductive connection layer electrically connected with the electron emission layer is formed on the outer surface of the optical fiber, so that the electron source is prepared.

[0081] It should be noted that the forming method of the three-dimensional nanomaterial is not specifically required and specially limited in the present application, and the person skilled in the art can reasonably select the actual material. For example, the three-dimensional nanomaterial can be formed by direct preparation or transfer. For example, it can be prepared by liquid phase method or magnetron sputtering.

[0082] The third aspect of the present application provides an electron gun, which comprises a shell, a grid, an anode and an electron source as described in the first aspect.

[0083] The electron source is fixed in the shell, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

[0084] It should be noted that the grid in the present application is used to limit the shape of the electron beam, and the anode is used to accelerate the electrons. When the 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 then being emitted from the anode for use.

[0085] In the 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 comprises at least one of an electron microscope, an electron beam exposure machine, an X-ray tube, a free electron laser and a display.

[0086] The embodiments of the present application will be described in detail below with reference to the examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods not specified in the following examples are preferred to refer to the guidelines given in the present application, and can also be carried out according to the experimental manual or conventional conditions in the art, or according to the conditions suggested by the manufacturer, or by referring to the known experimental methods in the art.

[0087] The conductive connection layer comprises a titanium layer with a thickness of 5 nm and a gold layer with a thickness of 60 nm which are sequentially stacked away from the surface of the optical fiber.

[0088] Example 1

[0089] The present embodiment provides an electron source, which comprises an optical fiber and an electron excitation layer composed of a three-dimensional nanomaterial, wherein Figure 1 As shown in the figure, the electronic source comprises a solid core optical fiber 110a, an electron excitation layer 120a and a conductive connecting layer 130a, wherein the conductive connecting layer 130a covers the side wall of the solid core optical fiber 110a and forms an annular layer on the side of the laser exit end face of the solid core optical fiber 110a, the annular layer does not cover the core of the solid core optical fiber 110a, a 50nm-thick lanthanum hexaboride nanosheet is arranged on the side of the laser exit end face of the solid core optical fiber 110a as the electron excitation layer 120a, the electron excitation layer 120a covers the core of the solid core optical fiber 110a and is electrically connected to the conductive connecting layer 130a by being arranged on the annular layer.

[0090] The embodiment also provides a preparation method of the electronic source, comprising:

[0091] A 50nm-thick lanthanum hexaboride nanosheet is formed on a silicon wafer by magnetron sputtering, then a polycarbonate film is coated on the lanthanum hexaboride nanosheet, and a polycarbonate film with a lanthanum hexaboride nanosheet is obtained after peeling off;

[0092] The conductive connecting layer 130a is evaporated on the solid core optical fiber 110a to form an annular layer on the laser exit side of the solid core optical fiber 110a, then the polycarbonate film with the lanthanum hexaboride nanosheet is transferred to the laser exit side of the solid core optical fiber 110a, so that the polycarbonate film with the lanthanum hexaboride nanosheet is attached to the annular layer and covers the core of the solid core optical fiber 110a, after the polycarbonate is heated and melted, the residual polycarbonate film is removed by soaking in acetone, and an electron excitation layer 120a composed of a lanthanum hexaboride nanosheet is formed, thereby preparing the electronic source.

[0093] Embodiment 2

[0094] The embodiment provides an electronic source, which comprises a solid core optical fiber 110b, an electron excitation layer 120b, a conductive connecting layer 130b and a conductive supporting layer 140b. Figure 2 As shown in the figure, the electronic source comprises a solid core optical fiber 110a, an electron excitation layer 120a and a conductive connecting layer 130a, wherein the conductive connecting layer 130a covers the side wall of the solid core optical fiber 110a and forms an annular layer on the side of the laser exit end face of the solid core optical fiber 110a, the annular layer does not cover the core of the solid core optical fiber 110a, a 50nm-thick lanthanum hexaboride nanosheet is arranged on the side of the laser exit end face of the solid core optical fiber 110a as the electron excitation layer 120a, the electron excitation layer 120a covers the core of the solid core optical fiber 110a and is electrically connected to the conductive connecting layer 130a by being arranged on the annular layer.

[0095] Embodiment 3

[0096] The embodiment provides an electronic source, which comprises a solid core optical fiber 110b, an electron excitation layer 120b, a conductive connecting layer 130b and a conductive supporting layer 140b. Figure 3 As shown, the electron source 100c comprises a side-cut fiber 110c, an electron excitation layer 120c and a conductive connection layer 130c, wherein the electron excitation layer 120c is composed of a LaB6nanocone with a height of 10 μm, the LaB6nanocone is arranged at the tip of the side-cut fiber, and the conductive connection layer 130c coats the sidewall of the side-cut fiber 110c and is electrically connected with the LaB6nanocone.

[0097] Example 4

[0098] This embodiment provides an electron source, such as Figure 4 As shown, the electron source 100d comprises a side-cut fiber 110d, an electron excitation layer 120d, a conductive connection layer 130d and a conductive support layer 140d, wherein the electron excitation layer 120d is composed of four LaB6nanocones arranged on the conductive support layer 140d, the LaB6nanocones have a bottom side with a length of 10 μm and a height of 10 μm, the conductive support layer 140d is arranged on the side-cut surface of the side-cut fiber 110d, the conductive support layer is graphene with a thickness of 2 nm, and the conductive connection layer 130d coats the outer surface of the side-cut fiber 110d and is electrically connected with the conductive support layer 140d (the connection is not shown in the cross-sectional view).

[0099] Comparative Example 1

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

[0101] Comparative Example 2

[0102] The electron source was prepared according to the structure of Comparative Example 1, except that the electron excitation layer in Comparative Example 1 was replaced by a gold layer with a thickness of 1 nm.

[0103] As shown in Figure 5 The electron sources 100 prepared in the above examples and comparative examples were assembled into electron guns, and the electron guns further comprise a shell, a grid 200 and an anode 300. The performance of the prepared electron guns was tested, and the testing method comprises:

[0104] Stability test: at an excitation power of 50% of the damage power, a vacuum degree of 2×10 -5 Pa, a continuous emission current for 1 h, after removing the bad points, the difference between the maximum current and the minimum current and the average current were calculated, i.e. the stability parameter = (maximum current - minimum current) / average current.

[0105] Lifetime test: at an excitation power of 50% of the damage power, a vacuum degree of 2×10 -5Pa, the time for continuously emitting current until the current decays to less than 10% of the initial value, is defined as the lifetime.

[0106] Working vacuum test: at 50% of the damage power, continuously emit current, gradually increase the working environment vacuum degree of the electron gun until the current appears rapid decay (rapid decay is defined as the current decaying by more than 50% within 1 min), and the vacuum degree at this time is defined as the working vacuum degree.

[0107] Wherein, the damage power refers to the laser power at which the material is damaged under the irradiation of 100 fs pulse 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] As can be seen from the above table:

[0112] The three-dimensional nanomaterial is used as the material of the electron excitation layer in the application, the three-dimensional nanomaterial has a small size and a nanoscale tip, and can obtain strong light field enhancement and electron emission under the condition of laser back incidence. Moreover, the three-dimensional nanomaterial is integrated with an optical fiber, the optical fiber can provide a stable excitation source with adjustable wavelength, polarization and optical mode, can be suitable for different application scenarios, and does not need to provide a complex optical path, the electron source of the application has the characteristics of stable emission, high service life, small size and high integration.

[0113] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict, they should be considered as the scope of the description.

[0114] The above-described embodiments only express several implementation manners of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the application, some modifications and improvements can be made, which are all within the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. An electronic source, characterized in that, The electron source includes an optical fiber, a conductive connection layer, and an electron emission layer, wherein 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, and the electron excitation layer includes a three-dimensional nanomaterial with a nanoscale tip; 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 electronic source as described in claim 1, characterized in that, The structure of the three-dimensional nanomaterial includes at least one of the following: conical three-dimensional nanomaterials, star-shaped three-dimensional nanomaterials, and rod-shaped three-dimensional nanomaterials. The diameter of the outer sphere of the three-dimensional nanomaterial is 1 nm to 10 μm.

3. The electronic source as described in claim 1, characterized in that, The structure of the three-dimensional nanomaterial includes layered three-dimensional nanomaterials; The thickness of the layered three-dimensional nanomaterial is 1 nm to 100 nm.

4. The electronic source as described in claim 1, characterized in that, The three-dimensional nanomaterial includes at least one of lanthanum hexaboride, diamond, and gallium arsenide.

5. The electronic source as described in claim 1, characterized in that, The electron emission layer further includes an auxiliary layer, which is stacked on the side of the electron excitation layer closest 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 electronic source as described in claim 5, characterized in that, The auxiliary layer includes a transparent support layer, and the material of the transparent support layer includes at least one of polypropylene carbonate, boron nitride, mica and diamond. The thickness of the transparent support layer is 0.1nm~100nm, and the light transmittance is ≥10%.

7. The electronic source as described in claim 5, characterized in that, 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. The material of the conductive support layer includes at least one of conductive metal 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 fiber, a needle-tip fiber, a side-cut fiber, or a perforated fiber.

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

10. An electron gun, characterized in that, The electron gun includes a housing, a gate, an anode, and an electron source as described in any one of claims 1-8; The electron source is fixed inside the housing, and the gate and anode are sequentially arranged on the electron emission side of the electron source.

11. An application of the electronic source according to any one of claims 1-8, 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.

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