Electron source, electron gun and application of electron source

Abstract

The invention provides an electron source, which comprises an optical fiber, a conductive connection layer and an electron excitation layer, the conductive connection layer is arranged on the outer surface of the optical fiber, the electron excitation layer is arranged on a laser light emitting path of the optical fiber and is electrically connected with the conductive connection layer, and the electron emission layer comprises the electron excitation layer which is electrically connected with the conductive connection layer. The electron excitation layer comprises a zero-dimensional material, and laser emitted by the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons. The electron source provided by the invention is long in service life and good in stability.

Description

Technical Field

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

[0002] An electron source is a device for generating vacuum electrons. Traditional electron sources are mainly divided into thermionic electron sources, field emission electron sources, and photoemission electron sources according to the excitation method. Thermionic electron sources mainly select metal materials (for example, tungsten, lanthanum boride, etc.). 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 (for example, tungsten, lanthanum boride, etc.). Under the action of a strong electric field applied externally, a tip discharge effect is generated. A photoemission electron source uses a metal material (for example, gold) as a photocathode, and uses laser irradiation to excite the photocathode material to generate electrons.

[0003] However, the electron sources in traditional technologies cannot balance the emission efficiency and stability, and most of the reported photoemission electron sources adopt the form of laser side irradiation of metal tips, which has disadvantages such as high operation difficulty of the irradiation method. How to provide an electron source with high electron emission efficiency, good stability, and easy operation 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, an electron gun, and an application of the electron source with high lifespan and good stability.

[0005] The first aspect of the present application provides an electron source, including 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 is disposed on the laser output path of the optical fiber and is electrically connected to the conductive connection layer. The electron emission layer includes an electron excitation layer, and the electron excitation layer contains zero-dimensional materials. 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 to emit electrons.

[0006] In some embodiments of the present application, the density of the zero-dimensional materials in the electron excitation layer is 10 per mm 2 ~10 12 per mm 2 ;

[0007] Optionally, the gap between the particles of two adjacent zero-dimensional materials is zero.

[0008] In some embodiments of the present application, the zero-dimensional material includes one or more of fullerene, carbon black, nanodiamond, diamond color center, nano metal particles, perovskite quantum dots, graphite quantum dots, CdZnSe / ZnS zinc sulfide quantum dots, and CdZnS quantum dots;

[0009] It may be nano metal particles and / or graphite quantum dots.

[0010] In some embodiments of the present application, the average particle size of the zero-dimensional material is 1 nm to 100 μm.

[0011] In some embodiments of the present application, the thickness of the electron excitation layer is 0.3 nm to 100 μm.

[0012] In some embodiments of the present application, the electron emission layer further includes an auxiliary layer stacked with the electron excitation layer, and the auxiliary layer is disposed on the side of the electron emission layer relatively close to the optical fiber; or

[0013] The auxiliary layer is stacked on the side of the electron emission layer relatively far from the optical fiber.

[0014] In some embodiments of the present application, the auxiliary layer has electrical conductivity and / or heat dissipation, and the auxiliary layer is electrically connected to the conductive connection layer.

[0015] In some embodiments of the present application, the auxiliary layer satisfies at least one of the following conditions:

[0016] (1) The auxiliary layer contains a conductive material, and the conductive material includes at least one of a metal material, a semiconductor material, and a conductive carbon material;

[0017] Optionally, the conductive material includes at least one of chromium, titanium, gold, silver, palladium, cadmium, germanium, tin, lead, indium, silicon, and graphene;

[0018] (2) The thickness of the auxiliary layer is 0.3 nm to 10 nm, and the light transmittance is 10% to 98%.

[0019] In some embodiments of the present application, the conductive material is a metal material, and the laser wavelength in the optical fiber is 200 nm to 10 μm.

[0020] In some embodiments of the present application, the optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a perforated optical fiber.

[0021] In some embodiments of the present application, the optical fiber is a side-cut optical fiber. The optical fiber includes a core for transmitting laser and a cladding layer wrapping the core. A light leakage notch is formed along the radial direction of the light-emitting end of the optical fiber. The side-cut optical fiber is side-cut along the core of the optical fiber to expose the core. The electron emission layer is disposed on the side-cut surface of the side-cut optical fiber and is parallel to the core of the optical fiber.

[0022] A second aspect of the present application provides an electron gun, which includes a housing, a grid, an anode, and the electron source described in the first aspect of the present application. The electron source is fixed in the housing, and the grid and the anode are sequentially disposed on the electron-emitting side of the electron source.

[0023] A third aspect of the present application provides an application of the electron source described in the first aspect of the present application. The application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, an electron diffractometer, and a display.

[0024] For the electron source provided by the present application, the laser can be conducted through the core of the optical fiber to the end face of the optical fiber and irradiate the electron excitation layer. The zero-dimensional material contained in the electron excitation layer has typical discrete energy levels. Therefore, under the action of optical excitation, electrons mainly tunnel and excite into the vacuum from the discrete energy levels and can form an electron beam. The electrons emitted thereby have concentrated energy and small energy dispersion. In addition, the zero-dimensional material has an atomic-level thickness, and the excited electrons in the electron excitation layer can be emitted without long-distance transmission, and the electron emission efficiency is high. Moreover, the zero-dimensional material has no dangling bonds, is stable in nature and has a high melting point, is not easily damaged, can be applied to the scenario of high-power excitation, and has characteristics such as good stability and long service life. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of an electron source according to an embodiment of the present application.

[0026] Figure 2 It is a schematic radial cross-sectional structure diagram of an electron source according to an embodiment of the present application.

[0027] Figure 3 It is a schematic structural diagram of an electron source according to an embodiment of the present application.

[0028] Figure 4 It is a schematic radial cross-sectional structure diagram of an electron source according to an embodiment of the present application.

[0029] Figure 5 It is a schematic internal structure diagram of an electron gun according to an embodiment of the present application.

[0030] Figure 6 It is a schematic structural diagram of an electron source according to an embodiment of the present application.

[0031] Reference Numerals:

[0032] 100 Electron source; 200 Grid; 300 Anode; 110 Optical fiber; 120 Electron emission layer; 130 Conductive connection layer; 140 Auxiliary layer; 150 Electron excitation layer; 1101 Core. Detailed implementation

[0033] To facilitate the understanding of this application, the following will provide a more comprehensive description of this application. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosed content of this application more thorough and comprehensive.

[0034] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded; and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, although not explicitly recorded, each point or single value between the range endpoints is included in this range. Thus, each point or single value can be used as its own lower or upper limit and combined with any other point or single value or combined with other lower or upper limits to form a range not explicitly recorded.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application in this specification are only for the purpose of describing specific embodiments and are not intended to limit this application. It should be noted that unless otherwise stated, the term "and / or" used herein includes any and all combinations of one or more of the related listed items, "above" and "below" include the number itself, and "one or more" means two or more in "one or more".

[0036] The above application content of this application does not intend to describe each disclosed embodiment or each implementation of this application. The following description more specifically illustrates exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments, which can be used in various combinations. In each instance, the enumeration is only as a representative group and should not be construed as exhaustive.

[0037] In the traditional technology, materials with metallic properties such as tungsten filaments and lanthanum hexaboride are mainly selected as thermionic electron sources. 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 external electric field, 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, with good environmental adaptability and stability, but with low brightness and poor coherence. 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 vibrations. 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.

[0038] The photoemission electron source uses metal materials such as Au as the material of the electron emission layer, usually with a thickness of more than 50 nm, and even reaching hundreds of nanometers. However, the inventors of this application have found that due to the relatively large thickness of the electron emission layer of the metal material, the distance between the surface where the laser is incident in the electron emission layer (the bottom layer of the electron emission layer) and the opposite surface (the surface layer of 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 electron emission efficiency. Moreover, the conduction band of the metal material is a half-filled band, resulting in a wide energy distribution and large energy dispersion of the emitted electrons. In addition, the metal material is prone to damage under high-power laser irradiation, affecting the service life of the electron emission layer, and thus affecting the electron emission efficiency and stability. The reported photoemission electron sources mostly adopt the form of laser irradiating the side metal tip, which has disadvantages such as high operation difficulty of the irradiation method.

[0039] In addition, in the traditional technology, graphene can be used as a saturable absorber. Graphene has broadband saturable absorption characteristics and a fast recovery time, and is used in the Q-switching and mode-locking of lasers, or graphene can be used to adjust the laser spectrum for sensing detection. However, there are obvious differences between graphene laser regulation and graphene electron emission. The graphene electron source is based on the photoelectric effect, while graphene laser regulation is based on the principle of light absorption. The described graphene saturable absorber mainly utilizes the situation that the light absorption rate (or transmittance) of graphene increases (or decreases) with the increase of the incident light power and finally reaches the saturation threshold. It is mainly applied 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 from the beam splitter of the cavity in the form of a pulse.

[0040] Based on this, it is necessary to provide a method that can quickly and simply irradiate the electron emission layer with a laser, taking into account both the electron emission efficiency and a stable electron source.

[0041] The first aspect of the present application provides an electron source, as Figure 1 shown, including an optical fiber 110, a conductive connection layer 130, and an electron emission layer 120. The conductive connection layer 130 is disposed on the outer surface of the optical fiber 110. The electron emission layer 120 is disposed on the laser output path of the optical fiber 110 and is electrically connected to the conductive connection layer 130. The electron emission layer 120 includes an electron excitation layer, and the electron excitation layer contains zero-dimensional materials. The laser emitted from the optical fiber can directly irradiate the electron emission layer 120, so that the electron excitation layer is excited by the laser and emits electrons.

[0042] It should be noted that for the electron source of the present application, the laser is transmitted to the electron emission layer material through the optical fiber to excite electrons, which belongs to the back-illumination method and has the characteristics of being convenient, fast, simple, and easy to operate, which is significantly different from the method of laser side-irradiating the tip.

[0043] It should be noted that the "zero-dimensional material" in the present application refers to a substance with a nanoscale in all three spatial dimensions. It is generally composed of a small number of atoms and molecules and has typical discrete energy levels.

[0044] It should be noted that the "electrical connection" in the present application means that components are connected through the transmission of electrons. The purpose of the electrical connection between the conductive connection layer and the electron emission layer is to connect the zero-dimensional material to the external circuit, so that the excited and emitted electrons or electron beams in the electron emission layer can be supplemented to the electron emission layer through the external circuit, so that the electron emission process can continue.

[0045] As an implementation, the conductive connection layer can be directly connected to the electron emission layer. In some other implementations, 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 disposed on the side of the solid-core optical fiber, and the electron emission layer is disposed at the core of the solid-core optical fiber and covers the core, and the conductive connection layer and the electron emission layer are electrically connected.

[0046] It should be noted that the "laser output path of the optical fiber" in the present application refers to the path where the laser irradiates in the optical fiber. Taking a solid-core optical fiber as an example, the laser output position of the solid-core optical fiber is at the end face of the core, that is, the electron emission layer can be disposed at the core. Taking a side-cut optical fiber as another example, the laser output position of the side-cut optical fiber is on the side-cut side of the side-cut optical fiber, that is, the electron emission layer can be disposed at the side-cut.

[0047] It can be understood that the electron emission layer of the present application may only include an electron excitation layer, or may include an auxiliary layer in addition to the electron excitation layer. When the electron emission layer includes both an electron excitation layer and an auxiliary layer at the same time, the electron excitation layer and the auxiliary layer are stacked, and their relative positions can be adjusted according to actual needs.

[0048] It can be understood that in the present application, the electron excitation layer can be in direct contact with the laser output surface of the optical fiber, or other structural layers (such as an auxiliary layer) can be used to support the electron excitation layer. That is to say, it is only necessary to make the laser emitted from the optical fiber irradiate on the electron excitation layer. And the conductive connection layer has no overlap with the laser output surface of the optical fiber, that is, the laser output path of the optical fiber does not intersect with the conductive connection layer.

[0049] In the electron source provided by the present application, the laser can be conducted through the core of the optical fiber to the end face of the optical fiber and irradiate the electron excitation layer. The zero-dimensional material included in the electron excitation layer has typical discrete energy levels. Therefore, under the action of photoexcitation, electrons mainly tunnel from the discrete energy levels to the vacuum and can form an electron beam. There is no influence of metal lattice scattering. The electrons emitted therefrom have concentrated energy and small energy dispersion, and the electron emission efficiency is high.

[0050] In addition, the zero-dimensional material has an atomic thickness, and the excited electrons in the electron excitation layer can be emitted without long-distance transmission, and the electron emission efficiency is high; moreover, the zero-dimensional material has no dangling bonds, is stable in nature and has a high melting point, is not easily damaged, and can be applied to the scenario of high-power excitation, and has the characteristics of good stability, high service life and low working vacuum degree.

[0051] In addition, the zero-dimensional material and the optical fiber can also be directly integrated. The optical fiber transmits the laser, which can effectively reduce the scattering of the laser and effectively reduce the energy loss of the emitted laser, which is beneficial to the improvement of the excitation efficiency; and as the carrier of the zero-dimensional material, it can provide a stable excitation source with adjustable wavelength, polarization and optical mode, can be applied to different application scenarios, and does not require a complex optical path, and has the characteristics of small volume and high integration.

[0052] In some embodiments, the density of the zero-dimensional material in the electron excitation layer is 10 pieces / mm 2 ~10 12 pieces / mm 2 ;

[0053] Optionally, the gap between the particles of two adjacent zero-dimensional materials is zero.

[0054] It should be noted that when the zero-dimensional material is densely arranged in the electron excitation layer, the electron excitation layer can directly cover part or all of the core on the end face of the optical fiber, and realize electrical connection between the electron excitation layer and the conductive connection layer. Among them, such as Figure 2As shown, "high-density arrangement" means that the gap between the particles of two adjacent zero-dimensional materials is zero.

[0055] When the zero-dimensional materials are arranged in high density in the electron excitation layer, it is beneficial to further increase the number and energy concentration of the emitted electrons.

[0056] In some embodiments, the zero-dimensional materials include one or more of fullerene, carbon black, nanodiamond, diamond color center, nano metal particles, perovskite quantum dots, graphite quantum dots, CdZnSe / ZnS zinc sulfide quantum dots, and CdZnS quantum dots.

[0057] Optionally, the zero-dimensional materials are nano metal particles and / or graphite quantum dots.

[0058] In some embodiments, the average particle size of the zero-dimensional materials is 1 nm to 100 μm.

[0059] In some embodiments, the zero-dimensional materials include doping elements.

[0060] In this application, by doping elements into the zero-dimensional materials, the conductivity and electron emission performance of the zero-dimensional materials are improved. For example, phosphorus elements can improve the conductivity and electron emission performance of the zero-dimensional materials.

[0061] Optionally, the doping elements include at least one of boron, nitrogen, phosphorus, lithium, and potassium.

[0062] In some embodiments, the thickness of the electron excitation layer is 0.3 nm to 100 μm.

[0063] When the thickness of the electron excitation layer is within the above range, it is beneficial to further reduce the transmission distance of the excited electrons between the two surfaces of the electron layer phase, and further improve the electron emission efficiency.

[0064] In some embodiments, as Figure 3 shown, the electron emission layer 120 further includes an auxiliary layer 140 stacked with the electron excitation layer 150, and the auxiliary layer 140 is stacked on the side of the electron excitation layer 150 relatively close to the optical fiber 110.

[0065] In some embodiments, the auxiliary layer is stacked on the side of the electron emission layer relatively far from the optical fiber.

[0066] When an auxiliary layer is added to the electron emission layer, when the electron excitation layer requires structural support, the auxiliary layer can be used to structurally support the electron excitation layer, that is, the electron excitation layer is disposed on the auxiliary layer, and electrical connection is achieved between the electron excitation layer and the conductive connection layer.

[0067] In some embodiments, the auxiliary layer has electrical conductivity and / or heat dissipation properties, and the auxiliary layer is electrically connected to the conductive connection layer.

[0068] When the electron excitation layer cannot be directly connected and conduct electricity with the conductive connection layer, such as when zero-dimensional materials are arranged at low density in the electron excitation layer, then it is connected to the conductive connection layer through the electrically conductive auxiliary layer, so as to achieve electrical conduction between the electron excitation layer and the conductive connection layer through the auxiliary layer. In addition, the auxiliary layer can also assist the electron excitation layer in heat dissipation and improve the heat dissipation effect. Among them, as Figure 4 shown, "low-density arrangement" means that there is a situation where the gap between adjacent two zero-dimensional material particles in the electron excitation layer is greater than zero.

[0069] In some embodiments, the auxiliary layer comprises a conductive material, and the conductive material includes at least one of a metal material, a semiconductor material, and a conductive carbon material.

[0070] Optionally, the conductive material includes at least one of chromium, titanium, gold, silver, palladium, cadmium, germanium, tin, lead, indium, silicon, and graphene.

[0071] In some embodiments, the thickness of the auxiliary layer is 0.3 nm to 10 nm, and the light transmittance is 10% to 98%.

[0072] It can be understood that the "light transmittance" referred to in this application refers to the transmittance of laser light in the auxiliary layer.

[0073] By controlling the thickness and light transmittance of the auxiliary layer, it can be ensured that the laser light passes through the auxiliary layer and irradiates the electron excitation layer.

[0074] In some embodiments, the conductive material is a metal material, and the laser wavelength in the optical fiber is 200 nm to 10 μm.

[0075] When the auxiliary layer uses a metal material, by controlling the laser parameters, the problem of laser irradiation causing the melting of the conductive metal can be avoided, ensuring that the auxiliary layer has the functions of support and electrical conduction.

[0076] In some embodiments of the present application, the optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a perforated optical fiber.

[0077] In some embodiments, the optical fiber is a tip optical fiber. The zero-dimensional material of the present application is arranged 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.

[0078] In some embodiments, the optical fiber is a side-cut optical fiber. The zero-dimensional material of the present application is arranged on the side-cut surface of the side-cut optical fiber, and the evanescent wave leaking from the core interacts with the zero-dimensional material in the horizontal direction.

[0079] In some embodiments, such as Figure 6 shown, the optical fiber is a side-cut optical fiber, which includes a core for transmitting laser light and a cladding layer wrapped around the core. A light leakage notch is formed along the radial direction of the light-emitting end of the optical fiber. The side-cut optical fiber is side-cut along the core of the optical fiber to expose the core, and the electron emission layer is disposed on the side-cut surface of the side-cut optical fiber and parallel to the core of the optical fiber.

[0080] In some embodiments, the optical fiber is a porous optical fiber. The porous optical fiber of the present application is a type of optical fiber with microstructures or completely hollow, including photonic crystal fibers, anti-resonant fibers, capillary fibers, etc. The zero-dimensional material can be disposed on the inner wall of the air holes of the porous optical fiber, so that the laser has a long interaction distance with the zero-dimensional material, thereby realizing high-brightness electron emission. Since the porous optical fiber itself has a special light transmission mode, and different types or dimensions of materials can be continuously grown or transferred on the inner wall of the air holes where the zero-dimensional material has been grown or filled to form a heterojunction, multi-functional electron emission can be realized.

[0081] In some embodiments, the optical fiber is a solid-core optical fiber. The zero-dimensional material of the present application is disposed at the core of the solid-core optical fiber, and the evanescent wave leaking from the core can interact with the zero-dimensional material surrounding the optical fiber. A long light-material interaction distance 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 zero-dimensional material to realize electron emission with precisely controlled parameters.

[0082] It should be noted that the present application does not make specific requirements and special limitations on the size of the optical fiber, and those skilled in the art can reasonably select the size of the optical fiber according to actual use requirements.

[0083] In some embodiments, the electron emission layer is formed by at least one of dry transfer, wet transfer, and direct growth.

[0084] In some embodiments, the electron emission layer is prepared by dry transfer. The preparation method includes: transferring the zero-dimensional material to the tape by mechanical peeling, and transferring the zero-dimensional material to the laser output side of the optical fiber through the tape.

[0085] In some embodiments, the electron emission layer is prepared by wet transfer. The preparation method includes: directly preparing the zero-dimensional material in a solution and floating it on the liquid surface, and contacting the material on the liquid surface with the optical fiber and drying.

[0086] In some embodiments, the electron emission layer is prepared by direct growth. The preparation method includes: directly preparing the electron emission layer on the laser emission side of the optical fiber by at least one of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy, and liquid filling.

[0087] In the second aspect of the present application, an electron gun is provided. The electron gun includes a housing, a grid, an anode, and an electron source as described in the first aspect.

[0088] The electron source is fixed inside the housing, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

[0089] It should be noted that in the present 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 emitting from the anode for use.

[0090] In the third aspect of the present application, an application of the electron source as described in the first aspect is provided. The application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, an electron diffractometer, and a display.

[0091] Embodiment

[0092] The following are specific embodiments. The following embodiments more specifically describe the content disclosed in the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0093] In the following embodiments, the optical fiber is a single-mode solid-core optical fiber with a core diameter of 8.2 μm, an optical fiber diameter of 125 μm, and an excitation wave wavelength of 1550 nm transmitted in the optical fiber. The conductive connection layer is a metal layer covering the side of the optical fiber with a thickness of (4 nm titanium + 50 nm gold), and the conductive connection layer is in contact connection with the auxiliary layer or the electron excitation layer.

[0094] Embodiment 1

[0095] See Figure 1, graphite quantum dots are grown on the end face of a solid-core optical fiber with a conductive connection layer by chemical vapor deposition (CVD) to prepare an electron excitation layer with a thickness of about 20 nm. The electron excitation layer is electrically connected to the conductive connection layer to obtain an electron source. Among them, the average particle size of the graphite quantum dots in the electron excitation layer is 10 nm, and the density is 10 10 pieces / mm 2 .

[0096] Example 2

[0097] See Figure 3 , an auxiliary layer with a thickness of 5 nm, made of gold, and a light transmittance of about 80% is deposited on the end face of the solid-core optical fiber with a conductive connection layer. Then, graphite quantum dots are grown on the surface of the auxiliary layer by CVD to prepare an electron excitation layer with a thickness of about 20 nm. The electron excitation layer is electrically connected to the conductive connection layer to obtain an electron source. Among them, the average particle size of the graphite quantum dots in the electron excitation layer is 10 nm, and the density is 10 10 pieces / mm 2 (high close-packed).

[0098] Example 3

[0099] Similar to the preparation method of Example 1, the difference is that: the graphite quantum dots are replaced with nano-gold particles.

[0100] Example 4

[0101] Similar to the preparation method of Example 1, the difference is that: the average particle size of the graphite quantum dots is 20 nm.

[0102] Example 5

[0103] Similar to the preparation method of Example 2, the difference is that: the material of the auxiliary layer is replaced with graphene, and the obtained light transmittance is about 98%.

[0104] Comparative Example 1

[0105] An electron source is prepared according to the structure of Example 1, the difference is that: the electron excitation layer in Example 1 is replaced with a gold layer with a thickness of 200 nm, and the gold layer is prepared by deposition.

[0106] Comparative Example 2

[0107] An electron source is prepared according to the structure of Example 3, the difference is that: the electron excitation layer in Example 3 is replaced with a gold layer with a thickness of 20 nm, and the gold layer is prepared by deposition.

[0108] As Figure 5As shown, the electron source 100 prepared by the above-mentioned examples and comparative examples is assembled into an electron gun. The electron gun further includes a housing, a grid 200, and an anode 300. Performance tests are carried out on the obtained electron gun, and the results are shown in Table 1 below. Among them, the test conditions or test standards for each performance test item are as follows:

[0109] (1) 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.

[0110] (2) Life 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 until the time when the current decays to less than 10% of the initial value, which is defined as the life.

[0111] (3) Working vacuum degree test: When the excitation power is 50% of the damage power, the continuous emission current is applied, and the working environment vacuum degree of the electron gun is gradually increased until the current shows a rapid decay (rapid decay is defined as the current decaying by more than 50% within 1 min). At this time, the vacuum degree is defined as the working vacuum degree.

[0112] 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 .

[0113] Table 1

[0114]

[0115] In Table 1 above, by comparing the examples with Comparative Examples 1 and 2, it can be seen that the performance of the examples is significantly better than that of Comparative Examples 1 and 2, indicating that the electron source performance of the present application using zero-dimensional materials as the electron excitation layer is superior to that of traditional metal layers and metal nanolayers.

[0116] The technical features of the above-mentioned embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-mentioned 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.

[0117] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on 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 the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. An electron source, characterized in that, It 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 is disposed on the laser output path of the optical fiber and is electrically connected to the conductive connection layer. The electron emission layer includes an electron excitation layer, and the electron excitation layer contains zero-dimensional materials. The laser emitted from 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.

2. The electron source according to claim 1, wherein The density of the zero-dimensional material in the electron excitation layer is 10 per mm 2 ~10 12 per mm 2 .

3. The electron source according to claim 1, characterized in that, The gap between the particles of two adjacent zero-dimensional materials is zero.

4. The electron source according to claim 1, characterized in that, The zero-dimensional material includes one or more of fullerene, carbon black, nanodiamond, diamond color center, nano metal particles, perovskite quantum dots, graphite quantum dots, CdZnSe / ZnS zinc sulfide quantum dots, and CdZnS quantum dots.

5. The electron source according to claim 4, characterized in that, The zero-dimensional material is nano metal particles and / or graphite quantum dots.

6. The electron source according to claim 1, characterized in that, The average particle size of the zero-dimensional material is 1 nm to 100 μm.

7. The electron source according to any one of claims 1-6, characterized in that, The thickness of the electron excitation layer is 0.3 nm to 100 μm.

8. The electron source according to any one of claims 1-6, characterized in that, The electron emission layer further includes an auxiliary layer stacked with the electron excitation layer. The auxiliary layer is disposed on the side of the electron emission layer relatively close to the optical fiber; or The auxiliary layer is stacked on the side of the electron emission layer relatively far from the optical fiber.

9. The electron source according to claim 8, wherein The auxiliary layer has conductivity and / or heat dissipation, and the auxiliary layer is electrically connected to the conductive connection layer.

10. The electron source according to claim 8, wherein The auxiliary layer satisfies at least one of the following conditions: (1) The auxiliary layer contains a conductive material, and the conductive material includes at least one of a metal material, a semiconductor material, and a conductive carbon material; Optionally, the conductive material includes at least one of chromium, titanium, gold, silver, palladium, cadmium, germanium, tin, lead, indium, silicon, and graphene; (2) The thickness of the auxiliary layer is 0.3 nm to 10 nm, and the light transmittance is 10% to 98%.

11. The electron source according to claim 10, characterized in that, The conductive material is a metal material, and the laser wavelength in the optical fiber is 200 nm to 10 μm.

12. The electron source according to any one of claims 1-11, characterized in that, The optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a perforated optical fiber.

13. The electron source according to claim 12, wherein The optical fiber is a side-cut optical fiber. The optical fiber includes a core for transmitting laser and a cladding layer wrapping the core. The light output end of the optical fiber is configured with a light leakage notch along the radial direction of the optical fiber. The side-cut optical fiber is side-cut along the core of the optical fiber to expose the core, and the electron emission layer is disposed on the side-cut surface of the side-cut optical fiber and is parallel to the core of the optical fiber.

14. An electron gun, characterized in that, It includes a housing, a grid, an anode, and the electron source according to any one of claims 1-13; The electron source is fixed in the housing, and the grid and the anode are sequentially disposed on the electron emission side of the electron source.

15. Use of an electron source according to any one of claims 1-14, 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, an electron diffractometer, and a display.

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