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 one-dimensional material and 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 that generates 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 (such as 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 (such as 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 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] In a first aspect of the present application, an electron source is provided, 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 includes a one-dimensional material and a zero-dimensional material. 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.

[0006] In some embodiments of the present application, the zero-dimensional material in the electron excitation layer is disposed on the one-dimensional material.

[0007] In some embodiments of the present application, the included angle between the axial direction of the one-dimensional material in the electron excitation layer and the laser output path of the optical fiber is 0 to 90°.

[0008] In some embodiments of the present application, the electron excitation layer includes a plurality of the one-dimensional materials, and the axial directions of any two of the one-dimensional materials are parallel to each other.

[0009] In some embodiments of the present application, the axial direction of the one-dimensional material in the electron excitation layer is parallel to the laser output path of the optical fiber.

[0010] In some embodiments of the present application, the electron excitation layer contains a plurality of the one-dimensional materials, and the gap between adjacent two of the one-dimensional materials along the radial direction of the one-dimensional material is zero.

[0011] In some embodiments of the present application, the diameter of the one-dimensional material is 1 nm to 500 nm, and the length of the one-dimensional material is 10 nm to 1 mm.

[0012] In some embodiments of the present application, the average particle size of the zero-dimensional material is 1 nm to 100 nm.

[0013] In some embodiments of the present application, the one-dimensional material includes at least one of a nanotube, a nanorod, a nanowire, a nanobelt, and a nanocoaxial cable;

[0014] Optionally, the one-dimensional material includes at least one of a carbon nanotube, a silicon nanowire, a germanium nanowire, a silver nanowire, a gold nanorod, and a boron nitride nanotube.

[0015] In some embodiments of the present application, the zero-dimensional material includes one or more of a fullerene, carbon black, a nanodiamond, a diamond color center, a nanometal particle, a perovskite quantum dot, a graphite quantum dot, a CdZnSe / ZnS zinc sulfide quantum dot, and a CdZnS quantum dot;

[0016] Optionally, it is a nanometal particle and / or a graphite quantum dot.

[0017] In some embodiments of the present application, the thickness of the electron excitation layer is 0.3 nm to 100 μm.

[0018] 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 stacked on the side of the electron emission layer relatively close to the optical fiber; or

[0019] The auxiliary layer is stacked on the side of the electron emission layer relatively far from the optical fiber.

[0020] 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.

[0021] In some embodiments of the present application, the auxiliary layer satisfies at least one of the following conditions:

[0022] (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;

[0023] Optionally, the conductive material includes at least one of chromium, gold, silicon, silicon oxide, and graphene;

[0024] (2) The thickness of the auxiliary layer is 0.3 nm to 10 nm, and the light transmittance is 10% to 98%.

[0025] 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.

[0026] 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 porous optical fiber. The second aspect of the present application provides an electron gun, including 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 arranged on the electron emission side of the electron source.

[0027] The third aspect of the present application provides an application of the electron source described in the first aspect of the present application, and 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.

[0028] 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, and the electron excitation layer contains one-dimensional materials and zero-dimensional materials. Under the action of photoexcitation, the one-dimensional materials and zero-dimensional materials have 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 one-dimensional materials and zero-dimensional materials have no dangling bonds, are stable in nature and have a high melting point, are not easily damaged, can be applied to high-power excitation scenarios, and have characteristics such as good stability and high service life. In addition, the one-dimensional materials and zero-dimensional materials can also be directly integrated with the optical fiber. The optical fiber transmits the laser and serves as a carrier for the one-dimensional materials and zero-dimensional materials, 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 characteristics such as small volume and high integration. In addition, 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-illuminating the tip. Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of an electron source according to an embodiment of the present application.

[0030] Figure 2 It is a schematic radial cross-sectional structure diagram of an electron source according to an embodiment of the present application.

[0031] Figure 3 Schematic structural diagram of an electron source according to an embodiment of the present application.

[0032] Figure 4 Schematic structural diagram of an electron source according to an embodiment of the present application.

[0033] Figure 5 Schematic structural diagram of an electron source according to an embodiment of the present application.

[0034] Figure 6 Schematic structural diagram of an electron source according to an embodiment of the present application.

[0035] Figure 7 Schematic radial cross-sectional structure diagram of an electron source according to an embodiment of the present application.

[0036] Figure 8 Schematic structural diagram of an electron source according to an embodiment of the present application.

[0037] Figure 9 Schematic internal structure diagram of an electron gun according to an embodiment of the present application.

[0038] Reference numerals:

[0039] 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 manners

[0040] For ease of understanding the present application, the present application will be described more comprehensively below. However, the present 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 disclosure of the present application more thorough and comprehensive.

[0041] For simplicity, the present application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and similarly any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, although not explicitly recited, each point or single value between the range endpoints is included in the 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 recited.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. 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 recited number, and "one or more" means two or more in the case of "more".

[0043] The above application content of this application does not intend to describe every disclosed embodiment or every implementation mode in 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 listings are only representative groups and should not be construed as exhaustive.

[0044] In the prior art, the thermionic electron source mainly selects 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. The field emission electron source mainly selects metal tips such as tungsten. Under the action of a strong electric field applied from the outside, the tip discharge effect occurs. 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 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.

[0045] The photoemission electron source uses a metal material 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.

[0046] In addition, graphene can be used as a saturable absorber in traditional technologies. Graphene has broadband saturable absorption characteristics and a fast recovery time, and is used in the Q-switching and pulse 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 graphene saturable absorber mainly utilizes the situation where the light absorption rate (or transmittance) of graphene increases (or decreases) with the increase in 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 the light energy of this part of the drop is output in the form of pulses from the optical splitter of the cavity.

[0047] Based on this, it is necessary to provide a way to quickly and simply irradiate the electron emission layer with laser light, taking into account both the electron emission efficiency and a stable electron source.

[0048] 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 light 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 one-dimensional materials and zero-dimensional materials. The laser light output from the optical fiber can directly irradiate the electron emission layer 120, so that the electron excitation layer is excited by the laser light and emits electrons.

[0049] It should be noted that the "zero-dimensional material" referred to in the present application refers to a substance with a nanoscale size in all three spatial dimensions. It is generally composed of a small number of atoms and molecules and has typical discrete energy levels. The "one-dimensional material" refers to a type of material (such as nanowires, nanoribbons, nanobars, nanocolumns, and nanotubes) with a radial size less than 500 nm, a length (axial) size much higher than the radial size, and an aspect ratio that can range from more than a dozen to thousands or tens of thousands, which can be hollow or solid, and electrons can only move freely in one non-nanoscale direction.

[0050] It should be noted that the "electrical connection" described in this application refers to the connection between components achieved 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.

[0051] As an implementation manner, the conductive connection layer 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 surface of the solid-core optical fiber, the electron emission layer is arranged 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.

[0052] It should be noted that the "laser output path of the optical fiber" described in this application refers to the path where the laser irradiates in the optical fiber. Taking a solid-core optical fiber as an example, the laser output position of the solid-core optical fiber is at the end face of the core, that is, the electron emission layer can be arranged at the core. Taking a side-cut optical fiber as an 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 arranged at the side-cut.

[0053] It can be understood that the electron emission layer of this application can only include an electron excitation layer, or can also 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.

[0054] It can be understood that the electron excitation layer in this application 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, as long as the laser output from the optical fiber can irradiate on the electron excitation layer. And the conductive connection layer does not 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.

[0055] The electron source provided by this application is such that 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, which contains one-dimensional materials and zero-dimensional materials. Under the action of photoexcitation, the one-dimensional materials and zero-dimensional materials have atomic-level thickness, and the excited electrons in the electron excitation layer can be emitted without long-distance transmission, with high electron emission efficiency. Moreover, the one-dimensional materials and zero-dimensional materials have no dangling bonds, are stable in nature and have high melting points, are not easily damaged, and can be applied to scenarios with high-power excitation, featuring good stability, high service life, and low working vacuum degree. In addition, the one-dimensional materials and zero-dimensional materials can also be directly integrated with the optical fiber. 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, facilitating the improvement of the excitation efficiency. And as the carrier of the one-dimensional materials and zero-dimensional materials, 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, featuring small size and high integration. Additionally, the one-dimensional materials and zero-dimensional materials can generate more electron energy levels and electron concentrations, achieving higher electron emission efficiency.

[0056] In some embodiments, the zero-dimensional material in the electron excitation layer is disposed on the one-dimensional material.

[0057] In the electron excitation layer, the one-dimensional material has the characteristic of a small radius of curvature (nanoscale), which can enhance the interaction between light and matter and provide a large field enhancement factor, ensuring multi-photon emission, optical field emission, etc., and is applied to scenarios requiring a high-brightness electron source. The zero-dimensional material 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. The electrons emitted thereby have concentrated energy and small energy dispersion, and the electron emission efficiency is high. By disposing the zero-dimensional material on the one-dimensional material, that is, by compounding the one-dimensional material and the zero-dimensional material, more electron energy levels and electron concentrations can be generated, and the zero-dimensional material can also be used to adjust the one-dimensional material to achieve higher electron emission efficiency, further improving the electron emission efficiency and stability.

[0058] In some embodiments of this application, the angle between the axial direction of the one-dimensional material in the electron generation layer and the laser output path of the optical fiber is 0 to 90°.

[0059] There is an angle between the axial direction of the one-dimensional material in the electron generation layer and the laser output path of the optical fiber, that is, there is an angle between the axial direction of the one-dimensional material and the emission direction of the laser, and the angle is 0 to 90°. When the laser excites the one-dimensional material to generate a linear electron source, it can also excite the zero-dimensional material to generate a point electron source, which can achieve an enhancement effect on the excited electron source and effectively improve the electron emission efficiency.

[0060] In some embodiments, the electron excitation layer includes a plurality of the one-dimensional materials, and the axes of any two of the one-dimensional materials are parallel to each other.

[0061] The axes of the one-dimensional materials in the electron excitation layer are arranged in parallel, and at the same time, the zero-dimensional materials are disposed on the one-dimensional materials, which is beneficial to obtaining an electron beam with consistent orientation and further enhancing the energy concentration.

[0062] In some embodiments, the axis of the one-dimensional material in the electron excitation layer is parallel to the laser output path of the optical fiber.

[0063] The axis of the one-dimensional material in the electron excitation layer is parallel to the laser output path of the optical fiber, that is, the axis of the one-dimensional material is the same as the laser emission direction. At the same time, the zero-dimensional materials are disposed on the one-dimensional materials, so that point emission of the electron source can be realized and the resolution is high.

[0064] In some embodiments, the electron excitation layer includes a plurality of the one-dimensional materials, and the gap between adjacent two of the one-dimensional materials along the radial direction of the one-dimensional material is zero.

[0065] It should be noted that when the one-dimensional materials in the electron excitation layer are densely arranged in the electron excitation layer, the electron excitation layer can directly partially or completely cover 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, as Figure 2 shown, "densely arranged" means that the gap between the one-dimensional materials in the electron excitation layer along the radial direction of the one-dimensional material is zero.

[0066] When the axis of the one-dimensional material in the electron excitation layer is parallel to the laser output path of the optical fiber and the gap between adjacent two one-dimensional materials along the radial direction of the one-dimensional material is greater than zero, the emitted electron energy dispersion is low, the brightness is high, and a large electron beam of the electron source can be realized.

[0067] In some embodiments, as Figure 3 shown, the axis of the one-dimensional material in the electron excitation layer is parallel to the laser output path of the optical fiber, and the gap between adjacent two of the one-dimensional materials along the radial direction of the one-dimensional material is zero, which is beneficial to further improving the energy concentration of the emitted electrons.

[0068] In some embodiments, in the electron excitation layer, the zero-dimensional material is disposed at the end and / or side wall of the one-dimensional material.

[0069] It can be understood that when the one-dimensional material is solid, the zero-dimensional material can be disposed at the end and / or outer side wall of the one-dimensional material; while when the one-dimensional material is hollow, the zero-dimensional material can be disposed at the end and / or inner and outer side walls of the one-dimensional material.

[0070] In some embodiments, as Figure 3As shown, the zero-dimensional material is disposed at the end of the one-dimensional material.

[0071] In some embodiments, as Figure 4 shown, the zero-dimensional material is disposed on the sidewall of the one-dimensional material.

[0072] In some embodiments, the diameter of the one-dimensional material is 1 nm to 500 nm, and the length of the one-dimensional material is 10 nm to 1 mm.

[0073] It can be understood that when the one-dimensional material is hollow, the diameter of the one-dimensional material refers to its outer diameter.

[0074] In some embodiments, the average particle size of the zero-dimensional material is 1 nm to 100 nm.

[0075] In some embodiments, the one-dimensional material includes at least one of nanotubes, nanorods, nanowires, nanobelts, and nanocoaxial cables.

[0076] Optionally, the one-dimensional nanomaterial includes at least one of carbon nanotubes, silicon nanowires, germanium nanowires, silver nanowires, gold nanorods, and boron nitride nanotubes.

[0077] In some embodiments, the zero-dimensional material includes one or more of fullerenes, carbon black, nanodiamonds, diamond color centers, nanometal particles, perovskite quantum dots, graphite quantum dots, CdZnSe / ZnS zinc sulfide quantum dots, and CdZnS quantum dots; optionally nanometal particles and / or graphite quantum dots.

[0078] In some embodiments, the nanotubes include at least one of carbon nanotubes, Si nanotubes, Se nanotubes, Te nanotubes, Bi nanotubes, BN nanotubes, BCN nanotubes, WS nanotubes, MoS2 nanotubes, TiO z nanotubes.

[0079] The nanorods referred to in this application refer to one-dimensional cylindrical (or polygonal in cross-section) solid nanomaterials with relatively short lengths and relatively straight longitudinal morphologies; while nanowires refer to one-dimensional solid nanomaterials with relatively long lengths and morphologies that are straight or curved.

[0080] In some embodiments, the nanowires include elemental nanowires such as Si and Ge; oxide nanowires such as SnO and ZnO; nitride nanowires such as GaN and Si z N4; sulfide nanowires such as CdS and ZnS; ternary compound nanowires such as BaTiO and PbTiO.

[0081] The nanobelts described in this application refer to those with a quadrilateral cross-section, and the aspect ratio generally ranges from several to more than a dozen. The nanobelts include ZnO nanobelts, SnO nanobelts, etc. The nanocoaxial cables refer to core / shell quasi-one-dimensional structures at the nanoscale in the radial direction, including C / BN / CSi / SiO2, Sic / SiO z etc.

[0082] In some embodiments, the one-dimensional material and the zero-dimensional material each independently include doping elements.

[0083] In this application, by doping elements into the one-dimensional material and / or the zero-dimensional material, the conductivity and electron emission performance of the one-dimensional material and / or the zero-dimensional material are improved. For example, phosphorus elements can improve the conductivity and electron emission performance of the one-dimensional material and / or the zero-dimensional material.

[0084] Optionally, the doping elements include at least one of boron, nitrogen, phosphorus, lithium, and potassium.

[0085] In some embodiments, the thickness of the electron excitation layer is 0.3 nm to 100 μm.

[0086] 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.

[0087] In some embodiments, as Figure 5 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 disposed on the side of the electron excitation layer 150 relatively close to the optical fiber 110.

[0088] In some embodiments, the auxiliary layer is stacked on the side of the electron emission layer relatively far from the optical fiber.

[0089] 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 support the structure of 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.

[0090] In some embodiments, the auxiliary layer has conductivity and / or heat dissipation, and the auxiliary layer is electrically connected to the conductive connection layer.

[0091] When the electron excitation layer cannot be directly connected and conductively connected to the conductive connection layer, for example, when the one-dimensional materials in the electron excitation layer are arranged at a low density in the electron excitation layer, it is connected to the conductive connection layer through an auxiliary layer with conductivity, so as to achieve electron conduction between the electron excitation layer and the conductive connection layer through the auxiliary layer. In addition, the auxiliary layer also has heat dissipation properties and can assist the electron excitation layer in heat dissipation, improving the heat dissipation effect. Among them, as Figure 7 shown, "low-density arrangement" means that the electron excitation layer contains multiple one-dimensional materials, and there is a case where the gap between two adjacent one-dimensional materials along the radial direction of the one-dimensional material is greater than zero.

[0092] In some embodiments, the auxiliary layer includes a conductive material, and the conductive material includes at least one of a metal material, a semiconductor material, and a conductive carbon material.

[0093] Optionally, the conductive material includes at least one of chromium, gold, silicon, silicon oxide, and graphene.

[0094] In some embodiments, the thickness of the auxiliary layer is 0.3 nm to 10 nm, and the light transmittance is 10% to 98%.

[0095] It can be understood that the "light transmittance" described in this application refers to the transmittance of laser light in the auxiliary layer.

[0096] By controlling the thickness and light transmittance of the auxiliary layer, it can ensure that the laser light passes through the auxiliary layer and irradiates the electron excitation layer.

[0097] In some embodiments, the conductive material is a metal material, and the laser wavelength in the optical fiber is 200 nm to 10 μm.

[0098] When the auxiliary layer uses a metal material, by controlling the laser parameters, the problem of laser irradiation causing melting of the conductive metal can be avoided, ensuring that the auxiliary layer has the functions of support and conductivity.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] In some embodiments, such as Figure 8As shown, the optical fiber is a side-cut 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.

[0103] 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 in the pores or pore walls of the porous optical fiber, so that the laser has a long interaction distance with the zero-dimensional material, thereby achieving high-brightness electron emission. Since the porous optical fiber itself has a special optical transmission mode, and different types or dimensions of materials can be continuously grown or transferred in the pores or pore walls where the zero-dimensional material has been grown or filled to form a heterojunction, multi-functional electron emission can be achieved.

[0104] 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 optical interaction distance with the material can be achieved 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 achieve electron emission with precisely controlled parameters.

[0105] 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 usage requirements.

[0106] In some embodiments, the electron emission layer is formed by at least one of dry transfer, wet transfer, and direct growth.

[0107] In some embodiments, the electron emission layer is prepared by dry transfer. The preparation method includes: transferring the one-dimensional material provided with 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.

[0108] In some embodiments, the electron emission layer is prepared by wet transfer. The preparation method includes: directly preparing the one-dimensional material provided with 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.

[0109] 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 output side of the optical fiber by at least one of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy, and liquid filling.

[0110] In some embodiments, the one-dimensional material provided with the zero-dimensional material can be prepared by arc discharge method or chemical vapor deposition method.

[0111] The second aspect of the present application provides an electron gun, which includes a housing, a grid, an anode, and an electron source as described in the first aspect;

[0112] 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.

[0113] 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.

[0114] The third aspect of 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 exposure machine, an X-ray tube, an electron diffractometer, and a display.

[0115] Embodiment

[0116] 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 content disclosed in 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.

[0117] 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.

[0118] Embodiment 1

[0119] See Figure 3 , carbon nanotubes with an outer diameter of about 20 nm and a length of about 5 μm are grown on the end face of the solid-core optical fiber with a conductive connection layer by CVD method, and the axial direction of the carbon nanotubes is parallel to the laser output path of the optical fiber; then graphite quantum dots with an average particle size of about 5 nm are grown at the end of the carbon nanotubes to prepare an electron excitation layer with a thickness of about 20 nm, and the electron excitation layer is electrically connected to the conductive connection layer to obtain an electron source.

[0120] Example 2

[0121] See Figure 6 , deposit an auxiliary layer with a thickness of 5 nm, a material of gold, and a light transmittance of 60% on the end face of a solid-core optical fiber with a conductive connection layer. Then, use the CVD method to grow carbon nanotubes with an outer diameter of about 20 nm and a length of about 5 μm on the surface of the auxiliary layer. The axial direction of the carbon nanotubes is parallel to the laser output path of the optical fiber. After that, grow graphite quantum dots with an average particle size of about 5 nm at the end of the carbon nanotubes, prepare an electron excitation layer with a thickness of about 20 nm, and electrically connect the electron excitation layer to the conductive connection layer to obtain an electron source.

[0122] Example 3

[0123] Similar to the preparation method of Example 1, the difference is that: replace the graphite quantum dots with nano gold particles.

[0124] Example 4

[0125] Similar to the preparation method of Example 1, the difference is that: replace the carbon nanotubes with silicon nanowires.

[0126] Example 5

[0127] Similar to the preparation method of Example 2, the difference is that: replace the material of the auxiliary layer with graphene, and the obtained light transmittance is 98%.

[0128] Comparative Example 1

[0129] Prepare an electron source according to the structure of Example 1, the difference is that: replace the electron excitation layer in Example 1 with a gold layer with a thickness of 200 nm, and the gold layer is prepared by deposition.

[0130] Comparative Example 2

[0131] Prepare an electron source according to the structure of Example 3, the difference is that: replace the electron excitation layer in Example 3 with a gold layer with a thickness of 20 nm, and the gold layer is prepared by deposition.

[0132] As Figure 9 shown, assemble the electron sources 100 prepared by the above-mentioned examples and comparative examples into an electron gun. The electron gun further includes a housing, a grid 200, and an anode 300. Perform performance tests on the prepared 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:

[0133] (1) Stability test: When the excitation power is 50% of the damage power, the vacuum degree is 2×10 -5For Pa, with a continuous emission current for 1 h, after removing the defective 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.

[0134] (2) Lifetime test: When the excitation power is 50% of the damage power, the vacuum degree is 2×10 -5 Pa, with a continuous emission current, the time until the current decays to less than 10% of the initial value is defined as the lifetime.

[0135] (3) Operating vacuum degree test: When the excitation power is 50% of the damage power, with a continuous emission current, gradually increase the operating environment vacuum degree of the electron gun until the current shows a 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 operating vacuum degree.

[0136] 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 .

[0137] Table 1

[0138]

[0139] From the above Table 1, 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 using one-dimensional materials and zero-dimensional materials as the electron excitation layer in this application is better than that of traditional metal layers and metal nanolayers.

[0140] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not conflict, they should all be considered as within the scope described in this specification.

[0141] The above-described embodiments only represent several implementation manners of this application, and 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 this application patent should 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 one-dimensional materials and 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 zero-dimensional material in the electron excitation layer is disposed on the one-dimensional material.

3. The electron source according to claim 2, characterized in that, The included angle between the axial direction of the one-dimensional material in the electron excitation layer and the laser output path of the optical fiber is 0 to 90°.

4. The electron source according to claim 2 or 3, characterized in that, The electron excitation layer contains a plurality of the one-dimensional materials, and the axial directions of any two of the one-dimensional materials are parallel to each other.

5. The electron source according to claim 2, wherein The axial direction of the one-dimensional material in the electron excitation layer is parallel to the laser output path of the optical fiber.

6. The electron source according to claim 4 or 5, characterized in that, The electron excitation layer contains a plurality of the one-dimensional materials, and the gap between adjacent two of the one-dimensional materials along the radial direction of the one-dimensional material is zero.

7. The electron source according to any one of claims 1 to 3, characterized in that, The diameter of the one-dimensional material is 1 nm to 500 nm, and the length of the one-dimensional material is 10 nm to 1 mm.

8. The electron source according to any one of claims 1-3, characterized in that, The average particle size of the zero-dimensional material is 1 nm to 100 nm.

9. The electron source according to any one of claims 1 to 3, characterized in that, The one-dimensional material includes at least one of a nanotube, a nanorod, a nanowire, a nanobelt, and a nanocoaxial cable; Optionally, the one-dimensional material includes at least one of a carbon nanotube, a silicon nanowire, a germanium nanowire, a silver nanowire, a gold nanorod, and a boron nitride nanotube.

10. The electron source according to any one of claims 1-3, characterized in that, The zero-dimensional material includes one or more of fullerenes, carbon black, nanodiamonds, diamond color centers, nano metal particles, perovskite quantum dots, graphite quantum dots, CdZnSe / ZnS zinc sulfide quantum dots, and CdZnS quantum dots; Optionally, it is nano metal particles and / or graphite quantum dots.

11. The electron source according to any one of claims 1 to 3, characterized in that, The thickness of the electron excitation layer is 0.3 nm to 100 μm.

12. The electron source according to any one of claims 1-3, 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.

13. The electron source according to claim 12, characterized in that, The auxiliary layer has electrical conductivity and / or heat dissipation, and the auxiliary layer is electrically connected to the conductive connection layer.

14. The electron source according to claim 12, characterized in that, 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%.

15. The electron source according to claim 14, characterized in that, The conductive material is a metal material, and the laser wavelength in the optical fiber is 200 nm to 10 μm.

16. The electron source according to any one of claims 1-15, 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.

17. An electron gun, characterized in that, It includes a housing, a grid, an anode, and the electron source according to any one of claims 1-16; 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.

18. Use of an electron source according to any one of claims 1-16, 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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