Electron source, electron gun and application of electron source

Abstract

The invention provides an electron source and a preparation method and application thereof, the electron source comprises an optical fiber, a conductive connection layer, an electron emission layer and a heat dissipation layer, and the conductive connection layer is arranged on the outer surface of the optical fiber; the electron emission layer at least comprises an electron excitation layer electrically connected with the conductive connection layer, and the material of the electron excitation layer comprises at least one of a zero-dimensional material, a one-dimensional material and a two-dimensional material; the electron emission layer is arranged on a laser emission path of the optical fiber, 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, and the heat dissipation layer is arranged on the surface of the side, close to the optical fiber, of the electron emission layer and / or the surface of the side, away from the optical fiber, of the electron emission layer. According to the invention, the heat dissipation layer is adopted to dissipate heat and cool the low-dimensional material electron emission layer, so that the electron source can support electron excitation with higher optical power, and has the characteristics of good stability, long service life and the like; and the optical fiber can provide an adjustable and stable excitation source, and the application scene is wide.

Description

Technical Field

[0001] The present invention relates to the technical field of electron sources, and particularly to an electron gun of an electron source 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 classified into thermionic electron sources, field emission electron sources, and photoemission electron sources according to the excitation method. Thermionic electron sources mainly select metal materials. When heated to thousands of degrees Celsius, electrons are thermally excited to escape from the surface of the material to form vacuum electrons. Field emission electron sources mainly select metal tips. Under the action of a strong electric field applied externally, a tip discharge effect is generated. A photoemission electron source uses a metal material as a photocathode, and uses laser irradiation to excite the photocathode material to generate electrons.

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

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

[0005] In a first aspect, the present application provides an electron source, which includes an optical fiber, a conductive connection layer, an electron emission layer, and a heat dissipation layer. The conductive connection layer is disposed on the outer surface of the optical fiber;

[0006] The electron emission layer at least includes an electron excitation layer electrically connected to the conductive connection layer. The material of the electron excitation layer includes at least one of zero-dimensional materials, one-dimensional materials, and two-dimensional materials;

[0007] The electron emission layer is disposed on the laser emission path of the optical fiber, and the laser emitted by the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons. The heat dissipation layer is disposed on one or both of the surfaces of the electron emission layer close to and / or away from the optical fiber.

[0008] In some embodiments, the heat dissipation layer extends to the outer surface of the optical fiber.

[0009] In some embodiments, the electron source further includes a cooling layer stacked with a part of the heat dissipation layer located on the outer surface of the optical fiber. The cooling layer is used to cool the heat dissipation layer.

[0010] In some embodiments, the cooling layer includes at least one of a refrigeration layer and a cold storage layer.

[0011] In some embodiments, the cold storage layer includes a main body, and a liquid storage cavity for injecting a coolant is provided in the main body.

[0012] In some embodiments, the conductive connection layer, the cooling layer, and the heat dissipation layer are sequentially arranged on the outer surface of the optical fiber.

[0013] In some embodiments, the heat dissipation layer is disposed on a surface of the electron emission layer close to the optical fiber, the light transmittance of the heat dissipation layer is ≥10%, and the heat dissipation layer at least partially covers the electron emission layer.

[0014] In some embodiments, the heat dissipation layer is provided with a light-transmitting hole corresponding to the area where the electron emission layer is irradiated by laser.

[0015] In some embodiments, the thickness of the heat dissipation layer is 0.1 nm to 1 mm.

[0016] In some embodiments, the material of the heat dissipation layer includes at least one of graphite, boron nitride, carbon nanotubes, silver, aluminum, and copper.

[0017] In some embodiments, the electron emission layer further includes a conductive support layer, and the conductive support layer is disposed on a side of the electron emission base layer close to the optical fiber; or,

[0018] The conductive support layer is disposed on a side of the electron excitation layer away from the optical fiber.

[0019] In some embodiments, the zero-dimensional material includes at least one of quantum dots, fullerenes, NV color centers, and nanocrystals.

[0020] In some embodiments, the one-dimensional material includes at least one of nanotubes, nanoribbons, and nanowires.

[0021] In some embodiments, the two-dimensional material includes at least one of graphene, black phosphorus, transition metal chalcogenides, and hexagonal boron nitride.

[0022] In some embodiments, the optical fiber is a solid-core optical fiber, a tip optical fiber, a side-cut optical fiber, or a porous optical fiber.

[0023] In a second aspect, 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;

[0024] The electron source is fixed in the housing, and the grid and the anode are sequentially arranged on an electron emission side of the electron source.

[0025] In a third aspect, the present application provides an application of the electron source as described in the first aspect. The application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, a free electron laser, and a display.

[0026] Compared with the traditional technology, the present application has at least the following beneficial effects:

[0027] By adding a heat dissipation layer in the electron source, the heat dissipation layer is in contact with the electron emission layer for heat conduction, dispersing the heat in the electron emission layer into the heat dissipation layer, reducing the temperature rise of the electron emission layer due to laser irradiation, maintaining the temperature uniformity of the electron emission region of the electron excitation layer, ensuring stable electron emission, increasing the service life, and being able to support electron excitation with a larger optical power. Moreover, the present application integrates zero-dimensional materials, one-dimensional materials, and two-dimensional materials with optical fibers. The optical fibers can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, can be applicable to different application scenarios, and do not require a complex optical path. The electron source of the present application has the characteristics of stable emission, high service life, small volume, and high integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the electron source provided in Embodiment 1 of the present application. Among them, 110a - solid-core optical fiber; 120a - electron emission layer; 130a - conductive connection layer; 140a - heat dissipation layer.

[0029] Figure 2 It is a schematic structural diagram of the electron source provided in Embodiment 2 of the present application. Among them, 110b - solid-core optical fiber; 120b - electron emission layer; 130b - conductive connection layer; 140b - heat dissipation layer.

[0030] Figure 3 It is a schematic structural diagram of the electron source provided in Embodiment 3 of the present application. Among them, 110c - solid-core optical fiber; 120c - electron emission layer; 121c - conductive support layer; 122c - electron excitation layer; 130c - conductive connection layer; 140c - heat dissipation layer.

[0031] Figure 4 It is a schematic structural diagram of the electron source provided in Embodiment 4 of the present application. Among them, 110d - solid-core optical fiber; 120d - electron emission layer; 130d - conductive connection layer; 140d - heat dissipation layer.

[0032] Figure 5 It is a schematic structural diagram of the electron source provided in Embodiment 5 of the present application. Among them, 110e - solid-core optical fiber; 120e - electron emission layer; 130e - conductive connection layer; 140e - heat dissipation layer; 150e - cooling layer.

[0033] Figure 6Schematic structural diagram of the electron source provided in Embodiment 6 of the present application, where 110f is the tip optical fiber; 120f is the electron emission layer; 130f is the conductive connection layer; 140f is the heat dissipation layer.

[0034] Figure 7 Schematic structural diagram of the electron source provided in Embodiment 7 of the present application, where 110g is the perforated optical fiber; 120g is the electron emission layer; 130g is the conductive connection layer; 140g is the heat dissipation layer.

[0035] Figure 8 Schematic internal structural diagram of the electron gun provided in an embodiment of the present application, where 100 is the electron source; 200 is the grid; 300 is the anode. Detailed implementation manners

[0036] The present invention will be further described in detail below in combination with the implementation manners and embodiments. These implementation manners and embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. The purpose of providing these implementation manners and embodiments is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. It should also be understood that the present invention can be implemented in many different forms and is not limited to the implementation manners and embodiments described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. In addition, in the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. It should be understood that the present invention can be implemented without one or more of these details.

[0037] 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 the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0038] In the present invention, "optionally", "optional", "option" mean optional, that is, it refers to any one of the two parallel options of "yes" or "no". If "optional" appears in a technical solution for multiple times, without special explanation and without contradiction or mutual restriction relationship, each "optional" is independent of each other.

[0039] In the present invention, in "the first aspect", "the second aspect", etc., the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0040] In the present invention, among the technical features described in an open-ended manner, there are included closed technical solutions composed of the listed features, as well as open-ended technical solutions including the listed features.

[0041] In the present invention, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of the selectable numerical values within this numerical interval is regarded as continuous, and includes the two numerical endpoints of this numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in the present application should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" is allowed to broadly include quantitative intervals such as percentage intervals, ratio intervals, and ratio value intervals.

[0042] All documents mentioned in the present application are cited herein as references, just as if each document was cited separately as a reference. Unless it conflicts with the inventive purpose and / or technical solution of the present application, the cited documents related to the present invention are cited in their entirety and for all purposes. When the present application involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the present application involves cited documents, the examples and preferred methods of the relevant technical features cited can also be incorporated as references into the present application, but only to the extent that the present invention can be implemented. It should be understood that when the cited content conflicts with the description in the present application, the present application shall prevail or be amended adaptively according to the description in the present application.

[0043] In traditional technologies, for thermionic electron sources, materials with metallic properties such as tungsten filaments and lanthanum hexaboride are mainly selected. When heated to thousands of degrees Celsius, electrons are thermally excited to escape from the material surface to form vacuum electrons. For field emission electron sources, metal tips such as tungsten are mainly selected. 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 operate in a relatively poor vacuum environment, has good adaptability to the environment and good stability, but has a low brightness and poor coherence. The electron beam of the field emission electron source has a high brightness and good coherence, but has high requirements for the degree of vacuum, etc., and is very sensitive to vibrations, etc. Whether it is a thermionic electron source or a field emission electron source, the regulation of electron emission properties is limited, and it is impossible to balance the emission efficiency and stability.

[0044] The photoemission electron source uses metal materials such as Au as the material of the electron emission layer, with a thickness of more than 50 nm, even reaching hundreds of nanometers. However, the inventors of the present application have found through research that the electron emission layer made of metal materials has a relatively large thickness, and the distance between the surface directly affected by the laser in the electron emission layer (the bottom layer of the electron emission layer) and the surface from which electrons are emitted (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 emission efficiency. Moreover, metal materials are prone to damage under high-power laser irradiation, which affects the service life of the electron emission layer, and thus affects the emission efficiency and stability of electrons. Some electron sources use the method of laser side incidence to excite electrons. Compared with laser back incidence, side incidence requires modification of the vacuum chamber, and the irradiation method has a high operation difficulty and problems such as unstable excitation conditions.

[0045] In addition, in traditional technologies, graphene is used as a saturable absorber. Graphene has broadband saturable absorption characteristics and a fast recovery time, and is used in the Q-switching and mode-locking of lasers, or the laser spectrum is adjusted by using graphene to achieve sensing detection. However, there are differences between graphene laser regulation and graphene electron emission. The graphene photoexcitation electron source is based on the photoelectric effect to excite and emit electrons, while graphene laser regulation is based on the principle of light absorption to regulate the output parameters of the laser. Specifically, there are obvious differences between graphene laser regulation and graphene electron emission. Graphene electron emission is based on the photoelectric effect, while graphene laser regulation is based on the principle of light absorption. In laser regulation, the graphene saturable absorber mainly utilizes the situation where the light absorption rate (or transmittance) of graphene increases (or decreases) as the incident light power increases and finally reaches the saturation threshold. 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 pulses.

[0046] Based on this, it is necessary to provide an electron source that can balance the electron emission efficiency and stability.

[0047] In the present application, a heat dissipation layer is added to the electron source. The heat dissipation layer is in contact with the electron emission layer for heat conduction, thereby avoiding uneven electron emission or damage to the electron excitation layer caused by a high temperature of the electron excitation layer; ensuring stable electron emission, increasing the service life, and being able to support electron excitation with a larger optical power. In addition, in the present application, low-dimensional materials such as zero-dimensional materials, one-dimensional materials, and two-dimensional materials are directly integrated with the optical fiber. The optical fiber can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, and can be applicable to different application scenarios.

[0048] In the first aspect of the present application, an electron source is provided. The electron source includes an optical fiber, a conductive connection layer, an electron emission layer, and a heat dissipation layer. The conductive connection layer is disposed on the outer surface of the optical fiber;

[0049] The electron emission layer at least includes an electron excitation layer electrically connected to the conductive connection layer. The material of the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material;

[0050] The electron emission layer is disposed on the laser emission path of the optical fiber, and the laser emitted by the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons. The heat dissipation layer is disposed on one or both of the surfaces of the electron emission layer close to and / or away from the optical fiber.

[0051] In the present application, by adding a heat dissipation layer to the electron source, the heat dissipation layer conducts heat in contact with the electron emission layer, disperses the heat in the electron emission layer into the heat dissipation layer, reduces the temperature rise of the electron emission layer due to laser irradiation, maintains the temperature uniformity of the electron emission region of the electron excitation layer, ensures stable electron emission, increases the service life, and can support electron excitation with a larger optical power. Moreover, in the present application, a zero-dimensional material, a one-dimensional material, and a two-dimensional material are integrated with an optical fiber. The optical fiber 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. The electron source of the present application has the characteristics of stable emission, high service life, small volume, and high integration.

[0052] It should be noted that in the present application, the low-dimensional material refers to a zero-dimensional material, a one-dimensional material, or a two-dimensional material.

[0053] Among them, the zero-dimensional material has typical discrete energy levels. Under the action of laser excitation, electrons are mainly excited by tunneling from the discrete energy levels, and electrons with very high monochromaticity can be excited. The emitted electrons have concentrated energy and small energy dispersion. The one-dimensional material has the characteristic of a small radius of curvature (nanoscale), 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 that require a high-brightness electron source. The two-dimensional material has the characteristic of an atomic layer thickness. During the interaction between the laser and the two-dimensional material, the optical transmission mode is hardly affected, and the stability is high; moreover, the excited electrons can be directly emitted without internal scattering in the material, ensuring the purity of the properties of the emitted electrons and an extremely narrow pulse width.

[0054] In this application, zero-dimensional materials refer to substances with nanoscale dimensions in all three spatial dimensions, where electrons cannot move freely; one-dimensional materials refer to materials where electrons can move freely only in one non-nanoscale direction; two-dimensional materials refer to materials where electrons can move freely only in two non-nanoscale dimensions (i.e., planar motion). The nanoscale refers to 0.1 nm to 100 nm. Zero-dimensional materials, one-dimensional materials, and two-dimensional materials can emit electrons under laser excitation.

[0055] It should be noted that in this application, the light-emitting path of the optical fiber refers to the path of laser irradiation in the optical fiber. Taking a solid-core optical fiber as an example, the laser emission position of the solid-core optical fiber is located 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 emission position of the side-cut optical fiber is located on the side-cut side of the side-cut optical fiber, that is, the electron emission layer can be arranged at the side-cut. It can be understood that in this application, the electron emission layer can be in direct contact with the laser emission surface of the optical fiber, or can be supported by other structural layers. That is to say, it is only necessary to make the laser emitted from the optical fiber irradiate on the electron emission layer.

[0056] It should also be noted that the purpose of electrically connecting the conductive connection layer and the electron emission layer in this application is to connect the low-dimensional material with the external circuit to form a complete circuit and achieve charge replenishment and electric field control. As an implementation manner, the conductive connection layer in this application can be directly connected to the electron emission layer. In other implementation manners, the conductive connection layer and the electron emission layer can also be electrically connected through other conductive structures. For example, taking a solid-core optical fiber as an example, the conductive connection layer is arranged on the side of the solid-core optical fiber, the electron emission layer is arranged at the core of the solid-core optical fiber, and the conductive connection layer and the electron emission layer are electrically connected, and there is no conductive connection layer at the core.

[0057] In some embodiments, the zero-dimensional material, one-dimensional material, or two-dimensional material independently includes a doping element.

[0058] In this application, by doping elements into the low-dimensional material, the conductivity of the low-dimensional material is improved, the work function is changed, and the electron emission performance is adjusted. For example, alkali metal and alkaline earth metal elements can improve the conductivity of the low-dimensional material and reduce the work function of the low-dimensional material to increase the emission beam current at the same time; elements such as B, C, N, O, F, and rare earths can create discrete energy levels to obtain an electron beam with a narrow energy range.

[0059] Optionally, the doping element includes at least one of alkali metals, alkaline earth metals, transition metals, rare earth elements, halogen elements, and light elements. The light elements include at least one of B, C, N, and O.

[0060] In some embodiments, electrodes are provided on the conductive connection layer. Optionally, the conductive connection layer may entirely cover the outer surface of the optical fiber or partially cover the outer surface of the optical fiber, and there is no conductive connection layer in the light output path of the laser.

[0061] In some embodiments, the thickness of the conductive connection layer is 10 nm to 1 μm, and for example, it may be 10 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1 μm.

[0062] In some embodiments, the material of the conductive connection layer includes at least one of Al, Au, Pt, Ag, Cu, Cr, Pd, and Ti.

[0063] In some embodiments, the thickness of the electron excitation layer is 0.1 nm to 100 nm, and for example, it may be 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.

[0064] In some embodiments, the heat dissipation layer extends to the outer surface of the optical fiber.

[0065] In this application, by extending the heat dissipation layer to the outer surface of the optical fiber, the heat exchange area between the heat dissipation layer and the environment is increased, and thus the heat dissipation effect of the heat dissipation layer is improved.

[0066] In some embodiments, the heat dissipation layer located on the outer surface of the optical fiber has a fin structure. In this application, by designing the heat dissipation layer in contact with the environment into a fin structure, the contact area between the heat dissipation layer and the environment is increased, and thus the heat dissipation effect of the heat dissipation layer is improved.

[0067] In some embodiments, the electron source further includes a cooling layer stacked with a part of the heat dissipation layer located on the outer surface of the optical fiber, and the cooling layer is used to cool the heat dissipation layer.

[0068] In this application, by additionally providing a cooling layer, the cooling layer is used to cool the heat dissipation layer, improving the heat conduction of the heat dissipation layer and avoiding the influence of heat accumulation in the heat dissipation layer on its heat dissipation effect.

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

[0070] In some embodiments, the cold storage layer includes a main body, and a liquid storage cavity for injecting a coolant is arranged in the main body. Optionally, the liquid storage cavity is connected to a cooling source in a circulating manner. In the present application, the heat in the heat dissipation layer is further exported by the circulating coolant, thereby improving the heat dissipation stability.

[0071] In some embodiments, the cooling layer includes a refrigeration layer. Optionally, the refrigeration layer includes a Peltier element. Refrigeration is performed by the Peltier element, thereby reducing the temperature of the heat dissipation layer.

[0072] In some embodiments, the conductive connection layer, the cooling layer, and the heat dissipation layer are sequentially arranged on the outer surface of the optical fiber.

[0073] In some embodiments, the heat dissipation layer is arranged on the surface of the electron emission layer close to the optical fiber. The light transmittance of the heat dissipation layer is ≥10%, and the heat dissipation layer at least partially covers the electron emission layer. Optionally, the heat dissipation layer completely covers the electron emission layer. For example, the light transmittance can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%. In the present application, the heat dissipation layer with light transmittance (light transmittance ≥10%) is arranged on the side of the electron emission layer close to the optical fiber. The heat dissipation layer can not only contact and dissipate heat with the electron excitation layer, reducing the temperature rise of the electron emission layer; but also can serve as the structural support of the electron excitation layer. Taking zero-dimensional materials and one-dimensional materials as examples, the zero-dimensional materials and one-dimensional materials can be directly arranged on the heat dissipation layer, and the heat dissipation layer supports the zero-dimensional materials and one-dimensional materials; taking two-dimensional materials as an example, the two-dimensional materials can be laid flat on the heat dissipation layer, improving the flatness of the two-dimensional materials.

[0074] In some embodiments, the heat dissipation layer is provided with a light-transmitting hole corresponding to the area where the electron emission layer is irradiated by the laser

[0075] In the present application, when the heat dissipation layer has non-light-transmitting property (light transmittance <10%), a light-transmitting hole is arranged on the heat dissipation layer for transmitting the laser, avoiding the heat dissipation layer blocking the laser and affecting electron emission. Further, when the heat dissipation layer is located on the side of the electron emission layer away from the optical fiber, electrons can be emitted through the light-transmitting hole, avoiding the existence of the heat dissipation layer affecting the emission of electrons.

[0076] In some embodiments, the thickness of the heat dissipation layer is 0.1 nm to 1 mm. For example, it can be 0.1 nm, 1 nm, 10 nm, 100 nm, 1 μm, 10 μm, 100 μm, 500 μm, or 1 mm. Optionally, the thickness is 0.3 nm to 1 μm.

[0077] In some embodiments, the material of the heat dissipation layer includes at least one of graphite, boron nitride, carbon nanotubes, silver, aluminum, and copper.

[0078] In this application, by selecting the material of the heat dissipation layer, while ensuring that the heat dissipation layer has the heat dissipation function, it also has electrical conductivity or transparency, which can improve the functionality of the heat dissipation layer. For example, the material of the heat dissipation layer is selected as graphite. Graphite not only has good heat dissipation performance, but also has good electrical conductivity. Therefore, graphite is in contact with the electron excitation layer, and graphite is in contact with the conductive connection layer to achieve the electrical connection between the electron excitation layer and the conductive connection layer.

[0079] In some embodiments, the electron emission layer further includes a conductive support layer, and the conductive support layer is disposed on a side of the electron emission base layer close to the optical fiber; or,

[0080] The conductive support layer is disposed on a side of the electron excitation layer away from the optical fiber.

[0081] In some embodiments, the material of the conductive support layer includes at least one of conductive metal and graphene.

[0082] In some embodiments, the thickness of the conductive support layer is 0.1 nm to 100 nm, and for example, it can be 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0083] In some embodiments, the conductive support layer is disposed on a side where the electron excitation layer emits electrons, and the thickness of the conductive support layer is 0.1 nm to 10 nm. Thereby reducing the influence of the conductive support layer on the electron emission effect.

[0084] In some embodiments, the zero-dimensional material includes at least one of quantum dots, fullerenes, NV color centers, and nanocrystals. Among them, the NV color center refers to the nitrogen vacancy color center, and the quantum dots include at least one of carbon quantum dots, CdSe colloidal quantum dots, and GaAs semiconductor quantum dots.

[0085] In some embodiments, the one-dimensional material includes at least one of nanotubes, nanoribbons, and nanowires. Optionally, the nanowires include at least one of gold nanowires, semiconductor (GaAs) nanowires, and Te quantum wires; the nanotubes include carbon nanotubes.

[0086] In some embodiments, the two-dimensional material includes at least one of graphene, black phosphorus, transition metal chalcogenides, and hexagonal boron nitride. Optionally, the transition metal chalcogenides include at least one of WS2, WSe2, and NbSe2.

[0087] In some embodiments, the optical fiber is a solid-core optical fiber, a needle-tip optical fiber, a side-cut optical fiber, or a perforated optical fiber.

[0088] In some embodiments, the optical fiber is a tip optical fiber, and the heat dissipation layer is sleeved on the tip optical fiber and conducts heat in contact with the electron emission layer. In this application, the low-dimensional material 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 an electron source with higher brightness can be obtained. The low-dimensional material can be a two-dimensional material. Further, at least one of a zero-dimensional material and a one-dimensional material is arranged on the two-dimensional material, so as to realize functions such as high brightness, low energy dispersion, and narrow pulse width.

[0089] In some embodiments, the optical fiber is a side-cut optical fiber, and the heat dissipation layer is arranged on the side-cut surface of the side-cut optical fiber and conducts heat in contact with the electron emission layer. In this application, the low-dimensional material is arranged on the side-cut surface of the side-cut optical fiber, and the evanescent wave leaking from the core interacts with the low-dimensional material in the horizontal direction. For example, when the low-dimensional material is a two-dimensional material, edge states similar to one-dimensional materials are obtained at the side-cut, forming a new electron emission structure to realize functions such as high brightness, low energy dispersion, and narrow pulse width; when the low-dimensional material is a one-dimensional material, edge states of zero-dimensional materials are obtained at the side-cut, forming a new electron emission structure to realize functions such as high brightness, low energy dispersion, and narrow pulse width; when the low-dimensional material is a combination of two-dimensional materials, one-dimensional materials, and zero-dimensional materials, the energy band of the two-dimensional material can be modulated by doping one-dimensional and zero-dimensional materials, improving the interaction between light and materials, and realizing electron emission with functions such as high brightness, low energy dispersion, and narrow pulse width.

[0090] In some embodiments, the optical fiber is a holey optical fiber, and the heat dissipation layer is arranged at the core of the holey optical fiber and conducts heat in contact with the electron emission layer. The holey optical fiber in this application is a type of optical fiber with microstructures or completely hollow, including photonic crystal fibers, anti-resonant fibers, or capillary fibers, etc. The low-dimensional material can be arranged in the pores or pore walls of the holey optical fiber, so that the laser has a longer interaction distance with the low-dimensional material, thereby realizing high-brightness electron emission. Since the holey optical fiber itself has a special light transmission mode, and different types or dimensions of materials can continue to grow or be transferred in the pores or pore walls where the low-dimensional material has already grown or been filled to form a heterojunction, multi-functional electron emission can be realized.

[0091] In some embodiments, the optical fiber is a solid-core optical fiber, and the heat dissipation layer is disposed on the laser-emitting side of the solid-core optical fiber and is in contact with the electron emission layer for heat conduction. In the present application, the low-dimensional material is disposed at the core of the solid-core optical fiber, and the evanescent wave leaking from the core can interact with the low-dimensional material surrounding the optical fiber. In this system, a longer optical interaction distance with the material can be achieved to realize high-brightness electron emission. In addition, optical fibers with different micro-nano diameters can be drawn, enabling the interaction of light with different modes and intensities with the low-dimensional material to achieve precisely regulated electron emission parameters. In addition, different types or dimensions of materials can be grown or transferred on the grown or transferred low-dimensional material to form a heterojunction to achieve multifunctional electron emission.

[0092] It should be noted that the present application does not make specific requirements or special limitations on the size of the optical fiber, and those skilled in the art can reasonably select the size of the optical fiber according to actual usage requirements.

[0093] In some embodiments, the electron excitation layer is prepared by a dry transfer method. The preparation method includes: transferring zero-dimensional materials, one-dimensional materials, or two-dimensional materials to a tape by mechanical exfoliation, and transferring the zero-dimensional materials, one-dimensional materials, or two-dimensional materials to the laser-emitting side of the optical fiber through the tape.

[0094] In some embodiments, the electron excitation layer is prepared by a wet transfer method. The preparation method includes: directly preparing zero-dimensional materials, one-dimensional materials, or two-dimensional materials in a solution and floating them on the liquid surface, and using the optical fiber to contact the material on the liquid surface and drying.

[0095] In some embodiments, the electron excitation layer is prepared by a direct growth method. The preparation method includes: directly preparing the electron emission layer on the laser-emitting side of the optical fiber by at least one of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy, and liquid filling.

[0096] In a second aspect, 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;

[0097] 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.

[0098] 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 to form an electron beam with a certain shape and emit from the anode for use.

[0099] In a third aspect, the present application provides an application of the electron source as described in the first aspect, and the application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, an X-ray tube, a free electron laser, and a display.

[0100] The embodiments of the present invention will be described in detail below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions noted in the following examples, the guidance given in the present invention is preferentially referred to, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or by referring to the experimental methods known in the art.

[0101] Among them, the conductive connection layer is a gold layer with a thickness of 60 nm.

[0102] Example 1

[0103] This example provides an electron source, as Figure 1 shown, including a solid-core optical fiber 110a, an electron emission layer 120a, a conductive connection layer 130a, and a heat dissipation layer 140a. The electron emission layer 120a includes an electron excitation layer, and the electron excitation layer is provided on the laser output end face of the solid-core optical fiber 110a. The electron excitation layer is graphene with a thickness of 0.3 nm. The heat dissipation layer 140a is provided between the electron excitation layer and the laser output end face of the solid-core optical fiber 110a, and the heat dissipation layer 140a does not cover the area where the laser irradiates the electron emission layer 120a. The heat dissipation layer 140a is a graphite layer with a thickness of 10 μm. The conductive connection layer 130a is provided on the outer surface of the solid-core optical fiber 110a, and the electron excitation layer is electrically connected to the conductive connection layer 130a through the heat dissipation layer 140a.

[0104] Example 2

[0105] This example provides an electron source, as Figure 2 shown, including a solid-core optical fiber 110b, an electron emission layer 120b, a conductive connection layer 130b, and a heat dissipation layer 140b. The electron emission layer 120b includes an electron excitation layer, and the electron excitation layer is provided on the laser output end face of the solid-core optical fiber 110b. The electron excitation layer is graphene with a thickness of 10 nm. The heat dissipation layer 140b is provided between the electron excitation layer and the laser output end face of the solid-core optical fiber 110b. The heat dissipation layer 140b is a boron nitride layer with a thickness of 10 nm, and boron nitride has light transmittance. The conductive connection layer 130b is provided on the outer surface of the solid-core optical fiber 130b, and the electron excitation layer is in contact connection with the conductive connection layer 130b to achieve electrical connection.

[0106] Example 3

[0107] This example provides an electron source, as Figure 3As shown, it includes a solid-core optical fiber 110c, an electron emission layer 120c, a conductive connection layer 130c, and a heat dissipation layer 140c. The electron emission layer 120c includes a conductive support layer 121c and an electron excitation layer 122c that are stacked in a direction away from the laser output end face of the solid-core optical fiber 110c. The electron excitation layer 122c is carbon nanotubes dispersed on the conductive support layer 121c, and the axial direction of the carbon nanotubes is parallel to the plane of the conductive support layer 121c. The conductive support layer 121c is graphene with a thickness of 10 nm. The heat dissipation layer 140c is disposed on the surface of the electron excitation layer 122c away from the laser output end face of the solid-core optical fiber 110c and does not cover the area where the electron emission layer 120c is irradiated by the laser. The heat dissipation layer 140c is a copper layer with a thickness of 2 nm. The conductive connection layer 130c is disposed on the outer surface of the solid-core optical fiber 110c. The electron excitation layer 122c is electrically connected to the conductive connection layer 130c through the conductive support layer 121c, and the conductive support layer is a gold layer with a thickness of 5 nm.

[0108] Example 4

[0109] This example provides an electron source, as Figure 4 shown, which includes a solid-core optical fiber 110d, an electron emission layer 120d, a conductive connection layer 130d, and a heat dissipation layer 140d. Compared with Example 1, the only difference is that the edge of the heat dissipation layer 140d extends to the outer surface of the solid-core optical fiber 110d, covering the conductive connection layer 130d.

[0110] Example 5

[0111] This example provides an electron source, as Figure 5 shown, which includes a solid-core optical fiber 110e, a conductive connection layer 130e, an electron emission layer 120e, a heat dissipation layer 140e, and a cooling layer 150e. Compared with Example 1, the only difference is that a cooling layer 150e is added in the area where the heat dissipation layer 140e extends to the outer surface of the solid-core optical fiber 110e, and the cooling layer 150e is a Peltier cooler.

[0112] Example 6

[0113] This example provides an electron source, as Figure 6 shown, which includes a tip optical fiber 110f, a conductive connection layer 130f, an electron emission layer 120f, and a heat dissipation layer 140f. Compared with Example 1, the only difference is that the electron emission layer 120f is disposed at the tip of the tip optical fiber 110f, and the heat dissipation layer 140f is sleeved on the area where the electron emission layer 120f is located on the tip optical fiber 110f.

[0114] Example 7

[0115] This example provides an electron source, as Figure 7As shown, it includes a porous optical fiber 110g, a conductive connection layer 130g, an electron emission layer 120g, and a heat dissipation layer 140g. Compared with Embodiment 1, the only difference is that a heat dissipation layer 140g and an electron emission layer 120g are sequentially arranged along the direction away from the pore wall inside the pore wall of the porous optical fiber 110g.

[0116] Comparative Example 1

[0117] This comparative example provides an electron source. Compared with Embodiment 1, the only difference is that the heat dissipation layer is not provided, and the electron excitation layer is directly in electrical contact with the conductive connection layer.

[0118] Comparative Example 2

[0119] This comparative example provides an electron source. Compared with Embodiment 1, the only difference is that the electron excitation layer is replaced with a gold layer with a thickness of 60 nm.

[0120] Comparative Example 3

[0121] This comparative example provides an electron source. Compared with Embodiment 1, the only difference is that the electron excitation layer is replaced with a gold layer with a thickness of 1 nm.

[0122] As Figure 6 shown, the electron source 100 prepared by using the above-mentioned embodiment 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. The test methods include:

[0123] 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.

[0124] Lifetime 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 measured until the time when the current decays to less than 10% of the initial value, which is defined as the lifetime.

[0125] Operating vacuum degree test: When the excitation power is 50% of the damage power, the continuous emission current is measured, and the operating environment vacuum degree of the electron gun is gradually increased until the current shows a rapid decay (the 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 operating vacuum degree.

[0126] 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 / cm2 .

[0127] The test results are shown in Table 1.

[0128] Table 1

[0129]

[0130] It can be seen from the above table that

[0131] In this application, by adding a heat dissipation layer in the electron source, the heat dissipation layer is in contact with the electron emission layer for heat conduction, dispersing the heat in the electron emission layer into the heat dissipation layer, reducing the temperature rise of the electron emission layer due to laser irradiation, maintaining the temperature uniformity of the electron emission region of the electron excitation layer, ensuring stable electron emission, increasing the service life, and being able to support electron excitation with a larger optical power. Moreover, this application integrates zero-dimensional materials, one-dimensional materials, and two-dimensional materials with optical fibers. The optical fibers can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, can be applicable to different application scenarios, and do not require a complex optical path. The electron source of this application has the characteristics of stable emission, high service life, small volume, and high integration.

[0132] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0133] The above-described embodiments only represent several implementation manners of the present invention. The description 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 invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. An electron source, characterized in that, The electron source includes an optical fiber, a conductive connection layer, an electron emission layer, and a heat dissipation layer. The conductive connection layer is disposed on the outer surface of the optical fiber; The electron emission layer at least includes an electron excitation layer electrically connected to the conductive connection layer. The material of the electron excitation layer includes at least one of zero-dimensional materials, one-dimensional materials, and two-dimensional materials; The electron emission layer is disposed on the laser emission path of the optical fiber, and the laser emitted by the optical fiber can directly irradiate the electron emission layer, so that the electron excitation layer is excited by the laser and emits electrons. The heat dissipation layer is disposed on one surface of the electron emission layer close to the optical fiber and / or one surface away from the optical fiber.

2. The electron source according to claim 1, wherein The heat dissipation layer extends to the outer surface of the optical fiber.

3. The electron source according to claim 2, wherein The electron source further includes a cooling layer stacked with a portion of the heat dissipation layer located on the outer surface of the optical fiber. The cooling layer is used to cool the heat dissipation layer.

4. The electron source according to claim 3, characterized in that, The cooling layer includes at least one of a refrigeration layer and a cold storage layer.

5. The electron source according to claim 4, characterized in that, The cold storage layer includes a main body, and a liquid storage cavity for injecting a coolant is disposed in the main body.

6. The electron source according to claim 3, wherein The conductive connection layer, the cooling layer, and the heat dissipation layer are sequentially disposed on the outer surface of the optical fiber.

7. The electron source according to claim 1, characterized in that, The heat dissipation layer is disposed on one surface of the electron emission layer close to the optical fiber. The light transmittance of the heat dissipation layer is ≥10%, and the heat dissipation layer at least partially covers the electron emission layer.

8. The electron source according to claim 1, characterized in that, The heat dissipation layer is provided with a light-transmitting hole corresponding to the area where the laser irradiates the electron emission layer.

9. The electron source according to any one of claims 1-9, characterized in that, The thickness of the heat dissipation layer is 0.1 nm to 1 mm.

10. The electron source according to any one of claims 1-9, characterized in that, The material of the heat dissipation layer includes at least one of graphite, boron nitride, carbon nanotubes, silver, aluminum, and copper.

11. The electron source according to any one of claims 1-9, characterized in that, The electron emission layer further includes a conductive support layer. The conductive support layer is disposed on one side of the electron emission layer close to the optical fiber; or, The conductive support layer is disposed on one side of the electron excitation layer away from the optical fiber.

12. The electron source according to any one of claims 1-9, characterized in that, The electron source further satisfies at least one of the following conditions: (1) The zero-dimensional material includes at least one of quantum dots, fullerenes, NV color centers, and nanocrystals; (2) The one-dimensional material includes at least one of nanotubes, nanoribbons, and nanowires; (3) The two-dimensional material includes at least one of graphene, black phosphorus, transition metal chalcogenides, and hexagonal boron nitride.

13. The electron source according to any one of claims 1-9, 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.

14. An electron gun, characterized in that, The electron gun includes a housing, a grid, an anode, and the electron source according to any one of claims 1-14; 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. An application of the 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, a free electron laser, and a display.

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