CN-122025493-A - Electron emission structure, preparation method thereof and photoelectron source

CN122025493ACN 122025493 ACN122025493 ACN 122025493ACN-122025493-A

Abstract

The invention relates to an electron emission structure, a preparation method thereof and an photoelectron source, wherein the electron emission structure comprises a light conduction piece and an electron emission piece, the light conduction piece is in a strip shape and comprises a conduction body, a first end part and a second end part, the first end part and the second end part are arranged at two opposite ends of the conduction body along the axial direction, the light conduction piece allows incident light emitted from the second end part to be conducted to the first end part, the end surface of the first end part is an outwards convex cambered surface, the end surface of the first end part is provided with a light emission area for allowing light to emit, and the electron emission piece is arranged on the outer surface of the light emission area of the first end part and emits electrons after being excited by the light. When the electron emission structure provided by the invention is used as an emitter of an photoelectron source to be applied to an electron microscope, the imaging quality can be effectively improved.

Inventors

ZHOU XU
Mo Minlin
LIANG JING
LIANG ZHIWEI

Assignees

华南师范大学

Dates

Publication Date: 20260512
Application Date: 20251231

Claims (10)

1. An electron emission structure for an emitter of an electron source of an electron microscope is characterized by comprising a light conduction member and an electron emission member; The light conduction piece is in a strip shape and comprises a conduction body, a first end part and a second end part, wherein the first end part and the second end part are arranged at two opposite ends of the conduction body along the axial direction, the light conduction piece allows incident light emitted from the second end part to be conducted to the first end part, the end face of the first end part is an outwards convex cambered surface, and a light emergent area is arranged at the end face of the first end part so as to allow light rays to be emitted; The electron emission part is arranged on the outer surface of the first end light emergent area and emits electrons after being excited by light rays.
2. The electron emission structure according to claim 1, wherein: the light conducting member is an optical fiber.
3. The electron emission structure according to claim 2, wherein: The first end is spherical, elliptical or drop-shaped.
4. The electron emission structure according to claim 3, wherein: When the first end is spherical, the ratio of the diameter of the first end to the diameter of the conductive body is 1.6-3.2.
5. The electron emission structure according to claim 1, wherein: the orthographic projection area of the first end part on a plane perpendicular to the axial direction is larger than the orthographic projection area of the conductive body on the same plane.
6. The electron emission structure according to claim 1, wherein: The electron emission member is any one of graphene, fullerene, carbon nanotube, molybdenum disulfide, tungsten disulfide, molybdenum diselenide, tungsten diselenide, molybdenum ditelluride and tungsten ditelluride; Or the electron emission member is any one of lanthanum hexaboride, gallium arsenide and InGaAs, gaN, alGaN or a composite material of two or more of the above materials.
7. The electron emission structure according to any one of claims 1 to 6, wherein: the electronic supplementing piece is arranged at the first end part and is in contact with the electronic emitting piece so as to supplement electrons to the electronic emitting piece after power is obtained.
8. An optoelectronic source comprising an electron emission structure as defined in claim 7.
9. The preparation method of the electron emission structure is characterized by comprising the following steps: preparing a strip-shaped light conduction member, wherein the light conduction member comprises a conduction body, and a first end part and a second end part which are arranged at two opposite ends of the conduction body along the axial direction, the light conduction member allows incident light incident from the second end part to be conducted to the first end part, the end surface of the first end part is an outwards convex cambered surface, and a light emergent area is arranged at the end surface of the first end part so as to allow light rays to be emitted; an electron emission member is formed on an outer surface of the first end light emission region, wherein the electron emission member emits electrons after being excited by light.
10. The method for producing an electron emission structure according to claim 9, wherein: Before the electron emission member is formed on the first end portion outer surface, the following steps are further performed: forming an electron emission member on an outer surface of the first end portion; The electron emission member is in contact with the electron supplement member.

Description

Electron emission structure, preparation method thereof and photoelectron source Technical Field The present invention relates to the field of electron microscope photoelectron source technology, and in particular, to an electron emission structure, a method for preparing the same, and a photoelectron source. Background The electron source is a device that emits electrons in vacuum. The electron sources can be classified into three types of hot electron sources, field emission electron sources, and photoelectron sources according to excitation modes. The electron source and the field electron source make electrons directly escape from the surface of the emitter through the thermal effect and the high-voltage electric field respectively, and the photoelectron source makes electrons in the emitting material absorb photon energy through laser irradiation based on the photoelectric emission principle and then overcomes the surface barrier to realize electron escape. The core component of the photoelectron gun is a photoelectron source, which mainly comprises a shell, and an electron source (comprising an emitter), a grid and a receiving electrode which are arranged in the shell. The shell is internally provided with a cavity capable of forming a vacuum environment, the emitter, the grid and the receiving electrode are arranged in the cavity, wherein the emitter and the receiving electrode are oppositely arranged, and the grid is arranged between the emitter and the receiving electrode. The emitter emits electrons under the excitation of laser, the grid electrode is used for regulating electric field distribution and accelerating and focusing the electrons emitted by the emitter, and the receiving electrode is used for collecting the electrons passing through the grid electrode so as to obtain the required kinetic energy of the electrons and form beam current. Compared with a thermal electron source, the photoexcited electrons can provide electron beams with better characteristics, and compared with a field emission electron source, the photoelectron source has relatively lower requirement on vacuum degree, thereby having good application prospect in the imaging fields such as an electron microscope and the like. During the development of the photoelectron source, the structure of the emitter underwent an evolution from tip type to planar type. Early tip emitters were typically made of high melting point metals such as tungsten, titanium, etc. in a needle-tip configuration by focusing a laser on a nano-scale needle tip region to excite surface electron emission. However, the structure gradually exposes the problems of poor electron beam stability, easy pollution or damage to the needle tip, high manufacturing difficulty and the like in the practical application process, so that the structure is limited to be applied to long-time and high-stability imaging scenes. To overcome the shortcomings of the metal tip type emitter, a planar type emitter has been proposed and developed. Fig. 1 shows a specific structure of a conventional planar emitter electrode. The structure adopts a flat plate-shaped supporting substrate 1 with light transmittance, and a metal film emitting layer 2 such as gold, silver, copper and the like is generally adopted and attached to the side surface of the supporting substrate 1. The laser is injected into the emission layer 2 on the other side through one side of the supporting substrate 1 and is gathered on the other side, so that electrons on the surface of the emission layer 2 are excited to escape. Compared with a tip-type emitter, the planar emitter has obvious advantages in the aspects of electron beam stability and service life, and compared with a nano-scale-size needle point structure, the metal planar film is obviously simpler in manufacturing process. However, when the planar emission electrode is applied to high-resolution imaging such as an electron microscope, the quality of the formed image is still not ideal, and the problems of insufficient definition, difficult detail identification and the like exist, so that the requirement of precision imaging is difficult to meet. Disclosure of Invention Based on this, the present invention aims to overcome the defects or shortcomings of the prior art, and on one hand, provides an electron emission structure of an optoelectronic source, which can effectively improve imaging quality when being applied to the field of electron microscopy as an emitter. An electron emission structure for an emitter of an photoelectron source of an electron microscope comprises a light conduction piece and an electron emission piece, wherein the light conduction piece is in a strip shape and comprises a conduction body, a first end part and a second end part, the first end part and the second end part are arranged at two opposite ends of the conduction body along the axial direction, the light conduction piece allows incident light emitted from the second en