Preparation clamp for GaAs photoelectric cathode bonding

Abstract

The utility model provides a preparation clamp for GaAs photoelectric cathode bonding. The preparation clamp comprises a cathode tray, a positioning column, a spring, an AVG tray, anti-halation cathode glass, a gallium arsenide epitaxial wafer, an epitaxial wafer base, an epitaxial wafer positioning ring, a cathode pressure disc and a steel ball. The utility model has the advantages that parts are easy to replace and maintain, the structural design is simple, and the operation is easy. The separation of the internal working area and the external environment is realized, and the introduction of particulate matters in the process is avoided. The AVG glass and the gallium arsenide epitaxial wafer are limited, and bonding failure caused by dislocation of the AVG glass and the gallium arsenide epitaxial wafer during manual transfer and bonding is prevented. Temperature stability is considered in clamp design, temperature uniformity is guaranteed during bonding, the AVG glass and the gallium arsenide epitaxial wafer are effectively bonded, and the product percent of pass is increased. The annealing temperature is stable, the annealing rate is stable, the bonding temperature can be freely reduced to the room temperature without annealing points, the annealing temperature points can be reduced, the bonding time can be shortened, and the bonding efficiency can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of photoelectric detectors, in particular to a preparation fixture for GaAs photocathode bonding. Background Art

[0002] The third generation of low-light image intensifiers is mainly composed of two parts: the photocathode component and the anode component. The photocathode uses the second-generation semiconductor gallium arsenide as the emission layer. Gallium arsenide has the characteristics of high sensitivity, wide light response range, and high electron mobility, and is particularly suitable for making gallium arsenide photocathode electron sources. The gallium arsenide photocathode electron source mainly includes processes such as photon absorption, electron transition, electron diffusion, and electron escape. The gallium arsenide photocathode absorbs light of a certain wavelength, such as infrared and ultraviolet light, so that the electrons in the conduction band of the gallium arsenide semiconductor obtain the energy of the photon. Due to the large energy of the vibrating electrons, they break through the constraints of the gallium arsenide atoms and become free electrons, which diffuse to the crystal surface in the body. Finally, the electrons escape from the surface of the P-type gallium arsenide photocathode to make a gallium arsenide photocathode electron source. This electron source can realize the conversion of optical signals into electronic signals and is widely used in low-light night vision systems.

[0003] The photocathode is the window of the third-generation image tube. The level of its activation photocurrent and the field of view quality of the output surface affect the final imaging effect of the image tube. The photocathode uses AVG glass, which is bonded to the GaAs epitaxial wafer under vacuum conditions, high temperature conditions, and a certain pressure. Field of view quality problems and low activation photocurrent generally occur during the bonding process of the GaAs epitaxial wafer and 7056 glass.

[0004] (1) When AVG glass is bonded to GaAs epitaxial wafer, particles fall into the bonding surface during the downward pressing process of the pressure rod, affecting the field of view quality;

[0005] (2) When AVG glass is bonded to GaAs epitaxial wafer, the movement of the pressure rod and the vibration during vacuum acquisition cause the AVG glass and epitaxial wafer to be misaligned, resulting in bubbles and deformation, which affects the quality of the field of view;

[0006] (3) When AVG glass is bonded to GaAs epitaxial wafer, the glass needs to be annealed. The stress of the glass during annealing in the traditional bonding fixture is relatively large, which can easily cause the bonding to fall off. At the same time, bubbles are easily generated, and the GaAs surface is distorted, which affects the field of view quality.

[0007] (4) The bonding process of AVG glass and GaAs epitaxial wafer takes a long time, which reduces production efficiency. Utility Model Content

[0008] The purpose of the present invention is to solve at least one of the above technical deficiencies.

[0009] Therefore, one purpose of the present invention is to provide a preparation fixture for GaAs photocathode bonding to solve the problems mentioned in the background technology and overcome the deficiencies in the prior art.

[0010] In order to achieve the above-mentioned object, an embodiment of the utility model provides a preparation fixture for GaAs photocathode bonding, including a cathode tray, a positioning column, a spring, an AVG tray, an anti-halation cathode glass, a GaAs epitaxial wafer, an epitaxial wafer base, an epitaxial wafer positioning ring, a cathode pressure plate, and a steel ball, wherein the cathode tray, the positioning column, the AVG tray, the epitaxial wafer base, the epitaxial wafer positioning ring, and the cathode pressure plate are made of graphite;

[0011] The stepped hole at the bottom of the cathode tray and the positioning column play a fixing role, and the middle concave hole of the cathode tray is embedded with a spring;

[0012] The positioning column is a T-shaped structure, and the spring plays a supporting role, so that the anti-halation cathode glass and the gallium arsenide epitaxial wafer in the AVG tray are in a separated state;

[0013] The AVG tray plays a guiding role in the pressed state, and the anti-halation cathode glass is placed in the middle step hole to maintain the coaxial center;

[0014] The edge holes of the epitaxial wafer base avoid interference with the spring, and the finely ground surfaces at both ends are respectively fitted with the cathode tray, the gallium arsenide epitaxial wafer, and the epitaxial wafer positioning ring;

[0015] The edge holes of the epitaxial wafer positioning ring avoid interference with the spring, and the middle holes are embedded with the gallium arsenide epitaxial wafer;

[0016] The cathode pressure plate plays a guiding role in the pressed state, and a steel ball is placed in the middle blind hole; the steel ball is a smooth sphere, which transmits external power and the intermediate medium of the clamp.

[0017] Preferably, any of the above schemes is that the cathode tray is a constant temperature tank, and a stepped hole a is preset at the bottom of the cathode tray.

[0018] The above technical solution has the following advantages: the fixture structure is simple, parts can be easily replaced, quality problems such as parallelism and coaxiality of the bonding surface are solved, the bonding surface is flat and free of deformation, photoelectron propagation is evenly distributed, and the cathode field quality is further improved.

[0019] The core structure of the fixture is: cathode tray, positioning column, spring, AVG tray, epitaxial wafer base, epitaxial wafer positioning ring, cathode pressure plate, and steel ball.

[0020] The anti-halation cathode glass is simplified to AVG, and the gallium arsenide epitaxial wafer is simplified to epitaxial wafer.

[0021] The cathode tray is a constant temperature tray, the stepped hole at the bottom of the figure and the positioning column play a fixing role, and the concave hole in the middle layer forms a nesting effect with the spring; the positioning column is a T-shaped structure with a simple structure and easy disassembly and assembly; the spring plays a supporting role, so that the AVG in the AVG tray and the epitaxial wafer are in a separated state; there is a guide hole one on the edge of the AVG tray, which plays a guiding role with the positioning column in the pressed state, and the middle step hole is embedded with the AVG to form a consistent axis; the epitaxial wafer base is in the shape of a flange blind plate, the edge hole position one avoids interference with the spring, and the finely ground surfaces at both ends are respectively fitted with the cathode tray, epitaxial wafer, and epitaxial wafer positioning ring; the epitaxial wafer positioning ring is in the shape of a flange, the edge hole position two avoids interference with the spring, and the middle hole is embedded with the epitaxial wafer to form a consistent axis; there is a guide hole two on the edge of the cathode pressure plate, which plays a guiding role with the positioning column in the pressed state, and a steel ball is embedded in the middle blind hole; the steel ball is a smooth sphere, which transmits external power and the intermediate medium of the clamp.

[0022] Preferably, any of the above schemes is that a concave hole is provided in the middle layer of the cathode tray, and a guide hole 1 is opened at the edge of the AVG tray.

[0023] Preferably, any of the above schemes has a stepped hole in the middle of the AVG tray, and the epitaxial wafer base is in the shape of a flange blind plate.

[0024] Preferably, any of the above schemes has an edge hole position 1 opened at the edge of the epitaxial wafer base, the epitaxial wafer positioning ring is flange-shaped, an edge hole position 2 opened at the edge of the epitaxial wafer positioning ring, and an intermediate hole opened in the middle of the epitaxial wafer positioning ring.

[0025] Preferably, any of the above schemes is that a second guide hole is opened at the edge of the cathode pressure plate, and a middle blind hole is opened in the middle of the cathode pressure plate.

[0026] (1) The bonding process is protected by the cathode tray. During bonding, the cathode pressure plate is isolated from the AVG tray at the top, and the cathode tray is isolated at the side and bottom, so that the internal environment of the bonding fixture is isolated from the outside during bonding, preventing particles driven by the pressure rod from falling into the bonding surface.

[0027] (2) The AVG tray is designed with a positioning area. The AVG is positioned by the cathode pressure plate and the AVG tray. The epitaxial wafer is placed on the epitaxial wafer base, and the epitaxial wafer positioning ring limits the epitaxial wafer. At the same time, the positioning column fixes the cathode pressure plate and the AVG tray, the epitaxial wafer base and the epitaxial wafer positioning ring through the guide hole, and ensures their coaxiality. It ensures that the AVG glass and the epitaxial wafer will not be offset or misaligned under slight shaking, which is easy to bond and manually transfer.

[0028] (3) This bonding fixture is made of graphite and assembled from multiple parts. When bonding, the parts fit tightly together. When heated at high temperature, it can evenly transfer heat to ensure effective bonding between the AVG glass and the gallium arsenide surface during bonding. When cooled, the heat loss rate is stable, the heat radiation is uniform, the bonding cathode temperature drops evenly during the annealing process, and the stress is reduced.

[0029] (4) The annealing process is to set multiple cooling points starting from the AVG glass transition point and keep the temperature for a period of time, so that the temperature drops slowly and the stress caused by uneven temperature during the cooling process is reduced. This bonding fixture has a certain degree of heat preservation and heat radiation uniformity, which can ensure that the objects inside the fixture are cooled at a uniform rate, and can effectively ensure that the temperature of each part is stable and consistent when the bonding cathode is cooled, thereby solving the stress problem. Therefore, when using this bonding fixture, the annealing temperature points can be reduced or omitted, which greatly reduces the bonding time and improves production efficiency.

[0030] Preferably, in any of the above schemes, the steel ball is a smooth sphere.

[0031] Compared with the prior art, the advantages and beneficial effects of the utility model are:

[0032] 1. The preparation fixture for GaAs photocathode bonding protects the bonding process through the cathode tray. During bonding, the cathode pressure plate is isolated from the AVG tray at the top, and the cathode tray is isolated at the side and bottom, so that the internal environment of the bonding fixture is isolated from the outside during bonding, preventing particles driven by the pressure rod from falling into the bonding surface.

[0033] The AVG tray is designed with a positioning area. The AVG is positioned by the cathode pressure plate and the AVG tray. The epitaxial wafer is placed on the epitaxial wafer base, and the epitaxial wafer positioning ring limits the epitaxial wafer. At the same time, the positioning column fixes the cathode pressure plate and the AVG tray, the epitaxial wafer base and the epitaxial wafer positioning ring through the guide hole, and ensures their coaxiality. It ensures that the AVG glass and the epitaxial wafer will not be offset or misaligned under slight shaking, which is easy to bond and manually transfer.

[0034] 2. The preparation fixture for GaAs photocathode bonding is made of graphite and assembled from multiple parts. When bonding, the parts fit tightly together. When heated at high temperature, it can evenly transfer heat to ensure effective bonding between the AVG glass and the gallium arsenide surface during bonding. When cooling, the heat loss rate is stable, the heat radiation is uniform, the temperature of the bonding cathode decreases evenly during the annealing process, and the stress is reduced.

[0035] The annealing process is to set multiple cooling points at the AVG glass transition point and keep the temperature for a period of time, so that the temperature drops slowly and the stress caused by uneven temperature during the cooling process is reduced. This bonding fixture has a certain degree of heat preservation and heat radiation uniformity, which can ensure that the objects inside the fixture are cooled at a uniform rate, and can effectively ensure that the temperature of each part is stable and consistent when the bonding cathode is cooled, thereby solving the stress problem. Therefore, the annealing temperature points can be reduced or omitted when the bonding fixture is used, which greatly reduces the bonding time and improves production efficiency.

[0036] This fixture is composed of multiple parts, which are easy to replace and repair, with a simple structural design and easy operation. It achieves the separation of the internal working area and the external environment, and prevents the introduction of process particles. It limits the position of AVG glass and GaAs epitaxial wafers, and effectively prevents the dislocation of AVG glass and GaAs epitaxial wafers during manual transportation and bonding, resulting in bonding failure. The fixture design takes temperature stability into consideration, and ensures its temperature uniformity during bonding to effectively bond AVG glass and GaAs epitaxial wafers, thereby improving the product qualification rate. The annealing temperature is stable, the annealing rate is stable, and it has the performance of being able to cool freely from the bonding temperature to room temperature without stress without the need for an annealing point. It can reduce the annealing temperature point, reduce the bonding time, and improve the bonding efficiency.

[0037] Additional aspects and advantages of the present invention will be given in part in the following description and in part will become apparent from the following description or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0039] Figure 1 It is a schematic diagram of the explosion structure of the utility model;

[0040] Figure 2 It is a schematic diagram of the structure of assembling various parts of the utility model;

[0041] Figure 3 For this utility model Figure 2 Schematic diagram of the enlarged structure at V in the middle.

[0042] In the figure: 1-cathode tray, 1a-step hole, 1b-concave hole, 2-positioning column, 3-spring, 4-AVG tray, 4a-guide hole one, 4b-step hole, 5-anti-halo cathode glass, 6-GaAs epitaxial wafer, 7-epitaxial wafer base, 7a-edge hole one, 8-epitaxial wafer positioning ring, 8a-edge hole two, 8b-middle hole, 9-cathode pressure plate, 9a-guide hole two, 9b-middle blind hole, 10-steel ball. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] like Figure 1-3 As shown, the preparation fixture for GaAs photocathode bonding includes a cathode tray 1, a positioning column 2, a spring 3, an AVG tray 4, an anti-halation cathode glass 5, a GaAs epitaxial wafer 6, an epitaxial wafer base 7, an epitaxial wafer positioning ring 8, a cathode pressure plate 9, and a steel ball 10, wherein the cathode tray 1, the positioning column 2, the AVG tray 4, the epitaxial wafer base 7, the epitaxial wafer positioning ring 8, and the cathode pressure plate 9 are made of graphite;

[0046] The stepped hole at the bottom of the cathode tray 1 and the positioning column 2 play a fixing role, and the middle concave hole of the cathode tray 1 is embedded with a spring 3;

[0047] The positioning column is a T-shaped structure, and the spring 3 plays a supporting role, so that the anti-halation cathode glass 5 and the gallium arsenide epitaxial wafer 6 in the AVG tray 4 are in a separated state;

[0048] The AVG tray 4 plays a guiding role in the pressed state, and the anti-halation cathode glass 5 is placed in the middle step hole to maintain the coaxial center;

[0049] The edge holes of the epitaxial wafer base 7 avoid interference with the spring 3, and the finely ground surfaces at both ends thereof are respectively fitted with the cathode tray 4, the gallium arsenide epitaxial wafer 6, and the epitaxial wafer positioning ring 8;

[0050] The edge holes of the epitaxial wafer positioning ring 8 avoid interference with the spring 3, and the middle hole is embedded with the gallium arsenide epitaxial wafer 6;

[0051] The cathode pressure plate 9 plays a guiding role in the pressed state, and a steel ball 10 is placed in the middle blind hole; the steel ball 10 is a smooth sphere, which transmits external power and the intermediate medium of the clamp.

[0052] Embodiment 1: The cathode tray 1 is a constant temperature cathode tray, and a stepped hole 1a is preset at the bottom of the cathode tray 1. The fixture has a simple structure and convenient parts replacement. It solves the quality problems such as parallelism and coaxiality of the bonding surface. The bonding surface is flat and has no deformation. The photoelectron propagation is evenly distributed, which further improves the cathode field quality. The core structure of this fixture is: cathode tray 1, positioning column 2, spring 3, AVG tray 4, epitaxial wafer base 7, epitaxial wafer positioning ring 8, cathode pressure plate 9, and steel ball 10.

[0053] Embodiment 2: The middle layer of the cathode tray 1 is provided with a concave hole 1b, and a guide hole 1 4a is provided at the edge of the AVG tray 4. A step hole 4b is provided in the middle of the AVG tray 4, and the epitaxial wafer base 7 is in the shape of a flange blind plate. An edge hole position 1 7a is provided at the edge of the epitaxial wafer base 7, the epitaxial wafer positioning ring 8 is in the shape of a flange, an edge hole position 2 8a is provided at the edge of the epitaxial wafer positioning ring 8, and a middle hole position 8b is provided in the middle of the epitaxial wafer positioning ring 8. A guide hole 2 9a is provided at the edge of the cathode pressure plate 9, and a middle blind hole 9b is provided in the middle of the cathode pressure plate 9.

[0054] The working principle of the utility model is as follows:

[0055] The anti-halation cathode glass 5 is simplified to AVG, and the gallium arsenide epitaxial wafer 6 is simplified to epitaxial wafer.

[0056] Cathode tray 1 is a constant temperature tank. Figure 2 The bottom stepped hole 1a and the positioning column 2 play a fixing role, and the middle layer concave hole 1b and the spring 3 form a nesting effect; the positioning column 2 is a T-shaped structure with a simple structure and easy disassembly and assembly; the spring 3 plays a supporting role, so that the AVG in the AVG tray 4 is in a separated state from the epitaxial wafer; the edge of the AVG tray 4 has a guide hole 4a, which plays a guiding role with the positioning column 2 in the pressed state, and the middle step hole 4b is embedded with the AVG to form a consistent axis; the epitaxial wafer base 7 is in the shape of a flange blind plate, the edge hole position 7a avoids interference with the spring 3, and the finely ground surfaces at both ends are respectively fitted with the cathode tray 9, the epitaxial wafer 6, and the epitaxial wafer positioning ring 8; the epitaxial wafer positioning ring 8 is in the shape of a flange, the edge hole position 8a avoids interference with the spring 3, and the middle hole 8b is embedded with the epitaxial wafer to form a consistent axis; the edge of the cathode pressure plate 9 has a guide hole 9a, which plays a guiding role with the positioning column 2 in the pressed state, and the middle blind hole 9b is embedded with a steel ball 10; the steel ball is a smooth sphere, which transmits external power and the intermediate medium of the clamp.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. The preparation fixture for GaAs photocathode bonding protects the bonding process through the cathode tray 1. During bonding, the cathode pressure plate 9 is isolated from the AVG tray 4 at the top, and the cathode tray 1 is isolated at the side and bottom, so that the internal environment of the bonding fixture is isolated from the outside during bonding, preventing particles driven by the pressure rod from falling into the bonding surface.

[0059] The AVG tray 4 is designed with a positioning area, and the AVG is positioned by the cathode pressure plate 9 and the AVG tray 4; the epitaxial wafer is placed on the epitaxial wafer base 7, and the epitaxial wafer positioning ring 8 limits the epitaxial wafer; at the same time, the positioning column 2 fixes the cathode pressure plate 9 and the AVG tray 4, the epitaxial wafer base 7 and the epitaxial wafer positioning ring 8 through the guide hole 4a, and ensures their coaxiality. It ensures that the AVG glass and the epitaxial wafer will not be offset or misaligned under slight shaking, and is easy to bond and manually transfer.

[0060] 2. The preparation fixture for GaAs photocathode bonding is made of graphite and assembled from multiple parts. When bonding, the parts fit tightly together. When heated at high temperature, it can evenly transfer heat to ensure effective bonding between the AVG glass and the gallium arsenide surface during bonding. When cooling, the heat loss rate is stable, the heat radiation is uniform, the temperature of the bonding cathode decreases evenly during the annealing process, and the stress is reduced.

[0061] The annealing process is to set multiple cooling points at the AVG glass transition point and keep the temperature for a period of time, so that the temperature drops slowly and the stress caused by uneven temperature during the cooling process is reduced. This bonding fixture has a certain degree of heat preservation and heat radiation uniformity, which can ensure that the objects inside the fixture are cooled at a uniform rate, and can effectively ensure that the temperature of each part is stable and consistent when the bonding cathode is cooled, thereby solving the stress problem. Therefore, the annealing temperature points can be reduced or omitted when the bonding fixture is used, which greatly reduces the bonding time and improves production efficiency.

[0062] This fixture is composed of multiple parts, which are easy to replace and repair, with a simple structural design and easy operation. It achieves the separation of the internal working area and the external environment, and prevents the introduction of process particles. It limits the position of AVG glass and GaAs epitaxial wafers, and effectively prevents the dislocation of AVG glass and GaAs epitaxial wafers during manual transportation and bonding, resulting in bonding failure. The fixture design takes temperature stability into consideration, and ensures its temperature uniformity during bonding to effectively bond AVG glass and GaAs epitaxial wafers, thereby improving the product qualification rate. The annealing temperature is stable, the annealing rate is stable, and it has the performance of being able to cool freely from the bonding temperature to room temperature without stress without the need for an annealing point. It can reduce the annealing temperature point, reduce the bonding time, and improve the bonding efficiency.

Claims

1. A preparation fixture for GaAs photocathode bonding, characterized in that: It comprises a cathode tray (1), a positioning column (2), a spring (3), an AVG tray (4), an anti-halation cathode glass (5), a gallium arsenide epitaxial wafer (6), an epitaxial wafer base (7), an epitaxial wafer positioning ring (8), a cathode pressure plate (9), and a steel ball (10), wherein the cathode tray (1), the positioning column (2), the AVG tray (4), the epitaxial wafer base (7), the epitaxial wafer positioning ring (8), and the cathode pressure plate (9) are made of graphite; The stepped hole at the bottom of the cathode tray (1) plays a fixing role with the positioning column (2), and the middle concave hole of the cathode tray (1) is embedded with a spring (3); The positioning column is a T-shaped structure, and the spring (3) has a supporting function, so that the anti-halation cathode glass (5) and the gallium arsenide epitaxial wafer (6) in the AVG tray (4) are in a separated state; The AVG tray (4) plays a guiding role in the pressed state, and the anti-halation cathode glass (5) is placed in the middle step hole to maintain the coaxial center; The edge holes of the epitaxial wafer base (7) avoid interference with the spring (3), and the finely ground surfaces at both ends thereof are respectively fitted with the cathode tray (1), the gallium arsenide epitaxial wafer (6), and the epitaxial wafer positioning ring (8); The edge holes of the epitaxial wafer positioning ring (8) avoid interference with the spring (3), and the middle hole is embedded with the gallium arsenide epitaxial wafer (6); the cathode pressure plate (9) plays a guiding role in the pressed state, and the middle blind hole is used to place a steel ball (10); the steel ball (10) is a smooth sphere, which transmits external power and the intermediate medium of the clamp.

2. A preparation fixture for GaAs photocathode bonding as claimed in claim 1, characterized in that: The cathode tray (1) is a constant temperature tank, and a stepped hole (1a) is preset at the bottom of the cathode tray (1).

3. A preparation fixture for GaAs photocathode bonding as claimed in claim 2, characterized in that: The middle layer of the cathode tray (1) is provided with a concave hole (1b), and the edge of the AVG tray (4) is provided with a guide hole (4a).

4. A preparation fixture for GaAs photocathode bonding as claimed in claim 3, characterized in that: A stepped hole (4b) is provided in the middle of the AVG tray (4), and the epitaxial wafer base (7) is in the shape of a flange blind plate.

5. A preparation fixture for GaAs photocathode bonding as claimed in claim 4, characterized in that: An edge hole position 1 (7a) is provided at the edge of the epitaxial wafer base (7); the epitaxial wafer positioning ring (8) is flange-shaped; an edge hole position 2 (8a) is provided at the edge of the epitaxial wafer positioning ring (8); and a middle hole position (8b) is provided in the middle of the epitaxial wafer positioning ring (8).

6. A preparation fixture for GaAs photocathode bonding as claimed in claim 5, characterized in that: A second guide hole (9a) is provided at the edge of the cathode pressure plate (9), and a middle blind hole (9b) is provided in the middle of the cathode pressure plate (9).

7. A preparation fixture for GaAs photocathode bonding as claimed in claim 6, characterized in that: The steel ball (10) is a smooth sphere.

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