A method for preparing a high-gain photodetector

Abstract

The application discloses a preparation method of a high-gain photoelectric detector and relates to the technical field of photoelectric detectors.The application comprises the following steps: S1, structure design: according to the application scene requirement and working environment of the detector, an avalanche photodiode is prepared by selecting a corresponding photoelectric material; S2, wafer preparation: a semiconductor wafer is cleaned by using ultrasonic cleaning agent and chemical solution; S3, material processing: a doping operation is performed, ions containing phosphorus and boron elements are injected into semiconductor material by using an ion accelerator; S4, gain optimization: a circuit is optimized by using Cascode technology, and the circuits of two transistors are connected; and S5, packaging integration: a prepared chip is packaged into a shell; by optimizing the circuit of the semiconductor by using the Cascode technology, the bias voltage of the circuit, the configuration of the gain circuit and external signal processing are adjusted, the gain of the photoelectric detector can be improved, the influence on the output impedance is reduced, and therefore the high-frequency performance and the linearity of the overall circuit are improved.

Description

Technical Field

[0001] This invention relates to the field of photodetector technology, and in particular to a method for fabricating a high-gain photodetector. Background Technology

[0002] A photodetector is an electronic device used to detect optical signals and convert them into electrical signals. They are widely used in fields such as optical communication, laser ranging, and image sensors. The basic working principle of a photodetector is based on the photoelectric effect, which is the phenomenon of electric charge generated by the interaction of photons with materials. Photodetectors are mainly divided into photodiodes, photomultiplier tubes, photoconductive detectors, and CMOS sensors. Photodetectors utilize photons hitting the sensitive area of ​​the detector to excite electrons or other charge carriers in the material. The excited charge is converted into an electrical signal through internal circuitry. The electrical signal is then amplified and processed to extract useful information. The performance of a photodetector is usually determined by parameters such as its sensitivity, response time, noise level, and operating wavelength range. In fiber optic communication, photodetectors are used to receive and decode optical signals. In the medical field, they can be used for laser scanning and imaging. They can also be used in laser access control systems and detectors to prevent intrusion. In astronomical observation and particle physics experiments, they are used to detect weak light signals. In cameras and smartphones, they are used for image sensing. Before actual use, photodetectors usually need to be calibrated to ensure measurement accuracy. The settings of the photodetector, such as gain and bias voltage, need to be adjusted according to the actual application requirements. Regular inspection and maintenance of the photodetector are also required to ensure its long-term stable operation.

[0003] According to invention patent CN 113540273 B, a high-speed, high-gain avalanche photodetector and its fabrication method are disclosed. The chip comprises three steps arranged from top to bottom. The first step includes, from top to bottom, a P-electrode, a first ohmic contact layer, a first absorption layer, and an upper portion of the second absorption layer. The second step includes, from top to bottom, a lower portion of the second absorption layer, a transition layer, a first charge layer, a multiplication layer, a second charge layer, a transition layer, and an upper portion of the second ohmic contact layer. The third step includes, from top to bottom, a lower portion of the second ohmic contact layer and an insulating substrate. The horizontal projected area of ​​the three steps increases sequentially. The chip multiplication layer is made of ultrathin InAlAs material. The three-step chip is flip-bonded onto a substrate.

[0004] The fabrication method of this photodetector uses the method of increasing the bandwidth of the avalanche photodiode to improve the gain. However, increasing the bandwidth of the avalanche photodiode will affect the signal amplification effect. The increase in bandwidth may introduce more noise, thereby reducing the signal-to-noise ratio. In addition, high bandwidth operation usually requires higher current or power, thereby increasing power consumption. At the same time, increasing the bandwidth may also cause nonlinear distortion of the signal, affecting the signal quality. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings in real-world applications. Therefore, a method for fabricating a high-gain photodetector is proposed to solve the aforementioned problems.

[0006] The following technical solution was specifically adopted:

[0007] The preparation methods include the following:

[0008] S1 Structure Design: Based on the application scenario requirements and working environment of the detector, select photoelectric materials with corresponding wavelength range, sensitivity, response speed, noise level, and temperature stability to fabricate avalanche photodiodes. Generate photoelectric material thin films on the substrate using chemical vapor deposition technology, and define the structure of the photodetector on the wafer using photolithography technology.

[0009] S2 wafer preparation: The semiconductor wafer is cleaned using ultrasonic cleaning agent and chemical solution to remove contaminants and dust from the semiconductor surface. The cleaned wafer is then dried using nitrogen and dry air to remove any remaining moisture. The wafer is then mechanically polished to ensure its surface flatness, thereby improving light incidence efficiency and reducing defects. At the same time, a chemical etching method is used to remove the naturally formed oxide layer on the wafer surface.

[0010] S3 material processing: Doping operation is performed, using an ion accelerator to inject ions containing phosphorus and boron into the semiconductor material to adjust the electronic properties of the semiconductor, separating the semiconductor into p-type containing positive charge carriers and n-type rich in negative charge carriers, and forming a pn junction by heating diffusion, followed by annealing to improve the crystal structure and electrical properties of the material.

[0011] S4 Gain Optimization: The circuit is optimized using Cascode technology, connecting the circuits of two transistors to ensure that the output of the preceding circuit is connected to the input of the following circuit. Gauss's law is applied to determine the electric field distribution, and then numerical calculation methods are used to reshape the electric field distribution. At the same time, electric field simulation experiments are conducted to analyze the electric field parameters, and filters are used to optimize the resonance effect.

[0012] S5 package integration: The manufactured chip is packaged into a shell to protect it from external environmental influences and ensure smooth connection with external circuits. Quartz is used as the optical window of the photodetector to provide a channel for the light signal to enter. Finally, optical alignment and testing are performed.

[0013] Preferably, in step S1, during the structural design operation, silicon material is selected as the substrate for fabricating the avalanche photodiode. The infrared light detection range of the selected silicon substrate is 400-1100nm, and the breakdown voltage of the fabricated avalanche photodiode is 50-200V.

[0014] Preferably, in step S1, the structural design operation first involves substrate pretreatment, where the substrate to be deposited is cleaned and activated to remove surface impurities and oxides, increase the surface roughness of the substrate, increase the number of surface active sites, and ensure deposition uniformity. Then, the gaseous precursor is transported to the reaction chamber to ensure that the reactants effectively participate in the deposition reaction. Subsequently, the substrate is placed in the reaction chamber, and the reaction temperature is controlled at 200-350 degrees Celsius to allow the precursor to undergo a pyrolysis reaction on the substrate surface to generate the deposited material. After deposition, the sample is annealed, oxidized, and polished to ensure the crystallinity and flatness of the film attached to the substrate.

[0015] Preferably, in step S2, the ultrasonic cleaning agent used in the wafer preparation operation is an aqueous cleaning agent, the chemical solution used is deionized water, the cleaning time is 5-10 minutes, the number of cleaning cycles is 3-5, after cleaning, the wafer is air-dried at 40-50 degrees Celsius, and then the substrate surface is mechanically polished using a dual-wheel polishing machine, with the polishing head pressure set to 150-200N, the polishing speed at 35-50r / min, and the polishing time at 6-12h.

[0016] Preferably, in step S2, during the wafer preparation operation, a 4-10% hydrofluoric acid solution is used as the chemical etching solution. Before etching, the wafer is first cleaned with deionized water to remove surface dirt and impurities. The wafer is then immersed in the etching solution, and the etching time is set according to the thickness of the oxide layer. After etching is completed, the wafer is cleaned again with deionized water to remove any residue from the etching solution, and then the wafer surface is dried with nitrogen.

[0017] Preferably, in step S3, phosphide and boride are used as doping raw materials in the material processing operation. Before doping, the doping raw materials are placed in a doping furnace and heated at a temperature of 1000-1200 degrees Celsius for 5-8 minutes to allow the doping material to diffuse into the semiconductor wafer. After heating, the wafer is cooled to fix the dopant in the wafer. After doping, the doped layer image is inspected using an electron scanning microscope and an energy dispersive spectroscopy analyzer. At the same time, four-probe measurement and Hall effect measurement are performed on the semiconductor wafer to verify the doping effect and the electrical properties of the semiconductor.

[0018] Preferably, in step S5, during the gain optimization operation, a common-emitter amplifier is used as the basic amplifier. An additional gain cascade transistor is added between the input and output stages of the basic amplifier. The cascade transistor used is the same as the input transistor. This cascade transistor is used as a current source. At the same time, the input signal is connected to the gate of the amplifier, and its output terminal is connected to the gate of the cascade transistor. The drain of the cascade transistor is connected to the drain of the basic amplifier, providing bias voltage to all pins to ensure that the circuit operates stably at the operating point.

[0019] Preferably, in step S5, the gain optimization operation uses Gauss's law and the symmetry of charge distribution to analyze and determine the distribution law of the electric field, and uses the finite element method and finite difference method to discretize the electric field region. At the same time, numerical simulation is performed on a computer to obtain an approximate solution of the electric field distribution, thereby realizing the reshaping of the electric field distribution.

[0020] Preferably, in step S5, the avalanche photodiode is cut into individual devices, cleaned and pre-treated to remove surface impurities, leads are soldered to the contact points of the avalanche photodiode to ensure electrical connection, the avalanche photodiode is placed in a package base made of ceramic material to provide protection and support, and leads are connected to the pins of the package to provide a path for external circuit connection, and then it is sealed using soldering technology.

[0021] Preferably, in step S5, during the packaging integration operation, a laser is used to irradiate the photosensitive area of ​​the avalanche photodiode, and the distance between the light source and the avalanche photodiode is adjusted to ensure that the center of the beam is aligned with the photodetector area of ​​the avalanche photodiode. At the same time, the current and voltage response parameters of the avalanche photodiode are monitored to confirm the alignment effect of the beam.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention optimizes semiconductor circuits using Cascode technology. By adjusting the circuit's bias voltage, gain circuit configuration, and external signal processing, the gain of the photodetector can be improved. By increasing the gain of the photodetector's preamplifier and improving the signal amplification circuit design, the signal strength and sensitivity can be increased, thereby improving the overall performance of the detector. This, in turn, reduces photodetector noise and distortion, and enhances gain stability and linearity. By configuring two transistors in series, the Cascode structure can improve the amplifier's gain stability while reducing the impact on output impedance, thereby improving high-frequency performance and the linearity of the overall circuit.

[0024] 2. This invention uses a common-emitter amplifier as the basic amplifier, which provides higher bandwidth and relatively simple circuit design. It also offers higher voltage gain, lower input impedance, and higher output impedance. Furthermore, the common-emitter amplifier has a simple structure, is easy to implement and adjust. By applying Gauss's law and the symmetry of charge distribution, the distribution law of the electric field can be determined, which helps optimize the bandgap adjustment effect. It also provides a better understanding of the characteristics of the gain medium and the overall performance of the device. The electric field region is discretized using the finite element method and the finite difference method, transforming the continuous electric field distribution into a discrete computational region for numerical analysis and solution. This refinement makes the description of the changes in electric field, potential energy, and other related quantities in each small unit more accurate, thereby improving the accuracy of the calculation results. The discretized results can be visualized using visualization techniques to present the electric field distribution, potential energy distribution, etc. This visualization helps to understand the behavior of the electric field, identify potential problem areas, and verify the rationality of the calculation results. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the fabrication process of a high-gain photodetector according to the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Example 1:

[0028] like Figure 1 As shown, a method for fabricating a high-gain photodetector includes the following steps:

[0029] S1 Structure Design: Based on the application scenario requirements and working environment of the detector, select photoelectric materials with corresponding wavelength range, sensitivity, response speed, noise level, and temperature stability to fabricate avalanche photodiodes. Generate photoelectric material thin films on the substrate using chemical vapor deposition technology, and define the structure of the photodetector on the wafer using photolithography technology.

[0030] S2 wafer preparation: The semiconductor wafer is cleaned using ultrasonic cleaning agent and chemical solution to remove contaminants and dust from the semiconductor surface. The cleaned wafer is then dried using nitrogen and dry air to remove any remaining moisture. The wafer is then mechanically polished to ensure its surface flatness, thereby improving light incidence efficiency and reducing defects. At the same time, a chemical etching method is used to remove the naturally formed oxide layer on the wafer surface.

[0031] S3 material processing: Doping operation is performed, using an ion accelerator to inject ions containing phosphorus and boron into the semiconductor material to adjust the electronic properties of the semiconductor, separating the semiconductor into p-type containing positive charge carriers and n-type rich in negative charge carriers, and forming a pn junction by heating diffusion, followed by annealing to improve the crystal structure and electrical properties of the material.

[0032] S4 Gain Optimization: The circuit is optimized using Cascode technology, connecting the circuits of two transistors to ensure that the output of the preceding circuit is connected to the input of the following circuit. Gauss's law is applied to determine the electric field distribution, and then numerical calculation methods are used to reshape the electric field distribution. At the same time, electric field simulation experiments are conducted to analyze the electric field parameters, and filters are used to optimize the resonance effect.

[0033] S5 package integration: The manufactured chip is packaged into a shell to protect it from external environmental influences and ensure smooth connection with external circuits. Quartz is used as the optical window of the photodetector to provide a channel for the light signal to enter. Finally, optical alignment and testing are performed.

[0034] Specifically, in step S1, during the structural design operation, silicon material is selected as the substrate for the avalanche photodiode. The infrared light detection range of the selected silicon substrate is 400-1100nm, and the breakdown voltage of the prepared avalanche photodiode is 50-200V.

[0035] Specifically, in step S1, the structural design operation first involves substrate pretreatment, where the substrate to be deposited is cleaned and activated to remove surface impurities and oxides, increase the surface roughness of the substrate, increase the number of surface active sites, and ensure deposition uniformity. Then, the gaseous precursor is transported to the reaction chamber to ensure that the reactants effectively participate in the deposition reaction. The substrate is then placed in the reaction chamber, and the reaction temperature is controlled at 200-350 degrees Celsius to allow the precursor to undergo a pyrolysis reaction on the substrate surface to generate the deposited material. After deposition, the sample is annealed, oxidized, and polished to ensure the crystallinity and flatness of the film attached to the substrate.

[0036] As can be seen from the above, in the fabrication process of the photodetector, the Cascode technique is used to optimize the semiconductor circuit. By adjusting the bias voltage of the circuit, the configuration of the gain circuit, and the external signal processing, the gain of the photodetector can be improved. By increasing the gain of the preamplifier of the photodetector and improving the design of the signal amplification circuit, the signal strength and sensitivity can be improved, thereby improving the overall performance of the detector. This can reduce the noise and distortion of the photodetector, and improve the stability and linearity of the gain. By configuring two transistors in series, the Cascode structure can improve the gain stability of the amplifier and reduce the impact on the output impedance, thereby improving the high-frequency performance and the linearity of the overall circuit.

[0037] Example 2:

[0038] like Figure 1 As shown, in the wafer preparation operation, the ultrasonic cleaning agent used is an aqueous cleaning agent, the chemical solution used is deionized water, the cleaning time is 5-10 minutes, the cleaning is repeated 3-5 times, after cleaning, the wafer is air-dried at 40-50 degrees Celsius, and then the substrate surface is mechanically polished using a dual-wheel polishing machine. The pressure of the polishing head is set to 150-200N, the polishing speed is 35-50r / min, and the polishing time is 6-12h.

[0039] Specifically, in step S2, during the wafer preparation operation, a 4-10% hydrofluoric acid solution is used as the chemical etching solution. Before etching, the wafer is first cleaned with deionized water to remove surface dirt and impurities. The wafer is then immersed in the etching solution, and the etching time is set according to the thickness of the oxide layer. After etching is completed, the wafer is cleaned again with deionized water to remove any residue from the etching solution, and then the wafer surface is dried with nitrogen.

[0040] Specifically, in step S3, during the material processing operation, phosphides and borides are used as doping raw materials. Before doping, the doping raw materials are placed in a doping furnace and heated at a temperature of 1000-1200 degrees Celsius for 5-8 minutes to allow the doping material to diffuse into the semiconductor wafer. After heating, the wafer is cooled to fix the dopant in the wafer. After doping, the doped layer image is inspected using an electron scanning microscope and an energy dispersive spectroscopy analyzer. At the same time, four-probe measurements and Hall effect measurements are performed on the semiconductor wafer to verify the doping effect and the electrical properties of the semiconductor.

[0041] Specifically, in the gain optimization operation, a common-emitter amplifier is used as the basic amplifier. An additional gain cascade transistor is added between the input and output stages of the basic amplifier. The cascade transistor used is the same as the input transistor. This cascade transistor is used as a current source. At the same time, the input signal is connected to the gate of the amplifier, and its output terminal is connected to the gate of the cascade transistor. The drain of the cascade transistor is connected to the drain of the basic amplifier to provide bias voltage for all pins, so as to ensure that the circuit operates stably at the operating point.

[0042] As can be seen from the above, by using a common-emitter amplifier as the basic amplifier, the present invention can provide higher bandwidth and relatively simple circuit design, as well as higher voltage gain, while having lower input impedance and higher output impedance. Furthermore, the common-emitter amplifier has a simple structure and is easy to implement and adjust.

[0043] Example 3:

[0044] like Figure 1 As shown, in step S5, the gain optimization operation uses Gauss's theorem and the symmetry of charge distribution to analyze and determine the distribution law of the electric field. The electric field region is discretized using the finite element method and the finite difference method. At the same time, numerical simulation is performed on a computer to obtain an approximate solution of the electric field distribution, thereby reshaping the electric field distribution.

[0045] Specifically, in step S5, the avalanche photodiode is cut into individual devices and cleaned and pre-treated to remove surface impurities. Leads are soldered to the contact points of the avalanche photodiode to ensure electrical connection. The avalanche photodiode is placed in a package base made of ceramic material to provide protection and support. Leads are connected to the pins of the package to provide a path for external circuit connection. Finally, it is sealed using soldering technology.

[0046] Specifically, in step S5, during the packaging integration operation, a laser is used to irradiate the photosensitive area of ​​the avalanche photodiode. The distance between the light source and the avalanche photodiode is adjusted to ensure that the center of the beam is aligned with the photodetector area of ​​the avalanche photodiode. At the same time, the current and voltage response parameters of the avalanche photodiode are monitored to confirm the alignment effect of the beam.

[0047] As can be seen from the above, this invention uses Gauss's law and the symmetry of charge distribution for analysis, thereby determining the distribution law of the electric field, which helps to optimize the bandgap adjustment effect. At the same time, it can also better understand the characteristics of the gain medium and the overall performance of the device. The electric field region is discretized using the finite element method and the finite difference method, transforming the continuous electric field distribution into a discrete computational region for numerical analysis and solution. This refinement makes the description of the changes of electric field, potential energy and other related quantities in each small unit more accurate, thereby improving the accuracy of the calculation results. The discretized results can be visualized using visualization technology to present the electric field distribution, potential energy distribution, etc. This visualization helps to understand the behavior of the electric field, identify potential problem areas, and verify the rationality of the calculation results.

[0048] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. The substitutions may be replacements of some structures, devices, or method steps, or they may be complete technical solutions. Equivalent substitutions or modifications made to the technical solutions and inventive concepts of the present invention should all be covered within the scope of protection of the present invention.

Claims

1. A method for fabricating a high-gain photodetector, characterized in that, Includes the following steps: S1 Structure Design: Based on the application scenario requirements and working environment of the detector, select photoelectric materials with corresponding wavelength range, sensitivity, response speed, noise level, and temperature stability to fabricate avalanche photodiodes. Generate photoelectric material thin films on the substrate using chemical vapor deposition technology, and define the structure of the photodetector on the wafer using photolithography technology. S2 wafer preparation: The semiconductor wafer is cleaned using ultrasonic cleaning agent and chemical solution to remove contaminants and dust from the semiconductor surface. The cleaned wafer is then dried using nitrogen and dry air to remove any remaining moisture. The wafer is then mechanically polished to ensure its surface flatness, thereby improving light incidence efficiency and reducing defects. At the same time, a chemical etching method is used to remove the naturally formed oxide layer on the wafer surface. S3 material processing: Doping operation is performed, using an ion accelerator to inject ions containing phosphorus and boron into the semiconductor material to adjust the electronic properties of the semiconductor, separating the semiconductor into p-type containing positive charge carriers and n-type rich in negative charge carriers, and forming a pn junction by heating diffusion, followed by annealing to improve the crystal structure and electrical properties of the material. S4 Gain Optimization: The circuit is optimized using Cascode technology, connecting the circuits of two transistors to ensure that the output of the preceding circuit is connected to the input of the following circuit. Gauss's law is applied to determine the electric field distribution, and then numerical calculation methods are used to reshape the electric field distribution. Simultaneously, electric field simulation experiments are conducted to analyze the electric field parameters, and filters are used to optimize the resonance effect. A common-emitter amplifier is used as the basic amplifier, and an additional gain cascade transistor is added between the input and output stages of the basic amplifier. The cascade transistor used is the same as the input transistor and is used as a current source. The input signal is connected to the gate of the amplifier, and its output is connected to the gate of the cascade transistor. The drain of the cascade transistor is connected to the drain of the basic amplifier, providing bias voltage to all pins to ensure that the circuit operates stably at the operating point. S5 package integration: The manufactured chip is packaged into a shell to protect it from external environmental influences and ensure smooth connection with external circuits. Quartz is used as the optical window of the photodetector to provide a channel for the light signal to enter. Finally, optical alignment and testing are performed.

2. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S1, during the structural design operation, silicon material is selected as the substrate for the avalanche photodiode. The infrared light detection range of the selected silicon substrate is 400-1100nm, and the breakdown voltage of the prepared avalanche photodiode is 50-200V.

3. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S1, the structural design operation first involves substrate pretreatment, where the substrate to be deposited is cleaned and activated to remove surface impurities and oxides, increase the surface roughness, and increase the number of surface active sites to ensure deposition uniformity. Then, the gaseous precursor is transported to the reaction chamber to ensure that the reactants effectively participate in the deposition reaction. The substrate is then placed in the reaction chamber, and the reaction temperature is controlled at 200-350 degrees Celsius to allow the precursor to undergo a pyrolysis reaction on the substrate surface, generating the deposited material. After deposition, the sample is annealed, oxidized, and polished to ensure the crystallinity and flatness of the film attached to the substrate.

4. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S2, during the wafer preparation operation, the ultrasonic cleaning agent used is an aqueous cleaning agent, the chemical solution used is deionized water, the cleaning time is 5-10 minutes, the cleaning is repeated 3-5 times, after cleaning, the wafer is air-dried at 40-50 degrees Celsius, and then the substrate surface is mechanically polished using a dual-wheel polishing machine. The pressure of the polishing head is set to 150-200N, the polishing speed is 35-50r / min, and the polishing time is 6-12h.

5. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S2, during the wafer preparation operation, a 4-10% hydrofluoric acid solution is used as the chemical etching solution. Before etching, the wafer is first cleaned with deionized water to remove surface dirt and impurities. The wafer is then immersed in the etching solution, and the etching time is set according to the thickness of the oxide layer. After etching is completed, the wafer is cleaned again with deionized water to remove any residue from the etching solution, and then the wafer surface is dried with nitrogen.

6. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S3, during the material processing operation, phosphides and borides are used as doping raw materials. Before doping, the doping raw materials are placed in a doping furnace and heated at a temperature of 1000-1200 degrees Celsius for 5-8 minutes to allow the doping material to diffuse into the semiconductor wafer. After heating, the wafer is cooled to fix the dopant in the wafer. After doping, the doped layer image is inspected using an electron scanning microscope and an energy dispersive spectroscopy analyzer. At the same time, four-probe measurements and Hall effect measurements are performed on the semiconductor wafer to verify the doping effect and the electrical properties of the semiconductor.

7. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S4, the gain optimization operation uses Gauss's law and the symmetry of charge distribution to analyze and determine the distribution law of the electric field. The electric field region is discretized using the finite element method and the finite difference method. At the same time, numerical simulation is performed on a computer to obtain an approximate solution of the electric field distribution, thereby reshaping the electric field distribution.

8. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S5, the avalanche photodiode is cut into individual devices and cleaned and pre-treated to remove surface impurities. Leads are soldered to the contact points of the avalanche photodiode to ensure electrical connection. The avalanche photodiode is placed in a package base made of ceramic material to provide protection and support. Leads are connected to the pins of the package to provide a path for external circuit connection. Finally, it is sealed using soldering technology.

9. The method for fabricating a high-gain photodetector as described in claim 1, characterized in that, In step S5, during the packaging integration operation, a laser is used to irradiate the photosensitive area of ​​the avalanche photodiode. The distance between the light source and the avalanche photodiode is adjusted to ensure that the center of the beam is aligned with the photodetector area of ​​the avalanche photodiode. At the same time, the current and voltage response parameters of the avalanche photodiode are monitored to confirm the alignment effect of the beam.

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