CN112054086A - A kind of preparation method of silicon-based photodetector with lateral junction - Google Patents

Abstract

The invention relates to a method for preparing a transverse junction silicon-based photoelectric detector, which forms a transverse pn junction or a heterojunction through the current carrier conduction type or concentration difference between a black silicon surface prepared by pulse laser and an unprocessed silicon region, and can form the black silicon photoelectric detector with the transverse junction through the subsequent processes of annealing, passivation, photoetching, electrode preparation and the like. The transverse junction silicon-based photoelectric detector can efficiently absorb photons to generate electron-hole pairs under reverse bias voltage, and the electron-hole pairs are transversely moved under the action of an external electric field to finally form transverse photocurrent, so that optical signal detection is realized. Compared with the traditional longitudinal structure detector, the transverse junction silicon-based photoelectric detector prepared by the invention effectively inhibits dark current and improves the detection rate of the device, simplifies the preparation process of the device and is more beneficial to the preparation and integration of the device.

Description

A kind of preparation method of silicon-based photodetector with lateral junction

technical field

The invention relates to the field of silicon-based photoelectric devices, in particular to a preparation method of a photodetector, which is a lateral junction silicon-based photodetector with low dark current.

Background technique

In recent decades, with the rapid development of semiconductor technology, semiconductor devices with various functions have continuously improved people's lives and have great potential for the next generation of industrial revolutions (such as artificial intelligence, Internet of Everything, driverless vehicles, etc.). As the most common and important semiconductor material, silicon has the advantages of abundant content, low price, high purity and few defects. So far, silicon has played a huge potential in the field of microelectronics, constantly breaking through the limits of Moore's Law, and promoting the innovation and development of semiconductor technology. However, in the field of optoelectronics, due to the limitation of the energy band width of 1.12 eV and the high reflectivity of the single crystal silicon surface, the absorption rate of silicon, especially the absorption in the infrared band, is suppressed, which greatly limits the silicon photonics. development of.

Doping with different elements is an important method to improve the optoelectronic properties of semiconductor materials, and is a common modification method in the fields of photodetectors and solar cells. However, due to the limitation of solid solubility, the traditional thermal diffusion process is difficult to achieve supersaturated doping of doping elements. With the development of semiconductor technology, ion implantation and ultrafast pulsed laser supersaturation doping can achieve supersaturated doping beyond the solid solubility. supersaturated doping. In particular, after modification by ultrafast pulsed laser, a microcone structure and a supersaturated doped layer can be simultaneously formed on the surface of crystalline silicon, which can realize the characteristics of a broad spectrum and high response of the photodetector. However, this modification process will not be possible. Avoid introducing a large amount of impurities and lattice defects, which adversely affects the dark current and signal-to-noise ratio of the device, which greatly reduces the performance of the semiconductor device and limits the application range of the device.

SUMMARY OF THE INVENTION

In order to solve the above problems, the inventors have proposed a method for fabricating a lateral junction silicon-based photodetector through long-term experiments and research. On the one hand, it improves the shortcomings of high dark current and low signal-to-noise ratio of traditional silicon-based photodetectors, and on the other hand, it makes up for the shortcomings that silicon-based materials are difficult to be compatible with existing CMOS after supersaturated doping.

According to the technical solution of the present invention, a preparation method of a lateral junction silicon-based photodetector is provided, comprising the following steps:

Step 1: Select a semiconductor single crystal silicon wafer for pretreatment, including but not limited to slicing, RCA cleaning, and pre-coating a film containing doping elements on the silicon surface;

Step 2: Select the processed single-crystal silicon material, and irradiate a specific area of its surface with an ultrafast pulsed laser in a specific atmosphere to prepare a supersaturated doped layer, that is, to obtain a black silicon surface;

Step 3: annealing the prepared black silicon material, activating the impurity atoms in the supersaturated doped black silicon layer, repairing the lattice, and removing structural defects;

Step 4: Plate a passivation layer on the black silicon and the silicon surface where no electrode contact is required to protect the detector surface and isolate air pollution and oxidation;

Step 5: Plate contact electrodes on the silicon and black silicon regions respectively; so far, the preparation of the lateral junction silicon-based photodetector is completed;

The dark current of the lateral junction silicon-based photodetector under -5V bias voltage can be reduced to 783nA, which is much smaller than the black silicon photodetector of the traditional vertical structure; at the same time, the response band of the device is 500nm-1400nm, in the The peak responsivity under -5V bias is 3.23A/W, and the peak wavelength appears around 1080nm. The specific meaning of each mathematical symbol is: nm: nanometer, V: volt, A/W: ampere/watt, nA: nanoampere.

Further, the single crystal silicon substrate in step 1 can be either n-type or p-type, with a thickness of 5 μm-500 μm (microns), and the crystal orientation, resistivity and size of the semiconductor wafer are not limited; The bottom surface is flat, and the surface flatness, that is, the difference between the highest point and the lowest point on the surface of the material, is less than or equal to 10 μm.

Further, the pretreatment in step 1 can be selected but not limited to the following processes: (a) cutting the single crystal silicon wafer into small pieces of a certain size; (b) cleaning the single crystal silicon by the RCA cleaning method; (c) A thin film containing dopant substances is deposited on the silicon surface by a coating process or a thin film growth process.

Further, the specific steps of preparing the supersaturated doped black silicon layer by ultrafast pulsed laser irradiation described in step 2 are as follows:

(1) The cleaned single crystal silicon is fixed on a three-dimensional translation stage in a vacuum chamber, and driven by the translation stage, the sample moves two-dimensionally on a plane perpendicular to the incident laser. Select the appropriate moving range and moving speed through the parameter setting of the three-dimensional translation stage, and cooperate with the shutter switch to realize the preparation of different patterns and structures;

(2) Evacuate, the degree of vacuum is 10 ⁰ -10 ^-5 Pa, then, fill with a certain gas less than 1 standard atmospheric pressure, such as sulfur hexafluoride, nitrogen, etc., or evacuate to a vacuum state;

(3) Control the movement of the sample stage: control the area and scanning speed of ultrafast pulsed laser supersaturation doping and modification by controlling the moving speed and moving range, that is, two-dimensional movement on a plane perpendicular to the incident laser direction; A Glan-Taylor prism and a half-wave plate are used to adjust the polarization direction and power of the laser irradiated on the surface of single crystal silicon, so that the flux of the laser irradiated on the surface of single crystal silicon is 0.01kJ/m ² -100kJ/ m ² , the number of pulses received per unit area is 1-5000, and the pulse width of the ultrafast pulsed laser is 5fs-100ns, so as to control the surface modification intensity and doping concentration; it can process large areas by line-by-line scanning. The supersaturated doped layer of the micro-area can also be prepared by setting different scanning patterns and paths and cooperating with the shutter switch to prepare the supersaturated doped layer of the micro area and the supersaturated doped layer of different patterns;

(4) After scanning, pump out the gas in the vacuum chamber, then fill it with nitrogen to a standard atmospheric pressure, open the vacuum chamber cover, take out the sample silicon wafer, and detect that the processed area (ie black silicon layer) is black or dark gray; A quasi-periodically arranged micro-nano structure is formed on the surface of the single-crystal silicon material treated by the above steps, and a large amount of impurity elements are doped.

Preferably, the annealing method in step 3 can be selected but not limited to one of rapid thermal annealing, tube furnace annealing, ultrafast pulsed laser annealing, femtosecond laser annealing and the like.

Further, the preparation method of the passivation layer described in step 4 includes resistance thermal evaporation method, magnetron sputtering method, electron beam evaporation method, pulsed laser deposition method, chemical vapor deposition method, heteroepitaxial growth method, etc.; passivation The material is one or a combination of passivation materials such as Al ₂ O ₃ , SiN _x , Si ₂ O ₃ , a-Si:H, phosphosilicate glass, and polyimide. The preparation method may be to prepare the passivation layer after patterning by photolithography, or prepare the passivation layer after masking through a metal reticle.

Further, the preparation method of the contact electrode of the black silicon and the silicon region described in step 5 is a resistance thermal evaporation method, a magnetron sputtering method, an electron beam evaporation method or a pulsed laser deposition method; the electrode materials are aluminum, gold, silver, chromium , nickel, titanium or platinum, or one or a combination thereof; the shape of the electrode can be prepared as a rectangle, a ring, a circle, an ellipse, or other irregular patterns.

beneficial effect

Compared with the prior art, the present invention has the following advantages:

1. The lateral junction silicon-based photodetector prepared by the present invention has a more stable lateral pn junction or heterojunction. Compared with the vertical structure silicon-based photodetector, its dark current is reduced, and the stability of the device is improved.

2. In the present invention, positive and negative electrodes are plated on the black silicon and silicon material regions of the front simultaneously after the ultrafast pulsed laser irradiation, which is similar to that of conventional black silicon photodetectors by plated positive and negative electrodes on the front and back or plated with electrodes after etching the mesa. Compared with the method, the present invention not only ensures the stability of the device, reduces the leakage noise of the device, but also simplifies the preparation process;

3. The lateral junction silicon-based photodetector prepared by the present invention has an average external quantum efficiency of more than 100% in the range of 640--1170nm band under -5V bias voltage, and realizes wide spectrum and high gain under low bias voltage. In addition, the dark current of the lateral junction silicon-based photodetector prepared by the present invention is 783nA under -5V bias voltage, which overcomes the shortcomings of femtosecond laser supersaturation doping and the difficulty in suppressing the dark current of the modified photodetector .

4. The preparation processes used in the present invention are all CMOS compatible processes, which have the advantage of being compatible with existing CMOS, CCD and other semiconductor processes.

5. The present invention has the advantages of simple structure, simple process, easy acquisition of raw materials, easy processing and easy storage.

Description of drawings

FIG. 1 is a schematic flowchart of the preparation method of the lateral junction silicon-based photodetector provided by the present invention.

2 is a cross-sectional structural diagram of the lateral junction silicon-based photodetector provided by the present invention.

Detailed ways

The technical solutions in the embodiments 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 a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Additionally, the scope of the present invention should not be limited only to the specific structures or components or specific parameters described below.

The invention utilizes the lateral interface formed between black silicon and unprocessed silicon after ultrafast pulse laser modification, and utilizes the carriers at the lateral interface between black silicon and silicon through subsequent passivation, metal electrode preparation and other processes. Depending on the type and concentration, a lateral pn junction or an n ⁺ -i junction heterostructure is formed to form a lateral junction silicon-based photodetector. Among them, the surface of the black silicon layer has a quasi-periodically arranged micro-cone structure, and the surface has supersaturated doped impurity elements. After subsequent annealing treatment, the impurity elements in the black silicon doped layer are activated to make it within a wide spectrum range ( 0.25μm-2.5μm) has a light absorption rate greater than 80%, which greatly improves the absorption rate of semiconductor silicon materials and expands its spectral absorption range. The lateral junction silicon-based photodetector works under reverse bias voltage, absorbs photons to generate photo-generated electron-hole pairs, and migrates laterally to the electrodes on both sides under the action of the electric field, and is collected by the electrodes to form lateral photocurrents, thereby realizing Light Response and Detection.

In order to make the purpose, technical solutions and advantages of the present invention clearer, the following will further describe the preparation method of the lateral junction silicon-based photodetector of the present invention with reference to the accompanying drawings, including the following specific steps:

1 is a cross-sectional structure diagram of a lateral junction silicon-based photodetector provided by the present invention, wherein 1-1 is a single crystal silicon substrate, 1-2 is a black silicon layer after femtosecond laser supersaturation doping, 1-3 are the surface passivation layers, and 1-4 are the contact electrodes of black silicon and silicon, respectively.

FIG. 2 is a schematic flow chart of the preparation method of the lateral junction silicon-based photodetector provided by the present invention.

With reference to FIG. 2, a more detailed preparation method of a lateral junction silicon-based photodetector provided by the present invention is described, which includes the following steps:

Step 1: Select a single crystal silicon substrate with a clean and flat surface;

Step 2: Pre-processing the selected single crystal silicon wafer, including but not limited to slicing, RCA cleaning, and plating a film containing the element to be doped on the silicon surface;

Step 3: Put the treated single crystal silicon into the vacuum chamber and fix it on the sample holder, so that the incident laser light hits the surface of the sample vertically;

Step 4: Evacuate to 10 ⁰ -10 ^-5 Pa, and fill with a specific gas below 1 atmosphere or keep the vacuum according to the doping element;

Step 5: The surface micro-nano structure and supersaturated doped layer are prepared by irradiating a specific area of the single crystal silicon surface with a pulsed laser in a specific pressure and atmosphere. The sample is driven by a three-dimensional translation stage to perform a two-dimensional plane scanning motion. The speed is progressive scan, which can process a large area of black silicon layer.

Step 6: After the processing is completed, remove the gas in the processing chamber, fill it with nitrogen to a standard atmospheric pressure, open the chamber cover, and take out the sample. The color of the processed area can be seen to be black or dark gray through the above steps. The surface of the silicon material forms a quasi-periodically arranged micro-nano structure, and a large amount of impurity elements are doped, thereby obtaining a black silicon surface;

Step 7: Select an appropriate annealing method to further process the prepared black silicon material, such as rapid thermal annealing, tube furnace annealing, nanosecond laser melting annealing or femtosecond laser annealing, etc., and adjust parameters such as annealing temperature and annealing time. , to activate the doping elements in the black silicon layer, remove defects and repair the damaged lattice at the same time;

Step 8: Prepare a passivation layer on the black silicon and the area other than the silicon and the electrode contact, and retain the area that needs to be in contact with the electrode through a photolithography mask process or a physical mask process. The preparation method of the passivation layer can be a resistor Thermal evaporation, magnetron sputtering, electron beam evaporation, chemical vapor deposition, pulsed laser deposition, heteroepitaxial growth method, etc.; passivation materials can be Al ₂ O ₃ , SiN _x , Si ₂ O ₃ , a-Si: One or a combination of H, phosphosilicate glass, polyimide, etc.

Step 9: Through the photolithography mask process or the physical mask process, the electrode contact area retained in the process of step 8 is prepared separately for the contact electrode of black silicon and the contact electrode of silicon, and the metal contact of black silicon and silicon can be prepared at the same time Electrodes can also be prepared separately. The preparation methods of metal electrodes can be resistance thermal evaporation, magnetron sputtering, electron beam evaporation, pulsed laser deposition, etc.; electrode materials can be aluminum, gold, silver, chromium, nickel, titanium or platinum. One or a combination thereof; the shape of the electrode can be a rectangle, a ring, a circle, an ellipse, or other irregular shapes.

Wherein, the single crystal silicon substrate in step 1 can be either n-type or p-type, with a thickness of 100 μm-500 μm (microns), and the crystal orientation, resistivity and size of the semiconductor wafer are not limited; the single crystal silicon substrate The surface is required to be flat, and the surface flatness, that is, the difference between the highest point and the lowest point on the surface of the material, is less than or equal to 10 μm.

Further, the gas in the above-mentioned step 4 can be one or a combination of nitrogen, hydrogen, sulfur hexafluoride, oxygen, helium, argon, carbon tetrafluoride, etc., or a vacuum environment, and the pressure can be 10 ^-5 Pa to 1 atmosphere.

Further, the laser parameters and irradiation conditions in the above step 5 can be selected in various ways, such as nanosecond laser, picosecond laser, femtosecond laser, and attosecond laser. The laser parameters used in this case are that the center wavelength is 800 nm, A femtosecond laser with a pulse width of 120fs; the polarization direction and power of the laser irradiated to the surface of single crystal silicon can be continuously adjusted by a combination of a Glan-Taylor prism and a half-wave plate, so that the femtosecond laser flux is 0.8 kJ/m ² -8kJ/m ² , the number of pulses received per unit area can be 1-500 through the adjustment of the stepper motor;

The dark current of the fabricated lateral junction silicon-based photodetector under -5V bias voltage can be reduced to 783nA, which is much smaller than that of the traditional vertical structure black silicon photodetector; at the same time, the response band of the device is 500nm-1400nm, in - The peak responsivity under 5V bias is 3.23A/W, and the peak wavelength appears around 1080nm. The specific meaning of each mathematical symbol is: nm: nanometer, V: volt, A/W: ampere/watt, nA: nanoampere.

To sum up, the lateral junction silicon-based photodetector prepared by the above preparation method includes - preparing supersaturated doped black silicon surface and forming a lateral interface of black silicon-silicon; - annealing the prepared black silicon material; - passivation to protect the surface of the material; - to make black silicon and silicon-to-metal contact electrodes. So far, the fabrication of the lateral junction silicon-based photodetector device is completed.

Implementation Example 1:

A preparation method of a lateral junction silicon-based photodetector, comprising the following steps:

Step 1: Select a 2-inch n-type (100) zone fused single-crystal silicon wafer with a resistivity of 3000-5000Ω·cm and a thickness of 430±10μm;

Step 2: Pre-processing the selected single crystal silicon wafer, the specific steps are: (a) cleaning the single crystal silicon wafer by a standard RCA cleaning method; (b) cutting the single crystal silicon wafer into small units.

Step 3: Put the cleaned single crystal silicon into the vacuum chamber and fix it on the sample holder, so that the incident laser light hits the sample surface vertically. The sample holder is connected with a three-dimensional moving stage. Driven by the translation stage, the sample Two-dimensional motion can be performed on a plane perpendicular to the incident laser;

Step 4: evacuate to 10 ^-5 Pa, then fill with 0.67bar sulfur hexafluoride gas, and finally process in a 0.67 bar sulfur hexafluoride atmosphere;

Step 5: The center wavelength of the incident femtosecond laser is 800nm, the pulse width is 120fs, and the laser flux irradiated to the surface of the silicon wafer is 1.0kJ/m ² . The sample is driven by a two-dimensional translation stage to perform two-dimensional scanning motion. Line-by-line scanning, scanning a square area with an area of 1cm×1cm, the scanning line spacing is 50μm, and the scanning speed is 1mm/s;

Step 6: After the processing is completed, the chamber is evacuated to 10 ^-5 Pa, and then filled with nitrogen to atmospheric pressure, the chamber lid is opened, and the sample is taken out. The color of the processed area is black or dark gray by visual inspection, that is, the sulfur element is supersaturated. Doped black silicon layer, the thickness of the doped layer is about 100nm, while the unprocessed area still maintains the smooth polishing characteristics of single crystal silicon;

Step 7: Treat the sample irradiated by the femtosecond laser with the rapid thermal annealing method. The first step is to heat up, first to 240°C in 10s, and then to 600°C in 5s; in the second step, the temperature is kept constant at 600°C. ℃ to 600s; the third step is to naturally cool down to below 100 ℃, and take out the sample;

Step 8: A _SiO2 passivation layer is prepared on the surface of black silicon by plasma-enhanced chemical vapor deposition (PECVD) method, and the thickness of the passivation layer is about 1 μm; then, the surface of the material is protected with photoresist by UV lithography, and only exposed Part of the black silicon and silicon areas that need electrode contact; the sample was then rinsed in dilute hydrofluoric acid for 5 s to remove the _SiO2 passivation layer in the areas not covered by the photoresist; the photolithography was subsequently removed by an acetone rinse glue.

Step 9: Use the method of resistive thermal evaporation to prepare aluminum metal electrodes as positive and negative contact electrodes in the black silicon and silicon surface areas. The hollow area not covered by the photoresist corresponds to the black silicon and the area on the silicon that needs to be plated with electrodes. Fix the sample after the photolithography mask on the molybdenum boat of the evaporation coating machine, and put an appropriate amount in the molybdenum boat. The aluminum particles were evacuated to 3×10 ^-3 Pa, and then the aluminum electrodes were evaporated and evaporated; then the photoresist was removed by acetone cleaning, and the device fabrication was completed.

The dark current of the lateral junction silicon-based photodetector prepared through the above steps can be reduced to 783nA under -5V bias, the lateral heterojunction effectively solves the defect that the dark current of the black silicon photodetector is difficult to suppress; The characteristics of high gain and broad spectrum are achieved under low bias voltage. The response band of the device is 500nm-1400nm, and the peak responsivity under -5V bias voltage is 3.23A/W, of which the peak wavelength appears around 1080nm. The signal-to-noise ratio and dynamic range of the device are effectively improved.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. Substitutions should be covered within the protection scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (7)

1. A method for preparing a lateral junction silicon-based photoelectric detector with low dark current is characterized by comprising the following steps:

step 1: selecting a monocrystalline silicon wafer, and pretreating the selected silicon wafer;

step 2: selecting pretreated monocrystalline silicon, irradiating a specific area on the surface of the monocrystalline silicon in a specific atmosphere or vacuum by pulse laser, and preparing a supersaturated doping layer to obtain a black silicon surface;

and step 3: annealing the prepared black silicon material, activating impurity atoms in the supersaturated doped black silicon layer, repairing crystal lattices, and removing structural defects;

and 4, step 4: plating a passivation layer on the black silicon surface except the electrode contact area to protect the black silicon surface and isolate air pollution and oxidation;

and 5: respectively plating contact electrodes on electrode contact areas of the silicon and the black silicon; thus, the preparation of the transverse junction silicon-based photoelectric detector is completed.

2. The method of claim 1, wherein the single crystal silicon selected in step 1 is either n-type or p-type, and has a thickness of 5 μm-500 μm (micrometers), and the semiconductor wafer has unlimited crystal orientation, resistivity, and size.

3. The method of claim 1, wherein the preprocessing in step 1 includes but is not limited to: (1) cutting a monocrystalline silicon wafer into small blocks with a certain size; (2) cleaning the monocrystalline silicon by an RCA cleaning method; (3) and depositing a layer of film with a certain thickness and containing doping substances on the silicon surface by a coating process or a film growth process.

4. The method for preparing the lateral junction silicon-based photodetector as claimed in claim 1, wherein the step 2 of preparing the supersaturated doped black silicon surface by the pulsed laser irradiation comprises the following specific steps:

(1) fixing the pretreated monocrystalline silicon material on a three-dimensional translation table in a vacuum chamber, driving a sample to make two-dimensional motion on a plane vertical to incident laser under the drive of the translation table, selecting a proper moving range and moving speed through parameter setting of the three-dimensional translation table so as to control the area and scanning speed of a pulse laser supersaturation doping and modification region, and matching with a shutter switch to realize preparation of different patterns and structures;

(2) vacuum pumping is carried out, and the vacuum degree is 10⁰-10^-5Pa, then filling specific gas with pressure less than 1 standard atmosphere, such as sulfur hexafluoride, nitrogen and the like, or keeping the state of vacuum;

(3) pulsed laser scanning: controlling the translation stage to make the sample move in two dimensions on a plane perpendicular to the incident laser direction; the pulse width of the incident pulse laser is 5fs-100ns, and the polarization direction and power of the laser irradiated to the surface of the monocrystalline silicon are adjusted by a Glan-Taylor prism and a half-wave plate, so that the laser flux irradiated on the surface of the monocrystalline silicon is 0.01kJ/m²-100kJ/m²The number of received pulses per unit area is 1-5000, so that the surface modification strength and the doping concentration are controlled; the method can not only scan and process large-area supersaturated doping layers line by line, but also set different scanning patterns and paths or prepare a micro-area supersaturated doping layer and supersaturated doping layers with different patterns by matching with a shutter switch;

(4) after scanning is finished, pumping out gas in the vacuum cavity, refilling nitrogen to a standard atmospheric pressure, opening a vacuum cavity cover, taking out a sample silicon wafer, and detecting a processed area, namely a black silicon layer, which is black or dark gray; the silicon material surface processed by the steps forms a quasi-periodically arranged micro-nano structure, and a large amount of impurity elements are doped.

5. The method for manufacturing a lateral junction silicon-based photodetector as claimed in claim 1, wherein the annealing method in step 3 is one or a combination of rapid thermal annealing, tube furnace annealing, ultrafast pulsed laser annealing, femtosecond laser annealing, and the like.

6. According to the rightThe method for preparing the transverse junction silicon-based photoelectric detector according to claim 1, wherein the method for preparing the passivation layer in the step 4 comprises a resistance thermal evaporation method, a magnetron sputtering method, an electron beam evaporation method, a pulse laser deposition method, a chemical vapor deposition method, a heteroepitaxial growth method and the like; the passivating material being Al₂O₃、SiN_x、Si₂O₃a-Si: H. one or the combination of phosphorosilicate glass, polyimide and the like, and the masking mode can be that a passivation layer is prepared after photoetching patterns are carried out, the passivation layer of the electrode contact area is removed through photoetching after the passivation layer is prepared, or the passivation layer can be prepared after mask plate masking is carried out.

7. The method for preparing a lateral junction silicon-based photodetector as claimed in claim 1, wherein the method for preparing the contact electrode in the electrode contact region of the black silicon and the silicon in step 5 can be a resistance thermal evaporation method, a magnetron sputtering method, an electron beam evaporation method or a pulsed laser deposition method; the electrode material is one or the combination of aluminum, gold, silver, chromium, nickel, titanium or platinum; the shape of the electrode can be prepared into a rectangular shape, a ring shape, a round shape, an oval shape or other irregular figures; the mask mode can be to prepare the metal electrode after photoetching the pattern, can also be through preparing the metal electrode after the physical mask.

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