Photoelectric detector and preparation method thereof
By forming a convex surface protruding outwardly on the upper surface of the receiving area of the photodetector, the problem of reduced production capacity caused by excessive reception surface of the existing photodetector is solved, and a higher capacity per unit area and more efficient beam signal utilization is achieved.
Patent Information
- Application Number
- CN202411890312.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-04-15
AI Technical Summary
The receiving surface of existing photodetectors must be large to receive the light beam from the transmitting source, resulting in a reduction in production capacity per unit area and a waste of the receiving surface.
A photodetector is designed, and the upper surface of the receiving area is a convex surface protruding outward. By forming a convex portion on the epitaxial layer, the receiving area of the electrode layer can receive more beams of light of emission angles, thereby increasing the angle and area of the received light beam.
By reducing the plane area occupied by the receiving surface of the photodetector, the production capacity per unit area is improved, the waste of the receiving surface is avoided, and the utilization rate of the beam signal is improved.
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Figure CN119836048A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor devices, and in particular to a photodetector and a method for preparing the same. Background Art
[0002] A photodetector is a device that can convert light signals into electrical signals. Specifically, a photodetector works based on the photoelectric effect. When the energy of photons is absorbed by semiconductor materials, electrons jump from the valence band to the conduction band, generating electron-hole pairs, thereby changing the electrical properties of the material and realizing the conversion of light signals into electrical signals. For example, photodiodes, photoresistors, photomultiplier tubes, etc. are all common photodetectors. Among them, photoresistors, such as cadmium sulfide and cadmium selenide photoresistors, are widely used in photoelectric automatic detection systems, photoelectric tracking systems, missile guidance, infrared spectroscopy systems, etc.; photodiodes include ordinary photodiodes, PIN photodiodes, and avalanche photodiodes, etc., which have the characteristics of fast response speed, low dark current, and high reliability. They are suitable for the detection and conversion of various light signals, such as in optical fiber communications, industrial automation control and other fields.
[0003] The light beam received by the photodetector in the prior art is mainly laser. Although the laser has strong collimation, it still has a divergence angle from a microscopic perspective. Therefore, the receiving surface of the photodetector must be made larger than the light outlet of the emission source in order to receive most of the luminous energy of the emission source. The receiving surface of the photodetector in the prior art is set to a plane. Therefore, a larger receiving surface is set to receive the light beam from the emission end. This reduces the production capacity per unit area and causes a waste of the receiving surface. Summary of the invention
[0004] The purpose of the present application is to provide a photoelectric detector and a method for preparing the same, which can reduce the plane area occupied by the receiving surface of the photoelectric detector and improve the production capacity per unit area.
[0005] On the one hand, an embodiment of the present application provides a photodetector, including a substrate and an epitaxial layer and an electrode layer sequentially arranged on the substrate, the electrode layer having a receiving area, a portion of the epitaxial layer located in the receiving area convexly forms a convex portion, so that the upper surface of the receiving area is a convex surface protruding outward, and the receiving area is used to receive a light beam, and the light beam penetrates the electrode layer to excite the epitaxial layer to form an electrical signal.
[0006] As an implementable manner, the convex surface is a convex spherical surface.
[0007] As an implementable manner, the convex surface includes a plurality of coaxial annular surfaces arranged in sequence along the hierarchical direction, and upward along the hierarchical direction, the outer diameter of the next annular surface is smaller than the inner diameter of the previous annular surface.
[0008] As an implementable manner, the outer diameter of the next annular surface is connected to the inner diameter of the previous annular surface to form an inclined surface.
[0009] As an implementable manner, the outer diameter of one annular surface is connected with the inner diameter of the previous annular surface to form a vertical surface.
[0010] As an implementable manner, the angle between the edge of the received light beam in the receiving area and the plane where the electrode layer is located is less than 20 degrees.
[0011] On the other hand, an embodiment of the present application provides a method for preparing a photodetector, which is used to prepare the above-mentioned photodetector, including: providing a substrate, and sequentially forming epitaxial layers on the substrate; using a mask to form a convex portion protruding outward on the upper surface of the epitaxial layer by local exposure to different degrees; forming an electrode layer on the upper surface of the epitaxial layer, the electrode layer located on the convex portion forms a receiving area for receiving a light beam, and the light beam penetrates the electrode layer to excite the epitaxial layer to form an electrical signal.
[0012] As an implementable method, using a mask to form a protruding portion protruding outward on the upper surface of the epitaxial layer by locally exposing it to different degrees includes: coating a photoresist on the epitaxial layer, wherein the photoresist is a positive photoresist; setting a mask on the photoresist and exposing it to light, so that the photoresist forms concentric rings with different degrees of exposure; etching the epitaxial layer through the photoresist to form a protrusion; and removing the photoresist.
[0013] As an implementable manner, the photomask includes a plurality of concentric and sequentially connected circular rings, and the exposure amounts of the plurality of circular rings increase sequentially from the center to the periphery.
[0014] As an implementable manner, the photomask includes a substrate and a light shielding layer disposed on the substrate, and the thickness of the light shielding layers of the plurality of circular rings gradually decreases from the center to the periphery.
[0015] The beneficial effects of the embodiments of the present application include:
[0016] The photodetector provided by the present application includes a substrate and an epitaxial layer and an electrode layer sequentially arranged on the substrate, the electrode layer having a receiving area, the part of the epitaxial layer located in the receiving area convexly forms a convex portion, so that the upper surface of the receiving area is a convex surface protruding outward, the receiving area is used to receive a light beam, the light beam penetrates the electrode layer to excite the epitaxial layer to form an electrical signal, and the convex surface protrudes from other parts of the electrode layer. On the one hand, the convex surface can receive light beams with more emission angles, thereby increasing the angle of the convex surface receiving the light beam; on the other hand, the convex surface has a larger area relative to the plane occupied by the plane area, and the larger area of the convex surface makes it have a larger area for receiving the light beam, thereby increasing the area of the received light beam. Therefore, relative to the plane, the convex surface of the present application can increase the angle of the received light beam and the area of the received light beam, thereby increasing the production capacity per unit area. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0018] Figure 1 A schematic diagram of the structure of a photoelectric detector provided in an embodiment of the present application;
[0019] Figure 2 One of the structural schematic diagrams of a convex surface provided in an embodiment of the present application;
[0020] Figure 3 A second schematic diagram of a convex structure provided in an embodiment of the present application;
[0021] Figure 4 A flow chart of a method for preparing a photoelectric detector provided in an embodiment of the present application;
[0022] Figure 5 One of the state diagrams of a method for preparing a photodetector provided in an embodiment of the present application;
[0023] Figure 6 A second state diagram of a method for preparing a photoelectric detector provided in an embodiment of the present application;
[0024] Figure 7 A third state diagram of a method for preparing a photoelectric detector provided in an embodiment of the present application;
[0025] Figure 8 A fourth state diagram of a method for preparing a photoelectric detector provided in an embodiment of the present application;
[0026] Fig. 9 A fifth state diagram of a method for preparing a photoelectric detector provided in an embodiment of the present application;
[0027] Fig.10 A sixth state diagram of a method for preparing a photoelectric detector provided in an embodiment of the present application;
[0028] Fig.11 A schematic diagram of the structure of a photomask provided in an embodiment of the present application;
[0029] Fig.12 for Fig.11 Enlarged view of point A in the middle.
[0030] Icon: 100-photodetector; 110-substrate; 120-epitaxial layer; 121-N-type layer; 122-P-type layer; 130-electrode layer; 131-passivation material; 132-P electrode; 140-receiving area; 150-convex surface; 151-annular surface; 210-mask; 211-annular ring; 220-photoresist; 230-groove. DETAILED DESCRIPTION
[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.
[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0034] In the description of the present application, it should be noted that the terms "center", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0035] The photodetector is used to receive the light beam signal and convert the light beam signal into an electrical signal to detect the light beam signal. The area in the photodetector used to receive the light beam is the receiving area. In the prior art, the receiving area is usually set in a plane, so that the receiving area occupies a large chip area.
[0036] The present application embodiment provides a photodetector 100, such as Figure 1As shown, it includes a substrate 110 and an epitaxial layer 120 and an electrode layer 130 which are sequentially arranged on the substrate 110. The electrode layer 130 has a receiving area 140. The part of the epitaxial layer 120 located in the receiving area 140 is raised to form a convex portion, so that the upper surface of the receiving area 140 is a convex surface 150 protruding outward. The receiving area 140 is used to receive a light beam. The light beam penetrates the electrode layer 130 to excite the epitaxial layer 120 to form an electrical signal.
[0037] The photodetector 100 of the embodiment of the present application includes a substrate 110, an epitaxial layer 120 and an electrode layer 130, wherein the substrate 110 serves as the base of the photodetector 100 and supports the entire photodetector 100; the epitaxial layer 120 is used to generate an electrical signal under the irradiation of a light beam, that is, to convert the light beam signal into an electrical signal; and the electrode layer 130 is arranged on the epitaxial layer 120 to form an electrical connection with the epitaxial layer 120.
[0038] Among them, the electrode layer 130 has a receiving area 140, and the receiving area 140 is used to receive a light beam. The upper surface of the receiving area 140 is set as a convex surface 150 protruding outward. When the light beam is irradiated to the receiving area 140 of the photodetector 100, the entire convex surface 150 can receive the light beam. Since the convex surface 150 protrudes from other parts of the electrode layer 130, on the one hand, the convex surface 150 can receive more light beams with emission angles, thereby increasing the angle of the received light beam of the convex surface 150; on the other hand, the convex surface 150 has a larger area relative to the plane occupied by the plane area. The larger area of the convex surface 150 makes it have a larger area for receiving the light beam, thereby increasing the area of the received light beam. Therefore, relative to the plane, the upper surface of the receiving area 140 of the embodiment of the present application is provided with a convex surface 150, which can increase the angle of the received light beam and the area of the received light beam, thereby increasing the production capacity per unit area. In other words, under the condition of the same area of the received light beam, the plane area occupied by the receiving surface of the photodetector 100 can be reduced, and the production capacity per unit area can be increased.
[0039] In addition, if Figure 1 As shown, the part of the epitaxial layer 120 located in the receiving area 140 is raised to form a convex portion, and the convex portion serves as a support for the electrode layer 130 so that the electrode layer 130 forms a convex surface 150. In this way, the thickness of the electrode layer 130 in the hierarchical direction is the same. On the one hand, the epitaxial layer 120 has a thicker thickness, and it is easier to form a convex portion; on the other hand, the convex portion allows the light beam to be irradiated to the epitaxial layer 120 as quickly as possible, avoiding the attenuation of the light beam caused by the long propagation distance in the electrode layer 130, thereby improving the efficiency of light beam signal transmission.
[0040] The epitaxial layer 120 is used as the main functional layer of the photodetector 100 to convert the optical signal of the light beam into an electrical signal. In practical applications, the epitaxial layer 120 includes a PN junction, such as Figure 1As shown, the epitaxial layer 120 includes an N-type layer 121 and a P-type layer 122 which are sequentially arranged on the substrate 110. A space charge region is formed at the interface between the N-type layer 121 and the P-type layer 122. When the light beam is irradiated to the epitaxial layer 120, the atoms in the N-type layer 121 and the P-type layer 122 are separated from electrons due to the radiation energy of the light beam, forming electron-hole pairs. When an electric field exists at both ends of the epitaxial layer 120, a current is generated to form an electrical signal.
[0041] As can be seen from the above, when the epitaxial layer 120 is working, an electric field exists at both ends of the epitaxial layer 120 to lead out the electrical signal. It can be understood that electrodes need to be formed on both sides of the epitaxial layer 120 to lead out the electrical signal. In the embodiment of the present application, electrodes are respectively set on both sides of the receiving area 140 in the electrode layer 130 to form a P electrode 132, and transparent passivation material 131 is set at the remaining positions. Figure 1 As shown; a transparent conductive film may also be used as the electrode layer 130, so that the entire electrode layer 130 serves as a P electrode 132; an N electrode is provided on one side of the substrate 110, and the substrate 110 may also be used as an N electrode.
[0042] To summarize, the photodetector 100 provided in the present application has an upper surface of the receiving area 140 which is a convex surface 150 protruding outward. The receiving area 140 is used to receive a light beam. The light beam penetrates the electrode layer 130 to excite the epitaxial layer 120 to form an electrical signal. The convex surface 150 protrudes from other parts of the electrode layer 130. On the one hand, the convex surface 150 can receive light beams with more emission angles, thereby increasing the angle of the received light beam of the convex surface 150; on the other hand, the convex surface 150 has a larger area relative to the plane occupied by the plane area. The larger area of the convex surface 150 makes it have a larger area for receiving the light beam, thereby increasing the area of the received light beam. Therefore, relative to the plane, the convex surface 150 of the present application can increase the angle and area of the received light beam, thereby increasing the production capacity per unit area.
[0043] Optional, such as Figure 1 As shown, the convex surface 150 is a convex spherical surface.
[0044] As can be seen from the above, the convex surface 150 is used to increase the angle at which the photodetector 100 receives light. The convex surface 150 is set to a convex spherical surface, so that the surface of the convex surface 150 is relatively smooth, which is convenient for receiving the light beam. In addition, the convex spherical surface has a certain converging effect on the light beam, which can converge the light beam, so that more light beams enter the photodetector 100, thereby improving the utilization rate of the light beam signal.
[0045] In one possible implementation of the embodiment of the present application, Figure 2 and Figure 3As shown, the convex surface 150 includes a plurality of coaxial annular surfaces 151 arranged in sequence along the hierarchical direction. Going upward along the hierarchical direction, the outer diameter of the next annular surface 151 is smaller than the inner diameter of the previous annular surface 151 .
[0046] In actual applications, due to the limitations of semiconductor technology, it is difficult to form a standard spherical surface. The embodiment of the present application uses a mask 210 composed of multiple circular rings 211 with different exposure levels for exposure and etching. According to the different exposure levels, the degree of etching of the epitaxial layer 120 is different during subsequent etching, so that the upper surface of the convex portion includes multiple coaxial circular surfaces 151 arranged in sequence along the hierarchical direction. Along the hierarchical direction upward, the outer diameter of the next circular surface 151 is smaller than the inner diameter of the previous circular surface 151, forming a convex surface 150 similar to a spherical surface.
[0047] The ring width of each annular surface 151 and the height difference between two adjacent annular surfaces 151 are not limited in the embodiment of the present application, and those skilled in the art can set them according to actual conditions. It can be understood that the more the number of annular surfaces 151, the smaller the ring width of each annular surface 151, the closer the convex surface 150 is to a spherical surface, and the higher the requirements for etching; on the contrary, the smaller the number of annular surfaces 151, the larger the ring width of each annular surface 151, and the lower the requirements for etching. For example, Figure 2 and Figure 3 As shown, assuming that the plane area of the receiving area 140 is 30 μm, and the top of the convex surface 150 occupies a plane of 7 μm, 23 μm needs to be cut to form multiple pixel points. The more pixel points there are, the more spherical the shape can be. Figure 2 and Figure 3 11 and 17 pixels respectively. Similarly, 23um is cut into 46 pixels, each pixel is 0.5um wide and each height difference is 0.1um.
[0048] Optionally, the outer diameter of the next annular surface 151 is connected to the inner diameter of the previous annular surface 151 to form an inclined surface, that is, the sides of two adjacent annular surfaces 151 that are close to each other are connected by an inclined surface. The inclined surface has a certain refractive effect on the light beam, so that the light beam can be refracted in the direction of the epitaxial layer 120, thereby allowing more light beams to enter the epitaxial layer 120.
[0049] In one feasible method of the embodiment of the present application, the outer diameter of one annular surface 151 is connected to the inner diameter of the previous annular surface 151 to form a vertical surface, that is, the sides of two adjacent annular surfaces 151 that are close to each other are connected by an inclined surface, so that the structure of the convex surface 150 is relatively flat and easier to operate during preparation.
[0050] Optionally, the angle between the edge of the received light beam of the receiving area 140 and the plane where the electrode layer 130 is located is less than 20 degrees, so that the receiving area 140 can receive light beams at more angles, thereby improving the production capacity per unit area.
[0051] Another aspect of the present application provides a method for preparing a photodetector 100, which is used to prepare the above-mentioned photodetector 100. Figure 4 As shown, including:
[0052] S10: Figure 5 As shown, a substrate 110 is provided, and an epitaxial layer 120 is sequentially formed on the substrate 110;
[0053] The material of the substrate 110 , the material of the epitaxial layer 120 , and the formation method are not limited in the embodiment of the present application, and those skilled in the art may make settings according to actual conditions.
[0054] In addition, the substrate 110 may select an N-type substrate 110 as an N-electrode, and the epitaxial layer 120 includes an N-type layer 121 and a P-type layer 122 which are sequentially disposed on the substrate 110 .
[0055] S20: Figures 6 to 8 As shown, a mask 210 is used to form a convex portion protruding outward on the upper surface of the epitaxial layer 120 by local exposure at different degrees;
[0056] S30: Fig. 9 and Fig.10 As shown, an electrode layer 130 is formed on the upper surface of the epitaxial layer 120 , and the electrode layer 130 located on the protrusion forms a receiving area 140 for receiving a light beam. The light beam penetrates the electrode layer 130 to excite the epitaxial layer 120 to form an electrical signal.
[0057] When the electrode layer 130 is a passivation material 131, electrodes are provided on both sides of the receiving region 140 to form a P electrode 132. Fig. 9 As shown, a passivation material 131 is formed on the epitaxial layer 120, and then Fig.10 As shown, grooves 230 are formed by etching on both sides of the receiving area 140 , and then metal material is filled in the grooves 230 to form the P-electrode 132 .
[0058] The present application is implemented by using a mask 210 to form an outwardly protruding convex portion on the upper surface of the epitaxial layer 120 through different degrees of local exposure, so that the electrode layer 130 forms a receiving area 140 of the convex surface 150. The convex surface 150 protrudes from other parts of the electrode layer 130. On the one hand, the convex surface 150 can receive light beams with more emission angles, thereby increasing the angle of the received light beam of the convex surface 150; on the other hand, the convex surface 150 has a larger area relative to the plane occupied by the plane area. The larger area of the convex surface 150 makes it have a larger area for receiving the light beam, thereby increasing the area of the received light beam. Therefore, relative to the plane, the convex surface 150 of the present application can increase the angle and area of the received light beam, thereby improving the production capacity per unit area.
[0059] In one achievable manner of the embodiment of the present application, forming a convex portion protruding outward on the upper surface of the epitaxial layer 120 by using the mask 210 through local exposure to different degrees includes:
[0060] S21: Figure 6 As shown, a photoresist 220 is coated on the epitaxial layer 120, and the photoresist 220 is a positive photoresist;
[0061] S22: Figure 7 As shown, a photomask 210 is placed on the photoresist 220 and exposed, so that the photoresist 220 forms concentric rings with different degrees of exposure;
[0062] S23: Figure 8 As shown, the epitaxial layer 120 is etched by the photoresist 220 to form a convex portion;
[0063] S24: Figure 8 As shown, the photoresist 220 is removed.
[0064] Optional, such as Fig.11 and Fig.12 As shown, the mask 210 includes a plurality of concentric and sequentially connected circular rings 211 , and the exposure amounts of the plurality of circular rings 211 increase sequentially from the center to the periphery.
[0065] From the center to the periphery, the exposure amount of the plurality of rings 211 increases sequentially, and the etching depth of the photoresist 220 gradually increases, so that the etching depth of the epitaxial layer 120 gradually increases, thereby forming a convex surface 150 .
[0066] In one possible implementation of the embodiment of the present application, Fig.11 and Fig.12 As shown, the mask 210 includes a substrate and a light shielding layer disposed on the substrate. The thickness of the light shielding layer of the plurality of circular rings 211 gradually decreases from the center to the periphery.
[0067] Along the direction from the center to the periphery, the thickness of the shading layer of the multiple rings 211 gradually decreases. In this way, during exposure, along the direction from the center to the periphery, the energy of the light beam passing through the multiple rings 211 gradually increases. In this way, the etching depth of the photoresist 220 gradually increases, thereby making the etching depth of the epitaxial layer 120 gradually increase, thereby forming a convex surface 150.
[0068] In practical applications, the photomask 210 is usually a chromium layer disposed on a glass substrate, wherein the chromium layer is patterned to form a photolithography pattern. In the embodiment of the present application, the thickness of the chromium layer of the plurality of rings 211 gradually decreases from the center to the periphery. During photolithography, the exposure degree gradually increases from the center to the periphery, so that the etching depth gradually increases, thereby forming a convex portion.
[0069] It should be noted that a photodetector 100 includes a plurality of detection units. In order to form a plurality of convex portions during one exposure and etching, Fig.11 As shown, a photomask 210 includes a plurality of shading units, wherein each shading unit includes concentric and sequentially connected circular rings 211 , and the exposure amounts of the plurality of circular rings 211 increase sequentially from the center to the periphery.
[0070] It should also be noted that the embodiment of the present application is described with positive photoresist 220, which does not limit the photoresist 220 of the embodiment of the present application to only positive photoresist. When the photoresist 220 is a negative photoresist, the exposure amount of the multiple rings 211 decreases in sequence from the center to the periphery, and the thickness of the light shielding layer of the multiple rings 211 gradually increases.
[0071] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A photoelectric detector, characterized in that: It includes a substrate and an epitaxial layer and an electrode layer sequentially arranged on the substrate, the electrode layer has a receiving area, the part of the epitaxial layer located in the receiving area is raised to form a convex portion, so that the upper surface of the receiving area is a convex surface protruding outward, and the receiving area is used to receive a light beam, and the light beam penetrates the electrode layer to excite the epitaxial layer to form an electrical signal.
2. The photodetector according to claim 1, characterized in that: The convex surface is a convex spherical surface.
3. The photodetector according to claim 2, characterized in that: The convex surface includes a plurality of coaxial annular surfaces arranged in sequence along the hierarchical direction. Going upward along the hierarchical direction, the outer diameter of the next annular surface is smaller than the inner diameter of the previous annular surface.
4. The photodetector according to claim 3, characterized in that: The outer diameter of the next annular surface is connected with the inner diameter of the previous annular surface to form an inclined surface.
5. The photodetector according to claim 3, characterized in that: The outer diameter of one of the annular surfaces is connected with the inner diameter of the previous annular surface to form a vertical surface.
6. The photodetector according to claim 1, characterized in that: The angle between the edge of the received light beam in the receiving area and the plane where the electrode layer is located is less than 20 degrees.
7. A method for preparing a photoelectric detector, characterized in that: For preparing the photoelectric detector according to any one of claims 1 to 6, comprising: Providing a substrate, and sequentially forming epitaxial layers on the substrate; Using a photomask to form a convex portion protruding outward on the upper surface of the epitaxial layer by locally exposing the upper surface to different degrees; An electrode layer is formed on the upper surface of the epitaxial layer. The electrode layer located on the protrusion forms a receiving area for receiving a light beam. The light beam penetrates the electrode layer to excite the epitaxial layer to form an electrical signal.
8. The method for preparing a photoelectric detector according to claim 7, characterized in that: The method of using a photomask to form a convex portion protruding outward on the upper surface of the epitaxial layer by locally exposing the upper surface to different degrees comprises: Coating a photoresist on the epitaxial layer, wherein the photoresist is a positive photoresist; Placing a photomask on the photoresist and exposing the photoresist so that the photoresist forms concentric rings with different degrees of exposure; Etching the epitaxial layer through the photoresist to form a convex portion; Remove the photoresist.
9. The method for preparing a photoelectric detector according to claim 8, characterized in that: The photomask comprises a plurality of concentric and sequentially connected circular rings, and the exposure amounts of the plurality of circular rings increase sequentially from the center to the periphery.
10. The method for preparing a photoelectric detector according to claim 9, characterized in that: The photomask comprises a substrate and a light shielding layer arranged on the substrate, and the thickness of the light shielding layers of the plurality of circular rings gradually decreases in a direction from the center to the periphery.