A high-frequency blue light Schottky photodiode array

Abstract

The present invention discloses a high-frequency blue light Schottky photodiode array, the device includes a plurality of detection units and a plurality of isolation regions, the detection units are arranged into an array in rows and columns, each detection unit on a substrate includes an aluminum electrode layer, a silicon layer, a silicon dioxide insulating layer, a gold electrode layer and an air hole array, the upper surface of the substrate is covered with an aluminum electrode layer, the upper surface of the aluminum electrode layer is provided with a silicon layer, the upper surface of the silicon layer is covered with a silicon dioxide layer, the upper surface of the silicon dioxide layer is provided with a gold electrode layer, the detection unit array is composed of detection units arranged in rows and columns, and isolation grooves and fillers in the isolation grooves are between the detection units. The present invention can improve the response rate of the detection unit device, enhance the absorption efficiency of the photodiode array to blue light, and change the reflectivity and transmittance of visible light. As a high-frequency blue light Schottky photodiode array, the present invention can be widely used in the field of optoelectronic technology.

Description

Technical Field

[0001] The invention relates to the field of optoelectronic technology, and in particular to a high-frequency blue light Schottky photodiode array. Background Art

[0002] Photodetectors are one of the important devices at the receiving end of visible light communication systems, and their performance directly affects the quality of the entire system. The traditional receiving end is composed of an optical part and an electrical part, where the optical part includes the receiving end optical antenna, filter, and photodetector; the optical antenna mainly realizes the beam shaping of the transmitted light, so that the light is accurately transmitted to the receiving system. The main function of the filter is to remove stray light and other bands of visible light without loaded signals; the detector (photodiode) is the main part of the receiving system, and its function is to convert optical signals into electrical signals. The visible light carrying the signal is monochromatic light, so other visible light becomes interference light. If the detector has a large response wavelength range, the noise of the detector will increase, and the performance of the detector will also be affected. Therefore, a filter is usually added in front of the detection chip. Although the filter can filter out most of the interference light and stray light, the intensity of the incident light will change according to the degree of filtering of the filter. The better the filtering effect of the filter, the weaker the corresponding incident light intensity, which will also reduce the performance of the detector. The detector cannot respond to the demand in time, and when the intensity of the incident light reaches a certain level, the existing filter cannot meet the actual needs. Summary of the invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a high-frequency blue light Schottky photodiode array, which can improve the detector response speed while enhancing the detector's absorption efficiency and wavelength selectivity for blue light.

[0004] To achieve the above invention objectives, the technical solutions of the present invention are as follows:

[0005] A high-frequency blue light Schottky photodiode array comprises a plurality of detection units and a plurality of isolation regions, wherein the detection units are arranged into an array in rows and columns, wherein each detection unit on a substrate comprises an aluminum electrode layer, a silicon layer, a silicon dioxide insulating layer, a gold electrode layer and an air hole array, wherein the upper surface of the substrate is covered with an aluminum electrode layer, the upper surface of the aluminum electrode layer is provided with a silicon layer, the upper surface of the silicon layer is covered with a silicon dioxide layer, the upper surface of the silicon dioxide layer is provided with a gold electrode layer, the air hole array penetrates the gold electrode layer, the silicon dioxide layer and part of the silicon layer, the detection unit array is composed of detection units arranged in rows and columns, isolation grooves and fillers in the isolation grooves are between the detection units, and the isolation grooves are embedded in part of the silicon layer, wherein:

[0006] The substrate is used to support the detection unit array;

[0007] The aluminum electrode layer is used to form a fiber-like structure with the silicon layer to enhance the absorption efficiency of blue light;

[0008] The silicon layer is used to absorb photons to generate photogenerated carriers, and under a reverse bias voltage, the carriers move toward the electrodes on both sides to form a current in the external circuit, thereby achieving a photoelectric conversion effect;

[0009] The silicon dioxide layer is used to eliminate the electric field in the edge region, thereby reducing the generation of leakage current;

[0010] The air hole array is used to change the reflection, transmission and absorption efficiency of visible light;

[0011] The isolation grooves and fillers are used to divide the unit array;

[0012] The gold electrode layer is used as an upper electrode of the detection device.

[0013] Furthermore, the air holes of the air hole array are circular air holes, the air holes of the air hole array are circular air holes, the circular air holes are embedded in the detection unit, penetrate the gold electrode layer, the silicon dioxide layer and part of the silicon layer, and the shapes of the detection unit include circle, square, hexagon and rectangle.

[0014] Furthermore, the air hole array has a depth of 0.5 μm to 10 μm, a radius of 50 nm to 300 nm, and a period of 300 nm to 500 nm.

[0015] Furthermore, the substrate is a silicon substrate, and the thickness of the silicon substrate is 10 μm to 100 μm.

[0016] Furthermore, the upper surface of the substrate is covered with an aluminum electrode layer, and the thickness of the aluminum electrode layer is 10nm to 500nm.

[0017] Furthermore, the upper surface of the aluminum electrode layer is covered with a silicon layer, and the silicon layer includes n + type silicon substrate layer and n-type silicon absorber layer.

[0018] Furthermore, the silicon layer has n + The thickness of the n-type silicon substrate layer and the n-type silicon absorption layer is 1 μm to 10 μm.

[0019] Furthermore, the upper surface of the silicon layer is covered with a silicon dioxide layer, and the thickness of the silicon dioxide layer is 2nm to 10nm.

[0020] Furthermore, the filler in the isolation groove includes polyimide, silicon dioxide, polydimethylsiloxane, epoxy resin and polymethyl methacrylate, and the depth of the isolation groove is equal to the thickness of the n-type silicon absorption layer.

[0021] Furthermore, the thickness of the gold electrode layer is 5nm to 100nm.

[0022] The beneficial effects of the device of the present invention are as follows: the present invention divides the Schottky photodiode into an array to obtain a plurality of parallel detection units, the total photosensitive area does not change, but the photosensitive area of ​​a single detection unit is reduced, thereby reducing the junction capacitance of the diode, and improving the response speed of the detection unit device. The optical fiber-like structure is formed by an aluminum electrode layer, a silicon layer and air, thereby enhancing the absorption efficiency of the photodiode array for blue light. After the air hole array arranged on the surface of the photodiode array is irradiated with light, it can excite base film, guide film and cavity film modes, and the mutual coupling between various types of modes changes the chip's reflection, transmission and absorption of different bands of visible light, thereby realizing the wavelength selectivity of the photodiode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional schematic diagram of a high-frequency blue light Schottky photodiode array of the present invention;

[0024] Figure 2 It is a three-dimensional schematic diagram of a high-frequency blue light Schottky photodiode array of the present invention without a gold electrode layer and a silicon dioxide insulating layer;

[0025] Figure 3 It is a longitudinal cross-sectional view of a high-frequency blue light Schottky photodiode array of the present invention;

[0026] Figure 4 It is a geometric figure of an air hole array in a high-frequency blue light Schottky photodiode array of the present invention;

[0027] Reference numerals: 1, substrate; 2, aluminum electrode layer; 3, n + 1. n-type silicon substrate layer; 2. n-type silicon absorption layer; 3. silicon dioxide layer; 4. gold electrode layer; 5. isolation grooves and fillers; 6. air hole array. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0029] Reference Figure 1 and Figure 2The present invention provides a high-frequency blue light Schottky photodiode array, comprising a plurality of detection units and a plurality of isolation regions, wherein the detection units are arranged into an array according to row and column rules, wherein each detection unit on a substrate 1 comprises an aluminum electrode layer 2, a silicon layer, a silicon dioxide insulating layer, a gold electrode layer 6 and an air hole array 8, wherein the upper surface of the substrate 1 is covered with an aluminum electrode layer, the upper surface of the aluminum electrode layer 2 is provided with a silicon layer, the upper surface of the silicon layer is covered with a silicon dioxide layer 5, the upper surface of the silicon dioxide layer 5 is provided with a gold electrode layer 6, the air hole array 8 penetrates the gold electrode layer 6, the silicon dioxide layer 5 and a part of the silicon layer, and the isolation region between the detection units is an isolation groove and a filler in the isolation groove, and the isolation groove is embedded in a part of the silicon layer.

[0030] The air hole array 8 is used to change the reflection, transmission and absorption efficiency of visible light, wherein the air holes of the air hole array 8 are circular air holes, which are embedded in the detection unit and penetrate the gold electrode layer 6, the silicon dioxide layer 5 and part of the silicon layer. The shapes of the detection unit include circle, square, hexagon and rectangle. The depth of the air hole array 8 is 0.5μm~10μm, the radius is 50nm~300nm, and the period is 300nm~500nm.

[0031] The detection unit is used to improve the response speed of the device, wherein the detection unit is a Schottky photodiode.

[0032] The substrate 1 is used to support the detection unit array, wherein the substrate 1 is a silicon substrate, and the thickness of the silicon substrate is 10 μm to 100 μm.

[0033] The aluminum electrode layer 2 is used to form a fiber-like structure with the silicon layer to enhance the absorption efficiency of blue light, wherein the upper surface of the substrate 1 is covered with the aluminum electrode layer 2, and the thickness of the aluminum electrode layer 2 is 10nm to 500nm.

[0034] The silicon dioxide layer 5 is used to eliminate the electric field in the edge region, thereby reducing the generation of leakage current. The upper surface of the aluminum electrode layer 2 is covered with a silicon layer, and the silicon layer includes n + n-type silicon substrate layer 3 and n-type silicon absorption layer 4, the n-type silicon layer + The thickness of the n-type silicon substrate layer 3 and the n-type silicon absorption layer 4 is 1 μm to 10 μm, and the thickness of the silicon dioxide layer 5 is 2 nm to 10 nm.

[0035] The isolation groove and the filler are used to divide the unit array, wherein the filler in the isolation groove includes polyimide, silicon dioxide, polydimethylsiloxane, epoxy resin and polymethyl methacrylate, and the depth of the isolation groove is equal to the thickness of the n-type silicon absorption layer 4.

[0036] The gold electrode layer 6 is used as an upper electrode of the detection device, wherein the thickness of the gold electrode layer 6 is 5 nm to 100 nm.

[0037] Specifically, refer to Figure 3 and Figure 4 , the preparation method of the present invention is as follows:

[0038] Select n + The silicon wafer is used as the substrate 1, and the substrate 1 is ultrasonically cleaned, and then evaporated in a vacuum environment to obtain a silicon wafer with an aluminum electrode layer 2 on the surface, and the aluminum electrode layer 2 is fixed on the silicon substrate to obtain n + The chip has a silicon substrate layer 3 as the upper surface and a silicon base as the lower surface, and the chip is cleaned. + A silicon layer is deposited on the upper surface of the n-type silicon substrate layer 3, and an n-type silicon absorption layer 4 is formed by ion implantation. The chip is further cleaned, and a protective layer is spin-coated. The protective layer is subjected to a photolithography process, and then an isolation groove is formed by an etching process. In a vacuum environment, fillers such as polyimide, silicon dioxide, polydimethylsiloxane, epoxy resin and polymethyl methacrylate are filled into the isolation groove. After filling, the protective layer is removed, and a thin silicon dioxide insulating layer 5 is sputtered on the surface of the chip by a magnetron sputtering method. A gold electrode layer 6 is obtained on the upper surface of the silicon dioxide insulating thin layer by an evaporation process or magnetron sputtering, and a protective layer is spin-coated on the gold electrode layer 6. An air hole array 8 is formed by a photolithography process and an etching process, and finally the production of a high-frequency blue light Schottky photodiode array is completed.

[0039] The working principle of the device of the present invention is as follows:

[0040] A potential barrier is formed on the contact surface between the gold electrode layer 6 and the n-type silicon absorption layer 4. Since the electrons in the n-type silicon absorption layer 4 occupy a higher energy level than those in the gold electrode layer 6, the electrons pass from the high-concentration n-type silicon absorption layer 4 to the gold electrode layer 6. There are no holes in the gold electrode layer 6, and there is no diffusion movement of holes. As the electrons continue to diffuse, the Fermi levels of the two are leveled. At this time, the direction of the electric field is directed from the n-type silicon absorption layer 4 to the gold electrode layer 6. Due to the transfer of electrons, a space charge layer composed of ionized donors that have lost electrons and are neutralized appears on the surface of the silicon absorption layer, and a space charge layer formed by electron accumulation appears on the surface of the gold electrode layer 6. Electrical neutrality requires that the negative charge on the surface of the gold electrode layer 6 is equal to the positive charge on the surface of the n-type silicon absorption layer 4, but has an opposite sign. Since there are a large number of free electrons in the metal, the space charge layer on the metal surface is very thin. The donor concentration in the n-type silicon absorption layer 4 is several orders of magnitude lower than the electron concentration in the gold electrode layer 6, so the space charge layer of the silicon layer is relatively much thicker, and the electric field of the space charge will prevent the electrons in the n-type silicon absorption layer 4 from flowing into the gold electrode layer 6. When thermal equilibrium is reached, a certain space charge region width, a stable built-in electric field, and a certain built-in potential difference are formed. When a reverse bias is applied, the barrier width increases. When light is incident on the surface of the gold electrode layer 6, the air hole array 8 of the gold electrode layer 6 excites the plasmon effect, and photons are absorbed in the n-type silicon absorption layer 4 to form electron-hole pairs. Under the action of the built-in electric field, the electrons are accelerated to the n-type silicon absorption layer 4. + The silicon substrate layer 3 drifts and forms a current in the external circuit. Based on the photolithography process, the gold electrode layer with a protective layer is corroded by dry etching or wet etching to prepare an air hole array 8. After the air hole array 8 in the photodiode is irradiated with light, it can excite the base film, the guide film and the cavity film and other modes. The mutual coupling between various types of modes changes the chip's reflection, transmission and absorption of visible light. At the same time, the air, silicon layer and aluminum electrode layer form a fiber-like structure, which further enhances the absorption of blue light by silicon, thereby improving the quantum efficiency of the device. The photodiode array segmentation reduces the photosensitive area of ​​a single detection unit, thereby reducing the junction capacitance of the diode and improving the response speed of the device. The total photosensitive area of ​​the device is the sum of the photosensitive surfaces of multiple detection units, so it does not reduce the photosensitive surface of the detection device and improves the response speed of the device.

[0041] The contents of the above method embodiments are all applicable to the present system embodiments. The functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0042] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A high-frequency blue light Schottky photodiode array, It is characterized in that The invention comprises a plurality of detection units and a plurality of isolation regions, wherein the detection units are arranged into an array according to row and column rules, wherein each detection unit on the substrate comprises an aluminum electrode layer, a silicon layer, a silicon dioxide insulating layer, a gold electrode layer and an air hole array, wherein the upper surface of the substrate is covered with an aluminum electrode layer, the upper surface of the aluminum electrode layer is provided with a silicon layer, the upper surface of the silicon layer is covered with a silicon dioxide layer, the upper surface of the silicon dioxide layer is provided with a gold electrode layer, the air hole array penetrates the gold electrode layer, the silicon dioxide layer and part of the silicon layer, and the isolation region between the detection units is an isolation groove and a filler in the isolation groove, and the isolation groove is embedded in part of the silicon layer, wherein: The substrate is used to support the detection unit array; The aluminum electrode layer is used to form a fiber-like structure with the silicon layer to enhance the absorption efficiency of blue light; The silicon layer is used to absorb photons to generate photogenerated carriers, and under reverse bias voltage, the carriers move toward the electrodes on both sides to form current in the external circuit, thereby achieving the effect of photoelectric conversion; The silicon dioxide layer is used to eliminate the electric field in the edge region, thereby reducing the generation of leakage current; The air hole array is used to change the reflection, transmission and absorption efficiency of visible light; The isolation grooves and fillers are used to divide the unit array; The gold electrode layer is used as the upper electrode of the detection device; The air holes of the air hole array are circular air holes, which are embedded in the detection unit and penetrate the gold electrode layer, the silicon dioxide layer and part of the silicon layer. The shapes of the detection unit include circle, square, hexagon and rectangle; The upper surface of the aluminum electrode layer is covered with a silicon layer, and the silicon layer includes n + type silicon substrate layer and n-type silicon absorber layer.

2. A high-frequency blue light Schottky photodiode array according to claim 1, It is characterized in that The air hole array has a depth of 0.5 μm to 10 μm, a radius of 50 nm to 300 nm, and a period of 300 nm to 500 nm.

3. The high-frequency blue light Schottky photodiode array according to claim 1, It is characterized in that The substrate is a silicon substrate, and the thickness of the silicon substrate is 10 μm to 100 μm.

4. The high-frequency blue light Schottky photodiode array according to claim 1, It is characterized in that The upper surface of the substrate is covered with an aluminum electrode layer, and the thickness of the aluminum electrode layer is 10nm to 500nm.

5. The high-frequency blue light Schottky photodiode array according to claim 1, It is characterized in that The silicon layer + The thickness of the n-type silicon substrate layer and the n-type silicon absorption layer is 1 μm to 10 μm.

6. The high-frequency blue light Schottky photodiode array according to claim 1, It is characterized in that The upper surface of the silicon layer is covered with a silicon dioxide layer, and the thickness of the silicon dioxide layer is 2nm-10nm.

7. The high-frequency blue light Schottky photodiode array according to claim 1, It is characterized in that The filler in the isolation groove includes polyimide, silicon dioxide, polydimethylsiloxane, epoxy resin and polymethyl methacrylate, and the depth of the isolation groove is equal to the thickness of the n-type silicon absorption layer.

8. The high-frequency blue light Schottky photodiode array according to claim 1, It is characterized in that The thickness of the gold electrode layer is 5nm-100nm.

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