Microstructure silicon carbide ultraviolet photoelectric detector with high quantum efficiency and preparation method thereof

Abstract

The invention discloses a microstructure silicon carbide ultraviolet photoelectric detector with high quantum efficiency and a preparation method thereof, and belongs to the technical field of ultraviolet photoelectric detection. The detector adopts a bottom-to-top structural design and comprises a silicon carbide highly-doped n + type substrate, an n type buffer layer, a low-doped n-type absorption layer, a low-doped p-type absorption layer (containing a microstructure), an annular highly-doped p + type ohmic contact layer and a passivation isolation layer. Reverse bias voltage is applied to the p + type ohmic contact electrode to form a depletion electric field, and the microstructure promotes the p-i-n structure electric fields to be mutually connected and coupled, so that the photon-generated carrier depletion efficiency is improved, and the responsivity of the device and the external quantum efficiency are enhanced. And meanwhile, the microstructure enables a short-wave ultraviolet signal to directly penetrate through the p-type absorption layer to enter the internal absorption layer, so that photon-generated carrier recombination caused by surface defects of the p + type ohmic contact layer is avoided, the collection efficiency of photon-generated carriers is improved, and ultraviolet full-band detection is realized.

Description

Technical Field

[0001] The invention relates to an ultraviolet photoelectric detector, in particular to a microstructured silicon carbide ultraviolet photoelectric detector with high quantum efficiency and a preparation method thereof. Background Art

[0002] Ultraviolet photodetectors have extremely high application value in civil, industrial and military fields involving ultraviolet radiation measurement, such as atmospheric ultraviolet intensity monitoring, fire alarms, photolithography machines, high-voltage component aging monitoring, and aircraft guidance. Photomultiplier tubes have been widely used in the detection of weak ultraviolet signals, but there are some problems in their use, such as easy damage, large size, dependence on external high-voltage power supplies, inability to detect in arrays, and high cost. Therefore, semiconductor ultraviolet photodetectors with the advantages of small size, low cost, array integration, and high responsiveness have gradually become a research hotspot in the field of ultraviolet detection.

[0003] At present, the mainstream semiconductor detection technology for ultraviolet band signals mainly adopts silicon-based detectors. However, due to the narrow bandgap width (1.12 eV) of Si, it also responds to optical signals in the visible and infrared bands. Therefore, when performing ultraviolet detection, it is necessary to install an ultraviolet filter to eliminate the influence of visible and infrared band optical signals on the device response, which greatly increases the cost and volume of the device, and is not easy to integrate, which greatly limits its application. The third-generation wide-bandgap semiconductor silicon carbide single crystal has excellent physical properties as a substrate material for semiconductor ultraviolet photodetectors, such as wide bandgap, high critical electric field, high thermal conductivity, high saturated electron drift rate, high hole-electron ionization rate ratio, excellent physical and chemical stability, strong radiation resistance and high mechanical strength. Compared with photodetectors based on other semiconductor materials, silicon carbide ultraviolet photodetectors have the advantages of low dark current, controllable high responsivity, high gain, and low avalanche noise. At present, the international community, including the United States, Germany, Japan, Russia, Israel and other countries, attach great importance to the theoretical and applied research of silicon carbide ultraviolet photodetectors, and invest a lot of scientific research funds every year. Silicon carbide-based ultraviolet photodetectors generally include four types: Schottky, metal-semiconductor-metal (MSM), pin, and avalanche photodiode (APD). Among them, pin structure detectors generally have the advantages of low operating voltage, fast response speed, and high operating stability. However, due to the very thin spatial depletion layer of the p+ type ohmic contact layer of the traditional pin structure detector, the photogenerated carriers generated cannot be separated and collected by the electric field to form a response current, but disappear due to the carrier recombination effect, resulting in a decrease in the device's responsivity. At the same time, the incident short-wave ultraviolet signal cannot penetrate the highly doped p+ type ohmic contact layer, resulting in the detector being unable to detect the short-wave ultraviolet signal. Therefore, how to optimize the device structure of the traditional pin structure detector, improve the spectral responsivity and external quantum efficiency of the device, and enable the detector to detect short-wave ultraviolet signals has become a difficulty and focus in the research of silicon carbide ultraviolet photodetectors. Summary of the invention

[0004] The purpose of the present invention is to provide a microstructured silicon carbide ultraviolet photodetector with high quantum efficiency and a preparation method thereof, wherein the photocurrent of the detector is improved compared with the conventional silicon carbide pin structure ultraviolet photodetector. At the same time, the spectral responsivity and external quantum efficiency of the detector are effectively improved compared with the conventional silicon carbide pin structure ultraviolet photodetector, and the detection of the entire ultraviolet band can be realized.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions.

[0006] A high quantum efficiency microstructured silicon carbide ultraviolet photodetector, which is provided with a silicon carbide highly doped n+ type substrate, a silicon carbide n-type buffer layer, a silicon carbide low doped n-type absorption layer, a silicon carbide low doped p-type absorption layer, an annular silicon carbide highly doped p+ type ohmic contact layer, a microstructure, a silicon dioxide passivation isolation layer, a p+ type ohmic contact electrode and an n+ type ohmic contact electrode from bottom to top;

[0007] The silicon carbide highly doped n+ type substrate serves as the substrate of the device, providing the necessary conductivity and mechanical support; a silicon carbide n-type buffer layer is arranged on the n+ type substrate, and the silicon carbide n-type buffer layer is used for smooth transition and reducing interface defects; a silicon carbide low doped n-type absorption layer is arranged upward from the center of the silicon carbide n-type buffer layer, and the silicon carbide low doped n-type absorption layer serves as the main absorption layer, and is used for absorbing ultraviolet light and generating photogenerated carriers; a silicon carbide low doped p-type absorption layer is arranged upward from the center of the silicon carbide low doped n-type absorption layer, and the silicon carbide low doped p-type absorption layer and the silicon carbide low doped n-type absorption layer jointly form a depletion electric field; an annular silicon carbide highly doped p+ type ohmic contact layer is arranged on the outside of the silicon carbide low doped p-type absorption layer, and the annular silicon carbide highly doped p+ The type ohmic contact layer is used to form an ohmic contact and provide the necessary electric field distribution; a microstructure is uniformly etched in the silicon carbide low-doped p-type absorption layer, the microstructure is used to improve the depletion and collection efficiency of photogenerated carriers, and allow short-wave ultraviolet signals to penetrate into the device; a silicon dioxide passivation isolation layer is provided on the upper surface of the device, the silicon dioxide passivation isolation layer is used to protect the device surface and reduce surface recombination; a p+ type ohmic contact electrode is provided on the upper surface of the p+ type ohmic contact layer, and an n+ type ohmic contact electrode is provided on the back of the silicon carbide highly doped n+ type substrate; when the device is working, a reverse bias is applied to the p+ type ohmic contact electrode. Since the p+ type ohmic contact layer is connected to the p-type absorption layer, a depletion electric field can be generated between the p layer and the n-layer of the device, and the p adjacent to the microstructure - The electric fields of the p-in structure are interconnected and coupled, so that the absorption area directly below the microstructure can also be depleted, thereby improving the efficiency of photogenerated carrier depletion and obtaining higher device responsiveness and external quantum efficiency; at the same time, the incident short-wave ultraviolet signal can directly enter the internal absorption layer of the device through the microstructure in the p-type absorption layer, avoiding the problem of photogenerated carrier recombination caused by surface defects of the p+ type ohmic contact layer, improving the efficiency of photogenerated carrier collection, and realizing detection of the entire ultraviolet band.

[0008] The longitudinal section width of the high quantum efficiency microstructured silicon carbide ultraviolet photodetector can be 100-200 μm; the n+ type substrate can be a commercial n+ conductive substrate, the width of the substrate can be 100-200 μm, the thickness can be 50-800 μm, and the doping concentration can be 10 19 / cm 3 ~10 20 / cm3 The width of the n-type buffer layer can be 100 to 200 μm, the thickness can be 100 nm to 1 μm, and the doping concentration can be 10 18 / cm 3 ~10 19 / cm 3 The width of the n-type absorption layer can be 100 to 200 μm, the thickness can be 1 to 3 μm, and the doping concentration can be 10 15 / cm 3 ~10 16 / cm 3 The width of the p-type absorption layer can be 90 to 180 μm, the thickness can be 100 to 200 nm, and the doping concentration can be 10 16 / cm 3 ~10 17 / cm 3 The width of the p+ type ohmic contact layer can be 5 to 10 μm, the thickness can be 100 to 200 nm, and the doping concentration can be 10 19 / cm 3 ~10 20 / cm 3 ; The width of the microstructure is 2 to 4 μm and the thickness is 100 to 200 nm; a silicon dioxide passivation isolation layer is provided on the upper surface of the device, and the passivation isolation layer can also be made of a wide bandgap passivation isolation material such as hafnium oxide, and the thickness can be 10 to 2 μm.

[0009] The method for preparing the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency comprises the following steps:

[0010] 1) RCA standard cleaning of silicon carbide highly doped n+ type substrate;

[0011] 2) epitaxially growing a silicon carbide n-type buffer layer on a silicon carbide highly doped n+ type substrate;

[0012] 3) epitaxially growing a silicon carbide low-doped n-type absorption layer on the silicon carbide n-type buffer layer;

[0013] 4) epitaxially growing a silicon carbide low-doped p-type absorption layer on the silicon carbide n-type absorption layer;

[0014] 5) Forming a ring-shaped silicon carbide highly doped p+ type ohmic contact layer on the outside of the p-type absorption layer by using deposition, photolithography, etching, ion implantation and high temperature annealing techniques;

[0015] 6) Forming uniformly distributed microstructures in the p-type absorber layer using deposition, photolithography and etching techniques;

[0016] 7) Use thermal oxidation and PECVD technology to form a wide bandgap passivation isolation layer such as silicon dioxide or hafnium oxide on the upper surface of the device;

[0017] 8) Photolithography, magnetron sputtering and annealing techniques are used to prepare p+ type ohmic contact electrodes and n+ type ohmic contact electrodes on the surface of the highly doped p+ type ohmic contact layer and the bottom of the n+ type substrate, respectively.

[0018] The conventional pin structure silicon carbide ultraviolet photodetector of the prior art must simultaneously meet the requirements of complete depletion of the i-layer and good p-type ohmic contact to achieve high-performance ultraviolet detection, so a highly doped p+ type ohmic contact layer is required on the surface. However, the spatial depletion layer of the highly doped p+ type ohmic contact layer on the detector surface is very thin, and the generated photogenerated carriers cannot be separated and collected by the electric field to form a response current, but disappear due to the carrier recombination effect, resulting in a decrease in the device's responsiveness. At the same time, the incident short-wave ultraviolet signal cannot penetrate the highly doped p+ type ohmic contact layer, resulting in the detector being unable to detect the short-wave ultraviolet signal.

[0019] Compared with the prior art, the present invention has the following outstanding advantages: the high quantum efficiency microstructured silicon carbide ultraviolet photodetector designed by the present invention can be composed of a ring-shaped p + -in structure and multiple p - -in and in structures, when working, a reverse bias is applied to the p+ ohmic contact electrode. Since the p+ ohmic contact layer is connected to the p-type absorption layer, a depletion electric field can be generated between the p layer and the n-layer of the device. - The electric fields of the -in structure are interconnected and coupled, so that the absorption area directly below the microstructure can also be depleted, improving the efficiency of photogenerated carrier depletion and obtaining higher device responsiveness and external quantum efficiency. At the same time, the incident short-wave ultraviolet signal can directly enter the internal absorption layer of the device through the microstructure in the p-type absorption layer, avoiding the problem of photogenerated carrier recombination caused by surface defects of the p+ type ohmic contact layer, improving the efficiency of photogenerated carrier collection, and realizing detection of the entire ultraviolet band. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional schematic diagram of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency described in an embodiment of the present invention.

[0021] Figure 2 Schematic diagram of a top view of a microstructured silicon carbide ultraviolet photodetector with high quantum efficiency according to an embodiment of the present invention.

[0022] Figure 3 This is a comparison diagram of the photocurrent of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency described in an embodiment of the present invention and the traditional pin structure ultraviolet photodetector.

[0023] Figure 4 This is a comparison diagram of the spectral responsivity curves of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency described in an embodiment of the present invention and the traditional pin structure ultraviolet photodetector under a reverse bias voltage of 5V. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following embodiments will further illustrate the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims.

[0025] In order to make the structure of the present invention more clear and understandable, refer to the cross-sectional schematic diagram and top view schematic diagram of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency described in the embodiment of the present invention ( Figure 1 and 2 ).

[0026] The high quantum efficiency microstructured silicon carbide ultraviolet photodetector is provided with a commercial silicon carbide highly doped n+ type substrate (1) from bottom to top. The thickness of the silicon carbide highly doped n+ type substrate (1) can be 50 to 800 μm, and the doping concentration can be on the order of 10 19 / cm 3 ~10 20 / cm 3 The longitudinal section width can be 100 to 200 μm; a silicon carbide n-type buffer layer (2) is provided on a silicon carbide highly doped n+ type substrate (1), the width can be 100 to 200 μm, the thickness can be 100 nm to 1 μm, and the doping concentration can be on the order of 10 18 / cm 3 ~10 19 / cm 3 A silicon carbide low-doped n-type absorption layer (3) is provided upward from the center of the silicon carbide n-type buffer layer (2), the width of which can be 100 to 200 μm, the thickness of which can be 1 to 3 μm, and the doping concentration of which can be 10 15 / cm 3 ~10 16 / cm 3 A silicon carbide low-doped p-type absorption layer (4) is provided upward from the center of the silicon carbide low-doped n-type absorption layer (3), the width of which can be 90 to 180 μm, the thickness of which can be 100 to 200 nm, and the doping concentration of which can be 10 16 / cm 3 ~10 17 / cm 3A ring-shaped silicon carbide high-doped p+-type ohmic contact layer (5) is provided outside the silicon carbide low-doped p-type absorption layer (4), the width of which can be 5 to 10 μm, the thickness of which can be 100 to 200 nm, and the doping concentration of which can be 10 19 / cm 3 ~10 20 / cm 3 A uniformly distributed microstructure is provided in the silicon carbide low-doped p-type absorption layer (4), the width of which can be 2 to 4 μm and the thickness of which can be 100 to 200 nm; a passivation isolation layer (6) is provided on the upper surface of the device, the dielectric layer material of the passivation isolation layer (6) can be silicon dioxide, hafnium oxide or silicon nitride, etc., and the thickness can be 10 nm to 2 μm; a p+ type ohmic contact electrode (7) is provided on the upper surface of the annular silicon carbide highly doped p+ type ohmic contact layer (5), and an n+ type ohmic contact electrode (8) is provided on the back of the silicon carbide highly doped n+ type substrate (1). When the device is working, a reverse bias is applied to the p+ type ohmic contact electrode (8). Since the annular silicon carbide highly doped p+ type ohmic contact layer (5) is connected to the silicon carbide low-doped p-type absorption layer (4), a depletion electric field can be generated between the p layer and the n-layer of the device, and the p layers adjacent to the microstructures are depleted. - The electric fields of the -in structure are interconnected and coupled, so that the absorption area directly below the microstructure can also be depleted, thereby improving the efficiency of photogenerated carrier depletion and obtaining higher device responsiveness and external quantum efficiency. At the same time, the incident short-wave ultraviolet signal can directly enter the internal absorption layer of the device through the microstructure in the silicon carbide low-doped p-type absorption layer (4), avoiding the problem of photogenerated carrier recombination caused by surface defects of the annular silicon carbide high-doped p+ type ohmic contact layer (5), improving the efficiency of photogenerated carrier collection, and realizing detection of the entire ultraviolet band.

[0027] The method for preparing the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency comprises the following steps:

[0028] 1) Perform RCA standard cleaning on the SiC highly doped n+ type substrate (1) to remove surface contamination and oxide layer to ensure the quality of subsequent epitaxial growth. The cleaning process includes alkaline cleaning, acid cleaning and deionized water rinsing;

[0029] 2) epitaxially growing a layer of silicon carbide n-type buffer layer (2) on the cleaned silicon carbide highly doped n+ type substrate (1) by chemical vapor deposition (CVD) or molecular beam epitaxy (MBE) technology; the buffer layer helps to reduce the lattice mismatch and stress between the substrate and the subsequent absorption layer, thereby improving the stability of the device;

[0030] 3) epitaxially growing a silicon carbide low-doped n-type absorption layer (3) on the silicon carbide n-type buffer layer (2); the absorption layer has a lower doping concentration, which helps to form a wider depletion region, thereby improving the collection efficiency of photogenerated carriers;

[0031] 4) epitaxially growing a silicon carbide low-doped p-type absorption layer (4) on the silicon carbide low-doped n-type absorption layer (3); this layer serves as the main light absorption region of the device, and its doping concentration and thickness need to be precisely controlled to optimize the spectral response;

[0032] 5) using deposition, photolithography, etching, ion implantation and high temperature annealing techniques to form a ring-shaped silicon carbide high-doped p+-type ohmic contact layer (5) on the outside of the silicon carbide low-doped p-type absorption layer (4); the high doping concentration of the layer helps to form a good ohmic contact, reduce contact resistance and improve device performance;

[0033] 6) using deposition, photolithography and etching techniques to form uniformly distributed microstructures in the silicon carbide low-doped p-type absorption layer (4); these microstructures can enhance the electric field distribution, improve the depletion efficiency of photogenerated carriers, and promote the penetration and absorption of short-wave ultraviolet signals;

[0034] 7) A passivation isolation layer (6) of wide bandgap passivation isolation such as silicon dioxide or hafnium oxide is formed on the upper surface of the device by using thermal oxidation and PECVD (plasma enhanced chemical vapor deposition) technology; this layer can effectively isolate the device from the influence of the external environment and improve the stability and reliability of the device.

[0035] 8) A p+ type ohmic contact electrode (7) and an n+ type ohmic contact electrode (8) are prepared on the surface of the annular silicon carbide highly doped p+ type ohmic contact layer (5) and the bottom of the silicon carbide highly doped n+ type substrate (1) respectively by using photolithography, magnetron sputtering and annealing technology. The electrodes are used to connect to an external circuit to realize the electrical signal output of the device.

[0036] Specific examples are given below.

[0037] 1) Perform RCA standard cleaning on the silicon carbide highly doped n+ type substrate (1) sample, the steps are as follows:

[0038] a. Ultrasonic cleaning with toluene, acetone and ethanol at least twice, then rinse with deionized water.

[0039] b. Use liquid No. 3 to boil at 250°C for 20 min, and rinse with hot and cold deionized water. The volume ratio of the liquid No. 3 is H2SO4:H2O2=4:1.

[0040] c. Soak the sample in diluted hydrofluoric acid (hydrogen fluoride: deionized water = 1:10 by volume) for 3 min or more, then rinse with hot and cold deionized water.

[0041] d. Boil the sample in liquid No. 1 for 10 min or more, and rinse with hot and cold deionized water. The liquid No. 1 has a volume ratio of NH3·H2O:H2O2:H2O=1:1:4.

[0042] e. Boil the sample in liquid No. 2 for 10 min or more, and rinse with hot and cold deionized water. The volume ratio of liquid No. 1 is HCl: H2O2: H2O = 1:1:4.

[0043] f. Soak the sample in diluted hydrofluoric acid (hydrogen fluoride: deionized water = 1:10 by volume) for 3 min or more, then rinse with hot and cold deionized water, blow dry the substrate with nitrogen gas, and set aside.

[0044] 2) The doping concentration of the (0001) Si surface epitaxial growth of the highly doped n+ type silicon carbide substrate (1) after RCA standard cleaning is on the order of 10 18 / cm 3 ~10 19 / cm 3 , a silicon carbide n-type buffer layer (2) having a width of 100 μm to 200 μm and a thickness of 100 nm to 1 μm;

[0045] 3) Epitaxial growth of doping concentration on the silicon carbide n-type buffer layer (2) is on the order of 10 15 / cm 3 ~10 16 / cm 3 , a silicon carbide low-doped n-type absorption layer (3) having a width of 100 μm to 200 μm and a thickness of 1 μm to 3 μm;

[0046] 4) Epitaxial growth of a doping concentration of 10 on the SiC low-doped n-type absorber layer (3) 16 / cm 3 ~10 17 / cm 3 , a silicon carbide low-doped p-type absorption layer (4) having a width of 90 μm to 180 μm and a thickness of 100 nm to 200 nm;

[0047] 5) A mask is formed by photolithography, etching and deposition techniques, and aluminum ions are implanted into the silicon carbide low-doped p-type absorption layer (4) on this basis. High-temperature annealing is performed to activate the aluminum ions, and a ring-shaped silicon carbide high-doped p+ type ohmic contact layer (5) is formed on the outside of the silicon carbide low-doped p-type absorption layer (4), with a width of 5 μm to 10 μm, a thickness of 100 nm to 200 nm, and a doping concentration of 10 19 / cm 3 ~10 20 / cm 3 ;

[0048] 6) forming a uniformly distributed microstructure in the silicon carbide low-doped p-type absorption layer (4) by using deposition, photolithography and etching techniques;

[0049] 7) Clean the sample using RCA standard to remove impurities on the sample surface, and use dry oxygen, wet oxygen and dry oxygen to oxidize alternately to grow a layer of oxide on the positive surface of the sample (towards the upper surface of the n-type absorption layer) as a sacrificial layer; place the sample with the sacrificial layer grown in buffered hydrofluoric acid for etching to remove the sacrificial layer; use dry oxygen, wet oxygen, dry oxygen and nitrogen to oxidize alternately to grow a thermally oxidized silicon dioxide passivation isolation layer with a thickness of 10 nm to 60 nm. Alternatively, after removing the sacrificial layer, PECVD technology can be used to grow a passivation isolation layer of wide bandgap passivation materials such as silicon dioxide or hafnium oxide with a thickness of 10 nm to 2 μm (6);

[0050] 8) using a photolithography process to expose and develop the photoresist, using buffered hydrofluoric acid to etch the oxide layer on the upper part of the annular silicon carbide highly doped p+ type ohmic contact layer (5) to form an electrode window, using a magnetron sputtering process to prepare a layer of alloy to form a p+ type ohmic contact electrode (7), preparing a layer of photoresist on the front side of the sample for protection and isolation, using buffered hydrofluoric acid to etch the oxide layer on the bottom side of the substrate, using magnetron sputtering to prepare an alloy layer to form an n+ type ohmic contact electrode (8), and annealing the two electrodes so that the p+ type ohmic contact electrode (7) and the n+ type ohmic contact electrode (8) of the sample form good ohmic contacts with the annular silicon carbide highly doped p+ type ohmic contact layer (5) at the edge of the device and the silicon carbide highly doped n+ type substrate (1), respectively.

[0051] Figure 3 A comparison diagram of the photocurrent of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency described in the embodiment of the present invention and the conventional pin structure ultraviolet photodetector is given. The novel detector in the figure is the present invention. Compared with the conventional pin structure ultraviolet photodetector, the photocurrent of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency is increased by 36.0%.

[0052] Figure 4 A comparison chart of the spectral responsivity curves of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency described in the embodiment of the present invention and the traditional pin structure ultraviolet photodetector under a reverse bias voltage of 5 V is given. Compared with the traditional pin structure ultraviolet photodetector, the peak spectral responsivity of the microstructured silicon carbide ultraviolet photodetector with high quantum efficiency is increased by 35.6%, the peak external quantum efficiency is increased by 27.4%, and the detection of the entire ultraviolet band can be achieved.

[0053] The above embodiments are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector, characterized in that A silicon carbide highly doped n+ type substrate is provided, a silicon carbide n-type buffer layer is provided on the silicon carbide highly doped n+ type substrate, a silicon carbide low doped n-type absorption layer is provided upward from the center of the silicon carbide n-type buffer layer, a silicon carbide low doped p-type absorption layer is provided upward from the center of the silicon carbide low doped n-type absorption layer for generating and separating photogenerated carriers, an annular silicon carbide highly doped p+ type ohmic contact layer is provided on the outer side of the silicon carbide low doped p-type absorption layer for collecting photogenerated carriers, a microstructure is uniformly etched in the silicon carbide low doped p-type absorption layer for direct incidence of shortwave ultraviolet signals, a silicon dioxide passivation isolation layer is provided on the upper surface of the device, a p+ type ohmic contact electrode is provided on the upper surface of the annular silicon carbide highly doped p+ type ohmic contact layer, and an n+ type ohmic contact electrode is provided on the back side of the silicon carbide highly doped n+ type substrate.

2. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that When the device is working, a reverse bias is applied to the p+ type ohmic contact electrode. Since the annular silicon carbide highly doped p+ type ohmic contact layer is connected to the silicon carbide low doped p- type absorption layer, a depletion electric field can be generated between the p layer and the n- layer of the device. - The electric fields of the -in structure are interconnected and coupled, so that the absorption area directly below the microstructure can also be depleted, improving the efficiency of photogenerated carrier depletion and obtaining higher device responsiveness and external quantum efficiency; at the same time, the incident short-wave ultraviolet signal directly enters the internal absorption layer of the device through the microstructure in the silicon carbide low-doped p-type absorption layer, avoiding the problem of photogenerated carrier recombination caused by surface defects of the p+ type ohmic contact layer, improving the efficiency of photogenerated carrier collection, and realizing detection of the entire ultraviolet band.

3. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that The width of the silicon carbide highly doped n+ type substrate is 100-200 μm, the thickness is 50-800 μm, and the doping concentration is on the order of 10 19 / cm 3 ~10 20 / cm 3 .

4. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that The silicon carbide n-type buffer layer has a width of 100 to 200 μm, a thickness of 100 nm to 1 μm, and a doping concentration of 10 18 / cm 3 ~10 19 / cm 3 .

5. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that The width of the silicon carbide low-doped n-type absorption layer is 100-200 μm, the thickness is 1-3 μm, and the doping concentration is on the order of 10 15 / cm 3 ~10 16 / cm 3 .

6. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that The width of the silicon carbide low-doped p-type absorption layer is 90 to 180 μm, the thickness is 100 to 200 nm, and the doping concentration is on the order of 10 16 / cm 3 ~10 17 / cm 3 .

7. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that The width of the p+ type ohmic contact layer is 5-10 μm, the thickness is 100-200 nm, and the doping concentration is on the order of 10 19 / cm 3 ~10 20 / cm 3 .

8. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that The microstructure has a width of 2 to 4 μm, a thickness of 100 to 200 nm, and a shape of a circle, a triangle, or a star.

9. A high quantum efficiency microstructured silicon carbide ultraviolet photodetector according to claim 1, characterized in that The silicon dioxide passivation isolation layer is replaced by a passivation isolation layer made of a wide bandgap passivation isolation material such as hafnium oxide. The thickness of the passivation isolation layer can be 10 nm to 2 μm.

10. A method for preparing a microstructured silicon carbide ultraviolet photodetector with high quantum efficiency, characterized in that The following steps are involved: 1) RCA standard cleaning of silicon carbide highly doped n+ type substrates; 2) epitaxially growing a silicon carbide n-type buffer layer on a highly doped silicon carbide n+ substrate; 3) epitaxially growing a silicon carbide low-doped n-type absorber layer on the silicon carbide n-type buffer layer; 4) epitaxially growing a silicon carbide low-doped p-type absorption layer on the silicon carbide n-type absorption layer; 5) Using deposition, photolithography, etching, ion implantation and high temperature annealing techniques to form a ring-shaped silicon carbide highly doped p+ type ohmic contact layer on the outside of the p-type absorption layer; 6) Using deposition, photolithography, and etching techniques to form a uniformly distributed microstructure in the p-type absorber layer; 7) Using thermal oxidation and PECVD technology to form a wide bandgap passivation isolation layer such as silicon dioxide or hafnium oxide on the upper surface of the device; 8) Photolithography, magnetron sputtering and annealing techniques are used to prepare p+ type ohmic contact electrodes and n+ type ohmic contact electrodes on the surface of the highly doped p+ type ohmic contact layer and the bottom of the n+ type substrate, respectively.

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