Semiconductor neutron detector, preparation method and neutron flux measuring device

Abstract

The invention discloses a semiconductor neutron detector, a preparation method and a neutron flux measuring device, and relates to the field of neutron detection.The semiconductor neutron detector sequentially comprises an ohmic electrode, a substrate, a buffer layer, an epitaxial layer and a Schottky electrode from bottom to top; the substrate, the buffer layer and the epitaxial layer are all made of 4H-SiC; when the semiconductor neutron detector detects neutrons, the neutrons and the epitaxial layer are subjected to nuclear reaction, electron hole pairs excited by neutron energy deposition sequentially pass through the buffer layer and the substrate from the epitaxial layer to the ohmic electrode, and the ohmic electrode outputs neutron current signals which are converted into voltage signals in the sampling circuit so as to perform neutron detection. By adopting the characteristics of high hardness, high thermal conductivity, wide forbidden band and high displacement threshold energy of the 4H-SiC material, the high-fluence-rate neutron flux can be measured in real time, and the reliability and stability of the semiconductor neutron detector are improved.

Description

Technical Field

[0001] The present application relates to the field of neutron detection, and in particular, to a semiconductor neutron detector, a preparation method and a neutron flux measurement device. Background Art

[0002] With the continuous deepening of the current understanding and research on neutron characteristics and applications, neutron detectors have been widely used in many fields such as aerospace applications, nuclear medicine and clinical diagnosis, industrial safety assurance, environmental radiation detection, nuclear explosion and well logging. Currently, common testing methods include copper activation method, gas neutron detector, scintillator detector or semiconductor detector, etc.

[0003] The gas neutron detector has a low space utilization rate, while the scintillator detector often has relatively strict requirements for the working environment. During the process of testing by the copper activation method, the generation and decay of copper-64 is a relatively slow process. Therefore, after measurement, it is necessary to wait for a certain time to collect radioactive decay data, and it is difficult to perform real-time monitoring. At the same time, the complexity of the decay process and the change of neutron flux also require precise data processing and model correction, and the analysis is difficult. Traditional semiconductor detectors have excellent performance at low temperatures, are lightweight, have low power consumption, and have a fast response, making up for many deficiencies of the copper activation method, gas neutron detectors and scintillator neutron detectors, and playing an important role in the field of nuclear radiation detection. However, currently, traditional Si-based semiconductor neutron detectors have a weak radiation damage resistance ability, and the ionization effect of neutrons entering the semiconductor detector is extremely weak, making it difficult to generate detectable signals. Summary of the Invention

[0004] The purpose of the present application is to provide a semiconductor neutron detector, a preparation method and a neutron flux measurement device, which can directly and real-time measure the neutron flux with a high fluence rate, and at the same time improve the reliability and stability of the semiconductor neutron detector.

[0005] To achieve the above purpose, the present application provides the following solutions: In a first aspect, the present application provides a semiconductor neutron detector, which sequentially includes, from bottom to top: an ohmic electrode, a substrate, a buffer layer, an epitaxial layer and a Schottky electrode; the materials of the substrate, the buffer layer and the epitaxial layer are all 4H-SiC; When the semiconductor neutron detector detects neutrons, the neutrons undergo a nuclear reaction with the epitaxial layer, and the electron-hole pairs excited by the neutron energy deposition pass through the buffer layer and the substrate in sequence to reach the ohmic electrode from the epitaxial layer. The ohmic electrode outputs a neutron current signal, which is converted into a voltage signal in a sampling circuit for neutron detection.

[0006] In an embodiment, the inclination angles of the buffer layer and the epitaxial layer are 0.5° to 15°.

[0007] In a second aspect, the present application provides a method for manufacturing a semiconductor neutron detector, including: Growing a buffer layer and an epitaxial layer in sequence on the upper surface of a substrate by chemical vapor deposition step growth method; Sputtering a metal layer on the lower surface of the substrate by magnetron sputtering method to form an ohmic electrode, so as to obtain a semiconductor neutron detector.

[0008] In an embodiment, during the process of growing a buffer layer and an epitaxial layer in sequence on the surface of a substrate by chemical vapor deposition step growth method, deep level transient spectroscopy technology is used to detect Z 1 / 2 defects and EH 6 / 7 defects in the epitaxial layer, and adjust the process parameters of the chemical vapor deposition step growth method according to the Z 1 / 2 defects and EH 6 / 7 defects in the epitaxial layer. Wherein, the inclination angles of the substrate, the buffer layer and the epitaxial layer are 0.5° to 15°.

[0009] In an embodiment, the method for manufacturing a semiconductor neutron detector further includes: using a mask and evaporating a Schottky electrode on the surface of the epitaxial layer by thermal evaporation method to form a patterned front Schottky electrode.

[0010] In a third aspect, the present application provides a neutron flux measurement device, including: an electromagnetic shielding box, a semiconductor neutron detector, a sampling circuit, a filtering circuit and a processing terminal; The semiconductor neutron detector is located inside the electromagnetic shielding box; The cathode of the semiconductor neutron detector is connected to a DC power supply; the anode of the semiconductor neutron detector is connected to the sampling circuit; the sampling circuit is further connected to the filtering circuit; the filtering circuit is further connected to the processing terminal; The semiconductor neutron detector is used to detect the current signal generated after neutrons from a neutron source act on the semiconductor neutron detector, and output a neutron current signal; The sampling circuit is used to convert the neutron current signal into a voltage signal; The filtering circuit is used to filter out electromagnetic interference in the voltage signal to obtain a filtered signal; The processing terminal is used to obtain the neutron flux according to the filtered signal and the pre-constructed signal-flux calibration data.

[0011] In an embodiment, the cathode and anode of the semiconductor neutron detector are respectively led out to the outside of the electromagnetic shielding box by using SMA interfaces.

[0012] In one embodiment, both the cathode and anode of the semiconductor neutron detector are connected to the sampling circuit using double coaxial cables.

[0013] In one embodiment, the electromagnetic shielding box and the test site of the neutron source are connected to the same ground wire.

[0014] In one embodiment, the material of the electromagnetic shielding box is aluminum.

[0015] According to the specific embodiments provided by the present application, the present application has the following technical effects: The present application provides a semiconductor neutron detector, a preparation method, and a neutron flux measurement device. By using the characteristics of high hardness, high thermal conductivity, wide bandgap, and high displacement threshold energy of the 4H-SiC material itself, the semiconductor neutron detector has excellent mechanical reliability, electrical reliability, and radiation resistance performance, and is sufficient to withstand neutron irradiation with an extremely high cumulative flux, without the need to frequently replace the semiconductor neutron detector due to device life or reliability issues. Using the direct nuclear reaction between 4H-SiC and neutrons to generate signals enables the semiconductor neutron detector to directly and real-time measure the neutron flux, and improves the reliability and stability of the semiconductor neutron detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 Schematic diagram of a semiconductor neutron detector provided by an embodiment of the present application; Figure 2 Flow schematic diagram of a preparation method of a semiconductor neutron detector provided by an embodiment of the present application; Figure 3 Schematic diagram of a neutron flux measurement device provided by an embodiment of the present application; Figure 4 Top view sectional view of the package of a conductor neutron detector provided by an embodiment of the present application; Figure 5 Flux calibration fitting straight line diagram of an ultra-short high-energy neutron source provided by an embodiment of the present application; Figure 6 Schematic diagram of the structure for two-dimensional angular distribution detection of a fast neutron source provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0019] Currently, common neutron semiconductor detectors often come with a conversion layer containing 10 B4C and 6 LiF, and detect the secondary charged particles generated after the neutron undergoes a capture reaction with the conversion layer. In order to enable the conversion layer to fully undergo a capture reaction with the incident neutrons to ensure the detection efficiency, the conversion layer needs to have a sufficient thickness to ensure coverage of the penetration range of high-energy neutrons. However, the charged particles generated by the capture reaction usually have a limited penetration depth (<10 μm), which requires that the conversion layer cannot be too thick. In order to ensure the detection efficiency as much as possible, conversion layers with different thicknesses need to be equipped for neutrons of different energies. This causes great inconvenience to the development of scientific research work. Therefore, it is imperative to develop a detector with a direct detection function. In addition, a direct detector means that high-flux fast neutrons and high-energy neutrons will directly enter and deposit a large amount of energy in the detector, generating a great total dose effect and displacement damage effect in the detector. Therefore, the neutron detector for direct detection needs to have excellent radiation tolerance performance. In addition, the high-flux neutron signal will appear as a large current in the device, and the conventional charge-sensitive amplifier circuit cannot be adapted.

[0020] To address the above requirements, in order to solve the technical problem that existing semiconductor neutron detectors usually rely on a neutron conversion layer and cannot achieve direct real-time detection of neutron flux, the present application proposes a new semiconductor neutron detector and a neutron flux measurement device. Based on the 4H-SiC material, a corresponding highly sensitive, highly stable, radiation-tolerant wide-bandgap semiconductor neutron detector is designed and prepared, and a direct detection device for ultra-short fast neutron flux is developed. Different from the test method of existing semiconductor neutron detectors that use a conversion layer to measure the charged particles generated by the capture reaction between the conversion layer and the incident neutrons, the present application utilizes that fast neutrons and high-energy neutrons will react with Si or C atoms in the 4H-SiC material to generate 28 Si(n,α0) 25 Mg and 12 C(n,α0) 9The principle of Be and other nuclear reactions deposits energy within a semiconductor neutron detector. This process involves elastic collisions between neutrons and atoms, causing the neutron energy to transfer to the lattice, directly generating a current response signal in the semiconductor neutron detector for fast neutrons and high-energy neutrons. Subsequently, current-voltage signal conversion and filtering are performed through subsequent circuits. By comparing with pre-established signal-flux calibration data, the neutron flux of a fast neutron or high-energy neutron source can be measured in real time.

[0021] To make the above objects, features, and advantages of the present application more apparent and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] In an exemplary embodiment, as Figure 1 shown, a semiconductor neutron detector is provided, which sequentially includes, from bottom to top: an ohmic electrode 101, a substrate 102, a buffer layer 103, an epitaxial layer 104, and a Schottky electrode 105. It should be noted that Figure 1 only shows the positional relationship between each layer and does not limit the thickness of each layer. The thickness of each layer can be designed according to actual requirements.

[0023] Among them, the materials of the substrate 102, the buffer layer 103, and the epitaxial layer 104 are all 4H-SiC. The Schottky electrode 105 is a metal Schottky electrode.

[0024] When the semiconductor neutron detector detects neutrons, the neutrons undergo a nuclear reaction with the epitaxial layer 104, and the electron-hole pairs excited by the deposited neutron energy pass through the buffer layer 103 and the substrate 102 in sequence from the epitaxial layer 104 to reach the ohmic electrode 101. The ohmic electrode 101 outputs a neutron current signal, which is converted into a voltage signal in a sampling circuit for neutron detection. The present application can be applied to detection scenarios of steady-state and pulsed neutron fluxes, that is, the ohmic electrode outputs a steady-state pulsed neutron current signal.

[0025] The above semiconductor neutron detector is a 4H-SiC Schottky current-type detector.

[0026] In an exemplary embodiment, as Figure 2 shown, a method for fabricating a semiconductor neutron detector is provided, including the following steps 201 to step 203.

[0027] Step 201, using chemical vapor deposition (CVD) step growth method to sequentially grow an inclined 4H-SiC buffer layer 103 and an epitaxial layer 104 on the surface of the substrate 102.

[0028] Specifically, during the process of sequentially growing the buffer layer 103 and the epitaxial layer 104 on the surface of the substrate 102 by chemical vapor deposition step growth method, deep level transient spectroscopy technology is used to detect Z 1 / 2 defects and EH 6 / 7 defects inside the epitaxial layer 104, and the process parameters of the chemical vapor deposition step growth method are adjusted according to the Z 1 / 2 defects and EH 6 / 7 defects inside the epitaxial layer 104. Among them, the inclination angles of the substrate 102, the buffer layer 103 and the epitaxial layer 104 are 0.5° to 15°.

[0029] In this application, a high-quality substrate 102 is used as the substrate, and a high-quality low-doping concentration buffer layer 103 and an epitaxial layer 104 (30 μm - 200 μm) are prepared on the surface of the substrate 102 by CVD step growth method. The substrate 102 has a high carrier concentration, the buffer layer 103 has a lower carrier concentration, and the epitaxial layer 104 has an even lower carrier concentration. To achieve an epitaxial layer 104 with a thickness exceeding 100 μm, deep level transient spectroscopy technology is used to detect Z 1 / 2 defects and EH 6 / 7 defects inside the epitaxial layer 104 that significantly affect the carrier lifetime, ensure effective detection and optimization of these defects, further improve the CVD process parameters, significantly reduce the introduction of carbon vacancy defects and their complexes inside the epitaxial layer 104, thereby effectively reducing the defect state density and ensuring that it is lower than 1×10 14 cm -3 .

[0030] Step 202, a metal layer is sputtered on the lower surface of the substrate 102 by magnetron sputtering method to form an ohmic electrode 101, so as to obtain a semiconductor neutron detector.

[0031] In a specific application example, Ni / Pt or Ti / Pt metal layers are sequentially sputtered on the lower surface of the substrate 102 by magnetron sputtering method to form a high-quality ohmic contact electrode.

[0032] Step 203, a mask plate is used and a Schottky electrode 105 is evaporated on the surface of the epitaxial layer 104 by thermal evaporation method to form a patterned front Schottky electrode.

[0033] In a specific application example, a customized mask is used and metal Ni or Ti is evaporated by thermal evaporation to form a high-precision patterned front Schottky electrode, which significantly improves the sensitivity area of ​​the semiconductor neutron detector. The area of ​​the patterned front Schottky electrode directly determines the sensitive area of ​​the semiconductor neutron detector and expands the detection range of incident neutrons. Through the innovation of epitaxial process technology and patterning technology, the semiconductor neutron detector prepared in this application has achieved a breakthrough improvement in the area of ​​the sensitive area, with the maximum sensitive area exceeding 20×20mm 2 .

[0034] Furthermore, after the semiconductor neutron detector is prepared, the ohmic electrode of the semiconductor neutron detector is fixed on the base of the ceramic package or the high-frequency printed circuit board using conductive silver paste and led out from the base, and the Schottky electrode of the semiconductor neutron detector is led out through the silver wire electrode external lead to complete the preparation of the semiconductor neutron detector. This application not only improves the performance of the semiconductor neutron detector, but also achieves significant breakthroughs in accuracy and sensitivity, providing a new solution for the efficient detection of ultrashort fast neutron flux.

[0035] In an exemplary embodiment, Figure 3 and Figure 4 As shown, a neutron flux measurement device is provided, including: an electromagnetic shielding box 401, a semiconductor neutron detector 306, a sampling circuit 302, a filtering circuit 303 and a processing terminal 304.

[0036] The number of the semiconductor neutron detectors 306 may be one or more, and the angular distribution difference and axial distribution of the flux of the neutron source 301 may be measured by adding semiconductor neutron detectors 306 .

[0037] The neutron flux measurement device provided in the present application can be used to measure the neutron flux of a high-fluence rate pulse fast neutron source (such as picosecond width neutrons generated by laser target shooting, etc.).

[0038] The semiconductor neutron detector 306 is located inside the electromagnetic shielding box 401. The electromagnetic shielding box 401 is made of aluminum. Aluminum can effectively shield electromagnetic signals and charged particles, but has little effect on high-energy neutrons and fast neutrons, thereby preventing the radiation environment from interfering with the detector performance without affecting the neutron detection of the semiconductor neutron detector 306. The semiconductor neutron detector 306 contacts the electromagnetic shielding box 401 through the base 402.

[0039] The cathode 403 of the semiconductor neutron detector 306 is connected to the DC power supply 305. The anode 404 of the semiconductor neutron detector 306 is connected to the sampling circuit 302. The sampling circuit 302 is also connected to the filter circuit 303. The filter circuit 303 is also connected to the processing terminal 304.

[0040] The DC power supply 305 is a DC bias source, which ensures that a stable bias is input through the cathode 403 to make the semiconductor neutron detector 306 work in a reverse bias state and generate a depletion layer of sufficient thickness inside the device.

[0041] In a specific application example, the cathode 403 and the anode 404 of the semiconductor neutron detector 306 are respectively led out to the outside of the electromagnetic shielding box 401 using SMA interfaces. The cathode 403 and the anode 404 of the semiconductor neutron detector 306 are connected to the sampling circuit 302 using dual coaxial cables. The electromagnetic shielding box 401 and the test site of the neutron source 301 are connected to the same ground wire. Compared with the conventional single-interface test device, the cathode 403 and the anode 404 of the semiconductor neutron detector 306 are electromagnetically shielded and the shielding layer is grounded. The common ground of the semiconductor neutron detector 306, the electromagnetic shielding box 401, and the test site can avoid electromagnetic interference problems to the greatest extent and significantly improve the signal quality.

[0042] The semiconductor neutron detector 306 is used to detect the current signal generated after the neutrons from the neutron source 301 act on the semiconductor neutron detector 306, and output the neutron current signal. Specifically, the semiconductor neutron detector 306 and the electromagnetic shielding box 401 are arranged at a fixed distance from the neutron source 301, and the sensitive area of ​​the semiconductor neutron detector 306 is facing the neutron source 301, so as to control the experimental variables and obtain reliable output signals.

[0043] The sampling circuit 302 is used to convert the neutron current signal into a voltage signal.

[0044] In the present application, a large current adjustable sampling resistor is selected in the sampling circuit 302, and the resistance value can be adjusted according to the neutron source 301 with different fluxes to amplify or attenuate the sampling signal. For the case of low neutron flux and small current signal, an adaptive large resistance sampling resistor can be selected to increase the amplitude of the converted signal, so that the neutron flux measurement device has a good detection effect for fast neutrons with different fluxes.

[0045] Meanwhile, the sampling circuit 302 also includes appropriate protection capacitors to prevent signal loss due to large currents generated by extremely high flux neutron irradiation.

[0046] The filter circuit 303 is used to filter out electromagnetic interference in the voltage signal to obtain a filtered signal.

[0047] In a specific application example, the filter circuit 303 is a bandpass filter circuit, which removes low-frequency environmental current noise (such as power frequency noise in the test environment) and high-frequency strong associated electromagnetic interference signals of the neutron source triggering process as much as possible.

[0048] The processing terminal 304 is configured to obtain the neutron flux according to the filtered signal and the pre-constructed signal-flux calibration data.

[0049] In a specific application example, the processing terminal 304 is a high-sampling-rate oscilloscope (≥1 MHz). The high-sampling-rate oscilloscope is used to monitor and record the amplitude of the filtered signal, and compare it with the calibrated fitting line at the test position (such as Figure 5 shown), and then the neutron flux measured at the position of the semiconductor neutron detector 306 in this experiment can be obtained by conversion.

[0050] In this application, the semiconductor neutron detector 306 deposits energy in the semiconductor neutron detector 306 through the elastic scattering of fast neutrons with Si or C atoms. The fast neutron beam will generate a large current signal in the semiconductor neutron detector 306, which is led out to the sampling circuit 302 through a double coaxial cable and converted into a voltage signal. After being processed by the filtering circuit 303, it is recorded by the processing terminal 304, and then compared with the signal-flux calibration data to calculate the neutron flux at the position of the semiconductor neutron detector 306.

[0051] This application also provides two specific application examples: (1) As Figure 6 shown, six semiconductor neutron detectors 306 are respectively placed in the electromagnetic shielding box 401 (5×5×3 cm 3 ). The cathode 403 and the anode 404 of the semiconductor neutron detector 306 are led out using SMA ports. The electromagnetic shielding box 401 is arranged 4 meters away from the center of the sphere of the spherical short-pulse fast neutron source 301, and placed at intervals of 60° in the horizontal direction, so that the sensitive area of the semiconductor neutron detector 306 faces the center of the sphere. The cathode 403 port of the semiconductor neutron detector 306 is connected to the output terminal of the DC bias voltage source. The resistance value of the sampling resistor of the sampling circuit 302 is adjusted to 500 kΩ, and the protection capacitor is 1 μF. The filter in the filtering circuit 303 selects a band-pass filter of 50 Hz - 1000000 Hz. An oscilloscope is used to connect the pulse trigger signal of the neutron source 301 and the output signal of the filtered sampling circuit 302. The amplitude of the filtered signal is monitored and recorded using a high-sampling-rate oscilloscope and compared with the calibrated fitting line at the test position, and then the neutron flux measured by the semiconductor neutron detector 306 can be obtained by conversion. By comparing the neutron fluxes measured by all the semiconductor neutron detectors 306, the two-dimensional angular distribution uniformity of fast neutrons on the horizontal plane in this experiment can be roughly quantitatively evaluated. Further increasing the number of channels of the semiconductor neutron detector 306 can obtain more detailed neutron flux angular distribution data.

[0052] (2) Place the four semiconductor neutron detectors 306 in the electromagnetic shielding box 401 respectively. Lead out the cathode 403 and anode 404 of the semiconductor neutron detector 306 using SMA ports. Arrange the electromagnetic shielding box 401 at positions 1 meter, 3 meters, 5 meters, and 10 meters from the center of the spherical pulsed high-energy neutron source 301, and make the sensitive area of the semiconductor neutron detector 306 face the center of the sphere. Connect the cathode 403 port of the semiconductor neutron detector 306 to the output terminal of the DC bias voltage source. The resistance value of the sampling resistor in the sampling circuit 302 is uniformly set to 500 kΩ, and the protection capacitor is 1 μF. Select a band-pass filter with a frequency range of 50 Hz - 1000000 Hz for the filter in the filtering circuit 303. Connect the pulse trigger signal of the neutron source 301 and the output signal of the filtered sampling circuit 302 using an oscilloscope, and monitor and record the amplitude of the filtered signal using a high-sampling-rate oscilloscope. By comparing the signals obtained by the semiconductor neutron detectors 306 at different distances, the difference between the actual axial neutron distribution and the theoretical model during this experiment of the neutron source 301 can be calculated.

[0053] In summary, the beneficial effects of this application at least include the following points: (1) By using the characteristics of high hardness, high thermal conductivity, wide bandgap, and high displacement threshold energy of the 4H-SiC material itself, the semiconductor neutron detector 306 has excellent mechanical reliability, electrical reliability, and radiation resistance performance, and is sufficient to withstand neutron irradiation with extremely high cumulative flux, without the need to frequently replace the semiconductor neutron detector 306 due to device life or reliability issues.

[0054] (2) Adopt the epitaxial process optimized by deep level transient spectroscopy technology, and the defect state density of the epitaxial layer 104 of the substrate 102 is lower than 1×10 14 cm -3 . The high-quality epitaxial process ensures a low leakage current density under the working state of the large-area semiconductor neutron detector 306. The maximum sensitive area of the semiconductor neutron detector 306 can exceed 20×20 mm 2 .

[0055] (3) The electromagnetic shielding box 401 designed in this application has little influence on high-energy neutrons and fast neutrons, can effectively shield electromagnetic interference and charged particles, improve the signal-to-noise ratio of the detection signal in complex scenarios, and enhance the accuracy of the measurement results.

[0056] (4) The semiconductor neutron detector 306 designed in this application can directly measure fast neutrons or high-energy neutrons with a high fluence rate in real time without passing through a conversion layer, avoiding the time occupied by the capture reaction and improving the overall response rate of the semiconductor neutron detector 306.

[0057] (5) In the sampling circuit 302 of the present application, a high-power sampling resistor with high voltage resistance and adjustable resistance value is adopted, and the resistance value can be adjusted according to different fluxes of fast neutrons to optimize the amplification or attenuation effect of the signal, so as to achieve accurate matching measurement for different fast neutron fluxes, and also enable the neutron flux measurement device to have a higher detectable range for incident fast neutrons and high-energy neutron fluxes.

[0058] (6) The band-pass filter circuit 303 added after the sampling circuit 302 of the present application can filter high-frequency or low-frequency noise, making the neutron flux measurement device more adaptable in an environment with low signal amplitude and high background noise.

[0059] (7) The direct detection method used in the present application reduces the occupied space of the semiconductor neutron detector 306, can be arranged in a more compact manner, has a higher upper limit of spatial resolution ability, and can cooperate with the sampling circuit 302, the filter circuit 303 and the processing terminal 304 to conduct a more refined study on the spatial distribution of the neutron flux of the neutron source.

[0060] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data need to comply with relevant regulations.

[0061] In the present application, all actions of obtaining signals, information or data are carried out on the premise of complying with the corresponding data protection regulations and policies of the country where the location is located and obtaining the authorization given by the owner of the corresponding device.

[0062] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0063] In this article, specific examples are used to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A semiconductor neutron detector, characterized in that: The semiconductor neutron detector includes, from bottom to top, an ohmic electrode, a substrate, a buffer layer, an epitaxial layer and a Schottky electrode; the materials of the substrate, the buffer layer and the epitaxial layer are all 4H-SiC; When the semiconductor neutron detector detects neutrons, the neutrons undergo a nuclear reaction with the epitaxial layer, and the electron-hole pairs excited by the neutron energy deposition pass from the epitaxial layer through the buffer layer and the substrate in sequence to the ohmic electrode. The ohmic electrode outputs a neutron current signal, which is converted into a voltage signal in the sampling circuit to perform neutron detection.

2. The method for preparing a semiconductor neutron detector according to claim 1, characterized in that: The buffer layer and the epitaxial layer have an inclination angle of 0.5° to 15°.

3. A method for preparing a semiconductor neutron detector, used for preparing the semiconductor neutron detector according to any one of claims 1 to 2, characterized in that: The preparation method comprises: A buffer layer and an epitaxial layer are sequentially grown on the upper surface of a substrate by using a chemical vapor deposition step growth method; the materials of the substrate, the buffer layer and the epitaxial layer are all 4H-SiC; A metal layer is sputtered on the lower surface of the substrate by magnetron sputtering to form an ohmic electrode to obtain a semiconductor neutron detector.

4. The method for preparing a semiconductor neutron detector according to claim 3, characterized in that: In the process of sequentially growing a buffer layer and an epitaxial layer on the surface of a substrate by using a chemical vapor deposition step growth method, a deep level transient spectroscopy technique is used to detect the Z inside the epitaxial layer. 1 / 2 Defects and EH 6 / 7 defects, and according to the Z inside the epitaxial layer 1 / 2 Defects and EH 6 / 7 Defect adjustment of process parameters of chemical vapor deposition step growth method.

5. The method for preparing a semiconductor neutron detector according to claim 3, characterized in that: The method for preparing the semiconductor neutron detector further includes: A mask is used to evaporate a Schottky electrode on the surface of the epitaxial layer by a thermal evaporation method to form a patterned front Schottky electrode.

6. A neutron flux measuring device, characterized in that: The neutron flux measuring device comprises: an electromagnetic shielding box, the semiconductor neutron detector according to claim 1, a sampling circuit, a filtering circuit and a processing terminal; The semiconductor neutron detector is located inside the electromagnetic shielding box; The cathode of the semiconductor neutron detector is connected to a DC power supply; the anode of the semiconductor neutron detector is connected to the sampling circuit; the sampling circuit is also connected to the filter circuit; the filter circuit is also connected to the processing terminal; The semiconductor neutron detector is used to detect the current signal generated after the neutrons from the neutron source act on the semiconductor neutron detector, and output the neutron current signal; The sampling circuit is used to convert the neutron current signal into a voltage signal; The filter circuit is used to filter out electromagnetic interference in the voltage signal to obtain a filtered signal; The processing terminal is used to obtain the neutron flux according to the filtered signal and pre-constructed signal-flux calibration data.

7. The neutron flux measuring device according to claim 6, characterized in that: The cathode and anode of the semiconductor neutron detector are respectively led out to the outside of the electromagnetic shielding box using SMA interfaces.

8. The neutron flux measuring device according to claim 6, characterized in that: The cathode and anode of the semiconductor neutron detector are both connected to the sampling circuit using dual coaxial cables.

9. The neutron flux measuring device according to claim 6, characterized in that: The electromagnetic shielding box and the test site of the neutron source are connected to the same ground wire.

10. The neutron flux measuring device according to claim 6, characterized in that: The electromagnetic shielding box is made of aluminum.

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