SiC-based PNPN vertical structure semiconductor nuclear radiation detector and method

Abstract

The invention discloses a SiC-based PNPN vertical structure semiconductor nuclear radiation detector and a method, and relates to the field of radiation detectors, the SiC-based PNPN vertical structure semiconductor nuclear radiation detector comprises a substrate, a cathode electrode formed on the lower surface of the substrate, and a P3 region, a P2 region, an N1 region, a P1 region and an anode electrode on the P1 region which are sequentially formed on the upper surface of the substrate from bottom to top; the P1 region is a P-type heavily doped region; the N1 region is an N-type general doping region; the P2 region is a P-type lightly doped region; the P3 region is a P-type general doping region; the substrate is an N-type heavily doped substrate; the anode electrode and the cathode electrode are made of ohmic contact materials; a bias voltage is applied between the anode electrode and the cathode electrode, and the bias voltage is 720-3600 V; the N-type doping element is a nitrogen element, and the P-type doping element is an aluminum element.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear radiation detectors, in particular to a SiC-based PNPN vertical structure semiconductor nuclear radiation detector and method. BACKGROUND

[0002] A nuclear radiation detector is a device for detecting and quantifying the level of nuclear radiation, widely used in nuclear energy, medical treatment, environmental protection, safety, scientific research and other fields. It mainly works based on various effects produced by the interaction of nuclear radiation and matter, and the common types include gas ionization detectors, scintillation detectors and semiconductor detectors. Semiconductor detectors have the advantages of high energy resolution, high detection efficiency and fast response, in addition, they are small in size, which is conducive to miniaturization, integration and intelligentization, and are becoming one of the mainstream technologies in the field of nuclear radiation detection.

[0003] Traditional semiconductor detectors include PN junction type, lithium drift type and high-purity germanium detectors. Nuclear radiation generates electron-hole pairs in the sensitive volume of the semiconductor detector, and the electrons and holes drift under the action of an external electric field to generate a signal. The signal amplitude can reflect the energy information of the incident particles, and the signal is usually weak and needs to be amplified before transmission, processing and recording. The use of preamplifiers increases the volume and complexity of the system. Avalanche diode detectors can achieve internal gain of the signal, but it destroys the quantitative relationship between signal amplitude and energy. In order to achieve high performance, miniaturization and intelligentization of semiconductor nuclear radiation detection devices, it is an important direction to develop semiconductor nuclear radiation detectors with quantitative internal gain.

[0004] The third-generation semiconductor material represented by SiC has the advantages of large band gap, strong radiation resistance, high breakdown electric field, high saturated electron mobility, good heat conduction and dissipation performance, and small dark current at room temperature. Nuclear radiation detectors based on SiC material exhibit better radiation resistance than traditional silicon-germanium detectors, but the large band gap of SiC material also results in higher material ionization energy, which leads to a decrease in the number of carriers generated by nuclear radiation in SiC material, resulting in a smaller output signal of SiC-based detectors. Further developing nuclear radiation detectors with internal gain based on SiC material is an important way to achieve high performance, miniaturization and intelligentization of nuclear radiation detectors. Currently, SiC nuclear radiation detectors with gain characteristics mainly have NPN structure (authorized publication number CN115394875B), which has a gain characteristic by directly amplifying the current generated by radiation through the bipolar gain principle of NPN structure. However, due to the quality of the material and the preparation process of the device, the nuclear radiation detector with this structure has certain difficulties in achieving a high gain of more than 10 times. Therefore, it is necessary to further explore new SiC nuclear radiation detector structures with gain characteristics. SUMMARY

[0005] The application aims to provide a SiC-based PNPN vertical structure semiconductor nuclear radiation detector and method, and solve the technical problem that the existing semiconductor nuclear radiation detector cannot realize internal quantitative amplification of signals.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme: A SiC-based PNPN vertical structure semiconductor nuclear radiation detector comprises a substrate, a cathode electrode formed on the lower surface of the substrate, and a P3 region, a P2 region, an N1 region, a P1 region and an anode electrode on the P1 region formed on the upper surface of the substrate from bottom to top. The P1 region is P-type heavy doping, and the doping concentration of the P1 region is (1.0±0.1)×10 19 cm -3 , and the thickness is (1.00±0.2) μm; The N1 region is N-type general doping, and the doping concentration of the N1 region is (8.0±0.1)×10 17 cm -3 , and the thickness is (3.0±0.1) μm; The P2 region is P-type light doping, and the doping concentration of the P2 region is (8.0±0.1)×10 14 cm -3 , and the thickness is 30 μm ~ 100 μm; The P3 region is P-type general doping, and the doping concentration of the P3 region is (2.5±0.1)×10 17 cm -3 , and the thickness is (1.25±0.01) μm; The substrate is N-type heavy doping, and the substrate is an N-type on-axis SiC substrate with a doping concentration of 2×10 19 cm -3 or a high-resistance off-axis SiC substrate, and the thickness is 5.00 μm; The anode electrode and the cathode electrode are both ohmic contact materials; A bias voltage is applied between the anode electrode and the cathode electrode, and the bias voltage is 720 V ~ 3600 V; The N-type doping element is nitrogen element, and the P-type doping element is aluminum element.

[0007] Further, The doping concentration of the P1 region is 1.0×10 19 cm -3 , and the thickness is 1.00 μm; The doping concentration of the N1 region is 8.0×10 17 cm -3 , and the thickness is 3.0 μm; The doping concentration of the P2 region is 8.0 x 10 14 cm -3 , and the thickness is 30 μm; The doping concentration of the P3 region is 2.5 x 10 17 cm -3 , and the thickness is 1.25 μm.

[0008] Further, the bias voltage between the anode electrode and the cathode electrode is 1500 V; The area of the N1 region is ≥ 1 mm 2 , ≤ 4 cm 2 ; The area of the P2 region is ≥ 1 mm 2 , ≤ 4 cm 2 ; The area of the P3 region is ≥ 1 mm 2 , ≤ 4 cm 2 .

[0009] Further, the diameter of the anode electrode is equal to that of the P1 region, the P1 region is located in the middle of the N1 region, and the diameter of the P1 region is smaller than that of the N1 region; The diameters of the N1 region, the P2 region and the P3 region are equal, the P3 region is located in the middle of the substrate, and the diameter of the P3 region is smaller than that of the substrate; The diameters of the substrate and the cathode electrode are equal.

[0010] Further, the anode electrode, the P1 region, the N1 region, the P2 region, the P3 region and the cathode electrode are all prepared on the surface of the substrate by SiC material CVD epitaxial growth technology.

[0011] Further, it further comprises a peripheral packaging assembly; The peripheral packaging assembly comprises a substrate, a cathode terminal post, an anode terminal post, a gold wire bonding jumper, and a cathode pad, an anode pad respectively arranged on the upper surface of the substrate, and conductive silver paste arranged on the upper surface of the cathode pad; The upper surface of the conductive silver paste is connected with the lower surface of the cathode electrode; The anode pad is arranged on one side of the cathode pad, and a gap is left between the anode pad and the cathode pad; The cathode terminal post and the anode terminal post are respectively arranged on the substrate through the cathode pad and the anode pad; The anode electrode is connected with the anode pad through the gold wire bonding jumper.

[0012] Further, the substrate is a ceramic material or a material that is not easy to produce secondary particles under irradiation.

[0013] Further, the anode electrode and the cathode electrode are both nickel-gold materials.

[0014] Further, the P1 region and the N1 region form a first PN junction, the N1 region and the P2 region form a second PN junction, and the P3 region and the substrate form a third PN junction. The first PN junction forms a thin depletion region under the action of forward bias, the second PN junction forms a thick depletion region under the action of reverse bias, and the thick depletion region includes part of the N1 region, the entire P2 region, and part of the P3 region.

[0015] A radiation detection method using the SiC-based PNPN vertical structure semiconductor nuclear radiation detector includes the following steps. Step one: When nuclear radiation is incident on the entire device, carriers are generated in the P2 region by incident particles. Step two: The carriers drift under the action of an external electric field to form a current. Step three: Electrons accumulate in the N1 region, and holes accumulate in the P2 region and the P3 region, resulting in more carrier injection and forming a positive feedback mechanism to amplify the current signal and complete radiation detection.

[0016] Compared with the prior art, the present application has the following beneficial technical effects: 1) The detector has an internal gain function. The SiC doping and ohmic contact material are used to prepare a detector with three PN junctions, i.e., a first PN junction, a second PN junction, and a third PN junction, which form a thin depletion region, a thick depletion region, and a thin depletion region, respectively, to form a PNPN structure, so that the detector has an internal gain function. The internal gain function of the detector can directly detect weak signals, improve the sensitivity of the detector, reduce the introduction of external noise, improve the signal-to-noise ratio, and does not require an additional independent amplifier, which is conducive to the miniaturization of nuclear radiation detection equipment, reduces the complexity of the detector, and improves the reliability of the detector.

[0017] 2) Strong radiation resistance and long service life. The use of doped SiC material improves the radiation resistance of the detector, enhances the temperature stability, prolongs the service life, and improves the dark current level of the detector, which can meet the higher requirements of nuclear radiation detection environment.

[0018] 3) The internal gain of the detector is linear. By designing the doping concentration and thickness of each structure layer in the detector, the internal gain of the detector can be controlled to be linear, the gain multiple is relatively constant, and the input and output are in a linear relationship, which is conducive to the detection of particle energy and quantity.

[0019] 4) The gain multiple is adjustable. By designing the doping concentration of each structure layer in the detector, the range of the gain multiple can be adjusted. By applying different bias voltages, the depletion degree and thickness of the thin depletion layer and the thick depletion region can be controlled, so that the gain multiple of the signal of the detector can be changed.

[0020] 5) compact structure, convenient to use. The peripheral package assembly of the present application can lead out the electrodes of the detector, facilitating the application of bias voltage and the measurement of current, greatly facilitating the use of the detector.

[0021] 6) large area. The present application can realize large area, high quality, low defect, long life and uniform doping of the SiC radiation detector by using the SiC epitaxial growth CVD technology for detector preparation. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of the specification. The illustrative embodiments of the present application and their description serve to explain the present application. They do not, however, limit the present application.

[0023] Figure 1 Structure diagram of a SiC-based PNPN vertical structure semiconductor radiation detector embodiment of the present application; Figure 2 Typical power supply connection diagram of a SiC-based PNPN vertical structure semiconductor radiation detector embodiment of the present application; Wherein: 1-anode electrode, 2-P1 region, 3-N1 region, 4-P2 region, 5-P3 region, 6-substrate, 7-cathode electrode, 8-conductive silver glue, 9-gold wire bonding jumper, 10-anode terminal post, 11-cathode terminal post, 12-substrate, 13-cathode pad, 14-anode pad, 15-bias voltage, 16-ground, 17-load; Figure 3 Current change with bias voltage graph of the present application under different photo-generated carrier rates; Figure 4 Gain change with bias voltage graph of the present application under different photo-generated carrier rates; Figure 5 Gain change with photo-generated carrier rate graph of the present application under different bias voltages. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] Example 1 This invention improves upon materials and structure by designing three PN junctions. Through changes in bias voltage and the design of the thickness and doping concentration of each structural layer in the detector, the detector acquires internal amplification capabilities. Simultaneously, the detector is fabricated using SiC epitaxial growth CVD technology, achieving advantages such as large area, high quality, low defects, and uniform doping. This reduces detector leakage current, improves detection efficiency and yield, and extends the detector's lifespan.

[0027] Specifically, the present invention provides a SiC-based PNPN vertical structure semiconductor nuclear radiation detector, comprising: a substrate 6, a cathode electrode 7 formed on the lower surface of the substrate 6, and an anode electrode 1 formed sequentially from bottom to top on the upper surface of the substrate 6 in regions P3 5, P2 4, N1 3, P1 2 and P1 2. The anode electrode 1 and the P1 region 2 have the same diameter. The P1 region 2 is located in the middle of the N1 region 3, and the diameter of the P1 region 2 is smaller than the diameter of the N1 region 3. The diameters of N1 region 3, P2 region 4 and P3 region 5 are equal. P3 region 5 is located in the middle of substrate 6, and the diameter of P3 region 5 is smaller than the diameter of substrate 6. The substrate 6 and the cathode electrode 7 have the same diameter; The area of ​​region N1 3 is ≥ 1 mm. 2 ≤4 cm 2 ; The area of ​​region P2 4 is ≥1 mm. 2 ≤4 cm 2 ; The area of ​​region P3 5 is ≥1 mm. 2 ≤4 cm 2 .

[0028] The P1 region 2 is heavily doped with P-type doping, and the doping concentration of the P1 region 2 is (1.0±0.1)×10⁻⁶. 19 cm -3, thickness (1.00±0.2) μm; preferably, the doping concentration of the P1 region 2 is 1.0×10 19 cm -3 , thickness 1.00 μm; The N1 region 3 is N-type general doping, and the doping concentration of the N1 region 3 is (8.0±0.1)×10 17 cm -3 , thickness (3.0±0.1) μm; preferably, the doping concentration of the N1 region 3 is 8.0×10 17 cm -3 , thickness 3.0 μm; The P2 region 4 is P-type light doping, and the doping concentration of the P2 region 4 is (8.0±0.1)×10 14 cm -3 , thickness 30 μm ~ 100 μm; preferably, the doping concentration of the P2 region 4 is 8.0×10 14 cm -3 , thickness 30 μm; The P3 region 5 is P-type general doping, and the doping concentration of the P3 region 5 is (2.5±0.1)×10 17 cm -3 , thickness (1.25±0.01) μm; preferably, the doping concentration of the P3 region 5 is 2.5×10 17 cm -3 , thickness 1.25 μm; The substrate 6 is N-type heavy doping, and the substrate 6 is an N-type on-conductive off-axis SiC substrate or a high-resistance off-axis SiC substrate with a doping concentration of 2×10 19 cm -3 , thickness 5.00 μm; Preferably, the substrate 6 is an N-type on-conductive 4° off-axis SiC substrate or a high-resistance 4° off-axis SiC substrate with a doping concentration of 2×10 19 cm -3 ; The anode electrode 1 and the cathode electrode 7 are both ohmic contact materials; A bias voltage is applied between the anode electrode 1 and the cathode electrode 7, and the bias voltage is 720 V ~ 3600 V; preferably, the bias voltage between the anode electrode 1 and the cathode electrode 7 is 1500 V; The N-type doping element is nitrogen element, and the P-type doping element is aluminum element.

[0029] The anode electrode 1, the P1 region 2, the N1 region 3, the P2 region 4, the P3 region 5 and the cathode electrode 7 are all prepared on the surface of the substrate 6 by SiC material CVD epitaxial growth technology.

[0030] The peripheral package assembly comprises a substrate 12, a cathode terminal post 11, an anode terminal post 10, a gold wire bonding jumper 9, and a cathode pad 13 and an anode pad 14 respectively arranged on the upper surface of the substrate 12, and a conductive silver adhesive 8 arranged on the upper surface of the cathode pad 13; the upper surface of the conductive silver adhesive 8 is connected with the lower surface of the cathode electrode 7; the anode pad 14 is arranged on the right side of the cathode pad 13 and has a gap with the cathode pad 13; the cathode terminal post 11 and the anode terminal post 10 are arranged on the substrate 12 through the cathode pad 13 and the anode pad 14 respectively; and the anode electrode 1 is connected with the anode pad 14 through the gold wire bonding jumper 9.

[0031] The substrate 12 is a ceramic material or a material that is not easy to generate secondary particles under irradiation, and the anode electrode 1 and the cathode electrode 7 are both nickel-gold materials.

[0032] The working principle of the detector of the present application is as follows: The P1 region 2 and the N1 region 3 form a first PN junction, the N1 region 3 and the P2 region 4 form a second PN junction, and the P3 region 5 and the substrate 6 form a third PN junction; The first PN junction forms a thin depletion region under the action of a forward bias, the second PN junction forms a thick depletion region under the action of a reverse bias, the thick depletion region contains part of the N1 region 2, all of the P2 region 4 and part of the P3 region 5, and the third PN junction forms a thin depletion region under the action of a forward bias, and there is a non-depleted quasi-neutral region between the three depletion regions; When nuclear radiation is incident on the entire device, carriers are generated in the P2 region 4 by incident particles; The carriers drift under the action of an external electric field to form a current; Electrons accumulate in the N1 region 2, and holes accumulate in the P2 region 4 and the P3 region 5, which leads to the injection of more carriers and forms a positive feedback mechanism to achieve current signal amplification and complete radiation detection.

[0033] The present application solves the technical problems of the prior art semiconductor nuclear radiation detector, such as the limited internal quantitative amplification of the signal, and the technical problems of the traditional silicon-based detector, such as poor radiation resistance, short service life, poor temperature stability and large dark current. When nuclear radiation is incident, incident particles / rays can penetrate the P1 region 2 and generate carriers in the P2 region 4. The carriers drift under the action of an external electric field to form a current. Electrons accumulate in the N1 region 3, and holes accumulate in the P2 region 4 and the P3 region 5, which changes the potential of the corresponding region and leads to the injection of more carriers, eventually forming a positive feedback mechanism to achieve high-intensity amplification of the current signal.

[0034] The PNPN structure detector proposed in this invention has an additional P layer compared to the NPN structure, which enables coupling between the PNP and NPN structures. Through positive feedback, the device gain is further enhanced. In the operating state of this coupled structure, not only can the gain be increased, but a negative resistance effect can also be generated at a higher bias voltage, achieving a gain enhancement of several orders of magnitude.

[0035] Example 2 This invention discloses a SiC-based PNPN vertical structure semiconductor radiation detector, such as... Figure 1 As shown, it includes a substrate 6, a cathode electrode 7 formed on the lower surface of the substrate 6, and an anode electrode 1 formed sequentially from bottom to top on the upper surface of the substrate 6 in regions P3 5, P2 4, N1 3, P1 2 and P1 2. The core structural feature of the detector in this invention is the design of three PN junctions. The first, second, and third PN junctions form a thin depletion region, a thick depletion region, and a thin depletion region, respectively, thus forming a PNPN structure. During detector operation, a bias voltage 15 is applied between the anode electrode 1 and the cathode electrode 7. The bias voltage 15 ranges from 720 V to 3600 V. At 720 V, the thick depletion region can encompass the entire P2 region 4. If the bias voltage is lower than 720 V, the thick depletion region may not encompass the entire P2 region 4, resulting in a low carrier collection rate and negatively impacting the gain. Conversely, an excessively high bias voltage will lead to excessive dark current, affecting the accuracy of the measurement results. In this embodiment, the bias voltage is 1500 V, and the electrical connections are as follows... Figure 2As shown, the access bias voltage 15 and the load 17, while the ground 16, the second PN junction works under reverse bias voltage, forming a thick depletion region, the thick depletion region contains the entire P2 region 4, part of the N1 region 3 and part of the P3 region 5 close to the P2 region 4; the first PN junction works under the action of forward bias, forming a thin depletion region; the thin depletion region contains part of the P1 region 2 and part of the N1 region 3 close to the P1 region; the third PN junction works under the action of forward bias, forming a thin depletion region, the thin depletion region contains part of the P3 region 5 close to the substrate 6 and part of the substrate 6. There is no mutual overlap between the three depletion regions, and there is a non-depleted quasi-neutral region between the thick and thin depletion regions. The width of the quasi-neutral region is less than the diffusion length of electrons and holes in SiC. The diffusion length will increase with the increase of temperature, but the increase of temperature will also increase the dark current. Generally, the gap width is reduced by increasing the bias voltage, and the amplification is increased. The detector takes the thick depletion region as the detection sensitive area, converts the energy deposited in this area into carriers, and realizes the multiplication of the number of carriers inside the device. The width and range of the depletion region are controlled by two aspects: one is to design the structure thickness and doping concentration of the detector during device preparation, and the other is to control by adjusting the size of the bias voltage after preparation. By adjusting the bias voltage to control the width of the thick and thin depletion regions, the width of the quasi-neutral region is controlled. As the bias voltage gradually increases, the depletion region increases, and the thickness of the quasi-neutral region decreases.

[0036] In terms of materials, the P1 region 2 adopts P-type heavily doped SiC material; the N1 region 3 adopts N-type generally doped SiC material; the P2 region 4 adopts P-type lightly doped SiC material; the P3 region 5 adopts P-type generally doped SiC material; and the substrate 6 adopts N-type heavily doped SiC material. Among them, N-type doping is to dope a certain concentration of nitrogen ions during epitaxial growth, and P-type doping is to dope a certain concentration of aluminum ions during epitaxial growth. The anode electrode 1 and the cathode electrode 7 are both made of nickel gold material, the side of the nickel gold material close to SiC is nickel, and the outer side is thickened with gold. Specifically, the surface in contact with the epitaxial layer is a thin layer of nickel material, and the electrode is thickened to 100 nm-200 nm with gold material for easy bonding of the lead wire. The anode electrode 1 and the cathode electrode 7 can also be other ohmic contact materials. The concentration and thickness of each layer are designed as follows: the doping concentration of the P1 region 1 is (1.0±0.1)×10 19 cm -3 , the thickness is (1.00±0.2) μm; the doping concentration of the N1 region 2 is (8.0±0.1)×10 17 cm -3 , the thickness is (3.0±0.1) μm; the doping concentration of the P2 region (4) is (8.0±0.1)×10 14 cm -3Thickness 30 μm ~ 100 μm; doping concentration of P3 region (5) is (2.5±0.1)×10 17 cm -3 Thickness (1.25±0.01) μm; substrate with a doping concentration of 2×10⁻⁶ μm. 19 cm -3 The substrate used is an N-type conductive 4-degree off-axis SiC substrate or a high-resistivity 4-degree off-axis SiC substrate with a thickness of 5.00 μm; in this embodiment, the doping concentration and thickness of each layer are as follows: the doping concentration of the P1 region is 1.0 × 10⁻⁶. 19 cm -3 The thickness is 1.00 μm; the doping concentration of the N1 region is 8.0 × 10⁻⁶. 17 cm -3 The thickness is 3.0 μm; the doping concentration of the P2 region is 8.0 × 10⁻⁶. 14 cm -3 The thickness is 30 μm; the doping concentration of the P3 region is 2.5 × 10⁻⁶. 17 cm -3 The thickness is 1.25 μm. The detector of this invention is fabricated using CVD epitaxial growth technology on SiC material, achieving a detector area of ​​1 cm². 2 This technology enables the fabrication of large-area, high-quality, low-defect, and uniformly doped SiC detectors, further improving detection efficiency and production yield. Specifically, controlling the low defect density through CVD epitaxial growth technology reduces the detector's dark current, improving initial material properties, enhancing radiation resistance and temperature stability, extending service life, and lowering dark current levels to meet the requirements of radiation detectors.

[0037] To facilitate operation during use, this embodiment encapsulates the detector body using an external packaging component. This component primarily serves to bring out the detector electrodes for easy application of bias voltage and measurement of current. For example... Figure 1 As shown, the peripheral packaging assembly includes a substrate 12, a cathode terminal 11, an anode terminal 10, a cathode pad 13, an anode pad 14, a gold wire bonding jumper 9, and conductive silver paste 8 disposed on the upper surface of the cathode pad 13. The upper surface of the conductive silver paste 8 is connected to the lower surface of the cathode electrode. The anode pad 14 is disposed to the right of the cathode pad 13 and is spaced apart from the cathode pad 13. The cathode terminal 11 and the anode terminal 10 are disposed on the substrate 12 through the cathode pad 13 and the anode pad 14, respectively. The anode electrode 1 is connected to the anode pad 14 through the gold wire bonding jumper 9, which can be used to set the bias voltage during operation. The substrate 12 is made of ceramic material or a material that does not easily generate secondary particles under irradiation. The ceramic substrate provides structural support for the detector packaging.

[0038] The detector of the present application can change the dark current, response current and switching characteristics of the detector by adjusting the size of the bias voltage within a certain range. In the normal working state of the detector, the higher the bias voltage, the higher the charge collection efficiency, and the signal gain multiple increases; when a certain bias voltage is reached, the non-depleted N1 region gradually narrows, resulting in further increase in signal gain multiple; finally, when the bias voltage is large enough, the device enters a positive feedback state, realizing high gain characteristics. As shown in Figure 3 and Figure 4 As shown, at different light carrier rates (number of electrons and holes generated per unit time per unit volume), with the bias voltage from 720 V to 3600 V, the current and gain only increase slowly, almost unchanged. With different thickness, doping concentration and other parameters, the detector can have different dark current and signal gain multiple. When used, the detector with appropriate detection linear range needs to be selected according to the characteristics of the detection signal, and the bias voltage needs to be adjusted appropriately to ensure higher measurement accuracy and wider measurement dynamic range in the normal working state. In addition, the detector can be used independently or in multiple detection arrays to realize simultaneous measurement of multiple detectors and wide range coverage.

[0039] When using the detector of the present application, the change of radiation information can be observed by observing the voltage across the load resistor with an oscilloscope, or by connecting a digital ammeter between the anode and the ground to observe and record, or by using the backflow current function of some source meter to observe the current signal.

[0040] The detector provided by the present application can achieve better detection sensitivity, higher detection upper limit and wider linear measurement range than the same size silicon P-i-N type detector at room temperature or higher temperature. At the same time, the electron-hole pairs generated by the detector can be multiplied inside the detector, realizing the detection of weak signals that cannot be detected originally; the gain multiple is relatively constant when the bias voltage is unchanged, that is, the input and output show a linear relationship. As shown in Figure 5 When the bias voltage is at 1000 V, 2000 V and 3000 V, the gain almost linearly increases with the increase of the light carrier rate, which is conducive to the accurate quantification of the energy and number of detected particles; compared with the traditional silicon material detector, it has better radiation resistance, longer service life and better thermal stability, and is not limited to constant temperature environment, but can work at room temperature or even higher temperature.

[0041] It should be pointed out finally that the above embodiments are only used for illustrating the technical solutions of the present application but not for limiting the protection scope thereof, and although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be changed, modified or replaced equivalently by those skilled in the art after reading the present application, but these changes, modifications or equivalent replacements are all within the protection scope of the claims of the present application to be approved.

Claims

1. A SiC-based PNPN vertical-structure semiconductor nuclear radiation detector, characterized by, The SiC-based PNPN vertical structure semiconductor nuclear radiation detector comprises a substrate (6), a cathode electrode (7) formed on a lower surface of the substrate (6), and a P3 region (5), a P2 region (4), an N1 region (3), a P1 region (2) and an anode electrode (1) on the P1 region (2) sequentially formed from bottom to top on an upper surface of the substrate (6); The P1 region (2) is P-type heavily doped, and the doping concentration of the P1 region (2) is (1.0±0.1)×10 19 cm -3 -3, and the thickness is (1.00±0.2) μm; The N1 region (3) is N-type general doping, and the doping concentration of the N1 region (3) is (8.0±0.1)×10 17 cm -3 , and the thickness is (3.0±0.1) μm; The P2 region (4) is P type lightly doped, and the doping concentration of the P2 region (4) is (8.0±0.1)×10 14 cm -3 , and the thickness is 30 μm ~ 100 μm; The P3 region (5) is P-type generally doped, and the doping concentration of the P3 region (5) is (2.5±0.1)×10 17 cm -3 , and the thickness is (1.25±0.01) μm; The substrate (6) is N-type heavily doped, and the substrate (6) is an N-type on-axis SiC substrate or a high-resistance off-axis SiC substrate with a doping concentration of 2 x 10 19 cm -3 5.00 μm in thickness; The anode electrode (1) and the cathode electrode (7) are both ohmic contact materials; A bias voltage is applied between the anode electrode (1) and the cathode electrode (7), and the bias voltage is 720 V ~ 3600 V; The N-type doping element is nitrogen, and the P-type doping element is aluminum.

2. The SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 1, wherein The doping concentration of the P1 region (2) is 1.0 x 1018 cm-3 19 cm -3 , and the thickness is 1.00 μm; The doping concentration of the N1 region (3) is 8.0 x 1018 cm-3 17 cm -3 , and the thickness is 3.0 μm; The doping concentration of the P2 region (4) is 8.0 x 1018cm-3 14 cm -3 , thickness 30 μm; The doping concentration of the P3 region (5) is 2.5 x 1018cm-3 17 cm -3 , with a thickness of 1.25 μm.

3. A SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 1, characterized in that, The bias voltage between the anode electrode (1) and the cathode electrode (7) is 1500 V; The area of the N1 region (3) is > 1 mm 2 , < 4 cm 2 ; The area of the P2 zone (4) is > 1 mm 2 , < 4 cm 2 ; The area of the P3 zone (5) is ≥ 1 mm 2 , ≤ 4 cm 2 .

4. A SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 1, characterized in that, The anode electrode (1) and the P1 region (2) have equal diameters, the P1 region (2) is located in the middle of the N1 region (3), and the diameter of the P1 region (2) is smaller than the diameter of the N1 region (3); The N1 region (3), the P2 region (4) and the P3 region (5) have equal diameters, the P3 region (5) is located in the middle of the substrate (6), and the diameter of the P3 region (5) is smaller than the diameter of the substrate (6); The substrate (6) and the cathode electrode (7) have equal diameters.

5. A SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 1, characterized in that, The anode electrode (1), the P1 region (2), the N1 region (3), the P2 region (4), the P3 region (5) and the cathode electrode (7) are all prepared on the surface of the substrate (6) by a SiC material CVD epitaxial growth technology.

6. A SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 1, characterized in that, Further comprising a peripheral packaging assembly; The peripheral packaging assembly comprises a base (12), a cathode terminal post (11), an anode terminal post (10), a gold wire bonding jumper (9), a cathode pad (13) and an anode pad (14) respectively arranged on the upper surface of the base (12), and a conductive silver paste (8) arranged on the upper surface of the cathode pad (13); The upper surface of the conductive silver paste (8) is connected with the lower surface of the cathode electrode (7); The anode pad (14) is arranged on one side of the cathode pad (13) and has a gap with the cathode pad (13); The cathode terminal post (11) and the anode terminal post (10) are arranged on the base (12) through the cathode pad (13) and the anode pad (14) respectively; The anode electrode (1) is connected with the anode pad (14) through the gold wire bonding jumper (9).

7. A SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 6, characterized in that, The base (12) is a ceramic material or a material that is not easy to generate secondary particles under irradiation.

8. A SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 1, characterized in that, The anode electrode (1) and the cathode electrode (7) are both nickel-gold materials.

9. A SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to claim 1, characterized in that, The P1 region (2) and the N1 region (3) form a first PN junction, the N1 region (3) and the P2 region (4) form a second PN junction, and the P3 region (5) and the substrate (6) form a third PN junction; The first PN junction forms a thin depletion region under the action of a forward bias, the second PN junction forms a thick depletion region under the action of a reverse bias, the thick depletion region contains part of the N1 region (2), all of the P2 region (4) and part of the P3 region (5), and the third PN junction forms a thin depletion region under the action of a forward bias.

10. A radiation detection method using a SiC-based PNPN vertical structure semiconductor nuclear radiation detector according to any one of claims 1 to 9, characterized by, The method comprises the following steps: Step one, when the whole device is irradiated by nuclear radiation, the incident particles generate carriers in P2 region (4); Step two, the carriers drift under the action of the external electric field, forming a current; Step three, the electrons accumulate in N1 region (2), and the holes accumulate in P2 region (4) and P3 region (5), leading to more carrier injection, forming a positive feedback mechanism, achieving current signal amplification, and completing radiation detection.

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