A laminated slow neutron detector based on metal-insulator-semiconductor structure and its preparation method

Abstract

The present invention discloses a laminated slow neutron detector based on a metal-insulator-semiconductor structure and a preparation method thereof. The laminated slow neutron detector is composed of a plurality of basic detection units superimposed in series or in parallel. The basic detection unit comprises an isolation layer, a gate electrode metal layer, a neutron conversion material insulating layer, a semiconductor layer, a substrate and an ohmic contact metal layer, and the neutron conversion material film grown on the semiconductor layer is an insulating layer, which constitutes a metal electrode-neutron conversion material film-semiconductor-metal electrode structure. The present invention adds a neutron conversion material film insulating layer on the basis of a traditional metal-semiconductor Schottky structure detector, realizes a response to slow neutrons, improves the compactness of the device, and can reduce the device dark current by 1 to 2 orders of magnitude compared to a traditional Schottky structure detector, thereby improving the signal-to-noise ratio and the energy resolution of characteristic peaks.

Description

Technical Field

[0001] The present invention relates to the field of radiation detection, and in particular to a laminated slow neutron detector based on a metal-insulator-semiconductor structure and a preparation method thereof. Background Art

[0002] In the past few decades, the demand for neutron detection equipment has continued to grow due to the continuous expansion of neutron detection applications in nuclear medicine and clinical diagnosis, nuclear power plant safety detection systems, environmental detection systems, nuclear explosion and hidden nuclear material detection, space physics, aerospace and industrial applications. 3 He gas detector, due to 3 The shortage of He gas caused 3 The price of He gas detectors has soared, and countries are looking for alternative neutron detectors. Semiconductor-based detectors have become an alternative due to their higher detection efficiency per unit volume, high energy resolution, and good n-γ discrimination capabilities. 3 He gas detector is an excellent choice. In recent years, many countries have actively carried out semiconductor neutron detection and application research to replace 3 He gas detector and achieved great results.

[0003] The Schottky structure has become the most commonly used semiconductor device structure for neutron detection devices due to its advantages such as simple preparation and thin dead layer. For example, the Lawrence Livermore National Laboratory in the United States proposed 10 B-coated Si Schottky semiconductor detector replacement 3 He gas detector solution (Nuclear Instruments and Methods in Physics Research, Section A. Accelerators, Spectrometers, Detectors and Associated Equipment, 2018, 877: 355-358.). Cree, an American company, has developed a high-resolution SiC Schottky semiconductor device based on 4H-SiC crystal, and used the device to make a SiC neutron detector, which was used in the TRIGA stack and NIST stack in the United States. The leakage current is about 4.4×10 -9 A / cm 2 (Nuclear Science Symposium Conference Record, 2005 IEEE Vol. 53, pp. 1713-1718). Jefferson College in the United States has developed a SiC Schottky semiconductor device, which is used in the American TRIGA stack. Its leakage current is about 1.1×10 -9A / cm 2 (Materials, 2021, 14.17:5105.). At the same time, related work has also been carried out in China. The China Academy of Engineering Physics has prepared SiC Schottky semiconductor devices for use in CFBR II stacks. The leakage current is about 2.28×10 -8 A / cm 2 (Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2015, 771: 17-20.); Xi'an Jiaotong University prepared Ni / 4H-SiC Schottky semiconductor devices, which were applied to the Xi'an pulse reactor. The leakage current was about 1.3×10 -8 A / cm 2 (Diamond and Related Materials, 2018, 88: 256-261.). It can be seen that the Schottky structure has a large reverse leakage current. Since the detection signal is directly superimposed on the reverse leakage current, the reverse leakage current directly affects the noise signal size and the energy resolution of the characteristic peak. Therefore, the smaller the reverse leakage current of the detector, the better. In addition, the metal semiconductor contact lattice mismatch of the Schottky structure will lead to the Fermi level pinning effect, which seriously affects the performance of the detection device (Journal of Applied Physics, 1965, 36.10: 3212-3220.; Applied surface science, 2011, 257.23: 10172-10176.).

[0004] By inserting an insulating dielectric layer between the metal and the semiconductor to form an MIS structure, the leakage current of the device can be effectively reduced; by changing the thickness of the insulating dielectric layer to modulate the Schottky barrier height, the Fermi level pinning effect can be suppressed to obtain better detector performance. For example, in 2021, the Changchun Institute of Optics, Fine Mechanics and Physics prepared MIS structure detection devices of Ni / SiO2 / 4H-SiC with different thicknesses of SiO2. The results showed that when there was no SiO2 insulating layer, the leakage current was about 4.5×10-6A / cm2 under a bias of -100V, while the introduction of 100nm SiO2 reduced the leakage current to about 8.4×10-8A / cm2 under a bias of -100V, reducing the leakage current by about two orders of magnitude. For 5.48MeV alpha particles, an energy resolution of 0.55% was achieved under a bias of -40V (Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2021, 997:165166.). From 2021 to 2022, the University of South Carolina in the United States also successively confirmed the excellent characteristics of Ni / SiO2 / 4H-SiC structure MIS devices. The introduction of 100nm SiO2 has a leakage current of about 6.3×10-10A / cm2 at a bias of -200V, and an energy resolution of better than 0.5% is achieved for 5.48MeV alpha particles at a bias of -40V (Journal of Applied Physics, 2021, 130.7:074501.; Journal of Crystal Growth, 2022, 584:126566.). It can be seen that the MIS structure can reduce the reverse leakage current by about 1 to 2 orders of magnitude compared to the Schottky structure, which greatly improves the signal-to-noise ratio of the device and the energy resolution of the characteristic peak, allowing the detector to achieve more sophisticated detection tasks, such as neutron spectrum determination.

[0005] To apply MIS structure devices to the field of thermal neutron detection, it is necessary to add a layer of neutron conversion materials containing neutron sensitive elements such as 157Gd2O3, 6LiF, 10B, 10BC, 10BN, etc. to the outermost layer. The addition of the insulating layer further increases the thickness of the dead layer of the detector, reducing the energy resolution of the characteristic peak. Most neutron conversion materials are insulating materials. Therefore, this paper proposes to use neutron conversion materials as the insulating layer of the MIS structure, which can reduce the leakage current of the detector and improve the energy resolution of the device for the characteristic peak. At the same time, the neutron conversion material is used as an insulating layer to improve the compactness of the device, which will further expand the application of neutron detection. Summary of the invention

[0006] To solve the above technical problems, the present invention provides a laminated slow neutron detector based on a metal-insulator-semiconductor (MIS) structure and a method for preparing the same, which is a new type of laminated slow neutron detector based on a MIS structure with extremely low dark current and compact structure and a method for preparing the same.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A stacked slow neutron detector based on a metal-insulator-semiconductor structure is composed of a plurality of basic detection units stacked in series or in parallel; the basic detection unit comprises an isolation layer, a gate electrode metal layer, a neutron conversion material insulation layer, a semiconductor layer, a substrate and an ohmic contact metal layer arranged in sequence from top to bottom; the isolation layer is used for insulating and isolating the basic detection units; the gate electrode metal layer is used for connecting with the neutron conversion material insulation layer; the neutron conversion material insulation layer acts as an insulating layer structure in the metal-insulator-semiconductor structure, and the layer contains nuclides with a large slow neutron reaction cross section, which can convert slow neutrons into charged particles; the semiconductor layer is used for energy deposition and charge collection of charged particles; the substrate is used for growing the semiconductor layer; and the ohmic contact metal layer is used for forming an ohmic contact with the substrate.

[0009] As one of the preferred embodiments of the present invention, the isolation layer material is SiO2, or Si3N4, or Al2O3, or BN, or polyimide.

[0010] As one of the preferred embodiments of the present invention, the gate electrode metal layer material is W, or Ni, or Pt, or TiN, or Ni / Au alloy, or Pt / Au alloy.

[0011] As one of the preferred embodiments of the present invention, the neutron conversion material insulating layer material is Gd2O3, or HfO2, or 6 LiF, or 10 B4C, or 10 BN, or a mixed material layer of one or more of the above materials.

[0012] As one of the preferred embodiments of the present invention, the semiconductor layer material is CdTe, or CdZnTe, or Si, or Ge, or GaAs, or SiC, or GaN, or diamond.

[0013] As one of the preferred embodiments of the present invention, the substrate material is Si, or SiC, or sapphire, or diamond, or GaN.

[0014] As one of the preferred embodiments of the present invention, the ohmic contact metal layer material is Ni / Au alloy, or Pt / Au alloy, or graphene, or a single-layer metal or a multi-layer mixed metal that can form an ohmic contact.

[0015] The present invention also provides a method for preparing a laminated slow neutron detector based on a metal-insulator-semiconductor structure, which specifically comprises the following steps:

[0016] 1) growing a semiconductor layer and a neutron conversion material insulating layer in sequence on the substrate by using a growth method of metal organic chemical vapor deposition, molecular beam epitaxy or hydride vapor phase epitaxy;

[0017] 2) depositing an ohmic contact metal layer under the substrate by evaporation or sputtering, and forming a stable ohmic contact by annealing;

[0018] 3) depositing a gate electrode metal layer and an isolation layer in sequence on the substrate by evaporation or sputtering;

[0019] 4) Multiple basic detection units obtained from step 1) to step 3) are stacked in series or in parallel to form a laminated slow neutron detector.

[0020] As one of the preferred embodiments of the present invention, the ohmic contact metal layer in step 2) is grounded.

[0021] As one of the preferred embodiments of the present invention, the gate electrode metal layer in step 3) is in a square, circular or interdigitated shape; the gate electrode metal layer is connected to an external circuit for extracting the detection signal.

[0022] The advantages of the present invention compared to the prior art are:

[0023] (1) The MIS structure of the present invention is to add an insulating layer between the gate metal and the semiconductor. Compared with traditional devices, this structure can effectively reduce the leakage current of the device to improve the signal-to-noise ratio, and suppress the Fermi level pinning effect. The height of the Schottky barrier can be adjusted by the thickness of the insulating layer to improve the performance of the detection device;

[0024] (2) The present invention utilizes neutron conversion materials as the insulating layer of the MIS structure to achieve response to thermal neutrons, thereby effectively improving the compactness of the device.

[0025] (3) The present invention can realize efficient detection of slow neutrons through the design of the laminated structure, and can achieve 50% intrinsic detection efficiency of thermal neutrons, providing a new design scheme for slow neutron detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is an overall schematic diagram of the laminated slow neutron detector based on the metal-insulator-semiconductor structure of the present invention.

[0027] Attached Figure 1 Marking description: 1-isolation layer, 2-gate electrode metal layer, 3-neutron conversion material insulating layer, 4-semiconductor layer, 5-substrate, 6-ohmic contact metal layer, A-basic detection unit, B-laminated structure slow neutron detector. DETAILED DESCRIPTION

[0028] The following will be combined with the attached Figure 1 The present invention is further described in detail with reference to the embodiments. Obviously, the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all the contents. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, the laminated slow neutron detector based on the metal-insulator-semiconductor structure of the present invention is composed of a plurality of basic detection units A stacked in series or in parallel; the basic detection unit A includes an isolation layer 1, a gate electrode metal layer 2, a neutron conversion material insulation layer 3, a semiconductor layer 4, a substrate 5 and an ohmic contact metal layer 6. The isolation layer 1, the gate electrode metal layer 2, the neutron conversion material insulation layer 3, the semiconductor layer 4, the substrate 5 and the ohmic contact metal layer 6 are arranged in sequence from top to bottom. The gate electrode metal layer 2, the neutron conversion material insulation layer 3 and the semiconductor layer 4 constitute a metal-insulator-semiconductor structure, i.e., a MIS structure.

[0030] The isolation layer 1 is used for insulating isolation between basic detection units A; the gate electrode metal layer 2 is used to connect with the neutron conversion material insulating layer 3; the neutron conversion material insulating layer 3 acts as an insulating layer structure in the MIS structure, which contains nuclides with a large slow neutron reaction cross-section and can convert slow neutrons into charged particles; the semiconductor layer 4 plays the role of energy deposition and charge collection for charged particles; the substrate 5 is used to grow the semiconductor layer 4; the ohmic contact metal layer 6 is used to form an ohmic contact with the substrate 5.

[0031] As one of the preferred embodiments of the present invention, the material of the isolation layer 1 is SiO2, or Si3N4, or Al2O3, or BN, or polyimide.

[0032] As one of the preferred embodiments of the present invention, the material of the gate electrode metal layer 2 is W, or Ni, or Pt, or TiN, or Ni / Au alloy, or Pt / Au alloy.

[0033] As one of the preferred embodiments of the present invention, the neutron conversion material insulating layer 3 is made of Gd2O3, or HfO2, or 6 LiF, or 10 B4C, or 10 BN, or a mixed material layer of one or more of the above materials.

[0034] As one of the preferred embodiments of the present invention, the material of the semiconductor layer 4 is CdTe, or CdZnTe, or Si, or Ge, or GaAs, or SiC, or GaN, or diamond.

[0035] As one of the preferred embodiments of the present invention, the material of the substrate 5 is Si, or SiC, or sapphire, or diamond, or GaN.

[0036] As one of the preferred embodiments of the present invention, the material of the ohmic contact metal layer 6 is Ni / Au alloy, or Pt / Au alloy, or graphene, or a single-layer metal or a multi-layer mixed metal that can form an ohmic contact.

[0037] The present invention also provides a method for preparing a laminated slow neutron detector based on a metal-insulator-semiconductor structure, which specifically comprises the following steps:

[0038] 1) growing a semiconductor layer 4 and a neutron conversion material insulating layer 3 in sequence on the substrate 5 by metal organic chemical vapor deposition, molecular beam epitaxy or hydride vapor phase epitaxy;

[0039] 2) depositing an ohmic contact metal layer 6 under the substrate 5 by evaporation or sputtering, and forming a stable ohmic contact by an annealing process;

[0040] 3) depositing a gate electrode metal layer 2 and an isolation layer 1 in sequence on the substrate 5 by evaporation or sputtering;

[0041] 4) Multiple basic detection units A obtained from steps 1-3) are stacked in series or in parallel to form a laminated slow neutron detector B.

[0042] As one of the preferred embodiments of the present invention, the ohmic contact metal layer 6 in the step 2) is grounded.

[0043] As one of the preferred embodiments of the present invention, the gate electrode metal layer 2 in step 3) is in a square, circular or interdigital shape. The gate electrode metal layer 2 is connected to an external circuit for extracting detection signals.

[0044] The present invention is described in detail below with reference to specific embodiments.

[0045] Example 1

[0046] like Figure 1 As shown, the material of the semiconductor layer 4 of the embodiment of the present invention is a P-type CdTe film prepared by Sichuan University using a close-space sublimation method, with a thickness of 4.0 mm and a doping concentration of 1.0×10 18 cm -3 , area 2.0×2.0cm 2 , using the PLD vacuum coating equipment produced by Beijing Tianheng Chengyue Technology Co., Ltd. to grow a uniform and dense layer on the P-type CdTe 157 Gd2O3 (relative dielectric constant of 16, bandgap of 5.3eV) film, with a thickness of about 0.1μm, is used as the insulating layer of the device to reduce the leakage current of the device. After the neutron conversion material insulating layer is prepared, the sample is placed in the chamber of the SRT-300 resistance thermal evaporation coating instrument produced by Xinlei Vacuum Technology Co., Ltd., and a high-purity Au target and Ni target with a purity of 4N are used to prepare the ohmic contact metal layer on the back of the P-type CdTe semiconductor layer. The prepared Ni layer thickness is about 60nm and the Au layer thickness is about 100nm. After the ohmic contact metal layer is prepared, the sample is first soaked in acetone and alcohol solution to remove possible surface contamination. Then, after being blown dry with nitrogen, it is placed in the fast heating tube furnace OTF-1200X-4-RTP produced by Hefei Kejing Materials Co., Ltd., and the temperature is raised to 600℃ in a N2 environment, kept warm for 3min, then quickly cooled to room temperature, and the sample is taken out to form a stable ohmic contact. The sample was placed in the chamber of the SRT-300 resistance thermal evaporation coating instrument, and a high-purity Al target and an Al2O3 target with a purity of 4N were used to grow an Al metal film with a thickness of about 100nm and an Al2O3 metal film with a thickness of about 1μm on the Gd2O3 film. The K950 fully automatic optical module wire bonding machine produced by Shenzhen Kaijiu Automation Equipment Co., Ltd. was used to bond wires on the ohmic contact metal layer and the gate electrode metal layer respectively. Based on the above steps, the basic detection unit A described in the present invention can be obtained. 157 The cross section of the reaction between Gd nuclide and thermal neutrons is about 2.5×10 5 b. The reaction generates 7.94 MeV gamma photons, whose energy deposited in P-type CdTe is about 550 keV. The generated gamma light cannot be fully deposited in P-type CdTe. In addition, an additional gamma light shielding structure needs to be designed around the detector to reduce the gamma light background count in the radiation field. The detector can be used for counting scenarios such as pulse neutron intensity diagnosis.

[0047] In the specific implementation, the performance verification results show that in Example 1, a single basic detection unit has a working bias of Vg = -100V at room temperature, a depletion layer width of about 5μm, and can achieve an intrinsic detection efficiency of about 6% for thermal neutrons. Five basic detection units are connected in series to form a stacked slow neutron detector. For the DD quasi-monoenergetic 2.5MeV neutron tube developed by the Hefei Institutes of Physical Science, Chinese Academy of Sciences, the source strength is about 2.0×10 8 n / s, the detector is placed 0.5m away from the neutron tube target, and 5.0cm of polyethylene is placed in the middle for moderation, which can achieve about 4.3×10 3 s -1 The counting rate.

[0048] Example 2

[0049] like Figure 1 As shown, the substrate of the embodiment of the present invention adopts an N-type SiC substrate (resistivity of 0.015Ω·cm) with a thickness of 350μm and a diameter of 4 inches provided by Cree, USA. First, the N-type SiC substrate is cleaned according to the standard RCA process to remove the organic matter, metal and SiO2 oxide layer on the substrate. Then, an N-type SiC semiconductor with a thickness of 10μm and a doping concentration of 1.0×10 13 cm -3 , area 1.5×1.5cm 2 The sample was placed in the CPC-G plasma cleaning equipment produced by Huayixing (Beijing) Technology Co., Ltd. to clean the front of the N-type SiC semiconductor with hydrogen plasma to reduce the surface state density. The sample was placed in the metal organic compound vapor deposition method MOCVD device produced by AIXTRON in Germany to grow a layer of h- 10 The BN (relative dielectric constant of 5, bandgap of 6.5 eV) film, with a thickness of 0.1 μm, is used as an insulating layer of the device to reduce the leakage current of the device. 10 The cross section of the reaction between nuclide B and thermal neutrons is about 3.8×10 3 b, will generate 7The range of both Li and α charged particles in SiC does not exceed 5μm, and the 10μm SiC semiconductor layer can completely deposit the energy of the secondary charged particles. The sample was placed in the electron beam evaporation coating system produced by Lesker. Using electron beam evaporation technology, an Al / Ti / Au target with a purity of 5N was used to sequentially prepare Ti / Al / Ti / Au metal films on the back of the SiC semiconductor layer. The thickness of each metal layer was 30nm. After the ohmic contact metal layer was prepared, the samples were first soaked in acetone and alcohol solutions to remove possible surface contamination. Then, after being blown dry with nitrogen, they were placed in the fast heating tube furnace OTF-1200X-4-RTP produced by Hefei Kejing Materials Co., Ltd., heated to 500°C in a N2 environment, kept warm for 5 minutes, then quickly cooled to room temperature, and the sample was taken out to form a stable ohmic contact. The substrate etching method was used to etch the h- 10 Transfer 3-5 layers of graphene with BN film. Use spin coating to coat the prepared polyamic acid solution on the graphene, and heat it in sections in a muffle furnace to complete imidization. The heating process is as follows: from room temperature to 50°C, keep warm for 30 minutes, keep warm for 30 minutes for each increase of 50°C, and finally keep warm for 1 hour under 300°C vacuum conditions. Use the K950 fully automatic optical module wire bonding machine produced by Shenzhen Kaijiu Automation Equipment Co., Ltd. to bond wires to the ohmic contact metal layer and the gate electrode metal layer respectively. Based on the above steps, the basic detection unit A described in the present invention can be obtained.

[0050] In the specific implementation, the performance verification results show that in Example 2, under the working bias of Vg = -50V at room temperature, the depletion layer width of a single basic detection unit is about 6μm, and the device can achieve an intrinsic neutron detection efficiency of about 0.5%, and achieve an energy resolution of less than 0.5% for the generated 1.47MeV alpha particles. The leakage current is about 1×10 -10 A / cm 2 The leakage current of Schottky structure neutron detection devices is reduced by 1 to 2 orders of magnitude. 137 Csγ radiation source, when the system energy threshold is set to 300keV, the n / γ resolution can exceed 1000. The detector can be used for neutron spectrum measurement, neutron imaging, pulse neutron intensity diagnosis, etc. Six basic detection units are stacked up and down and connected in parallel to form a stacked slow neutron detector, and six basic detection units are connected in series to form a stacked slow neutron detector. For the single-energy 14.1MeV high-current fusion DT neutron generator developed by the Hefei Institutes of Physical Science, Chinese Academy of Sciences, the source intensity can reach 10 12 n / s level, the detector is placed 1m away from the neutron source target, and 10.0cm of polyethylene is placed in the middle for moderation, which can achieve about 1.0×10 4 s -1 The counting rate.

[0051] It should also be noted that the present invention can provide demonstrations of parameters including specific values, but these parameters do not need to be exactly equal to the corresponding values, but can be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint. The directional terms mentioned in the embodiments, such as "up", "down", "left", "right", etc., are only reference directions of the accompanying drawings and are not intended to limit the scope of protection of the present invention. In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to those listed above, and can be changed or rearranged according to the desired design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laminated slow neutron detector based on a metal-insulator-semiconductor structure, characterized in that: The stacked structure slow neutron detector (B) is composed of a plurality of basic detection units (A) stacked in series or in parallel; the basic detection unit (A) comprises an isolation layer (1), a gate electrode metal layer (2), a neutron conversion material insulating layer (3), a semiconductor layer (4), a substrate (5) and an ohmic contact metal layer (6) arranged in sequence from top to bottom; The isolation layer (1) is used for insulating isolation between basic detection units (A); the gate electrode metal layer (2) is used for connecting with the neutron conversion material insulating layer (3); the neutron conversion material insulating layer (3) acts as an insulating layer structure in a metal-insulation-semiconductor structure, and the layer contains nuclides with a large slow neutron reaction cross section, which converts slow neutrons into charged particles; the semiconductor layer (4) is used for energy deposition and charge collection of charged particles; the substrate (5) is used for growing the semiconductor layer (4); and the ohmic contact metal layer (6) is used for forming an ohmic contact with the substrate (5).

2. The laminated slow neutron detector based on a metal-insulator-semiconductor structure according to claim 1, characterized in that: The material of the isolation layer (1) is SiO2 or Si3N4 or Al2O3 or BN or polyimide.

3. The laminated slow neutron detector based on a metal-insulator-semiconductor structure according to claim 1, characterized in that: The material of the gate electrode metal layer (2) is W or Ni or P or TiN or Ni / Au alloy or Pt / Au alloy.

4. The laminated slow neutron detector based on a metal-insulator-semiconductor structure according to claim 1, characterized in that: The material of the neutron conversion material insulating layer (3) is Gd2O3 or HfO2 or 6 LiF or 10 B4C or 10 BN or a mixed material layer of one or more of the above materials; the thickness of the neutron conversion material insulating layer (3) is 0.1 μm to 2 μm.

5. The laminated slow neutron detector based on a metal-insulator-semiconductor structure according to claim 1, characterized in that: The material of the semiconductor layer (4) is CdTe or CdZnTe or Si or Ge or GaAs or SiC or GaN or diamond.

6. The laminated slow neutron detector based on a metal-insulator-semiconductor structure according to claim 1, characterized in that: The substrate (5) is Si or SiC or sapphire or diamond or GaN.

7. The laminated slow neutron detector based on a metal-insulator-semiconductor structure according to claim 1, characterized in that: The material of the ohmic contact metal layer (6) is Ni / Au alloy or Pt / Au alloy or graphene or a single-layer metal or a multi-layer mixed metal that forms an ohmic contact.

8. A method for preparing a laminated slow neutron detector based on a metal-insulator-semiconductor structure according to any one of claims 1 to 7, characterized in that: The steps include: 1) growing a semiconductor layer (4) and a neutron conversion material insulating layer (3) in sequence on a substrate (5) by using a growth method of metal organic chemical vapor deposition, molecular beam epitaxy or hydride vapor phase epitaxy; 2) depositing an ohmic contact metal layer (6) below the substrate (5) by evaporation or sputtering, and forming a stable ohmic contact by an annealing process; 3) depositing a gate electrode metal layer (2) and an isolation layer (1) in sequence on the substrate (5) by evaporation or sputtering; 4) Multiple basic detection units (A) obtained from step 1) to step 3) are stacked in series or in parallel to form a laminated slow neutron detector (B).

9. The preparation method according to claim 8, characterized in that: The ohmic contact metal layer (6) in the step 2) is grounded.

10. The preparation method according to claim 8, characterized in that: The gate electrode metal layer (2) in the step 3) has a shape of square, round or interdigitated; the gate electrode metal layer (2) is connected to an external circuit for extracting detection signals.

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