Simulation Method of Silicon Carbide Fast Neutron Detector Based on Geant4 and TCAD Software

Abstract

The present invention discloses a simulation method for a silicon carbide fast neutron detector based on Geant4 and TCAD software, and the steps are as follows: 1. Use Geant4 software for simulation, and determine the optimal thickness of the conversion layer according to the monoenergetic neutron conversion efficiency; 2. Under the condition of the optimal conversion layer thickness, simulate and obtain the energy and angle information of protons generated by the mixed-energy neutron source passing through the conversion layer and entering the detector; 3. Sample according to the calculated proton energy and angle information; 4. Use SRIM software to obtain the range and linear energy transfer of protons in the silicon carbide material; 5. In TCAD software, model and optimize the semiconductor device to obtain the basic electrical characteristics; 6. According to the sampling results and the optimized detector structure, perform simulation in TCAD software to obtain data such as particle pulse current and charge collection, realizing the optimization of the fast neutron detector and the coupled simulation of Gean4 and TCAD.

Description

Technical Field

[0001] The present invention belongs to the technical field of numerical simulation of neutron detection, and particularly relates to a simulation method for a silicon carbide fast neutron detector based on Geant4 and TCAD software. Background Art

[0002] As a third-generation semiconductor material, silicon carbide has excellent properties such as a wide bandgap, a high critical breakdown electric field, and radiation resistance. Its preparation process is relatively mature, and it is considered to be one of the most potential nuclear detector materials.

[0003] With the development of silicon carbide materials, the research and application of neutron detection have gradually been carried out. There are still certain gaps in how to systematically simulate and optimize neutron detectors. For the simulation of neutron detectors, it includes obtaining the energy and angle of secondary particles generated by neutrons, optimizing the structure of neutron detectors, and simulating pulse currents. General simulations only target some parts. How to combine various parts of the simulation and conduct systematic simulation requires the development of a systematic simulation method for silicon carbide neutron detectors. Summary of the Invention

[0004] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a simulation method for a silicon carbide fast neutron detector based on Geant4 and TCAD software. This method innovatively proposes to combine the simulations of Geant4 software and Sentauraus TCAD software, which can not only simulate and obtain the current pulse generated by particles but also optimize the structure of the silicon carbide fast neutron detector, realizing the systematic simulation of the silicon carbide neutron detector and providing a simulation basis for subsequent circuit-level simulation.

[0005] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0006] A simulation method for a silicon carbide fast neutron detector based on Geant4 and TCAD software couples Geant4 software and TCAD software to obtain the energy and angle information of recoil protons and the pulses generated by protons in the silicon carbide fast neutron detector, realizing the systematic simulation of the silicon carbide fast neutron detector and providing a simulation basis for subsequent circuit-level simulation;

[0007] This method includes the following steps:

[0008] Step 1: Construct a fast neutron detector model in Geant4, simulate monoenergetic neutrons with different energies incident on conversion layers with different thicknesses, and determine the optimal thickness of the conversion layer according to the conversion efficiency of monoenergetic neutrons with different energies;

[0009] Step 2: Under the condition of the optimal thickness of the conversion layer, use Geant4 to simulate the incidence of the mixed-energy neutron source. In the SteppingAction data statistics module provided by Geant4, according to the geometry judgment function, obtain the energy and angle information of the recoil protons when they enter the detector.

[0010] Step 3: Use matlab software to organize the energy and angle information of the recoil protons, draw the energy-angle distribution curve of the recoil protons, and perform proton energy and angle sampling according to the distribution curve.

[0011] Step 4: According to the proton energy obtained by sampling in Step 3, use SRIM software to obtain the range and linear energy transfer of protons with different energies in the silicon carbide material.

[0012] Step 5: Construct different silicon carbide fast neutron detector models in TCAD, perform electrical performance simulation and comparison on different silicon carbide fast neutron detector models, select the optimal silicon carbide fast neutron detector model, and complete the optimization of the silicon carbide fast neutron detector.

[0013] Step 6: Select the optimized model in Step 5, and according to the proton energy and angle obtained by sampling in Step 3, and the range and linear energy transfer obtained in Step 4, simulate and obtain the current pulse generated by the proton entering the detector in TCAD software.

[0014] The simulation method of the silicon carbide fast neutron detector based on Geant4 and TCAD software proposed by the present invention has the following beneficial effects compared with the existing simulation methods:

[0015] 1. The present invention simulates the PIN diode structure fast neutron detector of the silicon carbide material based on Geant4 software and TCAD software, and has systematicness and consistency in simulation compared with the single Geant4 simulation and TCAD simulation.

[0016] 2. The present invention couples Geant4 software and TCAD software, and is more accurate and the optimization design is more complete and reasonable compared with the single TCAD software for optimizing the structure.

[0017] 3. The present invention based on Geant4 software meets the requirement for obtaining the detailed distribution of the energy and angle of the protons generated by the neutrons colliding with the conversion layer by the recoil proton method.

[0018] 4. The present invention based on TCAD software samples and obtains the current pulses generated by the recoil protons with various energy and angles entering the device. Description of the Drawings

[0019] Figure 1 It is a flow chart of the simulation method of the fast neutron detector for Geant4 and TCAD software.

[0020] Figure 2 It is the conversion efficiency diagram of mono-energetic neutrons varying with the thickness of polyethylene.

[0021] Figure 3 It is the energy-angle spectrum of recoil protons.

[0022] Figure 4 It is the result of the 2MeV recoil proton current pulse. Detailed implementation manners

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Figure 1 It is the flowchart of the method for obtaining the energy and angle of recoil protons. The following will be specifically described in combination with cases. The steps are as follows:

[0025] Step 1: Construct a silicon carbide fast neutron detector model in the Geant4 detector structure module, simulate the incidence of mono-energetic neutrons, and determine the thickness of the conversion layer. The detailed steps are as follows:

[0026] Step 1-1: Set up the Geant4 platform and create a management module for initializing the detection structure class, physical process class, loading commands, and visualization management. In this case, the physical process uses the G4HadronPhysicsQGSP_BERT_HP physical model, which is a high-precision model mainly for neutron physical processes;

[0027] Step 1-2: In this case, the silicon carbide fast neutron detector model includes a conversion layer and a semiconductor detector. The polyethylene material is selected for the conversion layer, and the silicon carbide PIN diode is selected for the semiconductor detector. The thickness of the sensitive area is set to 30μm. This case simulates the incidence of 1-14MeV mono-energetic neutrons on a 10-20000μm thick polyethylene conversion layer;

[0028] Step 1-3: Through the geometry judgment function provided by Geant4, determine the number of protons reaching the diode, calculate the conversion efficiency, and the result is as Figure 2 shown. It can be seen from Figure 2 that when the thickness of the conversion layer is 1000μm, the conversion efficiency of neutrons with various energies is relatively high. Therefore, the optimal thickness of the conversion layer is determined to be 1000μm;

[0029] Step 2: Set the thickness of the conversion layer to 1000μm. In this case, simulate the incidence of an Am-Be neutron source. In the SteppingAction data statistics module provided by Geant4, according to the geometry judgment function, obtain the energy and angle information of recoil protons when they enter the silicon carbide fast neutron detector by judging the geometries where the protons are located in the previous step and the next step;

[0030] Step 3: Use Matlab software to organize the energy and angle information of recoil protons. Set the energy interval to 1 MeV and the angle interval to 1°, perform data processing, and plot the energy-angle distribution curve of recoil protons. The result is as Figure 3 shown. According to the Figure 3 distribution probability of proton energy and angle in

[0031] Step 4: Use SRIM software to obtain the range and linear energy transfer of 1-7 MeV protons in silicon carbide materials;

[0032] Step 5: In this case, use the semiconductor process simulation module SPROCESS to establish a silicon carbide fast neutron detector model. The simulated structure of the silicon carbide fast neutron detector is a common PIN diode structure and a PIN diode with a double-junction terminal extension structure. Use the SDEVICE module to simulate and compare the electrical performance of the devices. It is found that the PIN diode with the double-junction terminal extension structure has better performance. Therefore, the PIN diode structure with double-junction terminal extension is adopted;

[0033] Step 6: In this case, the bias voltage is set to -100 V. Adopt the PIN diode structure with double-junction terminal extension selected in Step 5. Set the corresponding range, linear energy transfer, and angle values in TCAD, and simulate recoil protons with different energies and angles to obtain current pulses. Figure 4 The pulse current of 2 MeV, 5-60° recoil protons is shown, which can provide support for subsequent circuit-level simulation.

[0034] The above content further elaborates on the simulation method of a silicon carbide material fast neutron detector based on Geant4 and TCAD software for a specific scheme. The parts not described in detail are common knowledge in the art.

Claims

1. A simulation method for a silicon carbide fast neutron detector based on Geant4 and TCAD software, characterized in that: The Geant4 software and the TCAD software are coupled to obtain recoil proton energy-angle information and the pulses generated by protons in the silicon carbide fast neutron detector, realizing the system simulation of the silicon carbide fast neutron detector and providing a simulation basis for subsequent circuit-level simulation; This method includes the following steps: Step 1: Construct a silicon carbide fast neutron detector model in Geant4, simulate monoenergetic neutrons with different energies incident on conversion layers with different thicknesses, and determine the optimal thickness of the conversion layer according to the conversion efficiency of monoenergetic neutrons with different energies; Step 2: Under the condition of the optimal thickness of the conversion layer, use Geant4 to simulate the incidence of a mixed-energy neutron source to obtain the recoil proton energy and angle information incident on the silicon carbide fast neutron detector; Step 3: Use matlab software to organize the recoil proton energy and angle information, plot the recoil proton energy-angle distribution curve, and perform proton energy and angle sampling; Step 4: According to the proton energy obtained by sampling in Step 3, use SRIM software to obtain the range and linear energy transfer of protons with different energies in the silicon carbide material; Step 5: Construct different silicon carbide fast neutron detector models in TCAD, perform electrical performance simulation and comparison on different silicon carbide fast neutron detector models, select the optimal silicon carbide fast neutron detector model, and complete the optimization of the silicon carbide fast neutron detector; Step 6: Select the optimized model in Step 5, and according to the proton energy and angle obtained by sampling in Step 3, and the range and linear energy transfer obtained in Step 4, simulate and obtain the current pulse generated by proton incidence on the detector in TCAD software.

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