Semiconductor radiation detector electrical property co-simulation method

Abstract

The invention provides a semiconductor radiation detector electrical property co-simulation method. The method comprises the following steps: establishing a device model of a semiconductor radiation detector; aiming at a given incident particle, simulating a transportation process of the incident particle in a semiconductor material by utilizing a first simulation tool so as to obtain ionization energy loss distribution along a transportation path of the incident particle; performing data conversion and structure reconstruction on the ionization energy loss distribution: converting the ionization energy loss distribution from an energy loss rate unit to a generated charge quantity unit within a unit distance based on the average ionization energy of the semiconductor material; discretizing the generated charge quantity which is obtained after conversion and continuously changes along the transport path into a step-shaped data structure composed of a plurality of space segments; taking the stepped data structure as input, and performing single-particle transient analysis on the device model by using a second simulation tool; and obtaining the electrical output characteristics of the semiconductor radiation detector. According to the invention, accurate simulation of the whole process from particle incidence to electric signal output is realized.

Description

Technical Field

[0001] The present invention relates to an electrical characteristic simulation method, in particular to a collaborative simulation method of the electrical characteristics of a semiconductor radiation detector, and belongs to the technical field of semiconductor device simulation. Background Art

[0002] Semiconductor radiation detectors, due to their low operating voltage, fast response, high resolution, and compact structure, play a vital role in key areas such as nuclear power plant monitoring, national defense security, and aerospace engineering. At their core is a semiconductor diode. The detection mechanism is as follows: when radiation particles enter the depletion region of a semiconductor diode, they ionize and generate a large number of electron-hole pairs. These carriers, under the influence of an external bias electric field, drift to electrodes where they are collected, generating a measurable weak current pulse signal.

[0003] During the detector development and design phase, a significant technical challenge arose: the current pulses induced by radiation particles in the detector are typically very small in amplitude and extremely short in duration, making them difficult to accurately observe and characterize experimentally. Consequently, the detector's electrical output characteristics, such as the precise shape, peak amplitude, duration, and total collected charge, remain unclear. This uncertainty significantly hinders the targeted design and optimization of the back-end readout electronics.

[0004] SRIM (The Stopping and Range of Ions in Matter) software is a Monte Carlo-based physics simulation tool that accurately simulates ion transport in materials and calculates their range and energy loss distribution. However, it is limited to physical process simulation and cannot calculate any device electrical properties. TCAD (Technology Computer-Aided Design) semiconductor simulation software is a device-level simulation tool that accurately simulates the electrical properties of semiconductor devices by solving semiconductor physics equations. However, TCAD itself cannot simulate the energy loss process of incident particles in materials. Therefore, since SRIM can only simulate physical processes, while TCAD can only simulate electrical processes, there is a clear technological gap between the two. This makes it impossible to simulate the entire chain from particle injection to electrical signal output, thus failing to provide an accurate reference for the design of back-end readout electronics. Summary of the Invention

[0005] Based on the above background, the purpose of the present invention is to provide a collaborative simulation method for the electrical characteristics of semiconductor radiation detectors. Through a complete solution connecting SRIM physical simulation and TCAD electrical simulation, accurate simulation of the entire process from particle incidence to electrical signal output is achieved.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A method for collaboratively simulating electrical characteristics of a semiconductor radiation detector, the method comprising the following steps: S1. Establishing a device model of the semiconductor radiation detector, wherein the device model includes definitions of the geometric structure, material composition, and electrical parameters of the semiconductor radiation detector, wherein the material composition includes a semiconductor material; S2. For a given incident particle, using a first simulation tool to simulate a transport process of the incident particle in the semiconductor material to obtain an ionization energy loss distribution along the transport path; S3. Performing data conversion and structural reconstruction on the ionization energy loss distribution to generate a charge generation profile suitable for device electrical simulation, wherein the data conversion and structural reconstruction include: S31. Converting the ionization energy loss distribution from an energy loss rate unit to a generated charge unit per unit distance based on an average ionization energy of the semiconductor material; S32, discretizing the continuously changing generated charge along the transport path obtained after the conversion in step S31 into a stepped data structure consisting of a plurality of spatial segments, wherein each spatial segment has a constant generated charge value; S4. Using the ladder-shaped data structure generated in step S32 as input, a second simulation tool is used to perform single-event transient analysis on the device model of the semiconductor radiation detector; S5. Obtaining electrical output characteristics of the semiconductor radiation detector according to the results of the single-particle transient analysis.

[0007] Preferably, the first simulation tool is SRIM ion implantation simulation software, and the second simulation tool is TCAD semiconductor process and device simulation software.

[0008] Preferably, in step S2, the incident particles are secondary charged particles generated by nuclear reactions between neutrons and the neutron conversion layer.

[0009] Preferably, the neutron conversion layer is 6 LiF, the secondary charged particles include α particles and 3 H particles; Step S2 is respectively for the α particles and the 3 H particles for simulation.

[0010] Preferably, in step S31, the unit of the energy loss rate is eV / Angstrom, and the unit of the generated charge per unit distance is pC / μm, and the conversion relationship is determined by the following formula: ; Wherein, q is the elementary charge, and ε is the average ionization energy of the semiconductor material.

[0011] Preferably, in step S32, the lengths of the multiple space segments are set according to the type of the incident particles.

[0012] Preferably, in step S5, the electrical output characteristic includes an instantaneous current pulse response curve and / or a total collected charge amount obtained by integrating the instantaneous current pulse response curve.

[0013] Preferably, the method further comprises, in step S4, setting the operating conditions of the semiconductor radiation detector at different reverse bias voltages to obtain the electrical output characteristics corresponding to the different reverse bias voltages.

[0014] Preferably, the method further includes: determining the minimum operating voltage at which both the total collected charge and the instantaneous current pulse amplitude reach saturation based on the changing relationship between the total collected charge and the instantaneous current pulse amplitude obtained under different reverse bias voltages, as the recommended operating voltage of the semiconductor radiation detector.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention provides a collaborative simulation method for the electrical characteristics of semiconductor radiation detectors, which innovatively proposes and implements a complete technical solution connecting SRIM physical simulation and TCAD electrical simulation, achieving accurate simulation of the entire process from particle incidence to electrical signal output. The method of the present invention can accurately obtain key electrical characteristics of semiconductor radiation detectors, such as the instantaneous current pulse shape, peak value, duration, and total collected charge, providing reliable design input for the design of back-end readout electronics. The method can systematically study the influence of key operating parameters such as reverse bias voltage on detector performance, and can scientifically determine the optimal operating voltage for saturating charge collection efficiency. The method can be applied to the electrical characteristics analysis of various types of semiconductor radiation detectors, and has wide applicability and important industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0017] Figure 1 Schematic diagram of the structure of a planar SiC neutron detector in an embodiment of the present invention; Figure 2The Bragg ionization distribution curves of α particles with an energy of 2.05 MeV incident on SiC material at different angles; Figure 3 The energy is 2.73 MeV 3 Bragg ionization distribution curves after H particles are incident on SiC material at different angles; Figure 4 The Bragg ionization distribution curves of α particles with different energies vertically incident on SiC material; Figure 5 For different energies 3 Bragg ionization distribution curve after H particles are vertically incident on SiC material; Figure 6 Schematic diagram of particle trajectories and electron-hole pair generation after alpha particles of different energies are vertically incident on a SiC diode; Figure 7 For different energies 3 Schematic diagram of the particle trajectory and electron-hole pair generation after H particles are vertically incident on the SiC diode; Figure 8 The instantaneous current pulse response curve and the total collected charge generated by the incident α particles of different energies; Figure 9 For different energies 3 The instantaneous current pulse response curve and the total collected charge generated by the H particle incident; Figure 10 The transient current pulse response curve and output characteristics of the device under different reverse bias voltages after the 2.05 MeV α particle is incident. Figure 11 2.73 MeV at different reverse bias voltages 3 The transient current pulse response curve generated by H particles and the relationship between output characteristics and voltage changes; In the figure: 1. 4H-SiC substrate; 2. 4H-SiC epitaxial layer; 3. P+ region formed by ion implantation; 4. Front ohmic contact; 5. Back ohmic contact; 6. Neutron conversion layer. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0019] In the present invention, unless otherwise specified, all parts and percentages are by weight. The equipment and raw materials used are commercially available or commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are all universal standard parts or components known to those skilled in the art. Their structures and principles are known to those skilled in the art through technical manuals or routine experimental methods.

[0020] The following detailed description of the embodiments of the present invention is made in conjunction with the accompanying drawings. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may be implemented by those skilled in the art without these specific details.

[0021] An embodiment of the present invention discloses a method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector, the method comprising the following steps: S1. Establishing a device model of the semiconductor radiation detector, wherein the device model includes definitions of the geometric structure, material composition, and electrical parameters of the semiconductor radiation detector, wherein the material composition includes a semiconductor material; S2. For a given incident particle, using a first simulation tool to simulate a transport process of the incident particle in the semiconductor material to obtain an ionization energy loss distribution along the transport path; S3. Performing data conversion and structural reconstruction on the ionization energy loss distribution to generate a charge generation profile suitable for device electrical simulation, wherein the data conversion and structural reconstruction include: S31. Converting the ionization energy loss distribution from an energy loss rate unit to a generated charge unit per unit distance based on an average ionization energy of the semiconductor material; S32, discretizing the continuously changing generated charge along the transport path obtained after the conversion in step S31 into a stepped data structure consisting of a plurality of spatial segments, wherein each spatial segment has a constant generated charge value; S4. Using the ladder-shaped data structure generated in step S32 as input, a second simulation tool is used to perform single-event transient analysis on the device model of the semiconductor radiation detector; S5. Obtaining electrical output characteristics of the semiconductor radiation detector according to the results of the single-particle transient analysis.

[0022] The following will use a planar PiN neutron detector based on 4H-SiC material as an example to explain the technical solution of the present invention in detail. It should be noted that this is merely a preferred embodiment for illustrating the core concept of the present invention, and the scope of protection of the present invention should not be limited to this.

[0023] Step S1, establishing a device model of a semiconductor radiation detector; First, use TCAD semiconductor process and device simulation software to build a device model that matches the actual device. Figure 1 As shown in FIG. 1 , the device model of the planar SiC neutron detector in this embodiment has the following structures from top to bottom: Neutron conversion layer 6: Material is 6 LiF; Front ohmic contact 4: Ni metal material; Semiconductor diode: This is a 4H-SiC PiN structure, including a P+ region 3 formed by ion implantation, a 4H-SiC epitaxial layer 2, and a 4H-SiC substrate 1.

[0024] Back ohmic contact 5: Ni metal material; The geometry, material composition, and electrical parameters of the model were defined in TCAD. The core semiconductor material was 4H-SiC.

[0025] Step S2: for a given incident particle, using a first simulation tool to simulate the transport process of the incident particle in the semiconductor material; This embodiment is for neutron detection. Neutrons themselves are not charged and need to be detected indirectly by generating secondary charged particles through nuclear reactions with the neutron conversion layer. 6 When the LiF neutron conversion layer is used, a nuclear reaction occurs, producing α particles and 3 Therefore, the incident particles that need to be simulated in this step are the two types of secondary charged particles with determined energies: α particles and 3 H particles. The first simulation tool is SRIM-2013 software. The simulation process is as follows: In SRIM, the target material is set to the semiconductor material 4H-SiC; The incident particles are set to 2.05 MeV α particles and 2.73 MeV 3 H particles; Since the energy loss of secondary charged particles passing through the front electrode of several hundred nanometers is minimal, the effect of the electrode can be ignored and the situation of particles incident on the SiC material can be directly simulated. The situation of particles incident at different angles is simulated, such as Figure 2 and Figure 3 As shown in Figure 2, the smaller the particle's incident angle (the closer it is to vertical incidence), the longer its range in the SiC material. Since vertical incidence places the most stringent requirements on the thickness of the detector's depletion region, the subsequent analysis focuses on the vertical incidence case. Run SRIM simulation to obtain alpha particles of different energies and 3After H particles are vertically incident on SiC material, the ionization energy loss distribution along its transport path (unit is eV / Angstrom) is as follows: Figure 4 and Figure 5 As shown in the figure, it can be seen that the greater the incident energy, the longer the range, and the energy is mainly deposited at the end of the range, forming a sharp Bragg peak.

[0026] Step S3, performing data conversion and structural reconstruction on the ionization energy loss distribution to generate a charge generation profile suitable for device electrical simulation; SRIM outputs ionization energy loss in units of eV / Angstrom, while TCAD single-particle transient analysis requires the amount of charge generated per unit distance, namely the linear energy transfer (LET), which is usually expressed in units of pC / μm. The conversion relationship is determined by the following formula: ; Where q is the elementary charge, which is 1.6×10 -19 C, ε is the average ionization energy of the semiconductor material 4H-SiC, which is 7.78 eV.

[0027] By calculating the value of each point on the ionization energy loss curve output by SRIM using this formula, we can obtain the distribution of generated charge (LET) that changes continuously along the transport path.

[0028] The single particle transient analysis function of TCAD usually does not directly support continuous curve input, but requires a segmented discretized charge generation profile. Therefore, it is necessary to approximate the continuous LET curve obtained above as a series of step-like data structures with segmented constant values. The segment length is set according to the type of incident particle: for alpha particles with relatively weak penetration ability and short range, a shorter spatial segment length of 0.2 μm is used for approximation within their range. For particles with stronger penetration ability and longer range, a shorter spatial segment length of 0.2 μm is used for approximation. 3 The H particles are approximated using a longer spatial segment length of 1 μm. The result of this discretization is Figure 4 and Figure 5 The interpolated line segments (i.e., staircase-shaped data) shown in are the final input to TCAD.

[0029] S4. using the ladder-shaped data structure as input, and performing single-event transient analysis on a device model of a semiconductor radiation detector using a second simulation tool; The second simulation tool used in this step is TCAD semiconductor process and device simulation software. The SiC PiN detector device model established in step S1 and the stepped data structure (charge generation profile) generated in step S3 are used as input. A reverse bias voltage is applied to the electrode of the device model, and then the simulation is run. TCAD generates a specified number of electron-hole pairs instantaneously at the corresponding position and depth inside the device model based on the input charge generation profile. Then, TCAD solves the semiconductor equations to simulate the drift and diffusion process of these carriers under the action of the electric field, as well as the entire process of being collected by the electrodes. The simulation results are visualized as follows: Figure 6 and Figure 7 As shown, the trajectory of the particles in the device model is clearly shown, as well as the situation where a large number of electron-hole pairs are excited at the end of the trajectory (i.e., the Bragg peak position).

[0030] S5. obtaining electrical output characteristics of the semiconductor radiation detector; According to the transient analysis results of step S4, key electrical output characteristics can be obtained: transient current pulse response curve and total collected charge.

[0031] The instantaneous current pulse response curve is as follows: Figure 8 and Figure 9 As shown in the figure, the horizontal axis is time and the vertical axis is output current. The peak value, rise time, fall time and duration of the curve are all important electrical characteristics. It can be seen that the higher the energy of the incident particle, the higher the peak value of the current pulse and the longer the duration. This is because as the alpha particles and 3 As the energy of H particles increases, the number of electron-hole pairs excited in the depletion region of the SiC diode will also increase. Therefore, more electron-hole pairs will be transported to the electrode end of the diode, and the output current pulse amplitude will increase. In addition, as the energy of secondary charged particles increases, their penetration depth in the SiC diode will also become deeper, and the excited electron-hole pairs will take longer to be transported to the external electrode end and completely collected, which leads to a longer duration of the instantaneous current pulse.

[0032] By integrating the instantaneous current pulse curve over time, the total amount of charge collected by the detector can be obtained. Figure 8 and Figure 9As shown in the illustration, the total collected charge has a good linear relationship with the incident particle energy. As the incident particle energy increases, the amplitude of the instantaneous current pulse and the output charge will increase linearly. This is because when the applied reverse bias is 200 V, the depletion region thickness of the SiC-based PiN diode is about 33 μm, and the electron-hole pairs excited by the secondary charged particles will be generated in the depletion region of the diode. Therefore, these electron-hole pairs can basically be efficiently collected by the external electrode. The electrical output characteristics obtained above can be directly used to guide the design of the back-end readout electronics.

[0033] In order to determine the optimal operating voltage of the detector, the method further performs the following steps.

[0034] Repeat steps S4 and S5, but in step S4, systematically change the reverse bias voltage applied to the device model, for example, sweep from 10V to 300V. Obtain a series of electrical output characteristics under different reverse bias voltages. Figure 10 and Figure 11 As shown, with the increase of reverse bias voltage, the duration of the current pulse decreases, while the peak amplitude and the total collected charge increase sharply at first and then tend to saturation.

[0035] At low voltages, the depletion region width is smaller than the particle range, and a large amount of charge is generated and recombined outside the depletion region, resulting in incomplete collection. As the voltage increases, the depletion region widens, covering the entire particle track, improving charge collection efficiency and enhancing the output signal. When the voltage is sufficiently high, the depletion region width exceeds the maximum range, allowing all excited charges to be efficiently collected. At this point, increasing the voltage no longer significantly increases the output signal, indicating saturation.

[0036] like Figure 10 and Figure 11 As shown in the illustration, by observing the curves of total collected charge and current pulse amplitude changing with voltage, the inflection point voltage at which the curve begins to enter the saturation region is found. In this embodiment, in order to ensure the highest energy 3 H particles can also be completely collected, and a reverse bias voltage greater than 200 V is required to saturate the output signal. Therefore, it can be determined that the recommended operating voltage of this SiC neutron detector should be greater than 200 V.

[0037] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for collaborative simulation of electrical characteristics of semiconductor radiation detectors, characterized by: The method comprises the following steps: S1. Establishing a device model of the semiconductor radiation detector, wherein the device model includes definitions of the geometric structure, material composition, and electrical parameters of the semiconductor radiation detector, wherein the material composition includes a semiconductor material; S2. For a given incident particle, using a first simulation tool to simulate a transport process of the incident particle in the semiconductor material to obtain an ionization energy loss distribution along the transport path; S3. Performing data conversion and structural reconstruction on the ionization energy loss distribution to generate a charge generation profile suitable for device electrical simulation, wherein the data conversion and structural reconstruction include: S31. Converting the ionization energy loss distribution from an energy loss rate unit to a generated charge unit per unit distance based on an average ionization energy of the semiconductor material; S32, discretizing the continuously changing generated charge along the transport path obtained after the conversion in step S31 into a stepped data structure consisting of a plurality of spatial segments, wherein each spatial segment has a constant generated charge value; S4. Using the ladder-shaped data structure generated in step S32 as input, a second simulation tool is used to perform single-event transient analysis on the device model of the semiconductor radiation detector; S5. Obtaining electrical output characteristics of the semiconductor radiation detector according to the results of the single-particle transient analysis.

2. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 1, wherein: The first simulation tool is SRIM ion implantation simulation software, and the second simulation tool is TCAD semiconductor process and device simulation software.

3. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 1, wherein: In step S2, the incident particles are secondary charged particles generated by nuclear reactions between neutrons and the neutron conversion layer.

4. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 3, wherein: The neutron conversion layer is 6 LiF, the secondary charged particles include α particles and 3 H particles; Step S2 is respectively for the α particles and the 3 H particles for simulation.

5. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 1, wherein: In step S31, the unit of the energy loss rate is eV / Angstrom, and the unit of the generated charge per unit distance is pC / μm. The conversion relationship is determined by the following formula: ； Wherein, q is the elementary charge, and ε is the average ionization energy of the semiconductor material.

6. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 1, wherein: In step S32, the lengths of the multiple space segments are set according to the type of the incident particles.

7. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 1, wherein: In step S5, the electrical output characteristics include an instantaneous current pulse response curve and / or a total collected charge amount obtained by integrating the instantaneous current pulse response curve.

8. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 1, wherein: The method further includes, in step S4, setting the operating conditions of the semiconductor radiation detector under different reverse bias voltages to obtain the electrical output characteristics corresponding to the different reverse bias voltages.

9. The method for collaboratively simulating the electrical characteristics of a semiconductor radiation detector according to claim 8, wherein: The method also includes: determining the minimum operating voltage at which both the total collected charge and the instantaneous current pulse amplitude reach saturation based on the changing relationship between the total collected charge and the instantaneous current pulse amplitude obtained under different reverse bias voltages, as the recommended operating voltage of the semiconductor radiation detector.

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