Spectral value analysis method for irradiation damage of wide bandgap semiconductor device

Abstract

The invention discloses a spectral value analysis method for irradiation damage of a wide bandgap semiconductor device. The method is used for irradiation damage analysis of GaN HEMT and SiC MOSFET wide bandgap semiconductor devices. Under the same filling and testing conditions, transient drain-source voltage response curves corresponding to trap release of a tested device before irradiation and after irradiation are respectively collected, and characteristic parameters such as trap relaxation time and peak amplitude in the curves are extracted by using a structure function method; and the microscopic damage of the tested device under the irradiation effect is visually presented in a visual peak spectrum form. The method not only can distinguish the influence of irradiation on different traps, but also can quantitatively characterize the trap relaxation time, amplitude and energy level change of the tested device in the irradiation environment through the spectrum peak position and intensity. Besides, the method is suitable for irradiation damage characterization of various semiconductor devices such as GaN HEMT and SiC MOSFET, has a good application basis, and provides an in-situ and nondestructive evaluation means for irradiation damage mechanism research of wide bandgap semiconductor devices and design of anti-irradiation devices.

Description

Technical Field

[0001] The present invention relates to radiation damage analysis and related testing of wide bandgap semiconductor devices, belonging to the field of power semiconductor device testing and reliability. Background Art

[0002] Wide-bandgap semiconductor devices, such as GaN HEMTs and SiC MOSFETs, have important applications in extreme radiation environments, such as aerospace, defense, and military applications, due to their superior properties, such as high voltage resistance, high frequency, and high temperature resistance. However, in space particle irradiation or nuclear radiation environments, high-energy particles such as protons, electrons, and gamma rays can cause displacement damage and ionization damage within the device, leading to reliability issues such as decreased carrier mobility, threshold voltage drift, and increased leakage current, severely restricting the long-term stability of the device in irradiated environments. Therefore, studying the mechanism of radiation damage and its impact on electrical performance is of great significance for improving the design of radiation-resistant devices and ensuring the reliability of critical equipment.

[0003] Currently, characterization of radiation damage in semiconductor devices relies primarily on static electrical parameter testing, such as transfer and output characteristics, as well as microanalysis techniques such as deep-level transient spectroscopy (DLTS) and transmission electron microscopy (TEM). These methods can reveal performance degradation after irradiation, but they struggle to intuitively quantify the dynamic evolution of defect traps, and their ability to spectrally characterize complex radiation damage is limited. Therefore, there is an urgent need to develop an in-situ, dynamic characterization method that can directly correlate radiation defects with electrical performance degradation, enabling more accurate assessment of the extent of radiation damage and its impact on device reliability.

[0004] The present invention proposes a spectral analysis method for radiation damage of wide-bandgap semiconductor devices based on transient voltage testing. By applying a bias signal to the device before and after irradiation, collecting the transient voltage response curve corresponding to the trap release process, and extracting characteristic parameters such as the trap relaxation time and peak amplitude in the curve, the device trap changes under irradiation are intuitively presented in the form of a peak spectrum. This method can not only distinguish the impact of irradiation on different traps, but also quantitatively analyze the defect energy level distribution through the spectral peak position and intensity, providing an in-situ, non-destructive evaluation method for the study of radiation damage mechanisms of semiconductor devices and the design of radiation-resistant devices. In addition, this method can be applied to the characterization of radiation damage of various wide-bandgap semiconductor devices such as GaN HEMT and SiC MOSFET, and has a good application basis. Summary of the Invention

[0005] Wide bandgap semiconductor devices such as GaN HEMT and SiC MOSFET have broad application prospects in aerospace, national defense and military industries, and the characterization of radiation damage to devices under irradiation environments has attracted the attention of researchers. At present, the characterization of radiation damage to semiconductor devices mainly relies on static electrical parameter testing and microscopic analysis technology. It is difficult to intuitively quantify the dynamic evolution process of defect traps, and the spectral characterization capability of complex radiation damage is limited. In order to solve this problem, the present invention proposes a spectral analysis method for device radiation damage based on transient voltage testing. By collecting the transient voltage response curves of the device before and after irradiation, the structure function method is used to construct the time constant spectrum and differential amplitude spectrum, and the change amount and change rate of parameters such as trap relaxation time, peak amplitude, and energy level are quantitatively extracted by spectral value shifting, and the device trap changes under irradiation are intuitively presented in the form of peak spectrum.

[0006] The technical solution adopted by the present invention is a spectrum-valued analysis method for radiation damage of wide-bandgap semiconductor devices. The implementation process of this method is as follows:

[0007] Step 1). Before irradiation, place the device under test on a constant temperature platform with a temperature of T1 and ground the source end of the device; the temperature range of T1 is 298K≤T1≤303K to evaluate the performance of the device at room temperature. Apply a gate filling voltage V GF and drain fill voltage V DF , the filling time is t1. Among them, the gate filling voltage V GF The range is -20V≤V GF ≤10V, drain filling voltage V DF The range is 0V≤V GF ≤50V, the filling time t1 range is 1μs≤t1≤100s. After completing the filling of t1 time, apply the gate terminal test voltage V GM and drain test current I DM , the test time is t2, and the transient response curve of the device drain-source voltage before irradiation is obtained and recorded as L1. Among them, the gate terminal test voltage V GM The range is -20V≤V GM ≤10V, leakage test current I DM The range is 50mA≤I DM ≤200mA, the test time t2 range is 1μs≤t2≤1000s. After irradiation, the same filling conditions (V GF 、V DF and t1) and test conditions (V GM , I DM and t2), obtain the transient response curve of the drain-source voltage of the device after irradiation and record it as L2.

[0008] Step 2) Process the transient response curve L1 of the drain-source voltage before irradiation to obtain the transient change V of the drain-source voltage of the device under test before irradiation. DS-1 (normalized)=|V DS-1 (t)-V DS-1 Repeat the above processing method for the transient response curve L2 of the device under test after irradiation to obtain the transient change of the drain-source voltage of the device under test after irradiation V DS-2 (normalized)=|V DS-2 (t)-V DS-2 (t2)|. The range of transient change of drain-source voltage before and after irradiation is 0.1≤V DS-1 (normalized)≤10 and 0.1≤V DS-2 (normalized)≤10.

[0009] Step 3). At V DS-1 (normalized) and V DS-2 Based on the (normalized) structure function method, the trap time constant spectrum before and after irradiation is constructed, and a spectrum-valued trap evolution analysis method is established. The movement of the trap peak in the time constant spectrum reflects the trap evolution of GaN HEMT after irradiation. m trap peaks are identified from the transient changes in the drain-source voltage before and after irradiation, and are named DP1...DPi...DPm in ascending order according to the relaxation time, where 1≤i≤m, and m and i are both positive integers. The horizontal axis corresponding to the trap peak is the relaxation time. Before irradiation, from V DS-1 The relaxation time of the i-th trap is identified as τ in (normalized) i-1 After irradiation, V DS-2 The relaxation time of the i-th trap is identified as τ in (normalized) i-2 Among them, the relaxation time before and after irradiation is τ i-1 and τ i-2 The range is 1μs≤τ i-1 ≤1000s and 1μs≤τ i-2 ≤1000s. Therefore, compared with the test results before irradiation, the change in relaxation time of the i-th trap after irradiation is △τ i =|τ i-1 -τ i-2 |, the rate of change of the trap relaxation time is r ti =|(τ i-1 -τ i-2 ) / τ i-1 ×100%|. The range of the change in trap relaxation time after irradiation is 0≤△τ i≤1000s, the range of the trap relaxation time change rate after irradiation is 0%≤r ti ≤100%.

[0010] Step 4). Based on the trap time constant spectrum before and after irradiation, add the data points corresponding to the ordinate of each trap peak, perform differential processing on the abscissa and swap the abscissa and ordinate to obtain the differential amplitude spectrum of the GaN HEMT trap before and after irradiation. The amplitude change of the trap can be intuitively reflected by the shift of the spectrum value. The amplitude of each trap before and after irradiation is presented in the form of a bar graph. The amplitude of the i-th trap before and after irradiation is A i-1 and A i-2 , where the trap amplitude before and after irradiation is in the range of 0≤A i-1 ≤10 and 0≤A i-2 ≤10. Therefore, compared with the test results before irradiation, the change in trap amplitude after irradiation is △A i =|A i-1 -A i-2 |, the rate of change of the trap amplitude is r ai =|(A i-1 -A i-2 ) / A i-1 ×100%|. The range of the trap amplitude change after irradiation is 0≤△A i ≤10, the range of the trap amplitude change rate after irradiation is 0% ≤r ai ≤100%.

[0011] Step 5). Increase the temperature T1 of the constant temperature platform in step 1 by n times, and repeat steps 1 to 4 after each increase in ΔT temperature. The range of n is 3≤n≤10, and the range of ΔT is 5K≤ΔT≤15K. After completing n steps, the relaxation time of m traps before and after irradiation at (n+1) temperatures is obtained. For example, the time constants of the i-th trap before and after irradiation at temperature T1 are τ i-1 and τ i-2 According to the Arrhenius formula, the Arrhenius curve is obtained, whose horizontal and vertical coordinates are ln(T 2 Based on the relaxation time of the i-th trap before and after irradiation at (n+1) temperature, the corresponding Arrhenius curves before and after irradiation are drawn respectively. The corresponding slope of the curve is the energy level E of the i-th trap before and after irradiation. Ai-1 and E Ai-2 , and thus quantitatively compare the changes in trap energy levels after irradiation. The trap energy level range is 0.01eV≤E Ai-1 ≤1eV and 0.01eV≤E Ai-2 ≤1eV. Therefore, compared with the test results before irradiation, the change in trap energy level after irradiation is △EAi =|E Ai-1 -E Ai-2 |, the rate of change of the trap energy level is r ei =|(E Ai-1 -E Ai-2 ) / E Ai-1 ×100%|. The range of the trap energy level change after irradiation is 0≤△E Ai ≤1eV, the range of the trap amplitude change rate after irradiation is 0% ≤r ei ≤100%.

[0012] This invention proposes a spectral-valued analysis method for radiation damage in wide-bandgap semiconductor devices. This method can display the damage of semiconductor devices after irradiation in a spectral-valued form. The beneficial effects of this invention are: the analysis method is convenient and fast, uses simple testing conditions, and can quantitatively characterize the changes and rates of trap relaxation time, amplitude, and energy level in semiconductor devices after irradiation, providing a highly sensitive assessment tool for radiation-resistant device design and lifespan prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 : Device test timing diagram involved in the present invention.

[0014] Figure 2 : Schematic diagram of the transient drain-source voltage and trap time constant spectrum before and after irradiation involved in the present invention.

[0015] Figure 3 : Schematic diagram of the trap differential amplitude spectrum before and after irradiation and comparison of amplitude changes involved in the present invention.

[0016] Figure 4 : Comparison diagram of trap energy levels before and after irradiation involved in the present invention. DETAILED DESCRIPTION

[0017] The following describes a more detailed method for analyzing spectral values of radiation damage to semiconductor devices in conjunction with the accompanying drawings and specific embodiments. A depletion-mode GaN HEMT is selected as the device under test, with an off-state breakdown voltage of 100V and a maximum operating current of 6A. The method of the present invention includes the following steps:

[0018] Step 1: Before irradiation, place the device under test on a constant temperature platform at 298K and ground the source terminal of the device. Apply a gate filling voltage V of -7V to the device. GF and a drain fill voltage of 10V V DF , the filling time t1 is 30s. After the filling of t1 time is completed, a gate terminal test voltage V of 0V is applied to the device. GM and 200mA leakage test current I DM, the test time t2 is 120s, and the transient response curve of the device drain-source voltage before irradiation is obtained and recorded as L1. After irradiation, the same filling condition (V GF 、V DF and t1) and test conditions (V GM , I DM and t2), obtain the transient response curve of the drain-source voltage of the device after irradiation and record it as L2. The test timing is as follows Figure 1 shown.

[0019] Step 2: Process the transient response curve L1 of the drain-source voltage before irradiation to obtain the transient change V of the drain-source voltage of the device under test before irradiation. DS-1 (normalized)=|V DS-1 (t)-V DS-1 Repeat the above processing method for the transient response curve L2 of the device under test after irradiation to obtain the transient change of the drain-source voltage of the device under test after irradiation V DS-2 (normalized)=|V DS-2 (t)-V DS-2 (t2)|, its change is compared with Figure 2 (a) shows the transient change in drain-source voltage V of the device under test before and after irradiation. DS-1 (normalized) and V DS-2 (normalized) are 0.288 and 0.243 respectively.

[0020] Step 3: In V DS-1 (normalized) and V DS-2 Based on the normalized model, the structure function method is used to construct the trap time constant spectrum before and after irradiation, and a spectrum-valued trap evolution analysis method is established. The movement of the trap peak in the time constant spectrum reflects the trap evolution of GaN HEMT after irradiation. Figure 2 As shown in (b), three trap peaks are identified from the transient changes of drain-source voltage before and after irradiation. They are named DP1, DP2 and DP3 in descending order of relaxation time. The horizontal axis corresponding to the trap peak is the relaxation time. DS-1 The relaxation times of the three traps identified in (normalized) are τ 1-1 =2ms, τ 2-1 =0.5s, τ 3-1 =12s. After irradiation, from V DS-2 The relaxation times of the three traps identified in (normalized) are τ 1-2 =1ms, τ 2-2 =0.2s, τ3-2 =8s. Compared with the test results before irradiation, the change in trap relaxation time after irradiation is △τ i =|τ i-1 -τ i-2 |, the rate of change of the trap relaxation time is r ti =|(τ i-1 -τ i-2 ) / τ i-1 × 100% |. Therefore, the changes in the relaxation time of the three traps are △τ1 = 1ms, △τ2 = 0.3s, △τ3 = 4s, and the change rates are r t1 =50.0%, r t2 =60.0%, r t3 =33.3%.

[0021] Step 4: Based on the trap time constant spectrum before and after irradiation, add the data points corresponding to the ordinate of each trap peak, perform differential processing on the abscissa, and then swap the abscissa and ordinate to obtain the differential amplitude spectrum of the GaN HEMT trap before and after irradiation. Figure 3 (a) shows that the amplitude change of the trap can be directly reflected by the shift of the spectrum value. The amplitude of each trap before and after irradiation is presented in the form of a bar graph, as shown in Figure 3 (b) The analysis results show that the amplitude of each trap decreases after irradiation, indicating that the radiation damage of the device under test is reduced after irradiation. Before irradiation, the amplitudes of the three traps DP1, DP2 and DP3 are A 1-1 =9.2, A 2-1 =10.6 and A 3-1 =9.0; the amplitudes of the three traps after irradiation are A 1-2 =8, A 2-2 =7.5 and A 3-2 =8.3. Therefore, compared with the test results before irradiation, the change in trap amplitude after irradiation is △A i =|A i-1 -A i-2 |, the rate of change of the trap amplitude is r ai =|(A i-1 -A i-2 ) / A i-1 ×100%|. Therefore, compared with the test results before irradiation, the changes in the amplitudes of the three traps after irradiation are △A1=1.2,△A2=3.1,△A3=0.7, and the change rates are r a1 =13.0%, r a2 =29.2%, r a3 =7.8%.

[0022] Step 5: Increase the temperature of the constant temperature platform in step 1 by 5K 4 times, and repeat steps 1 to 4. After completing 4 steps, the relaxation time of 3 traps before and after irradiation at 5 temperatures (298K, 303K, 308K, 313K and 318K) is obtained. For example, the time constant of the first trap before and after irradiation at 298K is 2ms and 1ms respectively. According to the Arrhenius formula, the Arrhenius curve is obtained, and its horizontal and vertical coordinates are ln(T 2 Based on the relaxation time of the first trap before and after irradiation at five temperatures, the corresponding Arrhenius curves before and after irradiation are drawn, and the corresponding slope of the curve is the energy level E of the first trap before and after irradiation. Ai-1 and E Ai-2 , and thus quantitatively compare the changes in trap energy levels after irradiation, such as Figure 4 As shown. Before irradiation, the energy levels of the three traps are E A1-1 =0.477eV, E A2-1 =0.385eV, E A3-1 =0.289eV; after irradiation, the energy levels of the three traps are E A1-2 =0.432eV, E A2-2 =0.335eV, E A3-2 =0.260eV. Therefore, compared with the test results before irradiation, the change in trap energy level after irradiation is △E Ai =|E Ai-1 -E Ai-2 |, the rate of change of the trap energy level is r ei =|(E Ai-1 -E Ai-2 ) / E Ai-1 ×100%|. Therefore, compared with the test results before irradiation, the changes in the amplitudes of the three traps after irradiation are △E A1 =0.045eV, ΔE A2 =0.05eV, ΔE A3 =0.029eV, and the rates of change are r e1 =9.4%, r e2 =13.0%, r e3 =10.0%.

Claims

1. A spectrum-valued analysis method for radiation damage of wide bandgap semiconductor devices, characterized in that: The measuring method comprises the following steps: Step 1: Before irradiation, place the device under test on a constant temperature platform with a temperature of T1 and ground the source end of the device; apply a gate filling voltage V to the device under test. GF and drain fill voltage V DF , the filling time is t1; after completing the filling of t1 time, the gate terminal test voltage V is applied to the device under test GM and drain test current I DM , the test time is t2, the transient response curve of the drain-source voltage of the device under test before irradiation is obtained and recorded as L1; after irradiation, the same filling condition (V GF 、V DF and t1) and test conditions (V GM , I DM and t2), obtain the transient response curve of the drain-source voltage of the device under test after irradiation and record it as L2; Step 2: Process the transient response curve L1 of the drain-source voltage of the device under test before irradiation to obtain the transient change V of the drain-source voltage of the device under test before irradiation. DS-1 (normalized)=|V DS-1 (t)-V DS-1 (t2) |; Repeat the above processing method for the transient response curve L2 of the device under test after irradiation to obtain the transient change of the drain-source voltage of the device under test after irradiation V DS-2 (normalized)=|V DS-2 (t)-V DS-2 (t2)|; Step 3: In V DS-1 (normalized) and V DS-2 Based on the normalized structure function method, the trap time constant spectrum before and after irradiation is constructed, and a spectrum-valued trap evolution analysis method is established. The movement of the trap peak in the time constant spectrum reflects the trap evolution of GaN HEMT after irradiation. m trap peaks are identified from the transient changes of drain-source voltage before and after irradiation. They are named DP1...DPi...DPm in ascending order of relaxation time, and the horizontal axis corresponding to the trap peak is the relaxation time. Before irradiation, the trap peak is from V DS-1 (normalized) and the relaxation time of the i-th trap is identified as τ i-1 ; After irradiation, from V DS-2 (normalized) and the relaxation time of the i-th trap is identified as τ i-2 Therefore, compared with the test results before irradiation, the change in trap relaxation time after irradiation is △τ i =|τ i-1 -τ i-2 |, the rate of change of the trap relaxation time is r ti =|(τ i-1 -τ i-2 ) / τ i-1 ×100%|; Step 4: Based on the trap time constant spectrum before and after irradiation, add the data points corresponding to the ordinate of each trap peak, perform differential processing on the abscissa and swap the abscissa and ordinate to obtain the differential amplitude spectrum of the GaN HEMT trap before and after irradiation, where the amplitude change of the trap is intuitively reflected by the shift of the spectrum value; display the amplitude of each trap before and after irradiation in the form of a bar graph; the amplitude of the i trap before and after irradiation is A i-1 and A i-2 Compared with the test results before irradiation, the change of the trap amplitude after irradiation is △A i =|A i-1 -A i-2 |, the rate of change of the trap amplitude is r ai =|(A i-1 -A i-2 ) / A i-1 ×100%|; Step 5: Increase the temperature T1 of the constant temperature platform in step 1 by n times, and increase the temperature by △T each time, and repeat steps 1 to 4; after completing n steps, obtain the relaxation time of each trap at (n+1) temperatures. According to the Arrhenius formula, the slope of each curve before and after irradiation is extracted as the energy level of each trap, thereby quantitatively comparing the changes in the trap energy level after irradiation; the energy levels of the i-th trap before and after irradiation are E Ai-1 and E Ai-2 Compared with the test results before irradiation, the change of trap energy level after irradiation is △E Ai =|E Ai-1 -E Ai-2 |, the rate of change of the trap energy level is r ei =|(E Ai-1 -E Ai-2 ) / E Ai-1 ×100%|.

2. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In step 1, the device under test is placed on a constant temperature platform with the source terminal of the device grounded. The temperature range of the constant temperature platform is 298K≤T1≤303K to evaluate the performance of the device at room temperature. Fill voltage is applied to the source and drain terminals of the device, where the gate terminal fill voltage V GF The range is -20V≤V GF ≤10V, drain filling voltage V DF The range is 0V≤V GF ≤50V, the filling time t1 range is 1μs≤t1≤100s; the gate terminal test voltage V GM The range is -20V≤V GM ≤10V, leakage test current I DM The range is 50mA≤I DM ≤200mA, test time t2 is 1μs≤t2≤1000s.

3. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: The devices under test in step 1 include GaN HEMT and SiC MOSFET. The filling conditions (V GF 、V DF and t1) and test conditions (V GM , I DM and t2) must remain exactly the same.

4. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In the test of step 2, the transient change of the drain-source voltage of the device before and after irradiation is used to characterize the trap change before and after irradiation. The transient change of the drain-source voltage of the device before irradiation is V DS-1 (normalized)=|V DS-1 (t)-V DS-1 (t2)|, the transient change of the device drain-source voltage after irradiation is V DS-2 (normalized)=|V DS-2 (t)-V DS-2 (t2) |; The range of transient change of drain-source voltage before and after irradiation is 0.1≤V DS-1 (normalized)≤10 and 0.1≤V DS-2 (normalized)≤10.

5. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In steps 3 to 5, the spectral analysis method of radiation damage of semiconductor devices includes analysis of time constant spectrum, differential amplitude spectrum and trap relaxation time, amplitude and energy level in Arrhenius diagram.

6. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In step 3, the change in trap relaxation time after irradiation is analyzed by the movement of the trap peak in the time constant spectrum; the number of trap peaks is identified as m, and m is a positive integer; the relaxation time τ of the i-th trap before and after irradiation is i-1 and τ i-2 The range is 1μs≤τ i-1 ≤1000s and 1μs≤τ i-2 ≤1000s.

7. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In step 3, the change in trap relaxation time after irradiation is defined as △τ i =|τ i-1 -τ i-2 |, the rate of change of the trap relaxation time is defined as r ti =|(τ i-1 -τ i-2 ) / τ i-1 ×100%|; where the range of the change in trap relaxation time after irradiation is 0≤△τ i ≤1000s, the range of the trap relaxation time change rate after irradiation is 0%≤r ti ≤100%.

8. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In step 4, the analysis method of the change of trap amplitude after irradiation is the movement of the visual spectral line in the differential constant spectrum, where the range of the trap amplitude before and after irradiation is 0≤A i-1 ≤10 and 0≤A i-2 ≤10; Compared with the test results before irradiation, the change in trap amplitude after irradiation is defined as △A i =|A i-1 -A i-2 |, the rate of change of the trap amplitude is defined as r ai =|(A i-1 -A i-2 ) / A i-1 ×100%|; where the range of the trap amplitude change after irradiation is 0≤△A i ≤10, the range of the trap amplitude change rate after irradiation is 0% ≤r ai ≤100%.

9. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In step 5, the temperature of the constant temperature platform is increased n times, and the ΔT temperature is increased each time, and steps 1 to 4 are repeated; wherein, the range of n is 3≤n≤10, and the range of ΔT is 5≤ΔT≤15; after completing the repetition of steps, the relaxation time of each trap at a total of (n+1) temperatures is obtained, and the energy level of each trap before and after irradiation is extracted according to the Arrhenius formula.

10. The spectral value analysis method for radiation damage of wide bandgap semiconductor devices according to claim 1, characterized in that: In step 5, the change in trap energy level after irradiation is analyzed by the change in the slope of the curve in the Arrhenius plot, where the range of trap energy level before and after irradiation is 0.01eV≤E Ai-1 ≤1eV and 0.01eV≤E Ai-2 ≤1eV; Compared with the test results before irradiation, the change in trap energy level after irradiation is defined as △E Ai =|E Ai-1 -E Ai-2 |, the rate of change of the trap level is defined as r ei =|(E Ai-1 -E Ai-2 ) / E Ai-1 ×100%|; where the range of the trap energy level change after irradiation is 0≤△E Ai ≤1eV, the range of the trap amplitude change rate after irradiation is 0% ≤r ei ≤100%.

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