Method for evaluating high-energy proton irradiation damage of back gate CNT device
By introducing a charge deposition layer into the back-gate CNT device and combining it with various simulation software, an irradiation damage model was constructed, which solved the problem of accuracy in assessing high-energy proton irradiation damage, realized the stability and performance prediction of the device under high radiation environment, and reduced R&D costs and time.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANGTZE DELTA REGION INST OF UNIV OF ELECTRONICS SCI & TECH OF CHINE (HUZHOU)
- Filing Date
- 2024-10-28
- Publication Date
- 2026-04-28
AI Technical Summary
Existing technologies make it difficult to accurately assess the damage of back-gate CNT devices under high-energy proton irradiation at the theoretical level, and high-energy proton irradiation experiments have limitations, which cannot effectively guide device design optimization and process improvement.
A charge deposition layer was introduced between the channel and dielectric layer of the back-gate CNT device. An irradiation damage model was constructed by combining Silvaco TCAD simulation software, Geant4 software and VASP first-theory simulation method. The high-energy proton irradiation damage of the device was evaluated by simulating the interface trapping effect caused by proton irradiation.
It enables accurate prediction of irradiation damage in back-gate CNT devices, guides device design optimization, reduces R&D costs and time, and ensures stable operation of devices in high-radiation environments.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-energy irradiation damage assessment technology for CNT devices, and specifically relates to a method for assessing high-energy proton irradiation damage in back-gate CNT devices. Background Technology
[0002] Carbon nanotubes (CNTs), as emerging nanomaterials, show great potential for applications in microelectronic devices, especially in applications requiring high performance and low power consumption. Back-gate CNT devices, with their unique structural design and material combination, exhibit multiple advantages and application prospects. First, due to the excellent electrical properties and size effect of CNTs, back-gate CNT devices can effectively reduce device size and improve integration density and performance density in integrated circuits. Second, their back-gate structure not only optimizes the electrical performance of the device but also significantly improves its stability and damage resistance in high-radiation environments. This is particularly important for applications in aerospace and nuclear industries, where equipment often needs to operate for extended periods in extreme radiation environments, requiring stable performance and reliable operation.
[0003] In extreme radiation environments, high-energy proton irradiation is a significant cause of device damage. Researchers have conducted extensive studies on this topic; however, conducting high-energy proton irradiation experiments faces numerous limitations, such as suitable proton sources, long experimental times, and radioactive contamination. Therefore, the importance of theoretically assessing high-energy proton irradiation damage in back-gate CNT devices has increased, and a theoretical method for accurately evaluating device irradiation damage is urgently needed. To address these issues, this invention proposes a method for assessing high-energy proton irradiation damage in back-gate CNT devices. By introducing a charge deposition layer between the channel and the dielectric layer, the method accurately reflects the effect of proton irradiation forming interface defects between the channel and the dielectric layer, thereby trapping the charge. Combined with Silvaco TCAD simulation software, Geant4 software, and VASP first-theory simulation methods, the method can accurately predict device performance changes in irradiation environments before actual device fabrication. This provides important guidance for device design optimization and process improvement, thereby reducing R&D costs and time. Furthermore, by assessing the device's performance in high-radiation environments in advance, device failure and performance degradation due to radiation damage can be effectively prevented, ensuring the long-term stable operation of the equipment. The simulation results of this invention are in good agreement with experimental results, achieving accurate prediction of irradiation damage to back-gate CNT devices and deepening the understanding of microscopic damage mechanisms. Summary of the Invention
[0004] To address the urgent need for accurate assessment of device irradiation damage, this invention introduces a charge deposition layer between the channel and dielectric layer of a back-gate CNT device. This constructs an irradiation damage model reflecting the trapping effect of interface traps induced by proton irradiation. By combining Silvaco TCAD simulation software, Geant4 software, and the VASP first-theory simulation method, the effects of proton irradiation on the charge deposition layer and other components of the device are obtained, thereby achieving the goal of assessing high-energy proton irradiation damage. The simulation results of this invention agree well with experimental results, achieving accurate prediction of irradiation damage in back-gate CNT devices and deepening the understanding of microscopic damage mechanisms.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A back-gate CNT device model is constructed, which includes a charge-deposited layer capable of capturing interfacial traps induced by proton irradiation. The structure is CNT / charge-deposited layer / SiO2 / P-Si.
[0007] A method for assessing high-energy proton irradiation damage to back-gate CNT devices includes the following steps:
[0008] 1. Construction of back-gate CNT device model
[0009] A device simulation model was constructed using Silvaco TCAD simulation software. The model includes components such as a CNT channel, a SiO2 dielectric layer, a P-Si substrate, a gate, a drain, and a source. The model was then meshed (source and drain materials include, but are not limited to, Au, Ti, and Cr). A charge deposition layer was added between the CNT layer and the SiO2 dielectric layer. The doping type and doping amount of the CNT layer, the charge deposition layer, and the P-Si substrate were set. The electrode positions were set, with one end of the CNT designated as the source (P-type doped) and the other end as the drain (N-type doped). The P-Si substrate was phosphorus doped.
[0010] 2. Setting electrical parameters and simulating output characteristics of each component
[0011] Set source voltage (V) Source ) and gate voltage (V Gate The electrical parameters of the back-gate CNT device, including band gap (EG300), carrier mobility (MUN, MUP), carrier concentration (NC300, NV300), affinity, and permittivity, are adjusted in the simulation model to achieve the output characteristics (Idrain-Vgate curve) of the simulated device.
[0012] 3. Simulation of high-energy proton irradiation process
[0013] Set the proton irradiation parameters (energy, dose). Use VASP software to simulate the cascade collision process of proton irradiation on the device. Calculate the electrical properties of each component to obtain the band gap, carrier mobility, and dielectric constant after irradiation. Use Geant4 software to simulate the charge deposition process of the device and statistically analyze the amount and type of charge deposited by proton irradiation in the charge deposition layer.
[0014] Furthermore, in step 3, the VASP software is used to simulate the cascade collision process caused by protons, the irradiation time is set to 5 ps, the time step is 1 fs, and the irradiated structure is relaxed to obtain a stable irradiated structure.
[0015] Furthermore, in step 3, the charge deposition of the charge deposition layer is calculated using Geant4 software, with the particle source (ParticleGun) set to protons and the step size (GetStepLength) set to 1 nm.
[0016] 4. Device irradiation damage assessment:
[0017] The electrical characteristics of each component in the charge deposition layer of the irradiated device are input into the simulation model in step 2 to simulate the output characteristics of the irradiated device. The damage of high-energy proton irradiation to the back-gate CNT device is evaluated by comparing the output characteristics of the device before and after irradiation.
[0018] In summary, the beneficial effects of the present invention are as follows:
[0019] 1. This invention combines Silvaco TCAD simulation software, Geant4 software, and VASP first-theory simulation method to construct a back-gate CNT device irradiation damage model that reflects the trapping effect of interface traps caused by proton irradiation, thereby achieving the goal of accurately assessing high-energy proton irradiation damage to the device. It has high application potential in the field of device irradiation damage detection.
[0020] 2. The radiation damage simulation and evaluation process of the device in this technical solution is applicable to the main CNT device types currently available, thus expanding the application scope of this invention. Attached Figure Description
[0021] The present invention will be described by way of example and with reference to the accompanying drawings, wherein...
[0022] Figure 1 This is a schematic diagram of the structural dimensions of the back-gate CNT device fabricated in this invention.
[0023] Figure 2 The drain current (I) of the back-gate CNT device in this invention before and after high-energy proton irradiation. Drain - Gate voltage (V) Gate Output characteristics change.
[0024] Figure 3 This is a schematic diagram of the theoretical model of the back-gate CNT device containing a charge deposition layer according to the present invention.
[0025] Figure 4 This is the pre-irradiation simulation output of the back-gate CNT device in this invention.
[0026] Figure 5 This shows the charge deposition of the CNT band structure and device before and after irradiation in this invention.
[0027] Figure 6 I, after irradiation, for simulating the back-gate CNT device in this invention Drain -V Gate Output characteristics. Detailed Implementation
[0028] The present invention will now be described in detail with reference to the accompanying drawings.
[0029] Example 1:
[0030] a) The fabricated back-gate CNT device was subjected to high-energy proton irradiation experiments in a proton source to verify the reliability of the damage assessment method proposed in this invention. The proton energy was 2.5 MeV, and the irradiation dose was 15.4 × 10⁻⁶. 12 Gy; the source voltage is set to 0.5V, and the gate voltage range is -15V to 15V. The changes in device structural dimensions and output characteristics before and after irradiation are as follows: Figure 1 and Figure 2 As shown.
[0031] b) Using Silvaco TCAD software, a 1:1 simulation model of the back-gate CNT device was constructed according to the device size parameters in step a), and the model was meshed. The source and drain materials were Au; the gate was positioned below the P-Si substrate; the CNT source side was P-type doped with 1×10⁻⁶. 18 cm 3 The drain side is N-type doped with 1×10⁻⁶ 20 cm 3 P-Si substrate with 1×10⁻⁶ P-type doping 18 cm 3 A 5nm thick charge deposition layer (green area) is set between the CNT channel and the dielectric layer; this layer is initially undoped. The source voltage is set to 0.5V, and the gate voltage ranges from -15V to 15V. The constructed theoretical model and simulation output are as follows: Figure 3 and Figure 4 As shown, the simulation output and experimental results are in good agreement.
[0032] c) A device model was constructed using VASP software, with the proton energy set to 2.5 MeV and the number of incident protons set to 0-10 to correspond to the experimental irradiation energy and dose. The cascade collision process caused by protons was simulated using VASP software, with an irradiation time set to 5 ps and a time step of 1 fs. The irradiated structure was then relaxed to obtain a stable irradiated structure. The electrical properties of the structure after irradiation were calculated using VASP software, obtaining the band gap, carrier mobility, and dielectric constant. The CNT band structure before and after irradiation is shown below. Figure 5 As shown; subsequently, Geant4 software was used to simulate the charge deposition of the device under proton irradiation. The irradiation source was set to protons, with an incident energy and dose of 2.5 MeV and an irradiation dose of 15.4 × 10⁻⁶. 12 Gy. Step size set to 1nm. Charge deposition details as follows: Figure 5 As shown, analysis reveals that there is significant charge deposition in the charge deposition layer between the channel and the dielectric layer, exhibiting N-type doping and possessing a certain electron trapping capability.
[0033] d) Input the electrical properties of each component of the irradiated device and the doping type and concentration parameters of the charge deposition layer into the simulation model in process (b) to simulate the output characteristics of the device after irradiation. By comparing the output characteristics of the device before and after irradiation, the damage of high-energy proton irradiation to the back-gate CNT device can be evaluated. The simulated output characteristics of the irradiated device are as follows: Figure 6 As shown, the changes in device characteristics obtained in the experiment are basically consistent, proving the reliability of the evaluation method proposed in this invention. Furthermore, this result also indicates that under high-energy proton irradiation, the changes in the output characteristics of the back-gate CNT device mainly originate from the alteration of electrical properties such as the band gap in the CNT portion during proton-induced cascade collisions, as well as the significant N-type doping in the charge deposition layer.
[0034] The embodiments described above are merely illustrative of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that any modifications and alterations made to the present invention by those skilled in the art without departing from the concept of the technical solution of this application are within the scope of protection of this application.
Claims
1. A method for assessing high-energy proton irradiation damage to back-gate CNT devices, characterized in that, A charge deposition layer is set in the back-gate CNT device, with a structure of CNT / charge deposition layer / SiO2 / P-Si.
2. The back-gate CNT device as described in claim 1, characterized in that, In this device structure, CNT serves as the device channel, SiO2 serves as the dielectric layer, and a charge deposition layer with a thickness ranging from 0 to 20 nm is set between the two. P-Si serves as the device gate, and the gate and drain are located on both sides of the CNT channel.
3. The back-gate CNT device as described in claim 1, characterized in that, The charge deposition layer can be doped with P-type or N-type doping, with a doping concentration ranging from 0 to 1 × 10⁻⁶. 20 cm 3 .
4. The back-gate CNT device as described in claim 1, characterized in that, The CNT portion of the device is doped with P-type and N-type at both ends, and the P-Si portion is doped with phosphorus (P, Phosphorus). The source and drain of the device are located on both sides of the CNT, and their material composition includes, but is not limited to, gold (Au), titanium (Ti), and chromium (Cr).
5. The back-gate CNT device as described in claim 1, characterized in that, The CNT portion of the device can be either a single-walled CNT or a multi-walled CNT.
6. A method for assessing high-energy proton irradiation damage to back-gate CNT devices, characterized in that, Includes the following steps: (1) Establish a simulation model of a back-gate CNT containing a charge deposition layer; (2) Adjust the doping type and concentration of the charge deposition layer in the simulation model, as well as the electrical parameters such as band gap, carrier mobility, and carrier concentration of other components, to achieve accurate simulation of the device output characteristics under non-irradiation conditions; (3) Simulate the energy deposition and cascade collision process of the device under proton irradiation, obtain the changes in doping type and doping concentration of the charge deposition layer after proton irradiation, as well as the electrical parameters of other components; (4) Substitute the electrical characteristic parameters of the charge deposition layer and other components after irradiation into the simulation model in process (2) to simulate the output characteristics of the device after irradiation. By comparing the output characteristics of the device before and after irradiation, the damage of high-energy proton irradiation to the back gate CNT device can be evaluated.