Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific d...Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific discovery approach.The total ionizing dose(TID)effects usually cause gain degradation of bipolar junction transistors(BJTs),leading to functional failures of bipolar integrated circuits.Currently,many experiments of TID effects on BJTs have been conducted at different laboratories worldwide,producing a large amount of experimental data which provides a wealth of information.However,it is difficult to utilize these data effectively.In this study,we proposed a new artificial neural network(ANN)approach to analyze the experimental data of TID effects on BJTs An ANN model was built and trained using data collected from different experiments.The results indicate that the proposed ANN model has advantages in capturing nonlinear correlations and predicting the data.The trained ANN model suggests that the TID hardness of a BJT tends to increase with base current I.A possible cause for this finding was analyzed and confirmed through irradiation experiments.展开更多
The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradati...The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.展开更多
Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/...Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.展开更多
The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measur...The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measured before and after radiation. The experimental results show that threshold voltage and hole-field-effect mobility decrease, while sub-threshold swing and low-frequency noise increase with the increase of the total dose. The contributions of radiation induced interface states and oxide trapped charges to the shift of threshold voltage are also estimated. Furthermore, spatial distributions of oxide trapped charges before and after radiation are extracted based on the LFN measurements.展开更多
Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrie...Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrier effect （HCE） has also been proven to be very weak. In this paper, the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail, and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation. The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology. In addition, the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers （the annular source nMOSFETs） are also studied to provide a possible alternative for the designers.展开更多
Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships amon...Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.展开更多
This paper investigates the effects of gamma-ray irradiation on the Shallow-Trench Isolation （STI） leakage currents in 180-nm complementary metal oxide semiconductor technology. No hump effect in the subthreshold re...This paper investigates the effects of gamma-ray irradiation on the Shallow-Trench Isolation （STI） leakage currents in 180-nm complementary metal oxide semiconductor technology. No hump effect in the subthreshold region is observed after irradiation, which is considered to be due to the thin STI corner oxide thickness. A negative substrate bias could effectively suppress the STI leakage, but it also impairs the device characteristics. The three-dimensional simulation is introduced to understand the impact of substrate bias, Moreover, we propose a simple method for extracting the best substrate bias value, which not only eliminates the STI leakage but also has the least impact on the device characteristics.展开更多
The 1-Mb and 4-Mb commercial toggle magnetoresistive random-access memories（MRAMs） with 0.13 μm and 0.18-μm complementary metal–oxide–semiconductor（CMOS） process respectively and different magnetic tunneling j...The 1-Mb and 4-Mb commercial toggle magnetoresistive random-access memories（MRAMs） with 0.13 μm and 0.18-μm complementary metal–oxide–semiconductor（CMOS） process respectively and different magnetic tunneling junctions（MTJs） are irradiated with a Cobalt-60 gamma source. The electrical functions of devices during the irradiation and the room temperature annealing behavior are measured. Electrical failures are observed until the dose accumulates to 120-krad（Si） in 4-Mb MRAM while the 1-Mb MRAM keeps normal. Thus, the 0.13-μm process circuit exhibits better radiation tolerance than the 0.18-μm process circuit. However, a small quantity of read bit-errors randomly occurs only in 1-Mb MRAM during the irradiation while their electrical function is normal. It indicates that the store states of MTJ may be influenced by gamma radiation, although the electrical transport and magnetic properties are inherently immune to the radiation. We propose that the magnetic Compton scattering in the interaction of gamma ray with magnetic free layer may be the origin of the read bit-errors. Our results are useful for MRAM toward space application.展开更多
Radiation effects of the floating gate read-only-memory （FG ROM） and the static random access memory （SRAM） have been evaluated using the 14 MeV neutron and 31.9MeV proton beams and Co-60 γ-rays. The neutron flue...Radiation effects of the floating gate read-only-memory （FG ROM） and the static random access memory （SRAM） have been evaluated using the 14 MeV neutron and 31.9MeV proton beams and Co-60 γ-rays. The neutron fluence, when the first error occurs in the FG ROMs, is at least 5 orders of magnitude higher than that in the SRAMs, and the proton fluence, 4 orders of magnitude higher. The total dose threshold for Co-60 γ-ray irradiation is about 104 rad （Si） for both memories. The difference and similarity are attributed to the structure of the memory cells and the mechanism of radiation effects. It is concluded that the FG ROMs are more reliable as semiconductor memories for storing data than the SRAMs, when they are used in the satellites or space crafts exposed to high energy particle radiation.展开更多
Total dose effects and annealing behavior of domestic n-channel VDMOS devices under different bias conditions were investigated. The dependences of typical electrical parameters such as threshold voltage, breakdown vo...Total dose effects and annealing behavior of domestic n-channel VDMOS devices under different bias conditions were investigated. The dependences of typical electrical parameters such as threshold voltage, breakdown voltage, leakage current, and on-state resistance upon total dose were discussed. We also observed the relationships between these parameters and annealing time. The experiment results show that： the threshold voltage negatively shifts with the increasing of total dose and continues to decrease at the beginning of 100 ℃ annealing; the breakdown voltage under the drain bias voltage has passed through the pre-irradiation threshold voltage during annealing behaving with a ＂rebound＂ effect; there is a latent interface-trap buildup （LITB） phenomenon in the VDMOS devices; the leakage current is suppressed; and on-state resistance is almost kept constant during irradiation and annealing. Our experiment results are meaningful and important for further improvements in the design and processing.展开更多
Considering the growing global demand for energy and the need for countries to achieve climate goals,there is an increasing global interest in small modular reactors(SMRs)and their applications.Accident source term an...Considering the growing global demand for energy and the need for countries to achieve climate goals,there is an increasing global interest in small modular reactors(SMRs)and their applications.Accident source term and radiological consequence evaluations of SMRs are key components of nuclear and radiation safety reviews,which affect the site,exclusion area(EAB),and low population zone outer boundaries.Based on the design characteristics of the SMR and accident analysis results,a theoretical model of a whole-core fuel cladding damage accident was constructed to study the radioactivity released into the environment and its consequences.The accident source term and radiation dose calculation models were established to analyze the released amounts of radionuclides and the total effective dose affecting individuals at the site boundary.The results showed that the amount of radionuclides released into the environment after a whole-core fuel cladding damage accident reached 10^(14) Bq,among which the release amount of ^(133)Xe was the largest.The total effective dose at the site boundary 30 days after the accident was 8.65 mSv.The highest total effective dose affecting individuals occurred to the east-north-east.The results of the accident source term and radiological consequence provide technical support for site boundary dose assessments and reviews of SMRs.展开更多
Partially-depleted Silicon-On-Insulator Negative Channel Metal Oxide Semiconductor （SOI NMOS） transistors with different layouts are fabricated on radiation hard Separation by IMplanted OXygen （SIMOX） substrate an...Partially-depleted Silicon-On-Insulator Negative Channel Metal Oxide Semiconductor （SOI NMOS） transistors with different layouts are fabricated on radiation hard Separation by IMplanted OXygen （SIMOX） substrate and tested using 10 keV X-ray radiation sources. The radiation performance is characterized by transistor threshold voltage shift and transistor leakage currents as a function of the total dose up to 2.0×10^6 rad（Si）. The results show that the total dose radiation effects on NMOS devices are very sensitive to their layout structures.展开更多
This paper investigates the total ionizing dose response of different non-planar triple-gate transistor structures with different fin widths. By exposing the pseudo-MOS transistor to different amounts of radiation, di...This paper investigates the total ionizing dose response of different non-planar triple-gate transistor structures with different fin widths. By exposing the pseudo-MOS transistor to different amounts of radiation, different interface trap densities and trapped-oxide charges can be obtained. Using these parameters together with Altal 3D simulation software, the total dose radiation response of various non-planar triple-gate devices can be simulated. The behaviors of three kinds of non-planar devices are compared.展开更多
The worst-case radiation effect in deep-submicron SRAM （static random access memory） circuits is studied through theoretical analysis and experimental validation. Detailed analysis about the radiation effect in diff...The worst-case radiation effect in deep-submicron SRAM （static random access memory） circuits is studied through theoretical analysis and experimental validation. Detailed analysis about the radiation effect in different parts of circuitry is presented. For SRAM cells and a sense amplifier which includes flip-flop structures, their failure level against ionizing radiation will have a connection with the storage state during irradiation. They are inclined to store or read the same state as the one stored during irradiation. Worst-case test scheme for an SRAM circuit is presented, which contains a write operation that changes the storage states into the opposite ones after irradiation and then a read operation with opposite storage states. An irradiation experiment is designed for one 0.25 μm SRAM circuit which has a capacity of I k×8 bits. The failure level against ionizing radiation concluded from this test scheme （150 krad（Si）） is much lower than the one from the simplest test scheme （1 Mrad（Si））. It is obvious that the failure level will be overestimated if the simplest test scheme is chosen as the test standard for SRAM circuits against ionizing radiation.展开更多
Three methods for simulating low dose rate irradiation are presented and experimentally verified by using 0.18 μm CMOS transistors.The results show that it is the best way to use a series of high dose rate irradiatio...Three methods for simulating low dose rate irradiation are presented and experimentally verified by using 0.18 μm CMOS transistors.The results show that it is the best way to use a series of high dose rate irradiations, with 100 °C annealing steps in-between irradiation steps, to simulate a continuous low dose rate irradiation.This approach can reduce the low dose rate testing time by as much as a factor of 45 with respect to the actual 0.5 rad（Si）/s dose rate irradiation.The procedure also provides detailed information on the behavior of the test devices in a low dose rate environment.展开更多
The total ionizing dose（TID） response of 65-nm CMOS transistors is studied by 10-ke V x-ray and 3-Me V protons up to 1 Grad（SiO_2） total dose.The degradation levels induced by the two radiation sources are differe...The total ionizing dose（TID） response of 65-nm CMOS transistors is studied by 10-ke V x-ray and 3-Me V protons up to 1 Grad（SiO_2） total dose.The degradation levels induced by the two radiation sources are different to some extent.The main reason is the interface dose enhancement due to the thin gate oxide and the low energy photons.The holes＇ recombination also contributes to the difference.Compared to these two mechanisms,the influence of the dose rate is negligible.展开更多
A systemic solution for radiation hardened design is presented. Besides, a series of experiments have been carried out on the samples, and then the photoelectric response characteristic and spectral characteristic bef...A systemic solution for radiation hardened design is presented. Besides, a series of experiments have been carried out on the samples, and then the photoelectric response characteristic and spectral characteristic before and after the experiments have been comprehensively analyzed. The performance of the CMOS image sensor with the radiation hardened design technique realized total-dose resilience up to 300 krad（Si） and resilience to singleevent latch up for LET up to110 Me V cm^2/mg.展开更多
This study investigated the irradiation effect of cascode-structure GaN HEMT(High Electron Mobility Transistor)devices,employing high-energy electrons with an energy of 10 MeV and irradiation doses ranging from 5 to 8...This study investigated the irradiation effect of cascode-structure GaN HEMT(High Electron Mobility Transistor)devices,employing high-energy electrons with an energy of 10 MeV and irradiation doses ranging from 5 to 80 Mrad(Si).The variation of electrical properties of the device under annealing condition was analyzed.Geant4 and TCAD simulations were used to analyze the irradiation effect and damage mechanisms.The results show that the threshold voltage has obvious negative drift and the drain current increases after irradiation.The threshold voltage deviation amplitude of the device increases with the increase of irradiation dose,and the maximum deviation is 1.41V.Annealing at high temperatures(80℃,120℃ and 145℃)partially restores the electrical properties,with a 0.49 V restoration in threshold voltage at 145℃.Geant4 simulations reveal that enhanced Si MOSFET is more susceptible to total dose effects.TCAD simulations of enhanced Si MOSFET devices demonstrate an increase in electric field intensity,trapped electron concentration,and hole concentration in Si and SiO_(2) layers with the increase of irradiation dose.These findings can provide support for the space application and irradiation hardening of cascode GaN HEMT devices.展开更多
This paper describes an approach to prediction of the thick insulators＇ radiation response based on modeling of the charge yield, which is dependent on irradiation temperature, dose rate, and electric field magnitude...This paper describes an approach to prediction of the thick insulators＇ radiation response based on modeling of the charge yield, which is dependent on irradiation temperature, dose rate, and electric field magnitudes. Temperature behavior of the charge yield and degradation saturation due to the interface precursor depletion has been modeled and simulated. Competition between the time-dependent and true dose rate （ELDRS） effects has been simulated and discussed within a framework of the rate-equation-based mathematical model. It was shown that the precursor trap in the thick insulating oxides can be important at high dose rates. It was also shown that full filling of the shallow hole traps in the insulating oxide bulk can cause suppression of dose-rate sensitivity at relatively high dose rates, especially in thick insulators.展开更多
Total ionizing dose （TID） effect and single event effect （SEE） from space may cause serious effects on bulk silicon and silicon on insulator （SOl） devices, so designers must pay much attention to these bad effec...Total ionizing dose （TID） effect and single event effect （SEE） from space may cause serious effects on bulk silicon and silicon on insulator （SOl） devices, so designers must pay much attention to these bad effects to achieve better performance. This paper presents different radiation-hardened layout techniques to mitigate TID and SEE effect on bulk silicon and SOl device and their corresponding advantages and disadvantages are studied in detail. Under 0.13μm bulk silicon and SOl process technology, performance comparisons of two different kinds of DFF circuit are made, of which one kind is only hardened in layout （protection ring for bulk silicon DFF, T-gate for SO! DFF）, while the other kind is also hardened in schematic such as DICE structure. The result shows that static power and leakage of SOI DFF is lower than that of bulk silicon DFF, while SOI DFF with T-gate is a little slower than bulk silicon DFF with protection ring, which will provide useful guidance for radiation-hardened circuit and layout design.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 11690040 and 11690043)。
文摘Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific discovery approach.The total ionizing dose(TID)effects usually cause gain degradation of bipolar junction transistors(BJTs),leading to functional failures of bipolar integrated circuits.Currently,many experiments of TID effects on BJTs have been conducted at different laboratories worldwide,producing a large amount of experimental data which provides a wealth of information.However,it is difficult to utilize these data effectively.In this study,we proposed a new artificial neural network(ANN)approach to analyze the experimental data of TID effects on BJTs An ANN model was built and trained using data collected from different experiments.The results indicate that the proposed ANN model has advantages in capturing nonlinear correlations and predicting the data.The trained ANN model suggests that the TID hardness of a BJT tends to increase with base current I.A possible cause for this finding was analyzed and confirmed through irradiation experiments.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11475255,U1532261 and 11505282
文摘The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.
基金Supported by the National Natural Science Foundation of China under Grant No 616340084the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2014101+1 种基金the International Cooperation Project of Chinese Academy of Sciencesthe Austrian-Chinese Cooperative R&D Projects under Grant No 172511KYSB20150006
文摘Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61574048 and 61204112the Science and Technology Research Project of Guangdong Province under Grant Nos 2015B090912002 and 2014A030313656the Pearl River S&T Nova Program of Guangzhou
文摘The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measured before and after radiation. The experimental results show that threshold voltage and hole-field-effect mobility decrease, while sub-threshold swing and low-frequency noise increase with the increase of the total dose. The contributions of radiation induced interface states and oxide trapped charges to the shift of threshold voltage are also estimated. Furthermore, spatial distributions of oxide trapped charges before and after radiation are extracted based on the LFN measurements.
基金supported by the Key Program of the National Natural Science Foundation of China(Grant No.60836004)the National Natural Science Foundation of China(Grant Nos.61006070 and 61076025)
文摘Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrier effect （HCE） has also been proven to be very weak. In this paper, the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail, and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation. The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology. In addition, the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers （the annular source nMOSFETs） are also studied to provide a possible alternative for the designers.
文摘Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.
文摘This paper investigates the effects of gamma-ray irradiation on the Shallow-Trench Isolation （STI） leakage currents in 180-nm complementary metal oxide semiconductor technology. No hump effect in the subthreshold region is observed after irradiation, which is considered to be due to the thin STI corner oxide thickness. A negative substrate bias could effectively suppress the STI leakage, but it also impairs the device characteristics. The three-dimensional simulation is introduced to understand the impact of substrate bias, Moreover, we propose a simple method for extracting the best substrate bias value, which not only eliminates the STI leakage but also has the least impact on the device characteristics.
基金supported by the National Natural Science Foundation of China(Grant No.61404161)
文摘The 1-Mb and 4-Mb commercial toggle magnetoresistive random-access memories（MRAMs） with 0.13 μm and 0.18-μm complementary metal–oxide–semiconductor（CMOS） process respectively and different magnetic tunneling junctions（MTJs） are irradiated with a Cobalt-60 gamma source. The electrical functions of devices during the irradiation and the room temperature annealing behavior are measured. Electrical failures are observed until the dose accumulates to 120-krad（Si） in 4-Mb MRAM while the 1-Mb MRAM keeps normal. Thus, the 0.13-μm process circuit exhibits better radiation tolerance than the 0.18-μm process circuit. However, a small quantity of read bit-errors randomly occurs only in 1-Mb MRAM during the irradiation while their electrical function is normal. It indicates that the store states of MTJ may be influenced by gamma radiation, although the electrical transport and magnetic properties are inherently immune to the radiation. We propose that the magnetic Compton scattering in the interaction of gamma ray with magnetic free layer may be the origin of the read bit-errors. Our results are useful for MRAM toward space application.
文摘Radiation effects of the floating gate read-only-memory （FG ROM） and the static random access memory （SRAM） have been evaluated using the 14 MeV neutron and 31.9MeV proton beams and Co-60 γ-rays. The neutron fluence, when the first error occurs in the FG ROMs, is at least 5 orders of magnitude higher than that in the SRAMs, and the proton fluence, 4 orders of magnitude higher. The total dose threshold for Co-60 γ-ray irradiation is about 104 rad （Si） for both memories. The difference and similarity are attributed to the structure of the memory cells and the mechanism of radiation effects. It is concluded that the FG ROMs are more reliable as semiconductor memories for storing data than the SRAMs, when they are used in the satellites or space crafts exposed to high energy particle radiation.
文摘Total dose effects and annealing behavior of domestic n-channel VDMOS devices under different bias conditions were investigated. The dependences of typical electrical parameters such as threshold voltage, breakdown voltage, leakage current, and on-state resistance upon total dose were discussed. We also observed the relationships between these parameters and annealing time. The experiment results show that： the threshold voltage negatively shifts with the increasing of total dose and continues to decrease at the beginning of 100 ℃ annealing; the breakdown voltage under the drain bias voltage has passed through the pre-irradiation threshold voltage during annealing behaving with a ＂rebound＂ effect; there is a latent interface-trap buildup （LITB） phenomenon in the VDMOS devices; the leakage current is suppressed; and on-state resistance is almost kept constant during irradiation and annealing. Our experiment results are meaningful and important for further improvements in the design and processing.
文摘Considering the growing global demand for energy and the need for countries to achieve climate goals,there is an increasing global interest in small modular reactors(SMRs)and their applications.Accident source term and radiological consequence evaluations of SMRs are key components of nuclear and radiation safety reviews,which affect the site,exclusion area(EAB),and low population zone outer boundaries.Based on the design characteristics of the SMR and accident analysis results,a theoretical model of a whole-core fuel cladding damage accident was constructed to study the radioactivity released into the environment and its consequences.The accident source term and radiation dose calculation models were established to analyze the released amounts of radionuclides and the total effective dose affecting individuals at the site boundary.The results showed that the amount of radionuclides released into the environment after a whole-core fuel cladding damage accident reached 10^(14) Bq,among which the release amount of ^(133)Xe was the largest.The total effective dose at the site boundary 30 days after the accident was 8.65 mSv.The highest total effective dose affecting individuals occurred to the east-north-east.The results of the accident source term and radiological consequence provide technical support for site boundary dose assessments and reviews of SMRs.
文摘Partially-depleted Silicon-On-Insulator Negative Channel Metal Oxide Semiconductor （SOI NMOS） transistors with different layouts are fabricated on radiation hard Separation by IMplanted OXygen （SIMOX） substrate and tested using 10 keV X-ray radiation sources. The radiation performance is characterized by transistor threshold voltage shift and transistor leakage currents as a function of the total dose up to 2.0×10^6 rad（Si）. The results show that the total dose radiation effects on NMOS devices are very sensitive to their layout structures.
基金supported by the National Science Foundation for Young Scholars of China(No.11105092)the Shenzhen Science and Technology Development Funds(Nos.JC201005280565A,JC201005280558A,GJHS20120621142118853)
文摘This paper investigates the total ionizing dose response of different non-planar triple-gate transistor structures with different fin widths. By exposing the pseudo-MOS transistor to different amounts of radiation, different interface trap densities and trapped-oxide charges can be obtained. Using these parameters together with Altal 3D simulation software, the total dose radiation response of various non-planar triple-gate devices can be simulated. The behaviors of three kinds of non-planar devices are compared.
基金supported by National Natural Science Foundation of China(No.11175271)
文摘The worst-case radiation effect in deep-submicron SRAM （static random access memory） circuits is studied through theoretical analysis and experimental validation. Detailed analysis about the radiation effect in different parts of circuitry is presented. For SRAM cells and a sense amplifier which includes flip-flop structures, their failure level against ionizing radiation will have a connection with the storage state during irradiation. They are inclined to store or read the same state as the one stored during irradiation. Worst-case test scheme for an SRAM circuit is presented, which contains a write operation that changes the storage states into the opposite ones after irradiation and then a read operation with opposite storage states. An irradiation experiment is designed for one 0.25 μm SRAM circuit which has a capacity of I k×8 bits. The failure level against ionizing radiation concluded from this test scheme （150 krad（Si）） is much lower than the one from the simplest test scheme （1 Mrad（Si））. It is obvious that the failure level will be overestimated if the simplest test scheme is chosen as the test standard for SRAM circuits against ionizing radiation.
文摘Three methods for simulating low dose rate irradiation are presented and experimentally verified by using 0.18 μm CMOS transistors.The results show that it is the best way to use a series of high dose rate irradiations, with 100 °C annealing steps in-between irradiation steps, to simulate a continuous low dose rate irradiation.This approach can reduce the low dose rate testing time by as much as a factor of 45 with respect to the actual 0.5 rad（Si）/s dose rate irradiation.The procedure also provides detailed information on the behavior of the test devices in a low dose rate environment.
文摘The total ionizing dose（TID） response of 65-nm CMOS transistors is studied by 10-ke V x-ray and 3-Me V protons up to 1 Grad（SiO_2） total dose.The degradation levels induced by the two radiation sources are different to some extent.The main reason is the interface dose enhancement due to the thin gate oxide and the low energy photons.The holes＇ recombination also contributes to the difference.Compared to these two mechanisms,the influence of the dose rate is negligible.
文摘A systemic solution for radiation hardened design is presented. Besides, a series of experiments have been carried out on the samples, and then the photoelectric response characteristic and spectral characteristic before and after the experiments have been comprehensively analyzed. The performance of the CMOS image sensor with the radiation hardened design technique realized total-dose resilience up to 300 krad（Si） and resilience to singleevent latch up for LET up to110 Me V cm^2/mg.
基金supported by the Grant of National Key Laboratory of Materials Behavior and Evaluation Technology in Space Environment,China(WDZC-HGD-2022-11)State Key Laboratory of Artificial Microstructure and Mesoscopic Physics,China,and the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(No.SJCX23_1930)National Natural Science Foundation of China(NSFC)Youth Project“Study on the Generation and Evolutionary behavior of Proton Irradiation Defects in temperature-dependent CsPbBr3 quantum Dots”(Project No.:12305310).
文摘This study investigated the irradiation effect of cascode-structure GaN HEMT(High Electron Mobility Transistor)devices,employing high-energy electrons with an energy of 10 MeV and irradiation doses ranging from 5 to 80 Mrad(Si).The variation of electrical properties of the device under annealing condition was analyzed.Geant4 and TCAD simulations were used to analyze the irradiation effect and damage mechanisms.The results show that the threshold voltage has obvious negative drift and the drain current increases after irradiation.The threshold voltage deviation amplitude of the device increases with the increase of irradiation dose,and the maximum deviation is 1.41V.Annealing at high temperatures(80℃,120℃ and 145℃)partially restores the electrical properties,with a 0.49 V restoration in threshold voltage at 145℃.Geant4 simulations reveal that enhanced Si MOSFET is more susceptible to total dose effects.TCAD simulations of enhanced Si MOSFET devices demonstrate an increase in electric field intensity,trapped electron concentration,and hole concentration in Si and SiO_(2) layers with the increase of irradiation dose.These findings can provide support for the space application and irradiation hardening of cascode GaN HEMT devices.
文摘This paper describes an approach to prediction of the thick insulators＇ radiation response based on modeling of the charge yield, which is dependent on irradiation temperature, dose rate, and electric field magnitudes. Temperature behavior of the charge yield and degradation saturation due to the interface precursor depletion has been modeled and simulated. Competition between the time-dependent and true dose rate （ELDRS） effects has been simulated and discussed within a framework of the rate-equation-based mathematical model. It was shown that the precursor trap in the thick insulating oxides can be important at high dose rates. It was also shown that full filling of the shallow hole traps in the insulating oxide bulk can cause suppression of dose-rate sensitivity at relatively high dose rates, especially in thick insulators.
文摘Total ionizing dose （TID） effect and single event effect （SEE） from space may cause serious effects on bulk silicon and silicon on insulator （SOl） devices, so designers must pay much attention to these bad effects to achieve better performance. This paper presents different radiation-hardened layout techniques to mitigate TID and SEE effect on bulk silicon and SOl device and their corresponding advantages and disadvantages are studied in detail. Under 0.13μm bulk silicon and SOl process technology, performance comparisons of two different kinds of DFF circuit are made, of which one kind is only hardened in layout （protection ring for bulk silicon DFF, T-gate for SO! DFF）, while the other kind is also hardened in schematic such as DICE structure. The result shows that static power and leakage of SOI DFF is lower than that of bulk silicon DFF, while SOI DFF with T-gate is a little slower than bulk silicon DFF with protection ring, which will provide useful guidance for radiation-hardened circuit and layout design.
