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The effect of super-cadmium neutron-induced defects on radiation detection performance of Schottky barrier diodes, fabricated on 250- $\mu \text{m}$ -thick 4H-SiC epitaxial layers with ultralow intrinsic defect concentration, has been studied. The epilayers were irradiated in a TRIGA Mark II nuclear reactor dry instrumentation tube [intrareflector irradiation system or (IRIS)] in the net neutron fluence range 1010–1013 cm−2. Current–voltage (I–V) and capacitance–voltage (C–V) characteristics revealed that the detectors irradiated up to a fluence of 1012 cm−2 maintained a Schottky diode behavior. Radiation detection measurements showed an energy resolution of 28 keV (0.5%) full-width at half-maximum (FWHM) when exposed to 5486-keV alpha particles for the epilayers irradiated up to a neutron fluence of 1011 cm−2, which broadened to 42 keV (0.8%) FWHM for a fluence of 1012 cm−2. I–V and C–V measurements revealed substantial donor compensation in the epilayer irradiated at a fluence of ~1013 cm−2; however, the detector still worked satisfactorily with an energy resolution of 76-keV (1.8%) FWHM. The degradation in the detector performance with increased neutron dose was attributed to the trapping of charge carriers in the radiation-induced trap centers. Deep-level transient spectroscopy studies in the detector irradiated with a fluence of 1010 cm−2 revealed the formation of EH5 centers along with an unidentified deep electron trap located at 1.8 eV below the conduction band edge, both usually absent in as-grown 250- $\mu \text{m}$ 4H-SiC epilayers. A drift-diffusion model of charge transport showed a degradation in hole diffusion length from 10 $\mu \text{m}$ at a neutron fluence of 1010 cm−2 to $2.6~\mu \text{m}$ at 1012 cm−2 indicating formation of hole-trap centers as well. [ABSTRACT FROM AUTHOR]

A critical step of radiation hardness assurance (RHA) for space systems is given by the parts selection in accordance with the observed (or estimated) radiation effects. Although radiation testing is the most decisive way of studying the radiation degradation of electronic components, the increasing use of commercial off-the-shelf (COTS) devices and the challenges posed by NewSpace are pushing the need of finding new approaches to assess the risk associated with radiation environments. This work tries to evaluate if valuable information might be extracted from archival data to carry out this assessment despite the well-known and dramatic lot-to-lot, or even part-to-part, variability for some technologies and the impact of the different test conditions, such as the bias conditions and the dose rate in enhanced low dose rate sensitivity (ELDRS). These factors are briefly analyzed for some examples. A new radiation database is briefly introduced, and some statistical approaches are cited, apart from the analysis herein followed. To finish, a first analysis on three families of bipolar transistors is presented together with the independent results from three external reports, with a good agreement between the experimental results and the expected ones. [ABSTRACT FROM AUTHOR]

This article investigates and assesses neutron radiation effects on attitude estimation (AE) processing, typically embedded in inertial navigation systems (INSs) and upcoming autonomous things. Findings highlight the importance of radiation-induced critical failures that can upset the on-board AE processing and consequently the inertial navigation. Radiation tests and analyses were conducted by considering as on-board AE processing the execution of classical AE algorithm on multi-core computer hardware exposed to 14-MeV neutron and thermal neutron radiation. Three computing strategies and different case-study scenarios were tested and compared. Results suggest that the contribution of radiation-induced soft errors to be mitigated on the embedded AE processing is essentially related to single-event functional interrupts (SEFIs) that can lead the inertial navigation to critical failures. [ABSTRACT FROM AUTHOR]

This article compares and assesses the effectiveness of three prominent machine learning (ML) models for tiny ML computing systems in tolerating neutron-induced soft errors. Results of 14-MeV and thermal neutron radiation tests suggest that the three case-study ML algorithms implemented—without any mitigation technique integrated—retain a certain intrinsic level of effectiveness in tolerating neutron effects, although all of them have been functionally interrupted on some occasions, requiring hardware resets. Notably, the implemented case-study ML algorithm “random forest” has performed no misclassification during the different radiation testing campaigns. [ABSTRACT FROM AUTHOR]

A benchmark between various radiation monitors employed at CERN for radiation to electronics applications and their simulated values with the FLUKA Monte Carlo is performed at the CHARM mixed-field irradiation facility. Comparisons are made for different operational conditions, using data recorded in the 2015–2018 period. [ABSTRACT FROM AUTHOR]

We investigated in situ the temperature influence on X-ray radiation-induced attenuation (RIA) levels and kinetics of an Al-doped single-mode optical fiber (OF) in the visible (vis) and near-infrared (NIR) spectral domains (400 nm– $2~\mu \text{m}$ , from room temperature (RT) up to 300 °C). The RIA spectra in the visible show no significant variation up to 200 °C. Above this temperature, the induced losses begin to decrease. The NIR RIA, on the other hand, appears to be more temperature-dependent, showing a monotonic decrease with increasing temperature throughout the whole investigated range. By studying the RIA growth kinetics at 1550 nm at the various temperatures, a linear dependence was found between the RIA levels and doses at which a steady state is reached, suggesting a direct generation process of the induced defects. Finally, the combination of the measurements led to the attribution of the RIA in the NIR domain to a single absorption component, whose generation process is correlated with the defects absorbing in the visible and characterized by a continuum of absorption states. [ABSTRACT FROM AUTHOR]

We investigated the X-ray radiation impact on the performances of “backup” erbium-doped fiber amplifiers (EDFAs) and erbium-ytterbium-doped fiber amplifier (EYDFA). These devices are exposed to the space radiation constraints, unpowered in the “OFF” mode, up to their hypothetic activation during the mission. This atypical profile of use must be considered as it could lead to a higher radiation vulnerability. To carry out this study, active optical fibers differing in terms of radiation hardness have been exposed to steady-state X-rays under different profiles of amplifier use: the gain degradation is measured by varying the pumping conditions, that drive the photobleaching (PB) phenomenon, during the radiation exposure: “ON” (100% ON), “OFF” (0% ON), and “OFF–ON–OFF” with powering 2% or 10% of the time. Our results show that the impact of the pump and its related PB efficiency depend on the selected active fiber to build the amplifier. An important result is that the “backup” EDFA designed with radiation-hardened Ce-doped fiber does not suffer from an extra-degradation due to the “OFF” mode, contrary to the one designed with a nonrad-hard fiber. For this latter one, it is indeed possible to reduce the extra-gain degradation by powering the amplifier for short time periods during the “OFF” state; otherwise, the EDFA recovers this extra-gain degradation in a few hours after turning “ON” in our test conditions. For the tested radiation-tolerant EYDFA, an enhanced vulnerability is observed for the “OFF” amplifier, that can be reduced too by briefly powering the amplifier. The origins of these effects are discussed based on the properties of point defects related to the aluminosilicate (EDFA) and phosphosilicate (EYDFA) glasses of the fiber. [ABSTRACT FROM AUTHOR]

This work presents an radiation hardness assurance (RHA) methodology that combines both component and system level data to predict system-level reliability, based on system instrumentation for system-level testing. The methodology is illustrated by its application to two system-on-modules based on recent generations of system-on-chips irradiated with protons. [ABSTRACT FROM AUTHOR]

The radioluminescence (RL) response under X-rays is investigated for five different types of multimode silica-based optical fibers doped with Ge, P, Al, F, or Ce. The results indicate that all tested fibers show a measurable RL signal at dose rates from 0.1 to 15 Gy(SiO2)/s, using 10-cm-long samples and a photomultiplier-based acquisition chain. Other influences of radiation, such as radiation-induced attenuation, are discussed in order to evaluate the potential of such fiber types for radiation detection or dosimetry applications. [ABSTRACT FROM AUTHOR]

Laser-assisted simulation is a fast, simple, and effective method for studying dose-rate effects. However, in some compound radiation environments (e.g., the coexistence of transient $\gamma $ -rays and neutrons), the effectiveness of laser simulation has not been studied. This article investigates the feasibility of laser-assisted simulation of the dose-rate effects of neutron-irradiated bipolar transistors by using a sequential radiation method. The accuracy of laser simulation is calculated by using peak photocurrent and charge collection as the equivalent factor, respectively. According to the comparison of the transient parameters (e.g., transient rise/fall time, transient duration time, peak magnitude, collected charge, correlation coefficients) between laser and $\gamma $ -rays, it is proved that the laser-assisted simulation method still works. This means a laser with proper parameters can be used to construct a compound radiation environment with neutron sources, which can provide a powerful solution for the study of the transient co-interaction process of the ionization effects and displacement effects in materials and devices. [ABSTRACT FROM AUTHOR]

Dosimetry Intercomparison and Miniaturization Experiment (DIME-1) is an experiment flying as part of NASA’s Space Experimental Testbed (SET-1) satellite project on the Air Force’s Demonstration and Science Experiments (DSX) satellite to compare novel dosimeters with the standard radiation field-effect transistor (RadFET) dosimeters. It consists of five operational RadFETs under different thicknesses of hemispherical Al and Ta shields and three commercial-off-the-shelf (COTS) floating-gate MOS transistor (FGMOS) UV Proms programmed as dosimeters. The flight path crosses the entire slot region and cuts the Van Allen belts on each 5.25-h orbit of the Earth. The dosimeters on DIME-1 and its sister board DIME-2, consisting of two linear energy transfer (LET) spectrometers, are capable of measuring total ionizing dose (TID) and single-event effects (SEEs) which are responsible for degrading or causing catastrophic failure of electronic circuits in space. Results comparing the different dosimeters with the standard RadFET devices are shown to be in quite good agreement in terms of the shape of the total dose versus time plots over the 1.75 year life of the DSX mission but not in agreement over the TID measured presumably due to short-range protons reaching the sensitive volume of FGMOS devices but not reaching that of RadFETs. DIME-1 traveled into a radiation environment that well-designed circuits, flown during solar minimum, will survive. [ABSTRACT FROM AUTHOR]

Total-ionizing-dose (TID) radiation response for 700 V double reduced surface field (RESURF) silicon-on-insulator (SOI) lateral double-diffused metal-oxide-silicon (LDMOS) is investigated in this article. Degradation mechanisms of breakdown voltage (BV), threshold voltage ($V_{\mathrm {th}}$), linear drain current ($I_{d\mathrm {lin}}$), and saturated drain current ($I_{d\mathrm {sat}}$) are revealed by simulation. Multi-interface irradiation damage with oxide trapped charge generation is analyzed, which causes complex modulation on electric field distribution and carrier transport. BV degradation is ascribed to the original charge balance broken in bulk. The doping concentration of the P-top layer is equivalently reduced by oxide trapped charge in field oxide (FOX), and the doping concentration of the N-drift region is equivalently increased by oxide trapped charge in buried oxide. Consequently, the surface electric field at source side is enhanced, and a more uniform distribution is achieved, resulting in BV increased. $I_{d\mathrm {lin}}$ and $I_{d\mathrm {sat}}$ increasing are ascribed to ON-resistance reduced. The inversion layer in the P-top layer and the accumulation layer at the bottom of the N-drift region provide low resistance conduction paths. Compared to $I_{d\mathrm {sat}}$ , $I_{d\mathrm {lin}}$ shows insensitivity to oxide trapped charge in FOX layer because of the P-top layer shielding at a low drain voltage ($V_{d}$). [ABSTRACT FROM AUTHOR]

Low-gain avalanche diode (LGAD) is the chosen technology for the ATLAS high-granularity timing detector (HGTD). According to previous studies, the acceptor removal effect due to the radiation and the single-event burnout (SEB) at high bias voltages are still a challenge for the LGAD. The Institute of High Energy Physics (IHEP), Beijing, China, cooperated with the Institute of Microelectronics (IME), Beijing, China, for the design and fabrication of the IHEP-IME LGAD sensors with shallow carbon and deep N++ layer to improve the radiation hardness of LGAD. After neutron irradiation up to $2.5 \times 10^{15}\,\,{\mathrm{ n}}_{\mathrm{ eq}}$ /cm2, the leakage current, the collected charge, and timing resolution of the three IHEP-IME sensors measured with a beta telescope setup meet the HGTD requirements ($< 125~\mu \text{A}$ /cm2, >4 fC, and <70 ps). The LGAD sensor with shallow carbon had the lowest operation voltage after irradiation and is very promising to avoid the SEB effect. A sensor with a deep N++ layer increased the breakdown voltage of the LGAD with a high dopant concentration, which could alleviate the problem of the early breakdown of radiation-hard LGAD before irradiation. [ABSTRACT FROM AUTHOR]

Analog single-event transient (ASET) and total ionizing dose (TID) characterization of a radiation-hardened bandgap voltage reference (BGR) is investigated in a 28-nm commercial bulk CMOS technology. Different radiation hardened by design (RHBD) techniques are used for ASET mitigation in the circuit and layout, and the circuit is optimized to ensure the BGR can still work correctly even using fast nMOS and slow pMOS for TID mitigation. Heavy-ion (linear energy transfer (LET) = 76.3 MeV $\cdot $ cm2/mg) experiments show the maximum amplitude of positive (negative) ASET is just 30 mV (90 mV), and Co60 gamma-ray experiments show the maximum output voltage reduction is just 37 mV after 1.2 Mrad(Si) irradiation, and the final output voltage reduction is just 11 mV after 48 h of annealing. All of the experiments indicate that ASET is significantly mitigated by the RHBD techniques, and the BGR has naturally good TID response due to the design margin. The investigation also indicates that the proposed BGR is a good substitute for space application due to the excellent ASET and TID tolerance capability. [ABSTRACT FROM AUTHOR]

An overview is presented of displacement damage (DD) effects, total-ionizing-dose (TID) effects, and single-event effects in AlGaN/GaN high electron mobility transistors (HEMTs). High-fluence proton-induced DD creates point defects and impurity complexes at fluences that are comparable to or higher than those encountered in space applications. Defect and impurity dehydrogenation also contributes significantly to the DD/TID response at fluences typical of realistic space environments. The bias applied during irradiation can affect the DD/TID response strongly. Bias stress before irradiation can lead to enhanced proton-induced degradation of AlGaN/GaN HEMTs. Low-frequency noise measurements and density functional calculations provide insight into defect microstructures and energy levels. GaN-based HEMTs can be quite vulnerable to single-event effects in space. Of particular concern is single-event burnout (SEB). The vulnerabilities of GaN-based devices to SEB at voltages below rated limits and significant device-to-device variations in SEB response lead to significant voltage derating for GaN-based power devices in space systems. Developing an improved understanding of the effects of defects and hydrogen on the radiation response of AlGaN/GaN HEMTs can improve the DD/TID response by reducing threshold-voltage shifts and transconductance degradation. Reducing defect densities may also reduce the variation in SEB response, enabling reliable device operation at higher voltages in future space systems. [ABSTRACT FROM AUTHOR]

This article investigates the transient dose rate effect (TDRE) of two types of level-shifting transceivers. Experimental results show that both transceivers have a high latch-up threshold. One uncommon phenomenon is found that there are photocurrents generated at the input ports for both transceivers when exposed to transient $\gamma $ radiation. Moreover, the polarity and amplitude of the photocurrents are related to the input voltage level. A hypothesis is proposed that this uncommon phenomenon is caused by the electrostatic discharge (ESD) circuits at the input ports and then it is successfully verified by TCAD simulations. The simulation results show that the vertical parasitic p-n-p transistor in pMOS of the ESD circuit could turn on under transient $\gamma $ radiation, and generate a positive photocurrent when the input port is configured to high-level voltage. On the contrary, when the input port is configured to low-level voltage, its lateral parasitic p-n-p transistor in pMOS could turn on and generate a negative photocurrent. The amplitude of the positive photocurrent is obviously larger than the negative photocurrent due to different gains of the parasitic transistors. Simulation results also show the number of pMOSs in n-well has significant impacts on the amplitude of photocurrents. [ABSTRACT FROM AUTHOR]

GYGAG(Ce) transparent ceramic garnet scintillators were irradiated with electrons from 0.5 to 2 MeV with fluences from $10^{16}\,\,\text{e}^{-}$ /cm2 to $10^{19}\,\,\text{e}^{-}$ /cm2, corresponding to doses from 0.3 to 310 Gigarad. Absorption spectra were measured before and after irradiations. Light yields from alpha, beta, and gamma excitations were measured before and after irradiation and compared to preirradiation values to gain a deeper understanding of how electron irradiations can affect light yield, as well as defects generated in both the surface and bulk. Within experimental error, no degradation in light yield was observed for the electron-irradiated samples, as measured via beta or gamma excitation, with minimal degradation observed via alpha excitation. A small increase in optical absorption near the wavelength of emission was observed following the largest dose irradiation. These results suggest that GYGAG(Ce) is radiation hard to electron irradiation up to $10^{19}\,\,\text{e}^{-}$ /cm2 and doses up to 310 Gigarad. This robustness to irradiation indicates that transparent ceramic garnets may prove useful for applications such as scintillation-based nuclear batteries by allowing for higher energy beta emitters, increased power densities, and enabling long service lifetimes. [ABSTRACT FROM AUTHOR]

Double silicon-on-insulator (DSOI) technology featuring two buried oxide layers under silicon film has drawn excessive attention to space applications by modulating the electric field in back channel. This article studied the impact of the total ionizing dose (TID) effect on the n-channel metal oxide semiconductor field effect transistors (nMOSFETs) based on DSOI materials. Radiation-induced degradation in performance only appeared in the metal oxide semiconductor field effect transistor (MOSFET) with $W/L = 0.15~\mu \text{m}$ /10 $\mu \text{m}$ after 1.5 Mrad(Si) irradiation and recovered with negative $V_{\mathrm {bg}}$ applied. However, due to the weak coupling effect between the front and back gates, the threshold voltage ($V_{\mathrm {th}}$) of nMOSFET with $W/L = 10~\mu \text{m}$ /10 $\mu \text{m}$ and $10~\mu \text{m}/0.13~\mu \text{m}$ declined 0.06 V compared with devices before irradiation when $V_{\mathrm {bg}}$ is set to 0 V. The TCAD simulation and testing results reveal that the electric field introduced by negative back-gate bias could effectively mitigate the TID-induced performance degradation in DSOI nMOSFETs. The investigation will facilitate the application of DSOI technology for high-radiation-dose conditions. [ABSTRACT FROM AUTHOR]

We report on the radiation response of a novel p-type photogate pixel. Sensors are exposed to gamma rays, and fusion neutrons during deuterium plasma operation at W–Tungsten–Environment in Steady-state Tokamak (WEST), showing dark current increase with total dose. [ABSTRACT FROM AUTHOR]

The effects of total ionizing dose (TID) on MOSFETs fabricated in a 22-nm fully depleted silicon-on-insulator (FD-SOI) technology are analyzed. TID causes positive-trapped charge to accumulate in transistor isolation regions [e.g., the buried oxide (BOX)], thereby generating negative TID-induced threshold-voltage shifts $\Delta V_{\mathrm {th}}$ that facilitate nMOSFET turn-on and inhibit pMOSFET turn-on. Back-gate biasing options in the technology can be used to offset the threshold-voltage shifts. Applying a bias to the back gates of MOSFETs in a conventional-well back-gate configuration mitigates TID-induced $\Delta V_{\mathrm {th}}$ in nMOSFETs (where a negative bias is applied to the P-well back-gate), while enhancing the same in pMOSFETs (where a positive bias is applied to the N-well back-gate). To mitigate and potentially reverse TID-induced $\Delta V_{\mathrm {th}}$ of both nMOSFETs and pMOSFETs simultaneously, a single back-gate bias can be applied to MOSFETs in a common isolated P-well back-gate configuration. 3-D technology computer-aided design (3-D TCAD) device simulation results of the 22-nm FD-SOI technology confirm the conventional-well circuit-level radiation response and support the effectiveness of using the common isolated P-well back-gate configuration for TID mitigation. These results justify the utility of dynamically tuning back-gate bias according to actively monitored TID-induced $\Delta V_{\mathrm {th}}$ feedback. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) has attracted great attention as a structural material for advanced microelectromechanical systems (MEMS), thanks to its excellent ensemble of electrical and mechanical properties. Here, we report on studying the effects of ion radiation-induced displacement damage on resonant MEMS made of GaN film grown on aluminum nitride (AlN) buffer layer. We design and fabricate GaN/AlN heterostructure doubly-clamped microstring resonators with length $L \,\, =100$ , 200, 300, 400, 500, 600, and 700 $\mu \text{m}$ , and irradiate the devices with 440-keV Ar $^{+}$ ions, to probe the effects of ion radiation-induced displacement damage on the resonance behavior. The ion energy and range have been selected so that the ions would stop within the GaN layer, thus allowing diagnostics to show the effects of damage in the structure. The multimode resonance frequencies of the devices decrease significantly ($\vert \Delta f\vert /f >50$ %) with the increase of fluence beyond 1014 cm−2. According to scanning electron microscopy (SEM) imaging, the irradiated GaN/AlN resonators are visibly deformed at high fluence, where the amount of curvature increases monotonically with the fluence. The deformation of the structures can be ascribed to the change in both Young’s modulus and built-in stress resulting from ion radiation-induced displacement damage. The results extend the understanding of radiation-induced damage mechanisms in resonant MEMS. [ABSTRACT FROM AUTHOR]

Nowadays, high-performance microprocessors are demanded in many fields, including those with high-reliability requirements. Commercial microprocessors present a good tradeoff between cost, size, and performance, albeit they must be adapted to satisfy the reliability requirements when they are used in harsh environments. This work presents a high-end multiprocessor hardened with macrosynchronized lockstep and additional protections. A commercial dual-core Advanced RISC Machine (ARM) cortex A9 has been used as a case study and a complete hardened system has been developed. Evaluation of the proposed hardened system has been accomplished with exhaustive fault injection campaigns and proton irradiation. The hardening approach has been accomplished for both baremetal applications and operating system (OS)-based. The hardened system has demonstrated high reliability in all performed experiments with error coverage up to 99.3% in the irradiation experiments. Experimental irradiation results demonstrate a cross-sectional reduction of two orders of magnitude. [ABSTRACT FROM AUTHOR]

Integrated silicon microwave pin diodes are exposed to 10-keV X-rays up to a dose of 2 Mrad(SiO2) and 14-MeV fast neutrons up to a fluence of $2.2\,\,\boldsymbol {\times }\,\,10\,\,^{\mathrm{ 13}}$ cm−2. Changes in both dc leakage current and small-signal circuit components are examined. Degradation in performance due to total-ionizing dose (TID) is shown to be suppressed by non-quasi-static (NQS) effects during radio frequency (RF) operation. Tolerance to displacement damage from fast neutrons is also observed, which is explained using technology computer-aided design (TCAD) simulations. Overall, the characterized pin diodes are tolerant to cumulative radiation at levels consistent with space applications such as geosynchronous weather satellites. [ABSTRACT FROM AUTHOR]

This article studies the radiation effects on the junction leakage random telegraph signal (JL-RTS). Using arrays of transistors, a statistical study of the phenomenon in MOSFETs source p-n junctions is performed and the impact of the electric field, the type of irradiation, and the source design is investigated. It appears that although JL-RTS originates both from the displacement damage dose (DDD)- and total ionizing dose (TID)-induced defects, the latter is the dominant contribution in MOSFETs sources due to an electric field enhancement (EFE). This article then completes the study with ab initio molecular simulations to investigate the origin of the JL-RTS. The results advocate for the adoption of the structural fluctuation model over the state charge fluctuation model to describe the origin of the phenomenon. [ABSTRACT FROM AUTHOR]

Model-order reduction (MOR) is a numerical approach that has been successfully applied across many disciplines to obtain computationally efficient reduced-order models (ROMs). Despite these successes and the potential to avoid physical assumptions and approximations, MOR has not yet been explored for the development of compact photocurrent models, where traditional analytic techniques dominate. In this article, we demonstrate the viability of MOR in this context by using proper orthogonal decomposition to develop a hybrid analytic-numerical compact model, which replaces analytic solutions of the ambipolar diffusion equation with numerical ROM solutions. We demonstrate our model by comparing its predictions with those of a state-of-the-art analytic model using photocurrent measurements obtained at the Little Mountain Test Facility. [ABSTRACT FROM AUTHOR]

In the aerospace industry, commercial-off-the-shelf (COTS) static random access memories (SRAMs) are a cost-effective solution for obtaining high performance at the system level, which is difficult to obtain using space-qualified components. In addition, the usage of dynamic voltage scaling (DVS) is commonly used in space environments, where low power consumption is a critical issue. This article presents an analysis of the sensitivity against single-event upsets (SEUs) of various COTS bulk SRAMs and advanced low-power SRAMs (A-LPSRAMs) against proton radiation when using DVS to save power. Experimental results will show clear evidence that the sensitivity to SEUs increases when the power is lowered. Two sets of successive technologies (130-, 90-, and 65-nm bulk SRAMs, and 150- and 110-nm A-LPSRAMs) are evaluated against 15-MeV protons and compared with results of 14-MeV neutrons presented in a previous work. Experimental data are finally compared with analytical simulations obtained by using the multiscales single-event phenomena predictive platform (MUSCA-SEP3) Monte Carlo tool to predict the effect of DVS on the SEE sensitivity on more modern technologies in the ITRS/IRDS roadmap. [ABSTRACT FROM AUTHOR]

Effects of ~35 years of aging during storage are investigated on the radiation response and 1/ $f$ noise of Oki nMOS and pMOS transistors with high oxygen vacancy densities in SiO2. Short-term interface-trap buildup during irradiation is enhanced significantly, relative to that observed in 1989, 1997, and 2008. In contrast, a similar latent interface-trap buildup is observed for aged pMOS devices irradiated and annealed at room and elevated temperatures at positive bias in this and earlier studies. The significant latent interface-trap buildup is observed for nMOS devices irradiated at 0 V and annealed at room and elevated temperatures under positive bias, a condition not evaluated in prior work. Results strongly suggest that latent interface-trap buildup is due to H2 diffusion and dissociation at charged or dipolar O vacancies in SiO2, followed by proton transport to the Si/SiO2 interface and reactions with Si–H complexes. Models that attribute latent interface-trap buildup to long-term proton trapping at O vacancies in SiO2 appear to be ruled out by these results. Additional insight is provided into mechanisms of postirradiation interface- and border-trap buildup after long-term MOS device storage. [ABSTRACT FROM AUTHOR]

Recent advancements in radiation detection and computer vision have enabled small unmanned aerial systems (sUASs) to produce 3-D radiation maps, for example, composed of gamma rays and neutrons, in real time. Currently, these state-of-the-art systems require two operators: one to pilot the sUAS and another operator to monitor the detected radiation. In this work, we present a system that integrates real-time 3-D radiation visualization with semi-autonomous sUAS control. Our virtual reality (VR) interface enables a single operator to define trajectories using waypoints to abstract complex flight control and utilize the semi-autonomous maneuvering capabilities of the sUAS. The interface also displays a fused radiation visualization and environment map, thereby enabling simultaneous remote operation and radiation monitoring by a single operator. This interface and its underlying framework serves as the basis for development of a single system that can deploy and autonomously control a fleet of radiation-mapping sUASs. [ABSTRACT FROM AUTHOR]

Total ionizing dose (TID) degradation is caused by radiation-induced charge buildup in oxides. Radiation hardening of silicon-on-insulator (SOI) devices with deep submicrometer nodes or nanonodes is mainly concerned with the field oxide and buried oxide. In this article, a back-channel adjustment technique for TID hardening is proposed. The technique is compatible with the 130-nm partially depleted silicon on an insulator (PDSOI) commercial process with no extra effort applied to the design. After testing the key electrical parameters and characterizing the radiation tolerance of the typical T-gate I/O nMOS devices, the results show that the radiation tolerance of the devices can reach more than 1 Mrad(Si) with the back-channel adjustment technique, and electrical performance is comparable to that of commercial process devices. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) power switches are promising devices for power conversion applications because this new technology enables the design of power converters with higher efficiency and reduced size than those achievable with conventional silicon devices. For space applications, normally-OFF devices are mandatory to avoid potential current shoot through during startup or loss of power control. The use of these devices in space environment shall be carefully considered with respect to natural radiation and especially under heavy-ion impact that can induce the burnout of the device known as single-event effect (SEE) failure. Therefore, radiation hardness evaluation of GaN devices is of prime interest. Another important parameter affecting GaN power device reliability is the current collapse or dynamic $R_{\mathrm{\scriptscriptstyle ON}}$ since in particular functioning condition, the device can generate extra losses that may lead to failure. Five commercial off-the-shelf (COTS) GaN high-electron-mobility transistor (HEMT) references were selected and tested under heavy ions. This article presents first the testing methodology and device preparation used for heavy-ion test campaign. Then observations from the irradiation run are presented and discussed. At last, a potential dynamic $R_{\mathrm{\scriptscriptstyle ON}}$ issue with respect to heavy-ion safe operating area (SOA) of one reference is highlighted. [ABSTRACT FROM AUTHOR]

Radiation-hard photodiode structures implemented in medical applications are designed in 180-nm CMOS technology. Designed photodiodes were tested against total ionizing doses (TIDs) of 100, 200, and 400 Gy(Si), respectively, and they show high stability in terms of dark current characteristics. After TID of 400 Gy(Si), the dark current increased by up to 15%, compared to the unirradiated characteristics values. TCAD electrical simulations were performed and calibrated with the dark current measurements in order to explain the impact of generated defects due to ionizing radiation. Parameters that are used to model TID radiation have been varied in physical boundaries in order to achieve the desired fitting with the measurements. It is shown that due to the filling of acceptor interface traps with electrons, the space charge region extends, but the extension is limited and partially compensated by the fixed positive charges in the silicon nitride layer. The presented photodiodes result in the improved radiation hardness over the design in 350-nm CMOS technology. [ABSTRACT FROM AUTHOR]

In this study, we present a preprocess method using radiation energy intervals on a gamma-ray spectrum based on a deep learning algorithm to achieve real-time radionuclide identification. Data preprocessing is performed by classifying energy intervals, distinctly corresponding to pulse amplitudes of each radiation measurement system. Since the energy intervals are distinguished with noise, backscatter area, Compton edge, and photopeaks depending on radionuclides, raw data are sorted in each interval in preprocessed dataset using a deep learning algorithm. Using60Co,137Cs, and the energy interval preprocessing, the multi-source identification shows 100% accuracy in 2000 measured data compared with 70% accuracy for those without the preprocessing method. The measured time is 72 s for 2000 test data, dramatically reduced from the conventional data collection time of 60 min for 100 000 data. The proposed approach reduces the minimum number of data to identify radionuclides before visualizing the spectrum. With the preprocess method, radionuclide identification is completed in tens of seconds, applicable for low radiation activity areas such as decommissioning reactor sites. [ABSTRACT FROM AUTHOR]

We investigate the radiation effects on a Brillouin-based optical fiber sensor (OFS). This OFS exploits a single-mode optical fiber (SMF) having a Brillouin signature presenting multiple peaks. This specificity allows performing distributed and discriminated measurements of the temperature and strain time evolutions along the fiber. The particular structure (composition and refractive-index profile) of the investigated SMF was first conceived and optimized, thanks to a home-made simulation tool to assess its capability to discriminate between the two environmental parameters. At the same time, it should also present a good radiation tolerance in order that the sensor could operate in radiation-rich environments (up to MGy levels). The modeled germanosilicate SMF has then been manufactured by the modified chemical vapor deposition process by iXblue and its sensing performances have been experimentally demonstrated. Samples of the SMF have been irradiated under steady-state X-rays at a dose rate of 2.3 Gy(SiO2)/s up to 180 kGy at room temperature. The radiation tests showed that the Brillouin sensor can be implemented in such severe environments. At these dose levels, radiation-induced errors are limited to ~ 3 °C and ~ 0.15 με in the worst conditions. Finally, we discuss perspectives about possible new fiber structures to target even more challenging applications in terms of radiations and sensing requirements. [ABSTRACT FROM AUTHOR]

We develop methods for bounding part-to-part variation in total ionizing dose (TID) data. When used in conjunction with statistical radiation environment models, these methods allow development of RHA that deliver estimated piece part reliability for any desired confidence level (CL), moving beyond risk avoidance methodologies based on a radiation design margin. Two methods are developed, and their results compared for realistic data. [ABSTRACT FROM AUTHOR]

Analog-to-digital converters (ADCs) with different topologies respond differently to total ionizing dose (TID). A flexible behavioral modeling approach is proposed for system-level simulation of TID effects in successive-approximation-register (SAR) ADCs. The radiation-enabled approach can be adapted for a wide range of ADCs of various resolutions, clock speeds, and manufacturers. The empirical model is calibrated and validated, pre-rad and post-rad, for a particular ADC. Pre-rad calibration is performed by introducing distributions of static parameters corresponding to datasheet specifications. The post-rad calibration is accomplished by introducing error sources associated with the comparator and digital-to-analog converter (DAC), corresponding to experimental data. The calibrated model is used to examine the dynamic performance and to estimate the probability of parametric failure during the mission lifetime. [ABSTRACT FROM AUTHOR]

The electrical degradation in AlGaN/GaN high-electron-mobility transistors (HEMTs) is examined under irradiation with 7.6-MeV carbon (C), 20-MeV oxygen (O), and 30-MeV fluorine (F) ions in situ. To characterize the radiation damage in the HEMTs, the ionizing dose Di, displacement dose Dd, and number of vacancies versus the chip depth in the devices have been calculated for heavy ions. As expected, in all three types of HEMTs, the output current decreases more than 30% and threshold voltage positive shifts after the irradiation fluence of 4 × 1012 ions/cm2. The performance degradation of AlGaN/GaN HEMTs is caused by radiation-induced charged defects. Based on calculation and experimental results, it is shown that the nonionizing energy loss (NIEL) method is not suitable for estimating the degradation of AlGaN/GaN HEMTs either considering gallium vacancy or considering both gallium vacancy and nitrogen vacancy. In the same displacement damage dose, the threshold voltage degradation rate depends on the type of incident particles and independent of the channel length. The damage caused by carbon ions is the smallest and the damage caused by fluoride ions is the largest. [ABSTRACT FROM AUTHOR]

Dark current and associated random telegraph signals are studied in short-wave infrared image sensors. The effects of space radiation on these parameters are analyzed and modeled to understand the degradation in this indium–gallium–arsenide (InGaA)-based technology. Multiple proton tests were performed to cover the space mission range of radiation dose. Comparison with existing data and damage factors is provided and highlights the behavior of such technology against radiation doses. [ABSTRACT FROM AUTHOR]

Reliability-focused benchmarks are used to test systems in harsh operating conditions, including space and terrestrial radiation environment. The sensitivity to single-event effects of a microprocessor in a radiation environment depends on the set of input vectors used at the time of testing due to logical masking. This article analyzes the impact of the input test set on the cross section of the microprocessor and proposes a mechanism to derive a high-quality input test set using automatic test pattern generation (ATPG) for radiation testing of microprocessor’s arithmetic and logical units. [ABSTRACT FROM AUTHOR]

This article presents a radiation-hardened Cortex-R4F system-on-chip prototype with integrated total ionizing dose (TID) dynamic compensation capabilities, designed and fabricated in 28-nm fully depleted silicon-on-insulator (FD-SOI) technology. The processor was made robust to single-event effects, thanks to several design techniques: error correcting code (ECC) protected and bit-interleaved memories, optimized radiation-hardened sequential cells, and sensitive logic cells filtering. To counter the TID effects on the processor functionality and performances, the system embeds an integrated digital dosimeter. The dosimeter is capable of computing the TID in real time and providing the information to the system. Using a software lookup table (LUT), coupled with 28-nm FD-SOI technology support of asymmetric and wide-body-biasing, the reported TID can be converted to a request made to an external body-bias generator and be fully compensated. The system, operating at 0.9 V and 500 MHz, was tested under space grade radiations and has shown no failure in the 0 krad(Si) to 50 krad(Si) TID range. [ABSTRACT FROM AUTHOR]

We report on alpha and neutron irradiation of 7.8 $\boldsymbol {\mu }\text{m}$ single-photon avalanche diodes (SPADs) manufactured in 40-nm CMOS. Displacement damage leads to persistent dark count rate hot spots, due to carrier generation centers introduced by radiation. Defects are studied as a function of temperature and electrical stress, with live acquisitions evidencing large amounts of short-term annealing of the damage, and sometimes also random telegraph signal. Average damage factors and defect activation energies are consistent with a large field-enhancement of carrier generation. Since some radiation-induced defects lead to out-of-spec behavior, the implications for the reliability of SPAD-based systems are also discussed, by projecting the associated terrestrial failure rates. [ABSTRACT FROM AUTHOR]

In this article, authors explore radiation hardening techniques through the design of a test chip implemented in 16-nm FinFET technology, along with architectural and redundancy design space exploration of its modules. Nine variants of matrix multiplication were taped out and irradiated with neutrons. The results obtained from the neutron campaign revealed that the radiation-hardened variants present superior resiliency when either local or global triple modular redundancy (TMR) schemes are employed. Furthermore, simulation-based fault injection was utilized to validate the measurements and to explore the effects of different implementation strategies on failure rates. We further show that the interplay between these different implementation strategies is not trivial to capture and that synthesis optimizations can effectively break assumptions about the effectiveness of redundancy schemes. [ABSTRACT FROM AUTHOR]

Soft processors are often used within field-programmable gate array (FPGA) designs in radiation hazardous environments. These systems are susceptible to single-event upsets (SEUs) that can corrupt both the hardware configuration and software implementation. Mitigation of these SEUs can be accomplished by applying triple modular redundancy (TMR) techniques to the processor. This article presents fault injection and neutron radiation results of a Linux-capable TMR VexRiscv processor. The TMR processor achieved a $10\times $ improvement in SEU-induced mean fluence to failure with a cost of $4\times $ resource utilization. To further understand the TMR system failures, additional post-radiation fault injection was performed with targets generated from the radiation data. This analysis showed that not all the failures were due to single-bit upsets, but potentially caused by multibit upsets, nontriplicated IO, and unmonitored nonconfiguration RAM (CRAM) SEUs. [ABSTRACT FROM AUTHOR]

Total ionizing dose response of 14-nm bulk-Si FinFETs has been studied with a specially designed test chip. The radiation testing shows evidence of interface trap build-up on 14-nm Bulk FinFET technologies. These defects created in the isolation layer give rise to a new radiation-induced leakage path which might lead to a reliability issue in CMOS technologies at or below the 14-nm node. TCAD simulations are performed and an analytical model for TID-induced leakage current is presented to support analysis of the identified TID mechanism. TCAD simulation and analytical model results are consistent with the experimental data. [ABSTRACT FROM AUTHOR]

This article investigates the effect of ultra-high total ionizing dose up to 450 Mrad(SiO2) on 180-nm MOSFETs for analog applications. In particular, it studies the influence of the transistor size, design, type, bias, and the annealing on radiation-induced degradation. It studies the radiation effects on three parameters: the drive current, the threshold shift, and the leakage current. First, it reveals radiation-induced short-channel effects (RISCEs), which were until now only observed on more advanced technology nodes, and highlights that its mechanism of apparition differs from these advanced nodes. Second, it highlights the importance of bias during irradiation, not only on the magnitude of these effects but also on the type of defects at their origin. In particular, it demonstrates that the bias during irradiation plays a major role in the n-MOS–p-MOS dissymmetry. Third, it points out the capacity of the ELT and the butterfly rad-hard designs to mitigate the radiation-induced narrow channel effect (RINCE), the LPT, and several other radiation-related issues. Finally, it shows that the 3.3-V designs, compared to the 1.8-V designs, present a larger sensibility to radiation due to their thicker gates, but that they could stay a better choice for analog applications up to 400 Mrad(SiO2), thanks to their larger voltage range. [ABSTRACT FROM AUTHOR]

Functional verification schemes at a level different from component-level testing are emerging as a cost-effective tool for those space systems for which the risk associated with a lower level of assurance can be accepted. Despite the promising potential, system-level radiation testing can be applied to the functional verification of systems under restricted intrinsic boundaries. Most of them are related to the use of hadrons as opposed to heavy ions. Hadrons are preferred for the irradiation of any bulky system, in general, because of their deeper penetration capabilities. General guidelines about the test preparation and procedure for a high-level radiation test are provided to allow understanding which information can be extracted from these kinds of functional verification schemes in order to compare them with the reliability and availability requirements. The use of a general scaling factor for the observed high-level cross sections allows converting test cross sections into orbit rates. [ABSTRACT FROM AUTHOR]

Analog single-event transient (SET) results are analyzed for two different applications within one system architecture. Application-specific analyses are presented on the MAX4595 commercial device using single-event effects criticality and goal structuring notation (GSN). [ABSTRACT FROM AUTHOR]

An overview is presented of the significant influences of Moore’s Law scaling on radiation effects on microelectronics, focusing on historical trends and future needs. A number of milestones in the evolution and understanding of total-ionizing-dose and single-event effects are discussed within the context of classical Dennard scaling. This discussion focuses on the discovery of fundamental mechanisms, development of radiation-tolerant IC technology, and increasing maturity and complexity of Si-MOS-based devices, circuits, and systems. Examples are shown that illustrate how the end of Dennard scaling has influenced radiation effects in current technology generations, due to the increasingly complex and diverse materials and devices that are now incorporated. The radiation responses of devices with alternative channels to silicon and transistors based on 2-D materials are discussed, with an emphasis on opportunities and challenges for ultimately scaled devices. Particular challenges to ultimately scaled technologies are presented by single-particle-induced displacement damage and microdose effects. The article concludes with a look forward to a future in which many types of microelectronic devices and ICs are increasingly more vulnerable to radiation effects and increasingly more difficult to test in a practical and cost-effective manner. [ABSTRACT FROM AUTHOR]

Statistical analysis is performed on the totalionizing-dose (TID) response of fourth-generation silicon–germanium heterojunction bipolar transistors, revealing an increasing variance in base current with increasing dose. A 10-fold increase is observed after 2 Mrad(SiO2) of radiation exposure. The postirradiation performance is shown to be poorly correlated with initial performance, revealing potential difficulties for radiation hardness assurance testing. Simple analytical theory is used to demonstrate how TID exacerbates performance variations due to preexisting process-induced variations. Then, technology computer-aided design (TCAD) simulations are used to investigate the fundamental mechanisms driving these statistical changes, particularly process variations associated with the doping profiles. Simulation results reveal potential methods to both predict TID response and mitigate it at the process level. Finally, implications for hardness assurance testing and radiation-tolerant device and circuit design are discussed, especially the need to consider postirradiation variability in the design process for radiation-intense applications. [ABSTRACT FROM AUTHOR]

Numbers of citations of outstanding conference papers (OCPs) of IEEE Nuclear and Space Radiation Effects Conferences (NSRECs) from 1966 to 2017 are compared with citations of the most highly cited papers (HCPs) of the corresponding special issues of the IEEE TRANSACTIONS ON NUCLEAR SCIENCE (TNS), as well as average numbers of citations and cumulative $h$ index, $h_{\mathrm {cum}}$ , for all TNS papers published in the same year. 85% of NSREC OCPs are cited at a higher rate than the average for all TNS articles in that year. 55% of NSREC OCP citation totals are higher than $h_{\mathrm {cum}}$ for TNS in that year; these rank among the ~8% most highly cited TNS papers for that year. In ~10% of cases, the NSREC OCP is also the most HCP. Similarly high citation impact is found for papers nominated as candidates for OCPs. Radiation effects papers published in annual NSREC special issues comprise a significant fraction of all TNS articles cited $h_{\mathrm {cum}}$ times or more. These results support the use of $h_{\mathrm {cum}}$ as a metric of citation impact in this work and show that the NSREC OCP process generally meets awards criteria guidelines for impact. Potential reasons for variations in citation rates are discussed, and recommendations are provided to enhance the awards process. [ABSTRACT FROM AUTHOR]

The total ionization dose (TID) effect and negative bias temperature instability (NBTI) effect of 130-nm partially-depleted silicon-on-insulator (PDSOI) MOSFETs fabricated on hardened wafers with silicon ion implantation and unhardened wafers are investigated. A TID-hardened PDSOI MOSFET up to 1 Mrad(Si) is obtained by Si+ implantation in buried oxide (BOX). The hardening benefits from the electron traps in the BOX introduced by Si+ implantation. Although the radiation hardening process has a rare impact on nominal electrical characteristics of the device before irradiation, it will affect the NBTI reliability, which is manifested as the decrease in the NBTI lifetime for the radiation-hardened devices. The energy distribution of positive charges built up during NBTI stress is obtained. It proves that more damage-related traps exist near the gate oxide/silicon interface for the radiation-hardened device, which accelerates the threshold voltage shift during the NBTI stress. This conclusion is also verified by the low-frequency noise characteristics. [ABSTRACT FROM AUTHOR]