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This article studies the apparition and the fast annealing of a leakage current in p- and n-MOS transistors and structures. This leakage current is observed for total ionizing doses (TIDs) of 50 Mrad(SiO2) and above and anneals rapidly within the hours following the end of irradiation. An extensive set of specially designed and dedicated structures are used to study this phenomenon. In particular, the article presents the effects of the dose rate, the transistor type (n or p), the drain–source voltage, or the bias during annealing. Results show that the observed transient leakage current is an intensification followed by fast annealing of the generation current inside the drain and source depletion regions. It appears that this generation leakage current most likely originates from the creation of positive charges in the thick oxides of the devices, that is, the shallow trench isolation (STI) and the pre-metal dielectric (PMD), and it generally anneals at ambient temperature in less than 12 h after irradiation. [ABSTRACT FROM AUTHOR]

The advantages and the tradeoffs associated with the use of inverse-mode (IM) silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) biasing circuitry in radio-frequency (RF) voltage-controlled oscillators (VCOs) have been investigated and the performance of proposed VCOs (IM VCOs) is compared with VCOs with conventional forward-mode (FM) SiGe-HBTs (FM VCOs). Where the high-frequency performance of IM VCOs is inevitably degraded due to unfavorable device optimization unlike FM VCOs, IM VCOs provide acceptable low-GHz VCO circuit performance. In terms of single-event effects (SEEs), the IM VCOs show reduced transient peaks and duration in comparison with conventional FM VCOs. In addition, the performance of the VCOs is analyzed in terms of transient error vector magnitude (TEVM) in an RF receiver (RX) using quadrature phase-shift keying (QPSK) modulation under a radiation environment. The IM VCOs in the RX circuit show better reliability under SEEs, offering 28.2% lower TEVM at a 64 Mb/s data rate, than that of the RX circuit with conventional FM VCOs. Therefore, the application of IM SiGe-HBT biasing circuits for RF VCOs can be a viable SEE-hardening technique for space-based RF systems. The VCO prototype was fabricated using IHP 130-nm SiGe bipolar complementary metal-oxide-semiconductor (BiCMOS) technology. [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]

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]

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]

This article investigates the displacement damage on AlGaN/GaN high-electron-mobility transistors (HEMTs) using the 30-MeV fluorine ions. The electrical degradation and the defects in HEMTs were examined before and after irradiation. Three defect states are detected in a deep-level transient analysis system (DLTS), including a broad surface state peak ($N_{1}$) and two bulk defect peaks ($H_{1}$ and $H_{2}$). The energy levels of these two defects are $E_{\mathrm {C}} 0.63$ eV ($H_{2}$) and $E_{\mathrm {C}} 0.91$ eV ($H_{1}$), respectively. There is a linear relationship between the concentration of $H_{1}$ and the fluorine ion fluence. The radiation damage and electrical performance degradation of AlGaN/GaN HEMTs are simulated by combining with simulation software of different methods. The calculated results are in agreement with the experimental data. The performance degradation caused by heavy ion of the device is mainly caused by the $H_{1}$ defect. The effect of defects with shallow energy level is shielded by the Fermi-level pinning in deeper energy level. Moreover, the defect distribution of GaN in AlGaN/GaN heterojunction plays a major role. It is found that the method of combining experimental data with multiscale simulation is an effective way to predict the radiation damage of devices. [ABSTRACT FROM AUTHOR]

The CABRI experimental pulse reactor is devoted to the study of reactivity-initiated accidents (RIAs), for the purpose of the CABRI International Program (CIP), managed by the French Safety and Radiation Protection Institute (IRSN). CABRI’s hodoscope equipment detects the fast neutrons emitted during a power pulse by a tested rod, positioned inside a dedicated test loop reproducing either sodium reactor or pressurized water reactor (PWR) conditions. One of the most important parameters measured by the hodoscope detectors is the signal-to-noise ratio (SNR), characterizing the fraction of neutrons directly coming from the test rod (“signal”) over neutrons coming from the core (“noise”). In this article, the method used to calculate the SNR using a 2-D model of CABRI, with the MCNP6.2 Monte Carlo code, will be detailed. Comparisons between the calculated and measured SNRs for different configurations are in quite good agreement. Another parameter of interest is the so-called “scattering coefficient,” which corresponds to the fraction of neutrons coming from the test rod and being scattered between their birth and their detection. This parameter is used to enhance the analysis of the fuel displacement that may happen during the power transient. To estimate this coefficient, an innovative method using a combination of different options available in MCNP6.2 has been used. Computed coefficients show a slight discrepancy with the measurements. Finally, the sensitivity of the SNR and scattering coefficient to technological parameters and nuclear data libraries is discussed. [ABSTRACT FROM AUTHOR]

In this article, we present a unique method of measuring single-event transient (SET) sensitivity in 12-nm FinFET technology. A test structure is presented that approximately measures the length of SETs using flip-flop shift registers with clock inputs driven by an inverter chain. The test structure was irradiated with ions at linear energy transfers (LETs) of 4.0, 5.6, 10.4, and 17.9 MeV-cm2/mg, and the cross sections of SET pulses measured down to 12.7 ps are presented. The experimental results are interpreted using a modeling methodology that combines TCAD and radiation effect simulations to capture the SET physics, and SPICE simulations to model the SETs in a circuit. The modeling shows that only ion strikes on the fin structure of the transistor would result in enough charge collected to produce SETs, while strikes in the subfin and substrate do not result in enough charge collected to produce measurable transients. Comparisons of the cumulative cross sections obtained from the experiment and from the simulations validate the modeling methodology presented. [ABSTRACT FROM AUTHOR]

The impact of transient ionizing radiation effects on a 4-Mb static random access memory (SRAM) circuit which has an input–output (IO) supply voltage and a core supply voltage was studied. The experimental results indicate that a longer time is required to restore minimal operating voltage for core supply voltage. Based on the 180-nm bulk CMOS technology, 3-D mode numerical simulations with technology computer-aided design (TCAD) show that the parasitic bipolar effect plays a significant role in discrepancy in the recovery process between supply voltages. This effect will be discussed in depth in this article, and the simulation results illustrate that the n-well contact has a great impact on the operation mode of parasitic bipolar. Meanwhile, the supply voltage disturbance mitigation methods are presented through improving power supply voltage and placing more n-well contacts. [ABSTRACT FROM AUTHOR]

Ion-induced SETs were captured from a germanium photodiode (PD) in an integrated silicon photonics technology platform. Statistics from 400 ion-strike events were extracted for various optical powers and LETs incident on the PD. The results show that the transient peak decreases with increasing optical power. TCAD simulation results indicate that photo-generated carriers decrease the built-in electric field of the PD, thereby decreasing the transient peak. The photo-generated carriers also increase the probability of Auger recombination, which further reduces the transient peak under illuminated conditions, but this effect is small and does not contribute significantly to the transient peak reduction. Finally, a short case study with an ON–OFF keying modulation scheme is presented to show how these transients have the potential to corrupt bits in realistic communication systems. Furthermore, it is also shown that hardening techniques can be utilized to mitigate bit errors in communication systems that use integrated Ge PDs. [ABSTRACT FROM AUTHOR]

A general, computationally efficient, physics-based model for the continuous time-domain description of transient loss in silicon (Si) photonic waveguides due to impinging ionizing particles is presented. The model combines Beer–Lambert and Drude formalisms with the ambipolar transport equation (ATE) and applies a number of carefully vetted simplifying assumptions to obtain a highly compact form. The model is validated using nanosecond pulses of tightly focused 639-nm laser light to induce localized high-level generation events and mimic heavy-ion strikes within Si photonic waveguides of varying geometry. Electron–hole pairs (ehps) generated in these events cause free-carrier absorption (FCA) of a continuous 1535-nm probe signal in the waveguide, which is observed as a transient drop in detected photocurrent on a high-speed oscilloscope. Measured transients show excellent agreement with model predictions. [ABSTRACT FROM AUTHOR]

The present article applies the $k$ -nearest neighbors ($k$ -NN) machine learning (ML) algorithm to detect and correct single-event upsets (SEUs). In particular, this work focuses on SEUs resulting from single-event transients in RF systems carrying modulated data. Pulsed-laser measurements were performed, and the resulting SEUs were used to train separate $k$ -NN algorithms to detect and correct these upsets. The results show that the algorithm correctly classified data into “upset” and “no upset” 99.2% of the time. In addition, the number of symbol upsets was reduced by 30%. Some of the challenges to implementing and deploying this error correction approach in flight systems are discussed. The results of the present work demonstrate the potential benefits of applying ML techniques to the field of radiation effects. [ABSTRACT FROM AUTHOR]

The ORION chipset, a full-custom multichip readout and processing electronics for the X- $\gamma $ -ray imaging spectrometer (XGIS) on-board the transient high-energy sky and early universe surveyor (THESEUS) space mission, is presented. The XGIS detection plane is arranged in a matrix of 10 $\times $ 10 detection modules, each one composed of 64 CsI(Tl) scintillation bars (4.5 mm $\times $ 4.5 mm $\times $ 30 mm) optically coupled at the top and bottom ends to two 8 $\times $ 8 monolithic silicon drift detector (SDD) matrices. The top SDD, exposed to the X-ray entrance window, performs the double function of low-energy X-ray detection as well as scintillator’s readout, together with the bottom SDD, providing detection and spectroscopic energy range from 2 keV up to 20 MeV. The need to achieve a high-energy resolution, as well as a high sensitive area on the detection plane, led to the development of a chipset organized to have a minimum-area analog readout chip placed in close proximity of the SDD (ORION-FE) and a mixed-signal back-end (ORION-BE) placed a few centimeters further on the back-end board for the additional signal processing and digitization. The multichip readout electronics integrates two dedicated analog processors for low-energy photons up to 30 keV (X-processor) and high-energy photons up to 5 MeV ($\gamma $ -processor), allowing a spectroscopy-grade resolution in the 4 decades energy band (2 keV–20 MeV) of the XGIS, with a simulated power consumption of 1.55 mW/pixel. The ORION prototype was bonded to two ~25 mm2 SDDs, and extensively characterized in terms of pulse shaping, pulse discrimination, and stretching functionality, as well as linearity, dynamic range, and spectroscopic resolution. An optimum equivalent noise charge (ENC) at −20 °C of 24.3 el. r.m.s. on the X-channel [212 eV full-width at half-maximum (FWHM) on Si], and 39.6 el. r.m.s. on the $\gamma $ -channel [3.7 keV FWHM on CsI(Tl)] has been recorded. [ABSTRACT FROM AUTHOR]

This work presents measured data showcasing neutron-radiation-induced single-event transient (SET) pulse widths in distinct standard logic gate types, together with a detailed analysis on the choice of design parameters impacting the corresponding sampled pulsewidth distributions. The SET pulsewidth distributions are obtained from a high-density, array-based characterization vehicle, implemented in 65-nm planar CMOS and 16-nm FinFET processes, featuring a tunable, high-resolution pulse shrinking chain together with a closely embedded sampling circuit to avoid width distortion effects. The proposed macro uses standard logic gate chains in varying lengths, threshold voltages ($V_{\mathrm {TH}}$), and transistor width flavors as the devices under test (DUTs). The measured irradiation data for a range of operating voltages from nominal down to near-threshold reveal the relative impact of the chosen design parameters such as VDD, $V_{\mathrm {TH}}$ , device width, and the logic chain length and their interplay, impacting the overall soft error susceptibility and the sampled pulsewidth distributions among the different standard gate types. [ABSTRACT FROM AUTHOR]

A method to carry out a priori simulations of pulsed-laser-induced single-event effects experiments is reported. Nonlinear optical simulations are conducted to model the 3-D distributions of charge from a laser pulse. These pulsed-laser-induced charge distributions are then incorporated into a charge transport solver to model the movement of charge as the device returns to a steady state. The output of the simulation infrastructure is a current transient from which collected charge and the temporal characteristics of the transient can be determined. This complete approach to modeling, which includes full device structure information, nonlinear optical energy deposition, and the subsequent movement of optically generated charge in a device and measurement circuit, allows for direct comparison between experimental and simulated current transients. A large-area silicon diode was used as the test vehicle, and good agreement was found between simulations and experiments in both total injected charge as well as temporal characteristics. Importantly, the a priori simulation approach does not require knowledge from prior heavy-ion testing, making it a predictive tool with broad versatility and minimal reliance on approximations. [ABSTRACT FROM AUTHOR]

Field-programmable gate arrays (FPGAs) are susceptible to radiation-induced effects that can affect more than one memory cell. Radiation-induced microsingle event functional interrupts (micro-SEFIs) are one of such events that can upset several bits at a time. These events need to be studied because they can overcome protection from techniques such as triple modular redundancy (TMR) and error correction codes (ECCs). Extracting these events from radiation data helps to understand if specific resources of the FPGA are more vulnerable and the extent of this vulnerability. This article presents a method based on statistics and fault injection to identify micro-SEFIs from beam-test data in the configuration memory and block RAM (BRAM) of SRAM-based FPGAs. The results show the cross section of these events for the configuration RAM (CRAM) and BRAM for three families of Xilinx SRAM FPGAs gathered throughout three neutron tests. This article also contains data from a fault injection campaign to uncover the possible CRAM source bits causing micro-SEFIs in memory look-up tables (LUTs) of Xilinx 7-series and Ultrascale devices. [ABSTRACT FROM AUTHOR]

This article mainly focuses on the single event function interruption (SEFI) and single event latch-up (SEL) of 90 nm NOR flash memories. Devices were irradiated by ions with different linear energy transfer (LET) values from 12.9 to $65.8~MeV\cdot cm^{2}$ /mg. SEFI observed in the device is further divided into bit SEFI, column SEFI, and sector SEFI by severity of data corruption. Under irradiation with low LET value ions, SEL propagation-like phenomena were observed in this work, which was recognized as the process from local latch-up to global latch-up in the peripheral circuits. The underlying mechanisms for SEFI and SEL in NOR flash are discussed. Results indicate that the radiation-induced transient current should be responsible for SEFI, and different forms of SEFI depend on in which part of the circuit that transient current occurred. Besides, SEL in NOR flash is considered to be triggered from the peripheral circuits. [ABSTRACT FROM AUTHOR]

A methodology for automating the identification of single-event transients (SETs) through ionizing radiation effects spectroscopy (IRES) and machine learning (ML) is provided. IRES enhances the identification of SETs through statistical analysis of waveform behavior, allowing for the capture of subtle circuit dynamics changes. Automated identification of SETs is facilitated by a k-nearest neighbors (k NNs) ML algorithm with IRES data. One-hundred thousand waveforms were measured from CMOS phase-locked loop (PLL) circuits irradiated at the Naval Research Laboratory’s two-photon absorption (TPA) laser facility. Known SET signatures were used to train various k NN models based on statistical features derived from several standard circuit metrics and eight moment-generating functions. Results show that SETs can be automatically identified by the k NN models, with several features resulting in greater than 98% correct identification of SETs. The tradeoffs in ML-based anomaly detection, based on the size of available training sets, choice in signal metric, and the number of included statistical moment-generating functions are discussed, along with opportunities for the future development of specific event-type classification, in situ measurement, and real-time classification of data. [ABSTRACT FROM AUTHOR]

A study of the reset transient of charge-sensitive amplifiers operating with a pulsed switch in parallel to the feedback capacitance is presented. Analytical models have been developed for amplifiers in both linear and slew rate regimes during the reset phase. The models predict the time interval required to reset the amplifier that, in most cases, significantly differs by the simple discharge of the feedback capacitance through the switch resistance and strongly depends on the open-loop gain and bandwidth of the core amplifier and on the input capacitance. The models also quantitatively predict spurious voltage transients at the preamplifier’s input and possible ringings at the output, as a function of the main general parameters of the circuit. A case application study of the presented model is proposed for low-capacitance detectors, such as semiconductor drift detectors or small pixel detectors. [ABSTRACT FROM AUTHOR]

A pulsed laser has been effectively applied in dose rate effects simulation for its stable pulse output, low cost, simple operation, and lack of ionizing risks for users. The conversion factor (CF) was proposed to describe the equivalence between the responses generated by pulsed laser and pulsed ionizing radiation (e.g., γ-ray). Previously, the peak photocurrent was commonly used to calculate the CF and establish the equivalent relationship. But there are a number of shortcomings such as narrow effective equivalent range, inadequate information of waveform, as well as low accuracy of simulations. In this article, an improved method for obtaining the CF by using the charge collection as the equivalent factor is proposed, which considers not only the peak photocurrent but also the temporal information of the waveform. The advantages of the proposed method are proved both in theory and in experiments, including broader equivalent range and higher simulation accuracy. [ABSTRACT FROM AUTHOR]

The sensitivity of the LM139A quad voltage comparator toward simultaneous single-event transient has been investigated through laser single photon absorption. The results have been supported and compared to heavy-ion tests. The analysis of sensitivity leads to the observation of two sensitive cases related to internal charge-sharing mechanism between comparator function and input line coupling effects. [ABSTRACT FROM AUTHOR]

Peak transient currents due to pulsed-laser or heavy-ion irradiation of Ge $p$ MOS FinFETs are nearly independent of gate bias. This is because the prompt photocurrent is due primarily to a transient source–drain shunt. In contrast, long-term diffusion charge collection is strongly gate-bias dependent. This bias dependence results from hole injection from the source in response to the transient increase in electron concentration in the channel. The transients measured at the source terminal change polarity when the strike location moves from the source to the drain, but this effect does not occur for the transients measured at the drain terminal. Charge collection mechanisms are studied using TCAD simulations. [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]

In this article, five different cell placement structures of a vertical inverter chain were designed in a commercial bulk FinFET technology to investigate the effect of cell placement on a single-event transient (SET) pulse. 3-D TCAD mixed-mode simulation indicated that the cell placement has a significant effect on SET pulsewidths. Heavy-ion experiments at Cyclotron in the China Institute of Modern Physics in Lanzhou also indicated that the effect of cell placement on the SET pulse is obvious. The experiment also indicated that the effect of cell placement on P-hit SET is larger than that on N-hit SET, and charge sharing in vertical was becoming as important as that in horizontal. [ABSTRACT FROM AUTHOR]

Heavy-ion, focused X-ray, and pulsed laser single-event transient (SET) experiments are performed on a silicon epitaxial diode. Collected charge, transient rise times, and transient fall times are calculated and compared between different sources. The transient shape characteristics depend on the source (ion, X-ray, or laser), even when similar amounts of charge are generated. The observed differences are examined and explained in terms of basic charge collection mechanisms. [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]

Destructive single-event effects (SEEs) pose serious challenges for the reliable use of commercial off-the-shelf (COTS) devices in space systems. We modeled a simplified, redundant system to determine single-event latchup (SEL) rates that would likely compromise system reliability, resilience, and capabilities. We then assembled a representative data set of COTS Complementary Metal Oxide Semiconductor (CMOS) parts susceptible to SELs. After investigations of these parts revealed no compact distributions or other relationships useful for $a$ priori estimation of SEL rates and showed minimal correlation between Weibull fit parameters for the cross section versus linear energy transfer (LET) data, we used nonparametric statistical techniques to generate quantile plots that can be used to bound part SEL rates for a given confidence. We used these distributions to assess the threat posed to redundant systems by destructive SEEs. [ABSTRACT FROM AUTHOR]

This article compares and analyzes the single-event gate rupture (SEGR) response of silicon planar gate super-junction (SJ) power metal oxide semiconductor field effect transistors (MOSFETs) and vertical double diffused power MOSFETs (VDMOSs). When an incident heavy-ion strike is perpendicular to the gate oxide, the SEGR tolerances of SJ power MOSFETs (SJMOSs) and VDMOSs are similar. But, for heavy-ion strikes that are at different angles, SJMOS has better SEGR tolerance than VDMOS. This improved performance of SJMOS is due to the presence of an additional horizontal electric field component in SJMOS devices. This is validated using the experimental data and simulation results in this article. [ABSTRACT FROM AUTHOR]

Semiconductor–insulator interfaces play an important role in the reliability of integrated devices; however, the impact of these interfaces on the physical mechanisms related to single-event effects has not been previously reported. We present experimental data that demonstrate that single-event charge collection can be impacted by changes in interface quality. The experimental data, combined with simulations, show that single-event response may depend on surface recombination at interface defects. The effect depends on strike location and increases with increasing linear energy transfer (LET). Surface recombination can affect single-event charge collection for interfaces with a surface recombination velocity (SRV) of 1000 cm/s and is a dominant charge collection mechanism with SRV $> 10^{5}$ cm/s. [ABSTRACT FROM AUTHOR]

This article presents and develops a novel comprehensive simulation model for perimeter gated single-photon avalanche diode-based silicon photomultipliers (PGSPAD SiPMs). A PGSPAD is a modification of single-photon avalanche diodes (SPADs) that contains a third terminal to mitigate perimeter edge breakdown. It does this without excessively enlarging the device area. The applied gate voltage modulates the dynamic range, breakdown voltage, and dark current characteristics. The proposed PGSPAD SiPM model correctly mimics the current–voltage transfer function and the avalanche-quench process of the SiPM detector and is verified by the experimental measurements of a PGSPAD SiPM fabricated in a commercial 0.5- $\mu \text{m}$ CMOS process. The model includes the dark current of the PGSPAD device. This was not included in previous SiPM models. The effect of the number of triggered microcells versus the total number of microcells and the impact of different parameters on the PGSPAD SiPM performance with added gate terminal are evaluated. The photon–electron spectrum with the effect of an extra gate terminal has been studied. Simulation results show very good agreement with experimental measurements. [ABSTRACT FROM AUTHOR]

The RFX-mod2 Nuclear Fusion experiment is an upgrade of RFX-mod, which was shutdown in 2016. Among the other improvements in the machine structure and diagnostics, a larger number of electromagnetic probes (EMs) is foreseen to provide more information about plasma instabilities and to allow an improved real-time plasma control. An analog-to-digital converter (ADC) architecture able to provide, at the same time, both transient recording and real-time streaming, as well as field-programmable gate array (FPGA)-based time integration of the inputs, is foreseen in RFX-mod2. Transient recording provides full-speed data acquisition (up to 1 MSample/s) by recording data in local memory and reading memory content after the plasma discharge. Real-time streaming of the subsampled data is required for active control. The chosen technology is based on the XILINX Zynq architecture that provides, in the same chip, a multicore Advanced RISC Machines (ARM) processor tightly coupled to an FPGA. Time-critical functions are carried out by the FPGA, such as the management of the circular data buffer, low-pass filtering for subsampling of the samples to be streamed, and digital integration. Other functions are carried out by the processor, such as the management of the configuration setting, received via Transmission Control Protocol (TCP)/IP or Hypertext Transfer Protocol (HTTP), the data readout of acquired samples in transient recording buffers, and network data streaming of data collected for active real-time plasma control. [ABSTRACT FROM AUTHOR]

Single-event transient (SET) and single-event latchup (SEL) of a 4T pinned photodiode (PPD) complementary metal–oxide–semiconductor (CMOS) image sensor (CIS) fabricated with a 0.18-μm CMOS process were investigated using heavy ions and a picosecond pulsed laser. The SET bright spot characteristics were further studied, and the transient bright spots formed by laser and heavy ions were analyzed. The sensor exhibited SELs and micro-SEL. To determine the precise sensitive location where SEL occurred in the CIS, a pulsed laser with a 2-μm beam spot was used to scan the entire surface of the device. The results revealed that SEL occurred in the peripheral circuits of the CIS, including the analog signal processing circuit, row-addressing circuit, and analog-to-digital conversion (ADC). The cross section of the SELs for the sample were measured using a linear energy transfer (LET) ranging from 8.62 to 81.35 MeV ⋅ cm2 mg−1. The SEL rates in space for the used CIS were predicted using the CREME96 tool. [ABSTRACT FROM AUTHOR]

Power cycling of a point-of-load converter is observed during system-level heavy ions tests. This event has low cross section and is observed for reduced supply voltage of the device under test. Laser tests are used to reproduce this effect and show that it might be due to propagation of single-event transients from the voltage reference to the operational amplifier being part of the undervoltage protection circuit. Laser tests show that propagating transients are the ones with a high enough positive peak and an insignificant negative peak value, whereas some transients with a bigger maximum and/or peak-to-peak value do not propagate. SPICE simulation shows that in an operational amplifier with low voltage difference between V+ and V−, there is a difference in the propagation of unipolar and bipolar transients from the input to the output of the amplifier. Analysis of the voltage-controlled current source in the amplifier also explains the difference in propagation of bipolar transients with a negative peak followed by a positive peak and with a positive peak followed by a negative peak. [ABSTRACT FROM AUTHOR]

Low-noise amplifiers (LNAs) are necessary components for any communications system. Single-event transients (SETs) induced by energetic particles in space can corrupt the data in an RF receiver. Using p-n-p silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs), instead of their more common n-p-n counterparts, has been shown to be an effective mitigation technique in digital, analog, and RF circuits. Since p-n-p SiGe HBTs tend to have lower performance than n-p-n SiGe HBTs, in this article, the tradeoffs between performance and SET robustness have been evaluated through the use of simulations. Two LNAs were designed using an algorithmic design technique: one using only n-p-n SiGe HBTs, and the other using only p-n-p devices. The n-p-n LNA had higher peak gain and lower noise figure at the center frequency of 5 GHz when compared to the p-n-p LNA, by 3.2 and 0.4 dB, respectively. However, the n-p-n LNA also produced transients with amplitudes larger than the p-n-p LNA across all simulated linear energy transfers. Although the p-n-p LNA has lower overall performance, it is also more robust to SETs. Thus, the choice between using n-p-n and p-n-p SiGe HBTs for an RF design will depend on application requirements. [ABSTRACT FROM AUTHOR]

The high computing power of graphics processing units (GPUs) makes them attractive for safety-critical applications, where reliability is a major concern. This article uses an approximate computing perspective to relax application accuracy in order to improve the selective fault tolerance techniques. Our approach first assesses the vulnerability of a Kepler GPU to the transient effects through a neutron beam experiment. Then, it performs a fault injection campaign to identify the most critical registers and relax the result accuracy. Finally, it uses the acquired data to improve the selective fault tolerance techniques in terms of occupation and performance. The results show that it was possible to improve the GPU register file’s reliability on average by 71.6% by relaxing the application accuracy and, when compared with the selective hardening techniques, it was able to reduce the replicated registers by an average of 41.4%, while maintaining 100% fault coverage. [ABSTRACT FROM AUTHOR]

This article assesses, for the first time, a body/bulk built-in current sensor (BBICS) in a CMOS 65-nm test chip under thermal neutron, high-energy neutron, and laser radiation. Experimental results suggest that the on-chip current sensor is effective to detect transient faults in different case-study subcircuits of the chip exposed to the accelerated radiation effects, opening prospects for embedding this type of sensor in reliable, secure, and low-power integrated circuit applications. [ABSTRACT FROM AUTHOR]

Pulsed, laser-induced, single-event current measurements on silicon-on-insulator (SOI) FinFETs at subbandgap wavelength (1260 nm) are affected by the polarization of the laser light used in the experimental testing setup. Such polarization dependence is not observed during pulsed laser, single-event effects testing on large-area silicon diodes, suggesting that polarization dependence arises due to the presence of the nanoscale fin. Plasmonic enhancement is proposed as a likely mechanism for the polarization effects due to the metal/dielectric interfaces in the fin region. The observed polarization dependence has ramifications for collection and interpretation of data acquired by pulsed laser testing. Device orientation of FinFETs and other nanoscale devices during pulsed laser testing should be considered in order to ensure consistent testing conditions and reproducible measurement results across multiple measurement campaigns. [ABSTRACT FROM AUTHOR]

A comparison of heavy-ion-induced single-event transients (SETs) in silicon–germanium heterojunction bipolar transistors (SiGe HBTs) fabricated on both bulk and silicon-on-insulator (SOI) substrates is presented. Experimental heavy-ion data show a reduction of sensitive volume of ≈ 350 × for the SiGe HBTs fabricated on SOI compared to those on a bulk substrate. Furthermore, the results indicate that the sensitive volume of the SOI SiGe HBTs is confined to the intrinsic device. These results have been confirmed using pulsed laser data and TCAD simulations. Limiting the charge collection depth of SiGe HBTs by fabricating them on SOI facilitates correlation of ion and laser results. The improved ease of correlation is a result of suppressing diffusive charge collection mechanisms that are difficult to replicate with the charge deposition profile generated by two-photon absorption using a tightly focused laser beam. However, a potential issue with pulsed laser testing is determining the loss of the pulse energy through the buried oxide, which requires detailed knowledge of the semiconductor platform. Overall, the reduction of sensitive volume for the SOI SiGe HBTs compared to those on a bulk substrate is a clear advantage from a single-event upset vulnerability perspective. [ABSTRACT FROM AUTHOR]

Ionizing radiation effects spectroscopy (IRES) for characterization of single-event transients (SETs) in space-deployed electronics is demonstrated. IRES enhances time-frequency spectroscopy techniques with statistical analysis, allowing for the capture of subtle changes in circuit dynamics. This is illustrated through the use of experimental data captured from two-photon absorption laser experiments on a phase-locked loop (PLL) designed and fabricated in a 130 nm CMOS technology, and further explained through the use of behavioral modeling of the PLL. The technique leverages the computational benefits of discrete windowed analysis, requiring as little as 0.2% of the data samples required in high-resolution discrete Fourier transform analysis while providing a statistical method for accurately estimating the SET characteristics. [ABSTRACT FROM AUTHOR]

The propagation of single-event transients from the electrical to the photonic domain in a segmented Mach–Zehnder modulator was investigated using pulsed-laser measurements and lumerical simulations. Although electrical transients can heavily degrade the input data to the modulator, almost all of the degradation can be suppressed once it is converted into the optical domain. The mitigation of transients is primarily accomplished by increasing Vπ of each segment, making electrical transients up to 6 V essentially negligible. A “folding” effect of the optical transient is also explained in relation to Vπ. Two radiation-hardening-by-design (RHBD) approaches are suggested to mitigate transient effects. [ABSTRACT FROM AUTHOR]

This paper presents a general theory of time-dependent single-event effects in CMOS LC-oscillators. The analysis employs the oscillator’s impulse-sensitive function (ISF) to calculate the effect of a transient current due to an ionizing particle. A discussion is made on the dependence of the maximum junction collection current and the modulation of this current with the voltage-controlled oscillator (VCO) signal waveform, supported by TCAD simulations. An experimental study using a two-photon absorption (TPA) laser setup is performed to obtain accurate measurements of the time-dependent charge-to-phase transfer function of the oscillator. [ABSTRACT FROM AUTHOR]

Hardware-implemented intelligent systems running autonomous functions and decisions are today becoming more and more ubiquitous in many fields of applications, demanding reliable operation even under harsh conditions as in nuclear power plants and avionics altitudes. Support vector machine (SVM) is a prominent machine learning solution to optimize hardware-implemented autonomous systems. This paper is the first to assess the operation of a field-programmable gate array (FPGA)-designed SVM architecture under radiation effects. A fault emulation campaign along with radiation test experiments with a 14-MeV neutron generator has been performed, and the results show that 27% of the neutron radiation-induced errors in the target SVM architecture provoked critical failures. [ABSTRACT FROM AUTHOR]

The design methodology based on standard cells is widely used in a broad range of very-large-scale integration (VLSI) applications. Furthermore, several optimization algorithms can be employed to address different constraints such as power consumption or reliability. This paper evaluates the implications of the usage of complex logic cells from a 45-nm standard-cell library to the single-event transient (SET) sensitivity under heavy ions. Results show that even though a reduction in the layout area is obtained when adopting complex logic gates, a slight reduction in the total sensitive area of the circuit is observed. Moreover, the effectiveness of the logical masking can be suppressed, leading to a higher SET cross section for high particle linear energy transfer (LET). [ABSTRACT FROM AUTHOR]

The single-event transient (SET) response of silicon-on-insulator (SOI) tri-gate silicon nanowires is investigated using direct measurements of current transients. The impact of nanowire geometry is discussed using the major SET characteristics: duration, amplitude, and integrated value. The experimental results demonstrate the key influence of the nanowire width on the generated current transients induced by heavy ion irradiations. Both Monte-Carlo calculations of deposited energy and Technology Computer Aided Design (TCAD) simulations give evidence of the SOI tri-gate silicon nanowires ability to mitigate generated current transients. TCAD calculations are used to discuss the impact of the main nanowire geometrical parameters which include the nanowire width, thickness, and gate length, on transient charge collection mechanisms in SOI nanowire field-effect transistors (NWFET). Thin and narrow NWFET designs enhance the control of the surrounding gate over the electrostatic potential into the nanowire. The onset of floating body effects induced by heavy ion strike is reduced which mitigates the SET generation. [ABSTRACT FROM AUTHOR]

Single-event double transients (SEDTs) in 65-nm bulk CMOS inverter chains designed with different transistor widths are measured under pulsed laser irradiation. A 3-D TCAD simulations coupled with Monte Carlo calculation are performed to explain the experimental results. It is shown that the SEDTs result from the charge sharing between electrically connected inverters. Inverter chains designed with larger transistors are more resistant to SEDTs than those with smaller transistors for normal incidence. However, it is found through simulation that the advantage of inverter chains designed with larger transistors in suppressing SEDTs is compromised for ion incidence along the well direction. In addition to the transistor size optimization technique, an extra hardened design is needed for better mitigation of SEDTs. [ABSTRACT FROM AUTHOR]

Due to pulse pileup, photon counting detectors (PCDs) suffer from count loss and energy distortion when operating in high count rate environments. In this paper, we studied the pulse pileup of a double-sided silicon strip detector (DSSSD) to evaluate its potential application in a mammography system. We analyzed the pulse pileup using pulses of varied shapes, where the shape of the pulse depends on the location of photon interaction within the detector. To obtain the shaped pulses, first, transient currents for photons interacting at different locations were simulated using a Technology Computer-Aided Design (TCAD) software. Next, the currents were shaped by a CR–RC2 shaping circuit, calculated using Simulink. After obtaining these pulses, both the different orders of pileup and the energy spectrum were calculated by taking into account the following two factors: 1) spatial distribution of photon interactions within the detector and 2) time interval distribution between successive photons under a given photon flux. We found that for a DSSSD with a thickness of $300~\mu \text{m}$ , a pitch of $25~\mu \text{m}$ , and a strip length of 1 cm, under a bias voltage of 50 V, the variable pulse shape model predicts that the fraction free of pileup can be >90% under a photon flux of 3.75 Mcps/mm2 (million counts per second per square mm). The DSSSD is a promising candidate for digital mammography applications. [ABSTRACT FROM AUTHOR]

This paper presents a new approach for analyzing the effect of single-event transient (SET) in SRAM-based field-programmable gate array (FPGA) devices, which are widely used in the space environment. New SET characterizing and mitigation techniques, including continuous monitoring and controlling of the test, are proposed to ensure proper operation of the device under test. This is vital for verifying the proper functioning of the design and performing online reconfiguration if required, since the effect of a single-event upset (SEU) on the device configuration bits may disrupt the SET detection and mitigation design. While many studies focus on SEU, latch-up, and cumulative radiation [total ionizing dose (TID)] effects on SRAM-based FPGAs, only a few published works refer to the SET effect. Moreover, in contrast to previous SET studies, this paper presents a quantitative assessment for SET probability under the real radiation environment and provides cross-sectional analysis for both SET and SEU effects at low linear energy transfers (LETs) (up to 0.925 MeV $\cdot$ cm2/mg). The SET experiments have been carried out at UCL Cyclotron (Belgium) accelerator using heavy ions and under alpha source irradiation. Experimental results indicate that SET examinations on SRAM-based FPGAs should be performed only at low LETs due to the high SEU rate compared to the SET rate. Several kinds of filters have been implemented and proposed for SET mitigation demonstrating a significant reduction of the SET transient effects. The proposed methodology may provide a basic model for future research studies on SET radiation effects on SRAM-based FPGAs, and assisting in selecting an immune FPGA-based platform for satellites applications. [ABSTRACT FROM AUTHOR]

The transient responses in CMOS image sensors (CISs) during radiation are one of the most important key issues to the detector design, reliability, and applicability. The radiation experiments of transient responses in CISs are presented. The CISs have a four Megapixels and pinned photodiode (PPD) pixel architecture with a standard 0.18- $\mu \text{m}$ CMOS technology. The transient responses induced by the gamma radiation at the dose rates of 0.01, 0.02, 0.05, 0.1, 0.2, and 0.3 rad(Si)/s are compared to analyze the influence of dose rates. The transient responses of the PPD CISs at different integration times ranged from 1.02 to 20.51 ms during radiation are also analyzed. The transient response characteristics of the PPD CISs induced by the gamma radiation present a transient disturbance and a random signal distribution. The experimental results show that the mean signal levels increase linearly with increasing dose rates or integration times during radiation, which indicates a method to improve the CIS detector precision. The mechanisms of the transient responses in the PPD CISs are also demonstrated. [ABSTRACT FROM AUTHOR]

A method is presented to enhance single-event transient (SET) measurements by overcoming a common experimental limitation of minimum measurable pulse widths. As technology scales, SETs decrease in width and measurement circuits fundamentally cannot capture every fast transient capable of causing an error. A method has been developed to overcome this limitation by using a latch as a feedback-assisted fast transient capture circuit. Single-event upset (SEU) data are combined with SET data to extend pulsewidth acuity such that pulses faster than the minimum measurable SET pulsewidth are extracted. The method has been applied for a 14-/16-nm bulk FinFET technology node and predictions for logic single-event cross section reveal the impact of fast transients on the radiation response of logic circuits. Results including the extracted fast transients represent upper bound SEU cross sections. For high linear energy transfer (LET) particle irradiation, accounting for fast transients using the developed method results in negligible variation in logic SE cross section. However, for low LET particle irradiation, the method results in an order of magnitude increase in logic SE cross section. [ABSTRACT FROM AUTHOR]

The single-event transients (SETs) have become a main contributor to soft errors in deep sub-micrometer integrated circuits applied in space. The sensitivity of 65-nm very large scale integrated circuits (VLSI) to SET, especially to clock SET, is studied by heavy ion experiments and analyzed. Built-in scan chains in the VLSI are utilized for experimental tests and proven to be very useful for SET evaluation. The specially designed test chip is developed and tested to find the relation between errors’ distribution and clock tree structures. Error count per event (EPE) is proposed as a metric of SET, and EPE distribution is found to be able to reflect error sources in the circuit topology. The related mechanisms are analyzed and implications for error positioning and design enhancement are given. [ABSTRACT FROM AUTHOR]