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Focused, pulsed X-rays are used to generate single-event transients (SETs) in metal–insulator–semiconductor (MIS)-gate AlGaN/GaN high-electron-mobility transistors (HEMTs) in order to investigate the mechanisms responsible for SETs. Unlike Schottky-gate GaN HEMTs, where current flows between gate and drain when the device is biased “OFF,” for the MIS-gate HEMTs, current flows between the source and drain. The presence of the SiNx insulating layer under the gate effectively blocks electrons on the gate from moving into the semiconductor. Short-duration SETs at the gate are caused by the collection of holes injected by the X-rays. SETs collected at the source and drain have an initial short-duration component, followed by a long-duration tail that can last for hundreds of nanoseconds. The long tails are due to positive charges (holes) that are less mobile than the electrons and so take longer to exit the HEMT, and to holes that become trapped at defects in the material. The holes lower the potential barrier between the source and the region under the gate, allowing for the injection of electrons that flow from the source to the drain. The durations of the SET tails are determined by the lifetimes of the trapped holes that are found to vary with X-ray photon energy and electrical bias.

Using a laser-equivalent linear energy transfer (LET) approach, strong correlation is found for collected charge following heavy-ion and pulsed-laser excitation in a bulk diode device. By significantly modifying the size of the charge distribution generated by one- and two-photon absorption compared to the depth of the sensitive region, charge deposition in a large variety of device technologies is mimicked. Nearly one-to-one correlation is found with heavy-ion charge collection, independent of the laser focusing geometry or magnitude of LET. Finally, this approach is applied to the previous studies where empirical laser-ion correlations on highly scaled technologies were proposed. These correlations are reproduced through direct calculation of the laser-equivalent LET, and outstanding observations are explained despite the sensitive areas of these devices being up to 1000 times smaller than the laser-deposited charge profile. In total, these studies suggest that this quantitative methodology for laser-ion correlation is broadly applicable for a range of complex device technologies.

A focused, pulsed x-ray beam was used to compare SET characteristics in pristine and proton-irradiated Al0.3Ga0.7N/GaN HEMTs. Measured SET amplitudes and trailing-edge decay times were analyzed as was the collected charge, obtained by integrating the SET pulses over time. SETs generated in proton-irradiated HEMTs differed significantly from those in pristine HEMTs with regard to the decay times and collected charge. The decay times have previously been shown to be attributed to charge trapping by defect states that are caused either by imperfect material growth conditions or by proton-induced displacement damage. The longer decay times observed for proton-irradiated HEMTs are attributed to the presence of additional deep traps created when protons lose energy as they collide with the nuclei of constituent atoms. Comparison of electrical parameters measured before and immediately following exposure to the focused x-ray beam showed little change, confirming the absence of significant charge buildup in passivation layers by the x-rays themselves. A major advantage of the pulsed x-ray technique is that the region under the metal gate can be probed for single-event transients from the top side, an approach incompatible with pulsed-laser SEE testing that involves the use of visible light.

A cascode configuration with inverse-mode (IM) common-emitter silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) is proposed for the mitigation of single-event transients (SETs) in low-noise amplifiers (LNAs). Conventionally, despite their SET-mitigation capability, IM SiGe HBTs have been considered to be unsuitable for active gain stages due to severe degradation in RF performance. However, with the benefits of aggressive technology scaling, the high frequency performance of IM SiGe HBTs has been significantly improved, thereby enabling them to be utilized in active gain stages with acceptable RF performance. The cascode with IM common-emitter and common-base SiGe HBTs is used for a 2.4 GHz prototype LNA and it achieves adequate RF gain (10 dB) and noise figure (1.9 dB). With regard to SET mitigation, a through-wafer two-photon absorption pulsed-laser experiment is conducted to test the efficacy of this radiation-hardening approach in an advanced 90 nm SiGe BiCMOS platform. The proposed IM-SiGe-HBT-based LNA exhibits 85% reduction in transient peaks compared to the conventional forward-mode cascode LNA.

The single-event transient (SET) response of a W-band (75–110 GHz) radar receiver front-end is investigated in this paper. A new technique to facilitate the SET testing of the high frequency transceivers is proposed and demonstrated experimentally. The entire radar receiver front-end, including the high frequency signal sources and modulators, were designed and fully integrated in 90 nm 300 GHz SiGe process technology (Global Foundries SiGe 9HP). Two-photon absorption (TPA) laser pulses were utilized to induce transient currents in different devices in various circuit blocks. The study shows how short transient pulses from the high frequency tuned circuits are propagated throughout the receiver and are broadened while passing through low-pass filters present at supply nodes and the low-pass filter following the down-conversion mixer, thus affecting the digital data at the output of the receiver. The proposed methodology allows the study of the effect of SETs on the recovered digital data at the output of the high frequency receivers, thus allowing bit error rate calculations. Comprehensive device and circuit level simulations were also performed, and a close agreement between the measurement results and simulation data was demonstrated. To the authors’ best knowledge, this is the first study of SET on full receiver at millimeter-wave (mmW) frequencies.

The single-event transient (SET) response of the pre-amplification stage of two latched comparators designed using either npn or pnp silicon-germanium heterojunction bipolar transistors (SiGe HBTs) is investigated via two-photon absorption (TPA) carrier injection and mixed-mode TCAD simulations. Experimental data and TCAD simulations showed an improved SET response for the pnp comparator circuit. 2-D raster scans revealed that the devices in the pnp circuit exhibit a reduction in sensitive area of up to 80% compared to their npn counterparts. In addition, by sweeping the input voltage, the sensitive operating region with respect to SETs was determined. By establishing a figure-of-merit, relating the transient peaks and input voltage polarities, the pnp device was determined to have a 21.4% improved response with respect to input voltage. This study has shown that using pnp devices is an effective way to mitigate SETs, and could enable further radiation-hardening-by-design techniques.

Silicon-germanium heterojunction bipolar transistor (SiGe HBT) models are used in technology computer aided design (TCAD) to investigate single event transients induced by heavy-ion broadbeam and pulsed-laser two-photon absorption sources. A comparison between transient waveforms is provided, the proper extraction of heavy-ion broadbeam transients is discussed (along with circuit implications), and basic laser strike profiles are implemented in TCAD to provide insight into future design practices for simulation software to be used to describe laser-induced upsets in terms of an effective linear energy transfer (LET).

The single-event transient (SET) response of a SiGe-based, L-band low-noise amplifier (LNA) is investigated, with a focus on providing recommendations for radiation event simulation techniques. Pulsed-laser, two-photon absorption experiments show that the SET sensitivity of the SiGe LNA is highly dependent on operating conditions and strike location. Time and frequency-domain analyses raise potential concerns for digital data modulated on RF carrier signals. Device and circuit-level ion-strike TCAD simulations are utilized to compare alternative simulation approaches, highlight the importance of parasitics on SET simulation accuracy, and suggest best practices for modeling radiation-induced transients within RF/mm-wave circuits.

GaAs diode dark currents are correlated over a very large proton energy range as a function of displacement damage dose (DDD). The linearity of the dark current increase with DDD over a wide range of applied voltage bias deems this device an excellent candidate for a DD dosimeter. Additional proton testing performed in situ enabled error estimate determination to within 10% for simulated space use.

This paper investigates single-event effects in a W-Band (75-110 GHz) SiGe HBT down-conversion mixer intended for use in a space-based remote sensing radar system. Transient pulse propagation to the output of the mixer as a linear time variant system is analyzed theoretically. This study facilitates the understanding of transient propagation in RF receivers. Device- and circuit-level simulations were conducted to verify the results of the proposed theory. A two photon absorption laser was used to induce transients on different SiGe HBTs within the circuit to assess the impact of SETs on performance. This study shows that significant transients can be produced at the output of the mixer, which can potentially corrupt the received data or received pulse of the radar. It is shown that a differential double-balanced structure can effectively eliminate some of the transients at the output of the mixer. To the authors' best knowledge this is the first study of single event transients conducted on a millimeter-wave SiGe circuit.

Charge-collection experiments and simulations designed to quantify the effects of reflections from metallization during through-wafer TPA testing are presented. The results reveal a strong dependence on metal line width and metal line position inside the SiO 2 overlayer. The charge-collection enhancement is largest for the widest metal lines and the metal lines closest to the Si/SiO 2 interface. The charge-collection enhancement is also dependent on incident laser pulse energy, an effect that is a consequence of higher-order optical nonlinearities induced by the ultrashort optical pulses. However, for the lines further away from the Si/SiO 2 interface, variations in laser pulse energies affect the charge-collection enhancement to a lesser degree. Z-scan measurements reveal that the peak charge collection occurs when the axial position of the laser focal point is inside the Si substrate. There is a downward trend in peak collected-charge enhancement with the increase in laser pulse energies for the metal lines further away from the Si/SiO 2 interface. Metallization enhances the collected charge by same amount regardless of the applied bias voltage. For thinner metal lines and laser pulse energies lower than 1 nJ, the collected charge enhancement due to metallization is negligible.

Circuit parameters and configuration are very important when studying the synergistic effects total dose/SET. We explore a method combining dynamic parameter measurement and spectrum analysis which lead to a better understanding of this complex phenomenon. In this paper symbolic circuit analysis is used to obtain the relationship between input, output and noise injection due to photocurrent generation in the form of a rational function using symbolic variables in the complex frequency domain. This simulation technique was able to predict the impact of (i) total dose level, (ii) circuit parameters, and (iii) the injected energy on the ASET shapes. Basic mechanisms as field collapse and collection efficiency were also predicted and assessed.

Single-event transients (SETs) were investigated in Al 0.3 Ga 0.7 N/GaN high-electron-mobility transistors (HEMTs) using optical excitation via two-photon absorption and by heavy ions. The amplitudes and widths of the SETs were found to depend on a number of different factors, including bias conditions, strike location, and material quality.

Heavy-ion-induced single-event measurements for p-channel InGaSb quantum-well metal-on-insulator field-effect transistors (QW-MOSFETs) are demonstrated for a range of gate bias conditions. Two p-channel In0.33Ga0.67Sb QW structures were evaluated– a buried channel structure and a surface channel structure with and without an Al0.8In0.2Sb barrier layer respectively. The heavy-ion induced transient response is investigated for both structures. A slowly relaxing transient decay is observed in the buried channel device which is responsible for the bulk of the charge enhancement. It is effectively eliminated with the removal of the Al0.8In0.2Sb barrier, leading to a $10\times $ reduction in collected charge in the surface channel device. To analyze the transient response, a calibrated TCAD device simulation equipped with a heavy ion induced ionization model has been developed, which shows excellent agreement with the measured results for the entire range of evaluated gate bias conditions. The simulation analysis reveals that the charge collection enhancement phenomenon in a p-channel InGaSb QW-MOSFET is associated with the increased bipolar gain due to electron trapping in the Al0.8In0.2Sb barrier.

The single event effect (SEE) response of devices and differential pairs in a 32-nm SOI CMOS technology is explored using laser-induced carrier injection and TCAD simulations. Both nFETs and pFETs in this technology exhibit similar sensitive area to laser-induced SEE and are strongly dependent on the drain bias condition. TCAD simulations were conducted in order to confirm results and utilize a 3-D mixed-mode simulation approach to more accurately model testing conditions. The differential pair (diff. pair) circuit SEE response extends the discussion to include the use of these devices in a core analog/RF circuit block. The analysis includes the use of floating body (FB) and body-connected (BC) devices. Body-connected FETs tend to exhibit a transient response that is much shorter in duration when compared directly to its floating body counterpart.

Focused, pulsed laser-light is used to investigate single-event latchup in an analog-to-digital converter (AD9240) through the generation of charge collection spectra and their dependence on bias, laser pulse intensity and strike location. Large bipolar single-event transients were identified as precursors to latchup. They occurred at bias voltages just below the latchup holding voltage and in regions that became sensitive to single-event latchup at voltages above the holding voltage. Charge collection spectra obtained from spatial scans involving the pulsed laser had features similar to those obtained from heavy-ion irradiation. Both approaches indicated enhanced charge collection at supply voltages just below the holding voltage.

The effects of negative feedback, both external and internal, on single event transients (SETs) in SiGe HBT analog circuits are investigated. In order to examine internal negative feedback effects, basic common-emitter NPN current mirrors, with and without emitter degeneration resistors, are utilized. A Wilson current mirror and a Wilson mirror with its intrinsic external feedback removed are used to study external negative feedback effects under the influence of laser-induced single events. The measurement data clearly show notable improvements in SET response that can be made by employing both internal and external negative feedback. The peak transient in the output current is reduced, and the settling time upon a laser strike is shortened significantly by negative feedback. All four investigated current mirrors were fabricated with IBM 8HP 130 nm SiGe BiCMOS technology.

Carrier-density distributions generated via two-photon absorption from pulsed laser excitation are simulated using nonlinear-optical beam propagation software. These simulated carrier-density distributions are used to calculate depth profiles of the integrated collected charge using a rectangular-parallel-piped approach for two silicon diodes of different structure. Using a set of proposed correlation metrics, the resulting simulated charge collection profiles are found to exhibit good agreement with measured transient charge-collection data for most, but not all of the metrics. The physical phenomena underlying the correlation metrics are discussed in detail. The remaining discrepancies that exist between the simulated and experimental results are addressed and their potential causes are detailed.

Numerical simulation software is used to calculate quantitatively the two-photon absorption-induced carrier-density distributions generated under conditions that are experimentally relevant for single-event effects studies. The results provide valuable insight into how the magnitudes and shapes of the charge carrier distributions evolve over a large range of experimental conditions and the impacts this has for different device geometries. Furthermore, values of integrated charge are determined that can be more directly correlated with experimental observables.

We show the single-event effect characteristics of a production-level embedded resistive memory. The resistive memory under investigation is a reduction-oxidation random access memory embedded inside a microcontroller. The memory structure consists of Ir top electrode, Ta 2 O 5-δ /TaO x metal-oxide, and TaN bottom electrode. The radiation testing focused on the resistive memory array and peripheral circuits, while other portions of the microcontroller were shielded against the ion beam. We found that the resistive memory array is hardened against heavy ion and pulsed-laser-induced bit upsets. However, the microcontroller is susceptible to single-event functional interrupts due to single-event upsets in the resistive memory peripheral control circuits, which comprise of CMOS elements. Furthermore, the resistive memory architecture is not susceptible to functional failures during write, which is problematic for flash memories due to radiation-induced charge pump degradation.

A pulsed-laser dosimetry approach for two-photon absorption (TPA) single-event effects (SEE) measurements is presented. Development and implementation of three online beam monitors is described. The beam monitors permit characterization of the primary laser beam parameters of interest: the pulse energy delivered to the device under test, the pulse duration, and the focused laser spot size. A direct consequence of this methodology is the ability to monitor continuously the operating point of the TPA SEE pulsed-laser beamline and to make the necessary adjustments when parameters drift, either during an experiment or between experiments.

The single-event transient (SET) response of a third-generation bulk C-SiGe ( npn + pnp) BiCMOS platform is investigated for the first time. Pulsed-laser, two-photon absorption experiments show that the pnp SiGe heterojunction bipolar transistor (SiGe HBT) exhibits a significant reduction in sensitive area as well as an improved transient response compared with the npn SiGe HBT. Ion-strike simulations on 3-D TCAD, C-SiGe HBT models agree with experimental findings, showing a reduction in overall transient duration and collected charge for the pnp SiGe HBT. These improvements in device-level SETs are attributed to the n-well isolation layer present in the vertical material stack of the pnp HBT. These results suggest that precision analog, RF/mm-wave, and high-speed digital applications utilizing unhardened, high-performance bulk pnp SiGe HBTs should benefit from an inherently improved SEE response.

A SiGe RF low-noise amplifier (LNA) with built-in tolerance to single-event transients is proposed. The LNA utilizes an inverse-mode SiGe HBT for the common-base transistor in a cascode core. This new cascode configuration exhibits reduced transient peaks and shorter transient durations compared to the conventional cascode one. The improved SET response was verified with through-wafer two-photon absorption pulsed-laser experiments and supported via mixed-mode TCAD simulations. In addition, analysis of the RF performance and the reliability issues associated with the inverse-mode operation further suggests this new cascode structure can be a strong contender for space-based applications. The LNA with the inverse-mode-based cascode core was fabricated in a 130 nm SiGe BiCMOS platform and has similar RF performance to the conventional schematic-based LNA, further validating the proposed approach.

Nonlinear beam propagation software is used to calculate quantitatively the two-photon absorption (TPA)-induced charge-density profiles generated in silicon by focused femtosecond laser pulses under conditions that are experimentally relevant for single-event effects studies. The described approach permits simulation and prediction of the impact of various optical nonlinearities on the beam propagation through, and generation of free carriers in silicon for F/#s approaching one. It is found that, even at moderate incident laser pulse energies, the nonlinear-optical processes of nonlinear refraction, free-carrier absorption, and free-carrier refraction all contribute, and must be considered in describing the TPA-induced charge generation in silicon. Free-carrier refraction is found to play the dominant role in distorting the charge density profile at larger pulse energies. The simulation results are validated with experimentally measured beam sizes for different focusing conditions.

This paper presents an investigation of the impact of single-event transients (SETs) and total ionization dose (TID) on precision voltage reference circuits designed in a fourth-generation, 90-nm SiGe BiCMOS technology. A first-order uncompensated bandgap reference (BGR) circuit is used to benchmark the SET and TID responses of these voltage reference circuits (VRCs). Based on the first-order BGR radiation response, new circuit-level radiation-hardening-by-design (RHBD) techniques are proposed. An RHBD technique using inverse-mode (IM) transistors is demonstrated in a BGR circuit. In addition, a PIN diode VRC is presented as a potential SET and TID tolerant, circuit-level RHBD alternative.

International audience; LM124 operational amplifiers from three different manufacturers are irradiated with 60Co gamma rays and neutrons. During neutrons irradiation, one of the three integrated circuits exhibits an unexpected slew rates increase while its open loop gain and supply bias current follow the usual monotonic decrease as described in the literature. Analysis at circuit level shows that this phenomenon is due to an increase in the radiation-induced base current of the transistor used as buffer stage in the amplification chain. It is then demonstrated that a slight modification of the buffer transistor design, which is not implemented on the two other devices, enhances this phenomenon. Finally, the impact of the buffer transistor design on displacement damage and total ionizing dose response is investigated.

We investigate the impact of performance boosters using mechanical stress on the Single-Event Transient (SET) response of nanometer scaled Fully-Depleted Silicon-On-Insulator (SOI) devices. Laser SET measurements show that the active silicon layer thickness is the most important contributor to the SET response of highly scaled Ultra-Thin SOI (UTSOI) devices compared to the impact of strain. This is then demonstrated by dedicated TCAD calculations performed without taking into account any strain engineering technique. Finally, heavy ion-induced charge collection mechanisms are analyzed through the measurement of fast transients to get additional insights into the impact of short channel effects on the SET response of nanometer scaled SOI devices.

Ultraviolet optical pulses with a full-width-at-half-maximum diameter focused spot size of 0.32 μm are generated, characterized, and used to produce SEUs in a 90 nm CMOS/SOI SRAM. The results provide unequivocal experimental evidence for cell-to-cell variations in SEU sensitivity that can be identified with process variations at the individual transistor level.

This paper investigates total ionizing dose (TID) effects on the piezoelectric properties of lead zirconate titanate (PZT). The capacitance and contact voltage of thin-film, PZT-based relays were measured following incremental 60Co TID irradiations. The devices were held in several different bias conditions, during exposure. The direction of the biasing electric field during exposure, along with the polarization prior to exposure, has a measurable impact on post-irradiation operating voltage of the relay. In all cases, the switching voltage, as obtained via the peak values in a capacitance versus voltage sweep, shifted in a direction that would minimize the switching electric field in the direction of pre-exposure polarization. These effects were observed to be both significantly greater than the shifts experienced by a set of control samples, as well as reversible via aging at room temperature. The devices display remarkable robustness, operating during active TID exposure [dose rate = 855.6 rad(Si)/s], failing at a TID greater than 15 Mrad(Si).

Laser and heavy-ion data reveal the areas and shapes of single-event latchup (SEL)-sensitive regions in CMOS test structures and their positions relative to the affected p-n-p-n paths. Contrary to previous two-dimensional studies, this three-dimensional study shows that the position of maximum SEL sensitivity in these structures is not centered on a p-n-p-n region, but between two neighboring p-n-p-n regions, suggesting that synergistic triggering increases SEL sensitivity. The SEL-sensitivity maps suggest that laser light scattered from metal lines toward the silicon can contribute to the SEE response, for both back-side-incident two-photon absorption and front-side-incident single-photon absorption laser tests. We describe the metallization configurations and laser pulse energies for which reflected and/or diffracted laser light may contribute to the single-event effect (SEE) response.

Heavy ion, neutron, and laser experimental data are used to evaluate the effectiveness of various single event latchup (SEL) hardening strategies, including silicon-on-insulator (SOI), triple well, and guard rings. Although SOI technology is widely reported to be immune to SEL, conventional pnpn latchup can occur and has been observed in non-dielectrically isolated SOI processes. Triple well technologies are shown to be more robust against SEL than dual well technologies under all conditions used in this study, suggesting that the introduction of a deep N-well is an excellent zero-area-penalty hardening strategy. A single guard ring is shown to be sufficient for SEL immunity in the 180 nm CMOS technology investigated, and is likely sufficient for more modern CMOS technologies. After triggering latchup in a certain pnpn region, latchup was observed to spread to neighboring pnpn regions, which then infected other more distant regions until it had spread over a total distance of 700 micrometers. We discuss the physical mechanism of this latchup domino effect and its implications for device characterization and hardness assurance.

Laser-induced, time-resolved charge-collection measurements for In 0 . 33 Ga 0 . 76 Sb p-channel MOSFETS are reported for two different device structures; a buried-channel (quantum well) and surface-channel design. The charge-collection transient response is reported for different gate bias conditions. The two structures reveal dramatically different charge-collection transient response. The buried-channel MOSFET exhibits a slowly relaxing decay component that can persist on the order of microseconds, whereas the surface-channel MOSFET has a transient response that decays within ∼ 5 ns. The slowly-relaxing decay component previously has been associated with a charge enhancement processes that are eliminated in the surface-channel design. The collected charge is reduced by ∼ 2 orders of magnitude in the surface-channel device, making this design a very attractive candidate for space applications.

The effects of ionizing radiation on the single-event transient (SET) response of devices in a silicon-germanium (SiGe) bipolar and complementary metal oxide semiconductor (BiCMOS) platform is examined for the first time. Pulsed-laser measurements are leveraged to analyze the transient response of both npn SiGe HBT and nFET device structures after exposure to 10 keV X-rays. Measured data and simulations confirm a change to both the shape and magnitude of the transient response as a function of total ionizing dose (TID). This change is shown to be closely associated with the total dose degradation of the device via the introduction of trapped charge in the relevant oxides.

Single Photon Absorption technique with ultraviolet pulsed laser and focused X-ray beam is used to investigate single event transients in pristine AlGaN/GaN Schottky-Gate and MIS-Gate HEMTs. The results depend strongly on structure of devices.

3D mapping by scanning focused laser pulses throughout the charge collection paths and analysis of voltage transients resulting from two-photon absorption in a wide bandgap material is reported for high-breakdown voltage vertical GaN diodes.

Four pulsed-laser single-event effects systems, differing in wavelength and pulse width, were used to generate single event transients in a large-area silicon photodiode and an operational amplifier (LM124) to determine how transient amplitude and charge collection varied among the different systems. The optical wavelength and the focused spot size are the primary factors influencing the resultant charge density profile. In the large-area photodiode the transients can be distorted by high charge-injection densities that occur for tightly focused, higher energy optical pulses. When the incident laser-pulse energies are corrected for reflection losses and photon efficiency, with collection depth as a floating parameter (to account for diffusion), the photodiode data for all four devices lie on a single curve. The LM124 response varies with the specific transistor irradiated; similar transient shapes are measured for the different pulse wavelengths, with some deviations in the case of R1. These results reiterate that there is no single, optimum pulsed-laser system for SEE studies; that choice depends on the device to be tested, the intended application of that device, the goals of the test, and availability. For the specific devices evaluated here, any of the four laser systems would be sufficient for most tests.

An accelerated irradiation technique is used to study dose-ASET synergy effects. The impact of TID on SET is found to be identical when the dose rate is switched from high to low or from low to high.

Shapes of single event transients (SETs) in a linear bipolar circuit (LM124) change with exposure to total ionizing dose (TID) radiation. SETs shape changes are a direct consequence of TID-induced degradation of bipolar transistor gain. A reduction in transistor gain causes a reduction in the drive current of the current sources in the circuit, and it is the lower drive current that most affects the shapes of large amplitude SETs.

Carrier injection by single photon absorption using ultraviolet optical pulses is used to investigate single-event transients in pristine and proton-irradiated AlGaN/GaN HEMTs. The resulting transient shape and amplitude depends strongly on the specific location of the injected carriers, and varies with changes in gate and drain bias.

The propagation of Analog Single Event Transients (ASETs) to multiple outputs of Bipolar Junction Transistor (BJTs) Integrated Circuits (ICs) is reported for the first time. The results demonstrate that ASETs can appear at several outputs of a BJT amplifier or comparator as a result of a single ion or single laser pulse strike at a single physical location on the chip of a large-scale integrated BJT analog circuit. This is independent of interconnect cross-talk or charge-sharing effects. Laser experiments, together with SPICE simulations and analysis of the ASET’s propagation in the s-domain are used to explain how multiple-output transients (MOTs) are generated and propagate in the device. This study demonstrates that both the charge collection associated with an ASET and the ASET’s shape, commonly used to characterize the propagation of SETs in devices and systems, are unable to explain quantitatively how MOTs propagate through an integrated analog circuit. The analysis methodology adopted here involves combining the Fourier transform of the propagating signal and the current-source transfer function in the s-domain. This approach reveals the mechanisms involved in the transient signal propagation from its point of generation to one or more outputs without the signal following a continuous interconnect path.

GaAs diode dark currents are correlated over a very large proton energy range as a function of displacement damage dose (DDD). The linearity of the dark current increase with DDD over a wide range of applied voltage bias deems this device an excellent candidate for a displacement damage dosimeter. Additional proton testing performed in situ enabled error estimate determination to within 10% for simulated space use.

The synergistic effect between Total Ionizing Dose (TID) and Analog Single Event Transient (ASET) in LM124 operational amplifiers (opamps) from three different manufacturers is investigated. This effect is clearly identified on only two manufacturers by three, highlighting manufacturer dependent. In fact, significant variations were observed on both the TID sensitivity and the ASET response of LM124 devices from different manufacturers. Hypotheses are made on the cause of the differences observed. A previously developed ASET simulation tool is used to model the transient response. The effects of TID on devices are taken into account in the model by injecting the variations of key electrical parameters obtained during Co60 irradiation. An excellent agreement is observed between the experimental responses and the model outputs, independently of the TID level, the bias configuration and the manufacturer of the device.

The Synergistic effect between Total Ionizing Dose (TID) and Analog Transient Radiation Effects in Electronics (ATREE) in an operational amplifier (LM124) is investigated. A predictive methodology, based on a previously developed ATREEs simulation tool, is used to model the synergistic phenomena. This phenomenon is simulated for the first time and the duration of the ATREEs' is found to be identical to those measured experimentally. ATREEs induced by high dose-rate X-ray pulses are investigated using a flash X-ray facility. The ATREEs induced in the LM124 operational amplifier configured in three different bias configurations are investigated and simulated.

The Synergistic effect between TID and ATREEs (Analog Transient Radiation Effects on Electronics) in an operational amplifier (opamp) (LM124) is investigated for three different bias configurations. An accelerated irradiation technique is used to study these synergistic effects. The impact of TID on ATREEs is found to be identical regardless of whether the irradiation is performed at low dose rate or whether the dose rate is switched from high to low using the Dose Rate Switching (DRS) technique. The correlation between the deviations of the opamp's electrical parameters and the changes of ATREE widths is clearly established.

Unexpected recovery observed in previous dose-rate switching experiments is investigated. Irradiation and room-temperature annealing are performed on LM124 microcircuits and results are discussed in terms of hardness assurance.

Analog Transient Radiation Effects in Electronics (ATREE) induced by high dose-rate X-ray pulses are investigated using a flash X-ray facility. The ATREEs induced in a LM124 operational amplifier configured in three different bias configurations are investigated. A predictive methodology, based upon a previously developed ASET simulation tool, is used to model the ATREE phenomena. A semiempirical physical model is used to perform the correlation between the duration of the parasitic pulse signal induced in the LM124 and an equivalent value of the high dose-rate X-ray pulse level.

The enhanced radiation sensitivity exhibited at low dose rate by many bipolar devices remains one of the main concerns for spacecraft reliability. As an accelerated test technique, a new approach based on dose-rate switching experiments has been proposed to characterize bipolar devices. The foundations of this approach are detailed and guidelines for its use are given.

It is shown that the variety of shapes of the input current versus dose curve observed in several ICs is due to circuit effects, depending on the architecture, the value of the currents and the bias conditions. When stages are cascaded, the degradation of the second stage may add or subtract current to the collector current of the input transistor. The variations of the collector currents can be evaluated using the variations of the supply current. It is then possible to model the compensation effects using basic equations and study the impact of irradiation conditions. In some cases, the effect of biasing the circuit during irradiation is to reduce the compensation mechanism leading to an stronger increase in the input current. When a peak shaped degradation curve is recorded, annealing may either induce an additional degradation or a recovery depending on which side of the peak irradiation has brought the circuit.