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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. [ABSTRACT FROM AUTHOR]

Spatial variations of single-event transient (SET) sensitivity in Al0.25Ga0.75N/GaN HEMTs are revealed using focused, pulsed UV laser light. SETs in regions of enhanced sensitivity have larger amplitudes and are termed “hot spots.” They are the same regions where large temperature changes are observed with thermoreflectance thermography. Both effects are attributed to the presence of material defects: SETs with enhanced amplitudes have reduced decay times due to thermally assisted detrapping; increased temperature is due to carrier scattering by the same defects. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

Single-event transients (SETs) were investigated in Al0.3{Ga0.7}{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. [ABSTRACT FROM PUBLISHER]

This paper presents the impact of ion angle on the single-event latuchup (SEL) cross section with the aim of improving the interpretation of latchup cross section obtained during heavy-ion experiments and the consequences on the latchup sensitivity for parts operating in the quasi-isotropic space radiation environment. First, latchup cross sections obtained from heavy-ion beams are presented and discussed. Then, the electrical I–V measurements are presented that lead to calibration of the TCAD structure and electrical latchup model implemented in MUSCA SEP3 tool. The TCAD simulations highlight the impact of both angle and roll effects on the latchup sensitivity induced by the asymmetric layout dependence of the parasitic latchup circuit. An LET dependence of the impact of angles on the latchup sensitivity has been demonstrated. Finally, the consequences of the angular distribution of the space radiation environment on the in-orbit latchup rate are discussed. The results show that the angular analysis would be necessary if the latchup rate at normal incidence were borderline or higher than acceptable for the specifications of the space mission. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

The Variable Depth Bragg Peak method has been investigated for single event latchup testing by comparing latchup cross sections for heavy ions at low and high energies and by pulse height analysis. Results show that, unlike for an SOI device previously tested, where the charge collection depth is very small (70 nm), the comparison is not straightforward for latchup because of the large charge collection volumes involved. The variation in LET with depth for lower-energy ions greatly affects the comparison, but, if a charge collection depth of 50~\mu\m is assumed and the LET is averaged over that distance, the comparison improves significantly. [ABSTRACT FROM PUBLISHER]

The influence of external circuit designs on ASET shapes in a high speed current feedback amplifier (CFA) (AD844) is investigated by means of the pulsed laser single event effect (PLSEE) simulation technique. Changes of the feedback resistors modify circuit’s electrical parameters such as closed-loop gain and bandwidth, affecting amplifier stability and so ASET shapes. Qualitative explanations based on general electronic rules and feedback theories enable the understanding of a CFA operation establishing a correlation between the evolution of external feedback resistor values and ASET parameters. TID effects on the ASET sensitivity in AD844 CFA are also investigated in this work highlighting different behaviors according to the impacted bipolar transistor in the integrated circuit. [ABSTRACT FROM PUBLISHER]

The synergistic effect between displacement damage dose (DDD) and analog transient radiation effects on electronics (ATREE) in an operational amplifier (LM124) (opamp) from three different manufacturers is investigated. Pulsed X-ray experiments have highlighted ATREE sensitivity on devices significantly more important following exposure to fission neutrons than for unirradiated devices. A previously developed simulation tool is used to model ATREE responses taking into account the electrical parameters degradation due to displacement damage phenomenon. A good agreement is observed between model outputs and experimental ATREE results. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

Shapes of ATREEs (Analog Transient Radiation Effects on Electronics) in a bipolar integrated circuit change with exposure to Total Ionizing Dose (TID) radiation. The impact of TID on ATREEs is investigated in the LM124 operational amplifier (opamp) from three different manufacturers. Significant variations are observed on the ATREE responsesfrom different manufacturers. The ATREEs are produced by pulsed X-ray experiments. ASET laser mappings are performed to highlight the sensitive bipolar transistors, explaining the ATREE phenomena variations from one manufacturer to another one. ATREE modeling results are presented using a previously developed simulation tool. A good agreement is observed between experimental ATREE responses and model outputs whatever the TID level, the prompt dose level, the amplifier configuration and the device manufacturer. [ABSTRACT FROM PUBLISHER]

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 Co^60 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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

As an accelerated test to characterize bipolar devices, the switched dose rate technique is a suitable solution for obtaining the entire low dose rate curve. Several sets of devices are first irradiated at high dose rate. Subsequently, all the sets are irradiated at low dose rate at the same time, which saves a considerable amount of time. The overall low dose rate curve is reconstructed by translating the individual curves obtained at low dose rate so that they form a continuous curve. The main issue of such a technique is that it requires several sets of devices. In this paper, optimization tools are presented to reduce the number of device sets and guidelines for their use are given. [ABSTRACT FROM PUBLISHER]

A controlled microbeam facility based on electron-beam lithography is demonstrated as a means of observing total dose induced compensation effects on circuit parameters and understanding degradation mechanisms. The system uses electron-beam lithography techniques to perform on-chip microbeam irradiations on individual transistors or sub-circuits without any irradiation of the neighboring transistors. An experimental validation of the mechanisms proposed to explain the sensitivity of the input current of the LM139 as an illustration of this technique is provided [ABSTRACT FROM AUTHOR]