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An approach for determining the optimal laser parameters (i.e., pulse energy, focused spot size, wavelength, and pulse duration) for correlating single-event transients induced via two-photon absorption (TPA) and heavy ions is presented. The approach focuses on identification and extraction of waveform characteristics, or “features,” and minimizing the error between features produced by TPA and ions. Modifying optical parameters can directly impact the waveform features of the TPA-induced transients. Consequently, optimal laser parameters that minimize the error between features extracted for laser- and ion-induced waveforms can be determined. In this paper, the laser pulse energy and spot size were varied, while maintaining a fixed pulse duration and wavelength, and the resulting transients were compared to ion-induced transients. When the optimized optical parameters are used, excellent agreement was achieved between laser- and ion-induced transient waveforms in a silicon-germanium heterojunction bipolar transistor (SiGe HBT). In addition, a one-to-one correlation between heavy-ion linear energy transfer (LET) and laser pulse energy was obtained for a particular spot size ($\omega _{0} = 1.89\,\,\mu \text{m}$ (HW $1/e^{2}$)). These results show that a correlation between LET and pulse energy is achievable when the remaining optical parameters are selected appropriately. Although the results presented are for SiGe HBTs, the generality of the approach should allow it to be extended to other semiconductor platforms. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper demonstrates the use of an RF power detector to sense the occurrence of single-event transients (SETs) in RF circuits and systems. The detector was connected to a low-noise amplifier (LNA), and the relationship between the detector output and the LNA transients was investigated via two-photon absorption, pulsed-laser testing, together with mixed-mode TCAD simulations. The response of the detector shows a strong correlation with the RF power of the generated SET. An analytical expression for the detector output is derived and utilized to fit the data. The effects of parameters affecting circuit performance on the detector response to SETs are explored using calibrated TCAD mixed-mode simulations, and design tradeoffs are presented. Finally, a solution to distinguish between transients generated in the detector from those generated in the circuit being monitored is proposed and verified in simulation. The use of detectors to monitor SETs in RF systems could lead to judicious deployment of detection-driven SET mitigation techniques. [ABSTRACT FROM PUBLISHER]

Carrier lifetime control in thick silicon carbide (SiC) epilayers is essential for fabricating >10kV devices. Lifetime depth profiles were investigated in n-type and p-type SiC epilayers using photoluminescence (PL) decay excited by two-photon absorption (TPA), using 586nm laser pulses. TPA limits the excitation to a small volume, and the observed PL decays exhibit nonexponential behavior resulting from the three-dimensional carrier diffusion occurring during the decay. The results were analyzed using a formalism that includes the effects of carrier lifetime, carrier diffusion, and surface recombination on the PL decay. The lifetime depth profiles exhibited a nonuniform lifetimedegrading defect concentration within the epilayers. [ABSTRACT FROM AUTHOR]

This correspondence comments on the correlation between measured and simulated charge collection in two diode structures presented in [1]. In [1], results from pulsed-laser-induced charge deposition via two-photon absorption revealed reasonable correlation between experimental data and simulations in some aspects but showed lack of correlation in terms of the measured and predicted magnitudes of the collected charge. The source of this poor agreement has recently been determined, and is attributed to an incorrect pulse energy calibration used for those experiments. With the proper energy calibration applied, the agreement between simulation and experiment is nearly quantitative for all observables in both devices. These results significantly strengthen the validity of the nonlinear optical beam propagation method numerical approach for accurately predicting pulsed-laser-induced charge deposition. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

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). [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of two different silicon-germanium (SiGe) X-band (8–12 GHz) low noise amplifier (LNA) topologies is fully investigated in this paper. The two LNAs were designed and implemented in 130nm SiGe HBT BiCMOS process technology. Two-photon absorption (TPA) laser pulses were utilized to induce transients within various devices in these LNAs. Impulse response theory is identified as a useful tool for predicting the settling behavior of the LNAs subjected to heavy ion strikes. Comprehensive device and circuit level modeling and simulations were performed to accurately simulate the behavior of the circuits under ion strikes. The simulations agree well with TPA measurements. The simulation, modeling and analysis presented in this paper can be applied for any other circuit topologies for SET modeling and prediction. [ABSTRACT FROM PUBLISHER]

The impact of semiconductor process scaling on the overall transient response of SiGe BiCMOS platforms is investigated. Pulsed-laser two-photon absorption (TPA) and heavy-ion broad-beam testing of SiGe HBT device and digital test structures across several generations of SiGe technologies are utilized to investigate the potential impacts of semiconductor process scaling (e.g., lateral/vertical scaling, changes in doping, Ge content, etc.) on the overall transient shape, magnitude, and duration. Technology scaling is shown to increase the single-event effect (SEE) sensitivity of SiGe HBTs (i.e., elevated collected charge, where 1st Gen. QC <3 rd Gen. QC <4 th Gen. QC ). Modern third-generation and fourth-generation devices under a forward-active bias (i.e., forward-biased EB junction, reverse-biased CB junction) exhibit a large diffusive transient component between the emitter and collector terminals, driving an elevation in collected charge. 3-D TCAD modeling is utilized to understand the fundamental transient mechanisms and assess the primary scaling factors affecting SEE sensitivity. Ion-strike simulations show that bulk traps can substantially enhance the charge collection mechanisms within these devices. These results suggest that SiGe technology scaling may have a strong impact on the radiation-induced transient response of SiGe HBTs, with future SiGe technology generations potentially exhibiting increased sensitivities to single-event effects. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

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. High-precision spatial mapping of defects and traps in AlGaN/GaN HEMT devices identify regions of enhanced SET signals, or “hot spots” that are ascribed to the presence of lattice defects that modify the electric field in the structure. The resulting transient shape and amplitude depend strongly on the specific location of the injected carriers, and vary with changes in gate and drain bias. Proton irradiation significantly alters transient signal shapes, increases the integrated collected charge, and increases density of defects and traps. [ABSTRACT FROM PUBLISHER]

The capability of inverse-mode (IM) silicon- germanium (SiGe) heterojunction bipolar transistors (HBTs) for the mitigation of single-event transients (SETs) under large-signal operation was investigated in an RF down-conversion single- balanced mixer using a through-wafer, two-photon absorption pulsed-laser beam experiment and TCAD heavy-ion simulations. The IM SiGe HBTs replace conventional forward-mode (FM) SiGe HBTs in the differential pair, which provides full current steering for frequency mixing operation. Under steady-state conditions, the IM SiGe HBT differential pair exhibits smaller transient peaks with shorter durations compared to the FM SiGe HBTs. In addition, under the injection of a local oscillator (LO) signal with large swing, the IM SiGe HBTs show faster recovery (50% reduction in the best case) from the impact of SETs. In the frequency domain, it is observed that IM SiGe HBTs produce less distortion at the output for an intermediate frequency below 1 GHz. Based on the performance comparison between FM and IM SiGe HBT down-conversion mixers, system design guidelines to compensate the noise figure degradation associated with using IM SiGe HBTs are discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

The single-event effect sensitivity of three different commonly employed current mirror circuits, as well as an unconventional inverse-mode current mirror, all implemented in C-SiGe (NPN + PNP) HBT on SOI technology are investigated. Comparisons of the measured data of the basic NPN and PNP current mirror circuits show higher single-event radiation tolerance of PNP SiGe HBTs compared with NPN SiGe HBTs. The concept of utilizing inverse-mode SiGe HBTs in current mirror circuits is investigated. Measurement results validate the feasibility of employing inverse-mode PNP SiGe HBTs in current mirrors and show an excellent resilience against ion-strikes. Full 3-D NanoTCAD models of the SiGe HBTs are developed and used in mixed-mode TCAD simulations (within Cadence) to validate the measurement results. Finally, based on the measurement data and analysis of the four current mirrors, some practical suggestions and observations are offered for operation of such circuits in extreme environments. [ABSTRACT FROM PUBLISHER]