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The total-ionizing-dose response of third-generation SiGe HBTs was investigated at elevated temperatures (80 °C and 130 °C) and compared with the response at 30 °C. The devices show less damage to irradiation at higher temperatures. Annealing experiments and TCAD simulations are used to investigate the degradation mechanism. The reduced degradation in forward mode at elevated temperatures is caused by increased annealing of interface traps primarily due to diffusion and reactions of H2 within the oxide/nitride EB spacer. The degradation is modest at all measured temperatures, allowing these devices to be suitable for radiation-rich environments where elevated temperatures are expected. [ABSTRACT FROM AUTHOR]

Total-ionizing-dose effects are evaluated in vertical-charge-trapping NAND devices with silicon oxynitride (SiON) and SiO2 tunneling layers. Processing splits include SiON tunneling layers with and without H2/D2 high-pressure annealing. Programmed devices were irradiated to 500 krad(SiO2) with 10-keV X-rays and annealed for 30 min. Second programming after annealing does not fully restore the original, programmed state. Radiation-induced trapped holes compensate for deeply trapped electrons that are injected into the dielectric during device programming. Throughout the full irradiation and annealing sequence, threshold voltages remain large enough to enable successful nonvolatile (NV) memory application. [ABSTRACT FROM AUTHOR]

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

Abstract: The magnitude of the low-frequency 1/f noise in GaN/AlGaN HEMTs grown under Ga-rich, N-rich, and NH3-rich conditions varies in response to hot-electron stress. Density-functional-theory (DFT) calculations show that the Ga vacancies that are responsible for the positive shift in pinch-off voltage due to electrical stress in Ga-rich and N-rich devices do not contribute significantly to the observed changes in 1/f noise with electrical stress. The N anti-sites that cause negative shifts in pinch-off voltage in ammonia-rich devices can cause an increase in the noise magnitude after stress. DFT calculations also show that singly hydrogenated and dehydrogenated Ga–N divacancies also can contribute to the noise before and after stress, respectively. A decrease in noise magnitude is also observed in some devices after stress. [Copyright &y& Elsevier]

Total ionizing dose (TID) effects at the 7-nm bulk FinFET node are characterized through changes in ring oscillator (RO) frequencies and current as a function of $V_{\mathrm {DD}}$ to model delay and power degradations in digital circuits. At the 7-nm node, tests show that gate delay decreased, and power consumption increased as TID increased. Percent increase in parameter degradations shows an inverse relationship with supply voltage, while percent increase in power consumption shows a direct relationship with supply voltage. Annealing at room temperature did not affect degradations. Circuit-level degradations for the 7-nm technology were less than 1% after TID exposure of 380 krad(SiO2). These TID exposure results will provide insight to designers about circuit-level parameters of interest concerning the 7-nm technology node. [ABSTRACT FROM AUTHOR]

The energy distributions of electrons in gate-all-around (GAA) Si MOSFETs are analyzed using full-band 3-D Monte Carlo (MC) simulations. Excellent agreement is obtained with experimental current–voltage characteristics. For these 24-nm gate length devices, the electron distribution features a smeared energy peak with an extended tail. This extension of the tail results primarily from the Coulomb scattering within the channel. A fraction of electrons that enter the drain retains their energy, resulting in an out-of-equilibrium distribution in the drain region. The simulated density and average energy of the hot electrons correlate well with experimentally observed device degradation. We propose that the interaction of high-energy electrons with hydrogen-passivated phosphorus dopant complexes within the drain may provide an additional pathway for interface-trap formation in these devices. [ABSTRACT FROM AUTHOR]

Pulsed-laser-induced single-event current measurements on two geometries of waveguide-integrated germanium photodiodes were conducted over a range of operating voltages to examine the impact of photodiode geometry on the transient response. Vertical p-i-n photodiodes exhibit transients with a duration that is relatively independent of the operating voltage, while the transient duration in lateral p-i-n photodiodes depends on the operating voltage. Furthermore, the experimental measurements facilitate identification of device dimensions that impact the transient response. These results can be used to identify potential radiation mitigation strategies for photodiodes operating in a radiation environment. Understanding the implications of design choices is critical for designing integrated photonic systems that balance system performance with tolerance for radiation degradation. [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]

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

Heavy-ion measurements are used to define a multiply nested sensitive-volume model for a 180-nm static random access memory (SRAM) test structure using the Monte Carlo radiative energy deposition (MRED) tool. We demonstrate that the fundamental assumptions of simple rectangular-parallelepiped (RPP) or integral-RPP models are inappropriate for single-event latchup (SEL) in this test structure, indicating that more advanced modeling is needed. We develop an MRED model that agrees well with latchup data at normal incidence and at roll and tilt angles of 60°. This process should facilitate estimates of SEL cross section and event rates for this and similar technologies in space environments. [ABSTRACT FROM AUTHOR]

Charge transport mechanisms of forward and reverse leakage currents in vertical GaN Schottky barrier diodes are investigated by measuring the temperature-dependent current–voltage characteristics. The results show that the leakage current is primarily governed by dislocation-associated thermionic field emission (TFE). The primary transport path is the reduced, localized conduction band around the dislocation core rather than the continuum defect states. A refined phenomenological physical model is developed for conductive dislocations in GaN, emphasizing that: 1) surface donors, surrounding the core of dislocations, can significantly shrink the barrier region after ionization, causing severe TFE leakage; 2) the ON donors likely to be responsible for TFE have a typical density of ~ 1 × 1018 cm−3 at 300 K and activation energy of 78 meV; and 3) the barrier height at donor sites is ~0.65 eV at 300 K, which is reduced by ~0.4 eV with respect to the dislocation-free region. [ABSTRACT FROM AUTHOR]

Neuromorphic computing endeavors to imitate the way biological brains process information and solve problems. Uses for neuromorphic computing span disciplines and include applications in image processing, audio processing, optimization, and more. This work explores the effect of proton-induced single-event upsets (SEUs) on a neuromorphic computing architecture engaged in image recognition. Two main results are found. One, the overall classification accuracy is unchanged although a high number of hidden, tolerable errors occurred. Additionally, SEUs are found to alter the relative occurrence of false positives and false negatives, which occurred despite the overall classification accuracy remaining unaffected. [ABSTRACT FROM AUTHOR]

Total-ionizing-dose (TID) effects and low-frequency noise are evaluated in 30-nm gate-length bulk and silicon-on-insulator (SOI) FinFETs for devices with fin widths of 10–40 nm. Minimal threshold voltage shifts are observed at 2 Mrad(SiO2), but large increases in low-frequency noise are found, and significant changes in defect-energy distributions are inferred. Radiation-induced leakage current is enhanced for narrow- and short-channel bulk FinFETs. Short-channel SOI FinFETs show enhanced degradation compared with longer-channel devices. Narrow- and short-channel SOI devices exhibit high radiation tolerance. Significant random telegraph noise (RTN) is observed in smaller devices due to prominent individual defects. [ABSTRACT FROM AUTHOR]

We evaluate the total-ionizing-dose (TID) responses of InGaAs nMOS fin field-effect transistors (FinFETs) with a modified gate-stack irradiated with 10-keV X-rays under different gate biases. This modified InGaAs nMOS FinFET process shows decreased subthreshold leakage current and increased hysteresis in as-processed devices, and reduced hole trapping in irradiated devices, than first-generation development-stage devices. The reduction in subthreshold leakage current is attributed to changing the buffer layer from GaAs to In0.3Ga0.7As, thereby enhancing the material quality. Both the increased hysteresis in as-processed devices and reduced hole trapping in irradiated devices are attributed primarily to thinning the Al2O3 layer that separates the HfO2 from the InGaAs layers. This facilitates charge exchange with defects at the HfO2/Al2O3 interface and reduces the percentage of radiation-induced holes that are generated in Al2O3 and trapped in HfO2. The removal of a tungsten layer above the TiN gate reduces the interface dose enhancement. [ABSTRACT FROM AUTHOR]

Total-ionizing-dose mechanisms are investigated in 16-nm InGaAs FinFETs with an HfO2/Al2O3 gate-stack. Transistors are irradiated up to 500 krad(SiO2) and annealed at high temperatures. Irradiated devices show negative threshold-voltage Vth shifts, subthreshold stretch-out, and leakage current increases. These result from positive charge trapping in the gate oxide and shallow trench insulators, and increases in the interface and border-trap charge densities. Low-frequency noise measurements at different temperatures indicate a significant increase of noise magnitude in irradiated devices at an activation energy of ~0.4 eV. Density functional theory (DFT) calculations strongly suggest that transistor Vth shifts are due primarily to hole trapping at oxygen vacancies in HfO2, and the increased noise is due primarily to O vacancies in Al2O3. Additional contributions to the noise from defects in the GaAs buffer layer are also likely, primarily at low temperatures. [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 sensitive volume is developed using pulsed laser-induced collected charge for two bias conditions in an epitaxial silicon diode. These sensitive volumes show good agreement with the experimental two-photon absorption laser-induced collected charge at a variety of focal positions and pulse energies. When compared to ion-induced collected charge, the laser-based sensitive volume overpredicts the experimental collected charge at low bias and agrees at high bias. A sensitive volume based on ion-induced collected charge adequately describes the ion experimental results at both biases. Differences in the amount of potential modulation explain the differences between the ion- and laser-based sensitive volumes at the lower bias. Truncation of potential modulation by the highly doped substrate, at the higher bias, results in similar sensitive volumes. [ABSTRACT FROM AUTHOR]

We evaluate the total ionizing dose (TID) responses of InGaAs nMOS FinFETs with different gate lengths irradiated with 10-keV X-rays under different gate biases. The largest degradation after irradiation occurs at $V_{\mathrm {G}} = -1$ V. Radiation-induced trapped positive charge dominates the TID response of InGaAs FinFET transistors, consistent with previous results for InGaAs multifin capacitors. Shorter gate-length devices show larger radiation-induced charge trapping than longer gate-length devices, most likely due to the electrostatic effects of trapped charge in the surrounding SiO2 isolation and SiO2/Si3N4 spacer oxides. The 1/ $f$ noise measurements indicate a high trap density and a nonuniform defect-energy distribution, consistent with a strong variation of effective border-trap density with surface potential. [ABSTRACT FROM AUTHOR]

Silicon waveguide (WG) integrated p-i-n germanium photodiodes (PDs) from a monolithic electronic–photonic integrated circuit technology were exposed to ionizing radiation from a 10-keV X-ray source to investigate total ionizing dose effects. Existing work on radiation effects in PDs, which is almost entirely based on normal-incidence PDs (rather than WG-integrated PDs), is reviewed to provide context and a framework for understanding the measurement results. Back-end-of-line considerations suggest the enhancement of the ionizing dose due to high- $Z$ materials near the PD. PD performance was characterized in terms of dark current, S-parameters, dc photocurrent response, and optical-to-electrical conversion frequency response, shortly before and after irradiation. No significant degradation was observed, indicating that these devices may be suitable for applications in harsh radiation environments. [ABSTRACT FROM AUTHOR]

Tunneling-dominated charge transport is demonstrated in vertically stacked MoS2/interlayer/MoS2 heterostructures with Al2O3, hexagonal boron nitride (h-BN), and HfO2 dielectrics. All devices are highly resistant to 10-keV X-ray irradiation. Only small transient changes in X-ray-induced photocurrent are observed as a result of trap creation in the thin interlayer dielectric, with rapid passivation. Samples with Al2O3 and h-BN interlayer dielectrics show significant increases in conduction current during proton irradiation, due to displacement-damage-induced defects that lower the effective tunnel-barrier height. Density-functional-theory calculations provide insights into the pertinent defects. Devices with HfO2 interlayer dielectrics show great promise for use in radiation tolerant, ultimately scaled tunnel FETs. [ABSTRACT FROM AUTHOR]

Two-photon absorption (TPA) pulsed-laser testing is used to analyze the TPA-induced single-event latchup sensitive-area of a specially designed test structure. This method takes into account the existence of an onset region in which the probability of triggering latchup transits between 0 and 1 as the laser pulse energy increases. This variability is attributed to a combination of laser pulse-to-pulse variability and variations in local carrier density and temperature. For each spatial position, the latchup probability associated with a given energy is calculated. Calculation of latchup cross section at lower laser energies, relative to onset, is improved significantly by taking into account the full probability distribution. The transition from low probability of latchup to high probability is more abrupt near the source contacts than for surrounding areas. [ABSTRACT FROM PUBLISHER]

Angular single-event (SE) mechanisms and experimental upset data for 14-/16-nm bulk fin field-effect transistor (FinFET) technologies are presented and analyzed. The discrete structure of FinFETs introduces unique geometrical and orientation dependences for angular SE mechanisms and SE upset (SEU) responses of FinFET circuits. Geometric analyses and 3-D technology computer-aided design results effectively explain the angular mechanisms behind experimentally observed SE crosssectional responses. Results show that angular SEU crosssectional characteristics can be attributed to the proportional contributions of charge deposition regions in the fin structure and the subfin bulk substrate. [ABSTRACT FROM PUBLISHER]

We have evaluated the total-ionizing-dose response of graphene-based X-ray detectors fabricated from graphene oxide (GO) via laser scribing. Raman characterization shows that the resulting structures exhibit the desired conversion of GO to graphene; both high- and low-resistance detectors are formed. The detectors are quite radiation sensitive, as demonstrated by fast pulse testing. The response time of the detectors degrades with total-ionizing dose exposure as a result of electron trapping at residual oxygen from unreacted GO and/or adsorbed oxygen on the graphene surface. [ABSTRACT FROM PUBLISHER]

The radiation hardness of AlGaN/GaN high-electron-mobility transistors (HEMTs) is found to improve with increasing GaN channel thickness. Epitaxial MgCaO shows promise as a radiation-tolerant gate dielectric, with only small shifts in operating parameters of metal–oxide–semiconductor HEMTs observed at doses up to 1 Mrad(SiO2). Bias-induced electron trapping and radiation-induced-hole trapping can occur in the MgCaO, depending on the applied bias during stress and/or irradiation. AC transconductance measurements are used to help understand charge trapping in these devices. [ABSTRACT FROM PUBLISHER]

Total-ionizing-dose-induced resonance frequency shifts in piezoresistive micromachined cantilevers are experimentally shown to be dose-rate dependent. Devices were irradiated to 1 Mrad(SiO2) at rates from 5.4 to 30.3 krad(SiO2)/min, with lower rate exposures producing up to four-times more negative frequency shifts than higher rate exposures. Devices that were hydrogenated in a steam bath for 1 h showed shifts similar to those of control (not hydrogenated) devices at higher dose rates, and larger shifts than control devices at lower rates. All devices recovered to levels close to preirradiation after several hours of post-irradiation annealing. The dose-rate dependence is attributed to differences in carrier concentration caused by varying efficiencies of the depassivation of boron by hydrogen at higher and lower dose rates and/or surface charging effects, and the subsequent differences in Young’s modulus that occur as a result. Many of these processes are similar to effects that lead to ELDRS in linear bipolar transistors, emphasizing the need to include low-dose-rate testing of microelectromechanical systems devices when considering them for use in space systems. [ABSTRACT FROM PUBLISHER]

Single-event transient (SET) responses are compared for floating-body contact, T-gate body-contact (TB), and tunnel-diode body-contact (TDBC) silicon-on-insulator (SOI) MOSFETs. The influence of three body-contact schemes on SET sensitivity is examined via irradiations as functions of position, bias voltage, and device size. The mechanisms of SET in SOI devices are discussed. Although both TB and TDBC schemes suppress floating body effects (FBEs), the TDBC scheme has superior SET hardness because it effectively eliminates charge enhancement due to bipolar amplification originating from FBEs. Thus, TDBC-structure SOI devices can lead to improved single-event upset hardness in static random access memory cells. [ABSTRACT FROM PUBLISHER]

Single event burnout (SEB) of NLDMOSFETs on SOI initiated by pulsed laser irradiation is demonstrated for the first time. The sensitive region of the device for SEB and the effects of reverse voltage and laser energy are explored. The data indicate that the device is most sensitive to laser pulses in the drift region near the P-well. This is influenced by the electric field distribution in the drift region of the LDMOSFET at the time of the laser pulse. The SEB threshold depends on both the applied reverse voltage and the laser pulse energy. The laser pulse energy at a given reverse voltage required to initiate SEB is inversely proportional to the laser spot distance from the P-well. Simulation results for the device drain current following the radiation pulse indicate that the behavior of the npn parasitic bipolar transistor inherent in the LDMOS structure can explain the observations. [ABSTRACT FROM AUTHOR]

Silicon photonics is considered to be an ideal solution as optical interconnect in radiation environments. Our previous study has demonstrated experimentally that radiation responses of device are related to waveguide size, and devices with thick top silicon waveguide layers are expected to be less sensitive to irradiation. Here, we design radiation-resistant arrayed waveguide gratings and Mach-Zehnder interferometers based on silicon-on-insulator with 3 µm-thick silicon optical waveguide platform. The devices are exposed to 60 Co γ-ray irradiation up to 41 Mrad(Si) and 170-keV proton irradiation with total fluences from 1×10 13 to 1×10 16 p/cm 2 to evaluate performance after irradiation. The results show that these devices can function well and have potential application in harsh radiation environments.