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The NIST silicon lattice comparator has been in service, in various forms, since the 1970s. It is capable of measuring the difference in lattice spacing between specimens of high-quality float-zone silicon to Δd/d ≈ 6 × 10−9. It has recently undergone a thorough update of its control systems and mechanics. These upgrades result in the ability to collect data with improved stability, less settling time of the instrument, and less operator intervention. [ABSTRACT FROM AUTHOR]

A methodology is developed where a fundamental parameters approach (FPA) description of a laboratory powder diffraction instrument (configured in divergent‐beam Bragg–Brentano geometry) is used to determine GSAS‐II profile parameters for peak asymmetry and instrumental peak widths. This allows the instrumental contribution to peak shapes to be robustly determined directly from a physical description of the instrument, even though GSAS‐II does not directly implement FPA for peak shape computation. The FPA‐derived parameters can be used as the starting point for instrument characterization, or to characterize sample broadening without the use of a standard to determine the instrument profile function. This new method can facilitate generation of training sets for machine learning. A plot is generated that shows the differences between the two approaches, demonstrating upper bounds for the accuracy of the GSAS‐II profile model for a particular instrumental configuration. [ABSTRACT FROM AUTHOR]

The difference in the diffracted intensity of the σ‐ and π‐polarized components of an X‐ray beam in powder diffraction has generally been treated according to equations based on dipole scattering, also known as kinematic X‐ray scattering. Although this treatment is correct for powders and post‐sample analyzers known to be of high mosaicity, it does not apply to systems configured with nearly perfect crystal incident‐beam monochromators. Equations are presented for the polarization effect, based on dynamical diffraction theory applied to the monochromator crystal. The intensity of the π component relative to the σ component then becomes approximately proportional to |cos 2gθm| rather than to cos22gθm, where gθm is the Bragg diffraction angle of the monochromator crystal. This changes the predicted intensities of X‐ray powder diffraction patterns produced on instruments with incident‐beam monochromators, especially in the regions far from 2gθ = 90° in the powder pattern. Experimental data, based on well known standard reference materials, are presented, confirming that the dynamical polarization correction is required when a Ge 111 incident‐beam monochromator is used. The dynamical correction is absent as an option in the Rietveld analysis codes with which the authors are familiar. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to be used to evaluate specific aspects of the instrument performance of both X-ray and neutron powder diffractometers. This report describes SRM 640f, the seventh generation of this powder diffraction SRM, which is designed to be used primarily for calibrating powder diffractometers with respect to line position; it also can be used for the determination of the instrument profile function. It is certified with respect to the lattice parameter and consists of approximately 7.5 g of silicon powder prepared to minimize line broadening. A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the Si powder. Both statistical and systematic uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 °C of a = 0.5431144 ± 0.000008 nm. [ABSTRACT FROM AUTHOR]

This rather long-standing project has resulted in a National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for the analysis of crystallite size from a consideration of powder diffraction line profile broadening. It consists of two zinc oxide powders, one with a crystallite size distribution centered at approximately 15 nm, and a second centered at about 60 nm. These materials display the effects of stacking faults that broaden specific hkl reflections and a slight amount of microstrain broadening. Certification data were collected on the high-resolution powder diffractometer located at beamline 11-BM of the Advanced Photon Source, and on a NIST-built laboratory diffractometer equipped with a Johansson incident beam monochromator and position sensitive detector. Fourier transforms were extracted from the raw data using a modified, two-step profile fitting procedure that addressed the issue of accurate background determination. The mean column lengths, hLiarea and hLivol, were then computed from the Fourier transforms of the specimen contribution for each reflection. Data were also analyzed with fundamental parameters approach refinements using broadening models to yield hLiarea and hLivol values. These values were consistent with the model-independent Fourier transform results; however, small discrepancies were noted for the hLiarea values from both machines and both crystallite size ranges. The fundamental parameters approach fits to the laboratory data yielded the certified lattice parameters. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to evaluate specific aspects of instrument performance of both X-ray and neutron powder diffractometers. This report describes SRM 660c, the fourth generation of this powder diffraction SRM, which is used primarily for calibrating powder diffractometers with respect to line position and line shape for the determination of the instrument profile function (IPF). It is certified with respect to lattice parameter and consists of approximately 6 g of lanthanum hexaboride (LaB6) powder. So that this SRM would be applicable for the neutron diffraction community, the powder was prepared from an isotopically enriched 11B precursor material. The microstructure of the LaB6 powder was engineered specifically to yield a crystallite size above that where size broadening is typically observed and to minimize the crystallographic defects that lead to strain broadening. A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the LaB6 powder. Both Type A, statistical, and Type B, systematic, uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 °C of a = 0.415 682 6 ± 0.000 008 nm (95% confidence). [ABSTRACT FROM AUTHOR]

The use of an incident‐beam monochromator (IBM) in an X‐ray powder diffractometer modifies both the shape of the spectrum from the X‐ray source and the relation between the apparent diffracted angle and the actual wavelength of the X‐rays. For high‐accuracy work, the traditional assumption of a narrow line of typically Gaussian shape does not suffice. Both the shape of the tails of peaks and their width can be described by a new model which couples the dispersion from the optic to the dispersion from the powder sample, and to its transport to a detector. This work presents such a model, and demonstrates that it produces excellent fits via the fundamental parameters approach and requires few free parameters to achieve this. Furthermore, the parameters used are directly relatable to physical characteristics of the diffractometer optics. This agreement is critical for the evaluation of high‐precision lattice parameters and crystal microstructural parameters by powder diffraction. [ABSTRACT FROM AUTHOR]

Excitation of crystalline KBr, KCl, and LiF with electrons of energy 60–1000 eV produces weak emission in the 360–420 nm region, identified as the B→ X electronic transition in the CN radical. The emission is attributed to CN molecules that leave the surface of the crystal in their electronically excited B 2Σ+ state. The resulting spectra, which are rotationally unresolved, are analyzed by novel nonlinear fitting procedures to yield information about the vibrational and rotational population distributions. For CN(B) produced via electron-stimulated desorption from LiF, the vibrational populations approximate a temperature of 1500 K, while the rotational abundances can be represented as a sum of two Boltzmann distributions having temperatures of 660 K (81%) and 90 K (19%). For ESD from KBr, the rotational distribution is adequately represented as a single Boltzmann at ∼ 590 K. [ABSTRACT FROM AUTHOR]

This work presents a technique for extracting the detailed shape of peaks with extended, overlapping tails in an X‐ray powder diffraction pattern. The application discussed here concerns crystallite size broadening, though the technique can be applied to spectra of any origin and without regard to how the profiles are to be subsequently analyzed. Historically, the extraction of profile shapes has been difficult due to the complexity of determining the background under the peak, resulting in an offset of the low‐frequency components of the Fourier transform of the peak known as the 'hook' problem. The use of a carefully considered statistical weighting function in a non‐linear least‐squares fit, followed by summing the residuals from such a fit with the fit itself, allows one to extract the full shape of an isolated peak, without contributions from either the background or adjacent peaks. The extracted shape, consisting of the fit function recombined with the residuals, is not dependent on any specific shape model. The application of this to analysis of microstructure is performed independently of global parametric models, which would reduce the number of refined parameters; therefore the technique requires high‐quality data to produce results of interest. The effectiveness of the technique is demonstrated by extraction of Fourier transforms of peaks from two sets of size‐broadened materials with two differing pieces of equipment. A new method of extracting the individual shapes of overlapping powder peaks with Lorentzian (or other long‐range) tails is presented. This allows computation of microstructure directly in Fourier space, without the infamous 'hook' problem at low frequency. [ABSTRACT FROM AUTHOR]

This work provides a short summary of techniques for formally-correct handling of statistical uncertainties in Poisson-statistics dominated data, with emphasis on X-ray powder diffraction patterns. Correct assignment of uncertainties for low counts is documented. Further, we describe a technique for adaptively rebinning such data sets to provide more uniform statistics across a pattern with a wide range of count rates, from a few (or no) counts in a background bin to on-peak regions with many counts. This permits better plotting of data and analysis of a smaller number of points in a fitting package, without significant degradation of the information content of the data set. Examples of the effect of this on a diffraction data set are given. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of the performance of X-ray powder diffraction instruments. This report describes SRM 1878b, the third generation of this powder diffraction SRM. SRM 1878b is intended for use in the preparation of calibration standards for the quantitative analyses of α-quartz by X-ray powder diffraction in accordance to National Institute for Occupational Safety and Health Analytical Method 7500, or equivalent. A unit of SRM 1878b consists of approximately 5 g of α-quartz powder bottled in an argon atmosphere. It is certified with respect to crystalline phase purity, or amorphous phase content, and lattice parameter. Neutron powder diffraction, both time of flight and constant wavelength, was used to certify the phase purity using SRM 676a as an internal standard. A NIST-built diffractometer, incorporating many advanced design features was used for certification measurements for lattice parameters. [ABSTRACT FROM AUTHOR]

Variability in energy deposition caused by intrinsic statistical fluctuations is quantified for specific radiation environments. Differences in effective flux are observed for minimally ionizing particles, typically leading to a decrease in predicted soft error rate, the magnitude of which depends on the threshold LET. When compared to spectra accounting for energy-deposition fluctuations, predictions with traditional LET spectra in CREME96 are found to lead to conservative estimates in almost all situations. [ABSTRACT FROM AUTHOR]

The laboratory X-ray powder diffractometer is one of the primary analytical tools in materials science. It is applicable to nearly any crystalline material, and with advanced data analysis methods, it can provide a wealth of information concerning sample character. Data from these machines, however, are beset by a complex aberration function that can be addressed through calibration with the use of NIST Standard Reference Materials (SRMs). Laboratory diffractometers can be set up in a range of optical geometries; considered herein are those of Bragg-Brentano divergent beam configuration using both incident and diffracted beam monochromators. We review the origin of the various aberrations affecting instruments of this geometry and the methods developed at NIST to align these machines in a first principles context. Data analysis methods are considered as being in two distinct categories: those that use empirical methods to parameterize the nature of the data for subsequent analysis, and those that use model functions to link the observation directly to a specific aspect of the experiment. We consider a multifaceted approach to instrument calibration using both the empirical and model based data analysis methods. The particular benefits of the fundamental parameters approach are reviewed. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of the performance of X-ray powder diffraction instruments. This report describes SRM 1976b, the third generation of this powder diffraction SRM. SRM 1976b consists of a sintered alumina disc, approximately 25.6 mm in diameter by 2.2 mm in thickness, intended for use in the calibration of X-ray powder diffraction equipment with respect to line position and intensity as a function of 2θ-angle. The sintered form of the SRM eliminates the effect of sample loading procedures on intensity measurements. Certified data include the lattice parameters and relative peak intensity values from 13 lines in the 2θ region between 20° and 145° using CuKα radiation. A NIST-built diffractometer, incorporating many advanced and unique design features was used to make the certification measurements. [ABSTRACT FROM PUBLISHER]

MRED is a Python-language scriptable computer application that simulates radiation transport. It is the computational engine for the on-line tool CRÈME-MC. MRED is based on c++ code from Geant4 with additional Fortran components to simulate electron transport and nuclear reactions with high precision. We provide a detailed description of the structure of MRED and the implementation of the simulation of physical processes used to simulate radiation effects in electronic devices and circuits. Extensive discussion and references are provided that illustrate the validation of models used to implement specific simulations of relevant physical processes. Several applications of MRED are summarized that demonstrate its ability to predict and describe basic physical phenomena associated with irradiation of electronic circuits and devices. These include effects from single particle radiation (including both direct ionization and indirect ionization effects), dose enhancement effects, and displacement damage effects. MRED simulations have also helped to identify new single event upset mechanisms not previously observed by experiment, but since confirmed, including upsets due to muons and energetic electrons. [ABSTRACT FROM AUTHOR]

The impact of high-Z metals on energy deposition in thin volumes due to direct ionization by ions in space environments is examined. The importance of energy loss straggling in small volumes typical of those found in advanced devices is also evaluated. It is found that direct ionization by protons over a large energy range may contribute significantly to error rates in advanced silicon on insulator devices due to energy loss straggling. This improves on conventional event rate analysis based on linear energy transfer, which does not describe the contributions of direct ionization by protons to the error rate. [ABSTRACT FROM AUTHOR]

RRAM memory cells demonstrate resilience to ionizing dose and displacement damage, despite the presence of a nonhardened access transistor. Degradation in RRAM performance was not observed until large displacement damage doses and complete functionality was regained by cycling. A significant reduction in both the high and low resistance memory states and a complete collapse of the resistive window was observed for large proton fluences in RRAMs tested. Degradation in resistance states is associated with the generation of additional vacancies, which leads to (an) additional filament(s) in parallel to the existing conductive filament. Additional vacancies from displacement damage in the oxide of the resistive element do not permanently degrade device operation. The low resistance state is recovered to the pre-irradiation resistance through cycling at nominal high-speed switching conditions. Recovery of the resistive window to pre-irradiation values is obtained by applying longer write pulses which migrate remnants of radiation-induced filaments. [ABSTRACT FROM PUBLISHER]

Single-event upsets in \bf HfO\bf 2/{\bf Hf} 1T1R Resistive Random Access Memory (RRAM) structures are experimentally demonstrated by generating current transients in the access transistors of the memory cells. The relationship between the single-event upset threshold of the RRAM and the applied voltage is exponential, which is verified using TPA laser analysis and heavy-ion irradiation. Multiple-Event Upsets (MEUs) also occur, where individual ions incrementally change the RRAM’s resistance until their cumulative effect causes an upset. Single-event models are presented that allow direct correlation of the voltage across the RRAM, caused by the ion-generated current transient, and the change in RRAM resistance. The RRAM is vulnerable only in the high resistance state, when a voltage capable of writing to the cell is applied to the bit line. This is approximately 0.5% of the memory element’s operation time, leading to relatively low projected upset rates. [ABSTRACT FROM PUBLISHER]

Charge collection by multiple junctions is investigated using broadbeam heavy-ion and backside laser current transient measurements. The probability that significant charge is collected by more than one junction is greater for laser-generated events compared to heavy-ion measurements, which is attributed to the larger carrier generation track radius for the laser. With both sources, the probability of collecting charge on multiple junctions saturates at high charge generation levels. Effects caused by the interaction between junctions on the transient current waveforms is determined using position-correlated two-photon absorption laser analysis. The total charge collected for ion strikes between four adjacent junctions is shown to be approximately the same as for a direct strikes on a single junction, even though the incident ion does not pass through the depletion region of a biased junction. [ABSTRACT FROM PUBLISHER]

Measurements of single particle displacement damage are presented as discrete increases in reverse-biased diode leakage current, or current steps, caused by individual heavy ions in ^252Cf-irradiated JFET diodes. The maximum size of measured current steps agrees with calculations obtained from the expression for Shockley-Read-Hall generation when the radiation-induced defect density is derived from Monte Carlo simulations of atomic displacements and the electric field enhancement of defect emission is taken into account. The distribution of the current steps shows good agreement with experimental data. [ABSTRACT FROM PUBLISHER]

Spin-transfer torque film stacks and devices having in-plane magnetization were irradiated using a cobalt-60 gamma source. Samples were also exposed to 2 MeV and 220 MeV protons. Measurements of magnetization vs. field, ferromagnetic resonance, and tunnel magnetoresistance were performed on the film stacks before and after exposure to these sources and no changes were observed in the associated material properties. Spin-transfer torque devices were exposed to the same sources and show no changes in bit-state or write performance. [ABSTRACT FROM AUTHOR]

Single particle displacement damage events are reported in silicon diodes irradiated with ^252Cf and ^241Am. In situ measurements of reverse current show the result of displacement damage incurred from individual fission fragments in ^252Cf irradiated diodes. Discrete increases in reverse current exceeding 20 fA are measured. The increases are temporally correlated with fission fragment-induced ionization events. The ratio of the damage factor associated with fission fragments to the damage factor associated with alpha particles is in good agreement with the ratio of non-ionizing energy loss calculated for fission fragments to NIEL calculated for alpha particles. [ABSTRACT FROM AUTHOR]

Neutron-induced charge collection data and computer simulations presented here show that the presence of high-Z materials, like tungsten, can increase the single event upset (SEU) and multiple cell upset (MCU)cross sections of high critical charge (Qcrit) devices exposed to the terrestrial neutron environment because of interactions with high energy (> 100~\ MeV) neutrons. Time-of-flight data and computer simulations presented here demonstrate that 14 MeV neutrons do not produce highly ionizing secondary particles. Thus, 14 MeV neutrons can only simulate the SEU response of 65 nm SRAM devices in the terrestrial neutron environment for devices with a Qcrit < 27~\rm fC, and can simulate the 2-bit MCU response to within a factor of two only for very low Qcrit devices, < 1.2~fC.Additionally, it is shown that 14 MeV neutrons cannot adequately simulate the 3 or more bit MCU response for typical 65 nm SRAM devices. [ABSTRACT FROM PUBLISHER]

Experimental cross-section data for the interaction of protons with Al, Co, and Au at intermediate energies are compared with the predictions of the nuclear reaction models CEM03, BIC, Bertini INC, and INCL-ABLA. Fission cross-section data for the interaction of protons with W and Au in the energy range 50 MeV–3 GeV are also compared with the considered models. The study reveals that all of the models are satisfactory in limited ranges. However, of these, the CEM03 code from Los Alamos exhibits the broadest applicability for radiation effects computations. [ABSTRACT FROM PUBLISHER]

The effects of 10-keV and 400-keV endpoint-energy bremsstrahlung x-rays have been studied using the Monte Carlo simulator, MRED, for MOS capacitors with HfO2 gate dielectrics and TiN and TaN metal gates. We compute the reduction in dose that occurs for 10-keV x-ray irradiation of thin HfO2 gate dielectrics sandwiched between the metal gate and the Si substrate. We quantify the effects of back-end-of-line metallization layers, including copper interconnects, W vias, and borophosphosilicate glass (BPSG) and SiO2 passivation layers for low and medium energy x-rays. For thick metallization stacks irradiated by 10-keV x-rays, dose enhancement or attenuation can occur, depending on material type and overlayer thicknesses. For similar stacks irradiated with 400-keV endpoint-energy bremsstrahlung x-rays, significant dose enhancement is observed. [ABSTRACT FROM PUBLISHER]

Monte Carlo simulations demonstrate that electrons in a Europa-like radiation environment produce single events capable of depositing more than 100 keV in a shielded focal plane array (FPA). Aluminum shielding slows down high energy free space electrons through collisions. Incident electrons can also generate secondary particles within shielding through electromagnetic cascades, nuclear interactions, and other mechanisms. When incident electrons and secondary particles deposit energy in FPA pixels, the result is transient increases in background noise. We compare the energy deposition integral cross sections and estimate the single event effect rate for a range of electron energies incident upon an FPA shielded with 1, 5, and 10 cm of aluminum. [ABSTRACT FROM AUTHOR]

SEU enhancements were introduced into a radiation hardened 90 nm CMOS technology to achieve upset immunity. An incremental enhancement approach that enables various SEU/performance trade-off was demonstrated on the same basic SRAM cell to achieve various degrees of hardness, by the selective utilization of enhancement features. Single event upset testing, as well as MRED simulation, have demonstrated a significant enhancements achieved with a minimal performance penalty. [ABSTRACT FROM AUTHOR]

Charge collection measurements reveal that the presence of high-Z materials increases proton-induced charge collection cross sections for high charge collection events. The mechanism for this effect is proton-induced fission events as shown through validated Monte Carlo simulations. These fission fragments are emitted isotropically in contrast to high-LET secondary particles from proton-silicon interactions which tend to be forward directed. [ABSTRACT FROM AUTHOR]

The effects of 10-keV X-rays and 400-keV endpoint-energy bremsstrahlung X-rays on MOS capacitors with SiO2 or HfO2 gate dielectrics and Al and TaSi gate metallization have been studied using the Monte Carlo simulator, MRED. We compare these calculations with previous results in the literature obtained with other Monte Carlo and discrete ordinates codes, and with experiments on devices with SiO2 gate dielectrics, and find generally good agreement. There is a significant dose reduction in thin HfO2 layers exposed to 10-keV X-rays, when the HfO2 is surrounded by lower-Z materials (e.g., Si, Al). This dose reduction does not occur in a medium-energy bremsstrahlung X-ray environment; in that case, the dose in a HfO2 gate dielectric can be \sim10 times higher than the dose in a SiO2 dielectric, for the same incident X-ray fluence. These results demonstrate the capability of MRED to assist in the evaluation of dose enhancement and reduction in regions including or nearby high-Z materials in microelectronic materials and devices. [ABSTRACT FROM AUTHOR]

Experimental data are presented that show low-energy muons are able to cause single event upsets in 65 nm, 45 nm, and 40 nm CMOS SRAMs. Energy deposition measurements using a surface barrier detector are presented to characterize the kinetic energy spectra produced by the M20B surface muon beam at TRIUMF. A Geant4 application is used to simulate the beam and estimate the energy spectra incident on the memories. Results indicate that the sensitivity to this mechanism will increase for scaled technologies. [ABSTRACT FROM AUTHOR]

Monte-Carlo radiation transport simulations are used to quantify energy deposition from \delta-rays in sensitive volumes representative of future SRAM technologies. The results show that single and multiple \delta-ray events are capable of depositing sufficient energy to cause SEUs in nonadjacent SRAM cells separated by many micrometers. These results indicate the necessity of considering the variability of the charge track structure when evaluating the single event response of these highly scaled technology nodes. These effects have important implications forradiation hardening techniques that rely upon spatial separation of critical and redundant nodes, and simulation of device and circuit level response to heavy ions with respect to ion track structure. [ABSTRACT FROM AUTHOR]

In this paper, we describe a Monte Carlo approach for estimating the frequency and character of single event effects based on a combination of physical modeling of discrete radiation events, device simulations to estimate charge transport and collection, and circuit simulations to determine the effect of the collected charge. A mathematical analysis of the procedure reveals it to be closely related to the rectangular parallelepiped (RPP) rate prediction method. The results of these simulations show that event-to-event variation may have a significant impact when predicting the single-event rate in advanced spacecraft electronics. Specific criteria for supplementing established RPP-based single event analysis with Monte Carlo computations are discussed. [ABSTRACT FROM AUTHOR]

There is a need for improved physics models to correctly predict single event effects (SEEs) caused by nuclear reaction products from heavy ion radiation. Previous validations for nuclear fragmentation simulations are shown to be insufficient to support SEE analysis applications. A comparison of different physics models with experimental nuclear physics data coupled with energy deposition predictions is presented. [ABSTRACT FROM AUTHOR]

Monte-Carlo simulation using the MRED software suite, coupled with SPICE analysis, is used to identify internal mechanisms of SEU in DICE flip-flops. Low frequency cross-section measurements and simulations identify multiple-node charge collection SEU mechanisms as the dominant contributor. An increasingly isotropic response is predicted with increasing frequency due to latching of internal single-node transients near clock boundaries. Implications for heavy ion testing and SEU rate prediction are presented. [ABSTRACT FROM AUTHOR]

Factors that affect single-event transient pulse widths, such as drift, diffusion, and parasitic bipolar transistor parameters, are also strong functions of operating temperature. In this paper, SET pulse-width measurements are performed over a wide temperature range in both bulk and fully-depleted SOI (silicon on insulator) technologies. The average pulse-width increases with temperature for the bulk process, but not for the FDSOI process. [ABSTRACT FROM AUTHOR]

A comprehensive mathematical framework is established that encompasses both Monte Carlo single event effects (SEE) rate prediction and analytical approximations based on a single rectangulir parallelepiped (RPP). Criteria derived from consideration of multiple devices and technologies are presented that are useful in identifying situations where RPP-model predictions of SEE rates may not be appropriate and should be augmented or replaced by advanced physical modeling. [ABSTRACT FROM AUTHOR]

Direct ionization from low energy protons is shown to cause upsets in a 65-nm bulk CMOS SRAM, consistent with results reported for other deep submicron technologies. The experimental data are used to calibrate a Monte Carlo rate prediction model, which is used to evaluate the importance of this upset mechanism in typical space environments. For the ISS orbit and a geosynchronous (worst day) orbit, direct ionization from protons is a major contributor to the total error rate, but for a geosynchronous (solar mm) orbit, the proton flux is too low to cause a significant number of events. The implications of these results for hardness assurance are discussed. [ABSTRACT FROM AUTHOR]

The effects of materials surrounding the active devices on single event-induced charge generation in a proton-irradiated Si diode array are shown be significant. Particle scatters in layers underlying the device have an impact on the response of a focal plane array. This effect is likely to be important in a variety of semiconductor devices. [ABSTRACT FROM AUTHOR]