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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Methods for estimating X-ray machine output through measurement and simulation

We report ball grid arrays are increasingly being applied in the electronics industry and may require X-ray inspection to ensure the integrity and correct placement of solder pins. However, as the architecture of integrated circuits continues to narrow while simultaneously growing more complex, the risk of electronic failure due to radiation damage increases. While medical X-ray devices have been held to high standards and are repeatedly shown to be well characterized, devices used for electronic inspection are often lacking detailed characterization. This study presents unique methods to solve for important properties in X-ray inspection devices such as source to object distance and energy spectrum. This information can then be applied to Monte Carlo models to achieve better overall dose estimates to electronics, which will lead to superior manufactured products. Since X-ray devices can vary greatly in source characteristics, this work investigates spectral measurement and Monte Carlo representation of three X-ray devices. For a Philips SRO 33 100 medical diagnostic device, the spectral output followed expected trends given by the prediction software SpekCalc and Spektr. For the Dage XD7500NT, direct measurement showed a spectral artifact that through the use of Gafchromic films, was shown to be a contributing effect in the dose output. For the Rad Source RS1800, a high powered irradiation device, direct spectral measurement was not achieved. However, a Monte Carlo model using an assumed spectra was found to match ion chamber measurements to a high degree.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Countdown to perovskite space launch: Guidelines to performing relevant radiation-hardness experiments

Perovskite photovoltaics (PVs) are under intensive development for promise in terrestrial energy production. Soon, the community will find out how much of that promise may become reality. Perovskites also open new opportunities for lower cost space power. However, radiation tolerance of space environments requires appropriate analysis of relevant devices irradiated under representative radiation conditions. We present guidelines designed to rigorously test the radiation tolerance of perovskite PVs. We review radiation conditions in common orbits, calculate nonionizing and ionizing energy losses (NIEL and IEL) for perovskites, and prioritize proton radiation for effective nuclear interactions. Low-energy protons (0.05-0.15 MeV) create a representative uniform damage profile, whereas higher energy protons (commonly used in ground-based evaluation) require significantly higher fluence to accumulate the equivalent displacement damage dose due to lower scattering probability. Furthermore, high-energy protons may "heal" devices through increased electronic ionization. These procedural guidelines differ from those used to test conventional semiconductors.

14 SOLAR ENERGY↗
DOE OSTI2016

Effect of proton irradiation dose on InAlN/GaN metal-oxide semiconductor high electron mobility transistors with Al 2 O 3 gate oxide

The effects of proton irradiation on the dc performance of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with Al 2 O 3 as the gate oxide were investigated. The InAlN/GaN MOSHEMTs were irradiated with doses ranging from 1×10 13 to 1×10 15 cm –2 at a fixed energy of 5MeV. There was minimal damage induced in the two dimensional electron gas at the lowest irradiation dose with no measurable increase in sheet resistance, whereas a 9.7% increase of the sheet resistance was observed at the highest irradiation dose. By sharp contrast, all irradiation doses created more severe degradation in the Ohmic metal contacts, with increases of specific contact resistance from 54% to 114% over the range of doses investigated. These resulted in source-drain current–voltage decreases ranging from 96 to 242 mA/mm over this dose range. The trap density determined from temperature dependent drain current subthreshold swing measurements increased from 1.6 × 10 13 cm –2 V –1 for the reference MOSHEMTs to 6.7 × 10 13 cm –2 V –1 for devices irradiated with the highest dose. In conclusion, the carrier removal rate was 1287 ± 64 cm –1 , higher than the authors previously observed in AlGaN/GaN MOSHEMTs for the same proton energy and consistent with the lower average bond energy of the InAlN.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Ultrahigh‐Flux X‐ray Detection by a Solution‐Grown Perovskite CsPbBr 3 Single‐Crystal Semiconductor Detector

Abstract Solution‐processed perovskites are promising for hard X‐ray and gamma‐ray detection, but there are limited reports on their performance under extremely intense X‐rays. Here, a solution‐grown all‐inorganic perovskite CsPbBr 3 single‐crystal semiconductor detector capable of operating at ultrahigh X‐ray flux of 10 10 photons s −1 mm −2 is reported. High‐quality solution‐grown CsPbBr 3 single crystals are fabricated into detectors with a Schottky diode structure of eutectic gallium indium/CsPbBr 3 /Au. A high reverse‐bias voltage of 1000 V (435 V mm − 1 ) can be applied with a small and stable dark current of ≈60–70 nA (≈9–10 nA mm − 2 ), which enables a high sensitivity larger than 10 000 µC Gy air −1 cm − 2 and a simultaneous low detection limit of 22 nGy air s − 1 . The CsPbBr 3 semiconductor detector shows an excellent photocurrent linearity and reproducibility under 58.61 keV synchrotron X‐rays with flux from 10 6 to 10 10 photons s − 1 mm − 2 . Defect characterization by thermally stimulated current spectroscopy shows a similar low defect density of a synchrotron X‐ray and a lab X‐ray irradiated device. Solid‐state nuclear magnetic resonance spectroscopy suggests that the excellent performance of the solution‐grown CsPbBr 3 single crystal may be associated with its good short‐range order, comparable to the spectrometer‐grade melt‐grown CsPbBr 3 .

Pan, Lei↗
DOE OSTI2015

New fixed-point mini-cell to investigate thermocouple drift in a high-temperature environment under neutron irradiation

Temperature measurements in the nuclear field require a high degree of reliability and accuracy. Despite their sheathed form, thermocouples subjected to nuclear radiations undergo changes due to radiation damage and transmutation that lead to significant EMF drift during long-term fuel irradiation experiment. For the purpose of a High Temperature Reactor fuel irradiation to take place in the High Flux Reactor Petten, a dedicated fixed-point cell was jointly developed by LNE-Cnam and JRC-IET. The developed cell to be housed in the irradiation rig was tailor made to quantify the thermocouple drift during the irradiation (about two year duration) and withstand high temperature (in the range 950 deg. C - 1100 deg. C) in the presence of contaminated helium in a graphite environment. Considering the different levels of temperature achieved in the irradiation facility and the large palette of thermocouple types aimed at surveying the HTR fuel pebble during the qualification test both copper (1084.62 deg. C) and gold (1064.18 deg. C) fixed-point materials were considered. The aim of this paper is to first describe the fixed-point mini-cell designed to be embedded in the reactor rig and to discuss the preliminary results achieved during some out of pile tests as much as some robustness tests representative of the reactor scram scenarios. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2019

A Comparison of the Effects of Neutron and Gamma Radiation in Silicon Photomultipliers

The effects of radiation damage in silicon photomultipliers (SiPMs) from gamma rays have been measured and compared with the damage produced by neutrons. Several types of multipixel photon counters from Hamamatsu were exposed to gamma rays and neutrons at the Solid State Gamma Ray Irradiation Facility (SSGRIF) at the Brookhaven National Laboratory and the Institute for Nuclear Research (Atomki) in Debrecen, Hungary. The gamma ray exposures ranged from 1 krad to 1 Mrad and the neutron exposures ranged from 10 8 to 10 12 n/cm 2 . The main effect of gamma ray damage is an increase in the noise and leakage current in the irradiated devices, similar to what is seen from neutron damage, but the level of damage is considerably less at comparable high levels of exposure. In addition, the damage from gamma rays saturates after a few hundred krad, while the damage from neutrons shows no sign of saturation, suggestive of different damage mechanisms in the two cases. The change in optical absorption in the window material of the SiPMs due to radiation was also measured. This paper was carried out in order to evaluate the use of SiPMs for particle physics applications with moderate levels of radiation exposures.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Statistical analysis of displacement damage in small devices from neutron and ion irradiation

Modern semiconductor devices, such as gate-all-around nanosheet field-effect transistors (GAA NS FETs), are smaller than displacement damage cascades from fission neutrons. In this regime, device failure may occur through low-probability single events, rather than by parametric degradation previously seen in larger devices. Here, we present a statistical model that predicts the probability of a damage event in a small device and the probability distribution of the magnitude, i.e., number of displacements within the device, from each event. The model is developed first for neutron irradiation and then for energetic ion irradiation. The model is consistent with results from recent experiments in which lithium-ion irradiation produced stepwise increases in subthreshold current in GAA NS FETs.

Wampler, W. R.↗
DOE OSTI2016

Modeling of radiation-induced charge trapping in MOS devices under ionizing irradiation

The numerical model of the radiation-induced charge trapping process in the oxide layer of a MOS device under ionizing irradiation is developed; the model includes carrier transport, hole capture by traps in different states, recombination of free electrons and trapped holes, kinetics of hydrogen ions which can be accumulated in the material during transistor manufacture, and accumulation and charging of interface states. Modeling of n-channel MOSFET behavior under 1 MeV photon irradiation is performed. The obtained dose dependences of the threshold voltage shift and its contributions from trapped holes and interface states are in good agreement with experimental data.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Response of GaN-Based Semiconductor Devices to Ion and Gamma Irradiation

GaN has electronic properties that make it an excellent material for the next generation of power electronics; however, its radiation hardening still needs further understanding before it is used in radiation environments. In this work we explored the response of commercial InGaN LEDs to two different radiation environments: ion and gamma irradiations. For ion irradiations we performed two types of irradiations at the Ion Beam Lab (IBL) at Sandia National Laboratories (SNL): high energy and end of range (EOR) irradiations. For gamma irradiations we fielded devices at the gamma irradiation facility (GIF) at SNL. The response of the LEDs to radiation was investigated by IV, light output and light output vs frequency measurements. We found that dose levels up to 500 krads do not degrade the electrical properties of the devices and that devices exposed to ion irradiations exhibit a linear and non- linear dependence with fluence for two different ranges of fluence levels. We also performed current injection annealing studies to explore the annealing properties of InGaN LEDs.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Comparison of Calibration of Sensors Used for the Quantification of Nuclear Energy Rate Deposition

This present work deals with a collaborative program called GAMMA-MAJOR 'Development and qualification of a deterministic scheme for the evaluation of GAMMA heating in MTR reactors with exploitation as example MARIA reactor and Jules Horowitz Reactor' between the National Centre for Nuclear Research of Poland, the French Atomic Energy and Alternative Energies Commission and Aix Marseille University. One of main objectives of this program is to optimize the nuclear heating quantification thanks to calculation validated from experimental measurements of radiation energy deposition carried out in irradiation reactors. The quantification of the nuclear heating is a key data especially for the thermal, mechanical design and sizing of irradiation experimental devices in specific irradiated conditions and locations. The determination of this data is usually performed by differential calorimeters and gamma thermometers such as used in the experimental multi-sensors device called CARMEN 'Calorimetric en Reacteur et Mesures des Emissions Nucleaires'. In the framework of the GAMMA-MAJOR program a new calorimeter was designed for the nuclear energy deposition quantification. It corresponds to a single-cell calorimeter and it is called KAROLINA. This calorimeter was recently tested during an irradiation campaign inside MARIA reactor in Poland. This new single-cell calorimeter differs from previous CALMOS or CARMEN type differential calorimeters according to three main points: its geometry, its preliminary out-of-pile calibration, and its in-pile measurement method. The differential calorimeter, which is made of two identical cells containing heaters, has a calibration method based on the use of steady thermal states reached by simulating the nuclear energy deposition into the calorimeter sample by Joule effect; whereas the single-cell calorimeter, which has no heater, is calibrated by using the transient thermal response of the sensor (heating and cooling steps). The paper will concern these two kinds of calorimetric sensors. It will focus in particular on studies on their out-of-pile calibrations. Firstly, the characteristics of the sensor designs will be detailed (such as geometry, dimension, material sample, assembly, instrumentation). Then the out-of-pile calibration methods will be described. Furthermore numerical results obtained thanks to 2D axisymmetrical thermal simulations (Finite Element Method, CAST3M) and experimental results will be presented for each sensor. A comparison of the two different thermal sensor behaviours will be realized. To conclude a discussion of the advantages and the drawbacks of each sensor will be performed especially regarding measurement methods. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1983

Recovery of damage in rad-hard MOS devices during and after irradiation by electrons, protons, alphas, and gamma rays

This paper reports on the recovery properties of rad-hard MOS devices during and after irradiation by electrons, protons, alphas, and gamma rays. The results indicated that complex recovery properties controlled the damage sensitivities of the tested parts. The results also indicated that damage sensitivities depended on dose rate, total dose, supply bias, gate bias, transistor type, radiation source, and particle energy. The complex nature of these dependencies make interpretation of LSI device performance in space (exposure to entire electron and proton spectra) difficult, if not impossible, without respective ground tests and analyses. Complete recovery of n-channel shifts was observed, in some cases within hours after irradiation, with equilibrium values of threshold voltages greater than their pre-irradiation values. This effect depended on total dose, radiation source, and gate bias during exposure. In contrast, the p-channel shifts recovered only 20 percent within 30 days after irradiation.

Brucker, G. J.↗
DOE OSTI2016

TH-CD-201-12: Preliminary Evaluation of Organic Field Effect Transistors as Radiation Detectors

Purpose: To fabricate organic field effect transistors (OFETs) and evaluate their performance before and after exposure to ionizing radiation. To determine if OFETs have potential to function as radiation dosimeters. Methods: OFETs were fabricated on both Si/SiO{sub 2} wafers and flexible polymer substrates using standard processing techniques. Pentacene was used as the organic semiconductor material and the devices were fabricated in a bottom gate configuration. Devices were irradiated using an orthovoltage treatment unit (120 kVp x-rays). Threshold voltage values were measured with the devices in saturation mode and quantified as a function of cumulative dose. Current-voltage characteristics of the devices were measured using a Keithley 2614 SourceMeter SMU Instrument. The devices were connected to the reader but unpowered during irradiations. Results: Devices fabricated on Si/SiO2 wafers demonstrated excellent linearity (R{sup 2} > 0.997) with threshold voltages that ranged between 15 and 36 V. Devices fabricated on a flexible polymer substrate had substantially smaller threshold voltages (∼ 4 – 8 V) and slightly worse linearity (R{sup 2} > 0.98). The devices demonstrated excellent stability in I–V characteristics over a large number (>2000) cycles. Conclusion: OFETs have demonstrated excellent potential in radiation dosimetry applications. A key advantage of these devices is their composition, which can be substantially more tissue-equivalent at low photon energies relative to many other types of radiation detector. In addition, fabrication of organic electronics can employ techniques that are faster, simpler and cheaper than conventional silicon-based devices. These results support further development of organic electronic devices for radiation detection purposes. Funding Support, Disclosures, and Conflict of Interest: This work was funded by the Natural Sciences and Engineering Research Council of Canada.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1972

Irradiation of MOS-FET devices to provide desired logic functions

Gamma, X-ray, electron, or other radiation is used to shift threshold potentials of MOS devices on logic circuits. Before irradiation MOS gates to be shifted are biased positive and other gates are grounded to substrate. Threshold lasts 10 years. Thermal annealing brings circuit back to original configuration.

Danchenko, V.↗
NASA NTRS1990

Proton radiation effects on multi-pinned-phased CCDs

Three Tektronix 1024 x 1024 multi-pinned-phased (MPP) charge coupled devices were irradiated with protons to obtain data on CCD performance degradation in a proton radiation environment. The devices were irradiated with a spectrum of energies up to 120 MeV, simulating the total radiation dose of a long-term space experiment. Basic parameters such as charge transfer efficiency, dark current, noise, and full well were measured before and after irradiation. A test was also performed to determine the effectiveness of various thicknesses of tantalum shielding in protecting the CCD from damage. Dark current increase and CTE degradation were the most noticeable effects of proton radiation. This paper will present the objectives, test data, and conclusions of the proton testing, and will identify future testing to be performed.

Murata-Seawalt, D.↗
NASA NTRS1984

Total-dose and dose-rate dependence of proton damage in MOS devices during and after irradiation

Rad-hard CMOS/bulk inverters with input gates high and low were irradiated by protons with a nominal energy of 8 MeV in an effort to determine the total-dose and dose-rate dependence of threshold voltage shifts, both during and immediately after irradiation and over extended periods of time thereafter. It is shown that the effects in rad-hard MOS devices which are produced by specific proton and electron energies in the space environment could be simulated by cobalt-60 induced effects through careful and proper selection of total does and dose rates. This selection must be based on an experimentally established relationship of Co-60 to electron or proton damage. It is demonstrated that the simulation can be accomplished both during and after irradiation, in the long-term postirradiation period, as well as in the damage state immediately after bombardment.

Stassinopoulos, E. G.↗