Proton irradiation effects in MOS junction field-effect transistors and integrated circuits
Proton irradiation effects in MOS and junction field-effect transistors and integrated circuits
Breckenridge, R. A.↗
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Probing Dark Current Random Telegraph Signal in a Small Pitch Vertically Pinned Photodiode CMOS Image Sensor after Proton Irradiation
Dark Current degradation and Dark Current Ran- dom Telegraph Signal after proton irradiation are studied in new scale silicon microvolumes by using a commercial CMOS Image Sensor. Results show that previously reported empirical models describing the Displacement Damage induced degradations are still valid despite the 10 to 100 times smaller depletion volume used. In addition, no evidence of significant Total Ionizing Dose effects is observed. Finally the reduction of the fraction of Random Telegraph Signal (RTS) pixels detected and of the fraction of multi-level RTS pixels is directly linked to the reduction in pixel volume.
CMOS Image Sensor (CIS)↗
A two-parameter scintillation spectrometer system for measurement of secondary proton, deuteron, and triton distributions from materials under 558-MeV-proton irradiation
A two-parameter scintillation spectrometer system developed and used to obtain proton, deuteron, and triton double differential cross sections from materials under 558-MeV-proton irradiation is described. The system measures both the time of flight of secondary particles over a 488-cm flight path and the energy deposited in a scintillator, 12.7 cm in diameter and 30.48 cm long. The time resolution of the system is 0.39 nsec. The calculated energy resolution based on this time resolution varies with energy from 1.6 precent to 7.75 percent for 50- and 558-MeV protons. Various systematic and statistical errors are evaluated, and the double differential cross sections for secondary proton and deutron production at 20 deg from a 2.35 g/sq cm thick beryllium target are shown as an example of the results obtainable with this system. The uncertainly in the cross sections for secondary protons varies with particle energy from approximately + or - 9 percent at 50 MeV to approximately + or - 11 percent at 558 MeV.
Beck, S. M.↗
Quantification of rat retinal growth and vascular population changes after single and split doses of proton irradiation: translational study using stereology methods
This study quantified architectural and population changes in the rat retinal vasculature after proton irradiation using stereology. A 100 MeV conformal proton beam delivered 8, 14, 20 and 28 Gy as single and split doses to the whole eye. The vascular networks were prepared from retinal digests. Stereological methods were used to obtain the area of the retina and unbiased estimates of microvessel/artery/vein endothelial, pericyte and smooth muscle population, and vessel length. The retinal area increased progressively in the unirradiated, age-matched controls and in the retinas irradiated with 8 and 14 Gy, indicating uniform progressive retinal growth. No growth occurred after 20 and 28 Gy. Regression analysis of total endothelial cell number in all vessels (arteries, veins and capillaries) after irradiation documented a progressive time- and dose-dependent cell loss occurring over 15 to 24 months. The difference from controls was significant (P<0.01) after 28 Gy given in single and split doses and after 20 Gy given as a split dose (P<0.05). Total vessel length in microvessel was significantly shortened at 20 and 28 Gy compared to that of controls (P<0.05). No evident dose recovery was observed in the endothelial populations after split doses. At 10 Gy, the rate of endothelial cell loss, a dose parameter used to characterize the time- and dose-dependent loss of the endothelial population, was doubled.
NASA Discipline Radiation Health↗
A study to determine the presence of voltage breakdown due to proton irradiation in polymeric materials
Proton induced voltage breakdowns in polymeric materials
Hendricks, H. D.↗
Effect of proton irradiation temperature on persistent photoconductivity in zinc oxide metal-semiconductor-metal ultraviolet photodetectors
The electrical and structural characteristics of 50-nm-thick zinc oxide (ZnO) metal-semiconductor-metal ultraviolet (UV) photodetectors subjected to proton irradiation at different temperatures are reported and compared. The devices were irradiated with 200 keV protons to a fluence of 1016 cm−2. Examination of the x-ray diffraction (XRD) rocking curves indicates a preferred (100) orientation prior to irradiation, with decrease in crystal quality afterward. Additionally, peak shifts in XRD and Raman spectra of the control sample relative to well-known theoretical positions are indicative of tensile strain in the as-deposited ZnO films. Shifts toward theoretical unstrained positions are observed in the irradiated films, which indicates partial relaxation. Raman spectra also indicate increase in oxygen vacancies (VO) and zinc interstitial defects (Zni) compared to the control sample. Additionally, transient photocurrent measurements performed on each sample at different temperatures showed up to 2× increase in photocurrent decay time constants for irradiated samples vs the control. This persistent photoconductive behavior is linked to the activation of electron and hole traps near the surface, and to the desorption and reabsorption of O2 molecules on the ZnO surface under the influence of UV light. Using an Arrhenius model, trap activation energies were extracted and, by comparing with known energies from the literature, the dominant defects contributing to persistent photoconductivity for each irradiation condition were identified. The persistence of differences in photocurrent transients between different samples months after irradiation indicates that the defects introduced by the suppression of thermally activated dynamic annealing processes have a long-term deleterious effect on device performance.
Heuser, Thomas A. (ORCID:0000000225642400)↗
Investigation of hardening mechanisms and size effects in proton-irradiated HT-9 steels
Ferritic/martensitic steels, such as HT-9, are known for their complex microstructural features and mechanical properties. Here in this paper, in-situ micro-tensile tests and traditional fractography methods were utilized to study the fracture behavior of proton-irradiated HT-9 steels. First, to evaluate the viability of micro-tensile tests for nuclear material qualification process, meso-tensile tests on as-received HT-9 steels were performed. Fracture mechanisms of unirradiated HT-9 steels at both length scales were compared and underlying mechanisms discussed. The direct comparison of micro- and meso-scale data shows a distinctive size effect demonstrated by the increase in yield stress (YS). Upon completion of initial assessment, specimens were irradiated with 4 MeV + protons to three fluences, all of which were lower than 0.01 displacements per atom (dpa). As expected, the YS increases with irradiation. However, at 7 × 10 -3 dpa, the reversal of the trend was observed, and the YS exhibited sharp decline. We demonstrate that at lower length scales, grain structure has a more profound impact on the mechanical properties of irradiated materials, which provides information needed to fill in the gap in current understanding of the HT-9 fracture at different length scales.
36 MATERIALS SCIENCE↗
Effects of proton irradiation on a gas phase in which condensation takes place. I Negative Mg-26 anomalies and Al-26
In the present paper, isotopic effects in magnesium generated in a proton-irradiated gas phase are examined, taking only (p,n), (p,d), and (p, alpha) reactions in magnesium, aluminum, and silicon into consideration. In the presence of proton radiation, the three elements are 'removed' from the gas phase by condensation. It is required that a value of Al-26/Al-27 greater than 6 times 10 to the -5th must be reached, consistent with the value deduced by Lee Papanastassiou, and Wasserburg (1976) from their studies of the Allende meteorite. The calculations show that fast aluminum condensation reduces the required proton fluence substantially, that a significant fraction of aluminum remains uncondensed when the above value of the Al-26/Al-27 ratio is reached, that a detectable MG-24 excess is very likely to occur, that detectable negative MG-28 anomalies can be generated, and that proton fluxes and irradiation times can be varied simultaneously, and over a wide range of values, without significant changes in the required proton fluence.
Heymann, D.↗
Erythropoietic response in dogs given sublethal whole-body proton irradiation followed by hypoxic hypoxia
Erythropoietic response in anesthetized dogs subjected to sublethal whole-body proton irradiation followed by hypoxic hypoxia, discussing test procedure and results
Aceto, H., Jr.↗
Inferring relative dose-dependent color center populations in proton irradiated thoria single crystals using optical spectroscopy
In this work, we have utilized photoluminescence spectroscopy and optical ellipsometry to characterize the dose-dependence of the photoluminescence emission intensity and changes in optical absorption of thoria single crystals subject to irradiation with energetic protons at room- and elevated-temperatures. The photoluminescence peaks and the optical absorption bands are attributed to creation of new electronic states emerging from defects resulting from displacement damage. These bands are most likely associated with electrons trapped at the oxygen vacancy sites similar to color centers formed in other irradiated oxides and halides. Our experimental observations are supported by a standard density functional theory calculation of the electronic structure in pristine and oxygen vacancy-bearing thoria crystals. The dose-dependence of the intensity of the photoluminescence peaks is used to parameterize a rate theory model that estimates the concentration of color centers in the irradiated crystals. This parameterization provides optimized migration barrier parameters for oxygen interstitials and vacancies that simultaneously capture the optical response of the crystals irradiated at room- and elevated-temperature. These optical spectroscopy techniques offer a promising pathway to characterize the population of color centers formed at the sites of oxygen anion vacancies, particularly in irradiated nuclear fuels, where atomic-level defects cannot be readily imaged using electron microscopy. When combined with other direct and indirect characterization tools, our approach can provide new insight into defect formation and accumulation in energy materials over single atomic to extended length scales.
36 MATERIALS SCIENCE↗
Study of radiation induced deep-level defects in proton irradiated AlGaAs-GaAs solar cells
Radiation induced deep-level defects (both electron and hole traps) in proton irradiated AlGaAs-GaAs p-n junction solar cells are investigated along with the correlation between the measured defect parameters and the solar cell performance parameters. The range of proton energies studied was from 50 KeV to 10 MeV and the proton fluence was varied from 10 to the 10th power to 10 to the 13th power P/sq cm. Experimental tools employed include deep-level transient spectroscopy, capacitance-voltage, current voltage, and SEM-EBIC methods. Defect and recombination parameters such as defect density and energy level, capture cross section, carrier lifetimes and effective hole diffusion lengths in n-GaAs LPE layers were determined from these measurements.
Li, S. S.↗
Anisotropic growth of Ni 2 (Cr,Mo) ordered phase in proton irradiated Ni-Cr-Mo alloys
Ni-Cr-Mo alloys are widely used in the nuclear industry as structural materials due to their high temperature strength and corrosion resistance. Ni-based alloys containing around 33 at.% (Cr+Mo) developed a long-range ordered Ni 2 (Cr,Mo) phase after thermal aging and/or irradiation. The ordering mechanism for thermally-aged Ni 2 (Cr,Mo) phase is well-understood, characterized to be sluggish, homogeneous, and isotropic. The ordering mechanism for irradiation-induced Ni 2 (Cr,Mo) phase is not fully understood, characterized as having rapid formation and demonstrating anisotropic precipitation. Here, this work elucidates the anisotropic precipitation and anisotropic precipitation mechanism of Ni 2 (Cr,Mo) after proton irradiation in Ni-Cr-Mo alloys. Selected area electron diffraction and bright-field scanning transmission electron microscopy imaging are used to image superlattice reflections from the ordered phase and irradiation-induced defects, respectively. A higher degree of anisotropic precipitation is observed with increasing dislocation loop and void size; a phenomenon not observed in thermally aged samples.
36 - MATERIALS SCIENCE↗
Thermal annealing of proton-irradiated silicon solar cells.
Isochronal annealing effects on photovoltaic properties of n-on-p Si solar cells irradiated by energetic proton
Faraday, B. J.↗
Effects of thermal annealing on the deep-level defects and I-V characteristics of 200 keV proton irradiated AlGaAs-GaAs solar cells
Detailed characterization of deep-level defects and analysis of dark I-V data in 200 keV proton irradiated AlGaAs-GaAs solar cells have been carried out for several proton fluences (5 x 10 to the 11th, 10 to the 12th, and 10 to the 13th P/sq cm), using DLTS, C-V, and I-V measurement techniques. To study the effect of low temperature thermal annealing on the deep-level defect properties, these irradiated samples were annealed in vacuum at 300 C for one hour. Comparison was then made on the measured defect parameters (i.e., defect energy levels and densities) and the dark I-V characteristics for both the annealed and unannealed samples.
Li, S. S.↗
Effects of proton irradiation on luminescence and carrier dynamics of self-assembled III-V quatum dots
The effects of proton irradiation (1.5 MeV) on photoluminescence intensities and carrier dynamics were compared between III-V quantum dots and similar quantum well structures. A significant enhancement in radiation tolerance is seen with three-dimensional quantum confinement. Measurements were carried out in different quantum dot (QD) structures, varying in material (InGaAs/GaAs and InAlAs/AlGaAs), QD surface density (4x10^8 to 3x10'^10 cm^-2), and substrate orientation [(100) and (311) B]. Similar trends were observed for all QD samples. A slight increase in PL emission after low to intermediate proton doses, are also observed in InGaAs/GaAs (100) QD structures. The latter is explained in terms of more efficient carrier transfer from the wetting layer via radiation-induced defects.
nanotechnology DLTS optical properties pn diodes q↗
Studies of proton-irradiated SO2 at low temperatures Implications for Io
The infrared absorption spectrum from 3.3 to 27 microns of SO2 ice films has been measured at 20 and 88 K before and after 1-MeV proton irradiation. The radiation flux was chosen to simulate the estimated flux of Jovian magnetospheric 1-MeV protons incident on Io. After irradiation, SO3 is identified as the dominant molecule synthesized in the SO2 ice. This is also the case after irradiation of composite samples of SO2 with sulfur or disulfites. Darkening was observed in irradiated SO2 ice and in irradiated S8 pellets. Photometric and spectral measurements of the thermoluminescence of irradiated SO2 have been made during warming. The spectrum appears as a broad band with a maximum at 4450 A. Analysis of the luminescence data suggests that at Ionian temperatures irradiated SO2 ice would not be a dominant contributor to posteclipse brightening phenomena. After warming to room temperature, a form of SO3 remains along with a sulfate and S8. Based on these experiments, it is reasonable to propose that small amounts of SO3 may exist on the surface of Io as a result of irradiation synthesis in SO2 frosts.
Moore, M. H.↗
Low-temperature proton irradiation damage of isotropic nuclear grade IG-430 graphite
IG-430, a fine-grained, isotropic graphite grade is a promising candidate for the future Very High Temperature Reactors (VHTR). IG-430 which provides higher density, strength, and thermal conductivity, has already been developed as a graphite for next-generation HTGR, and is expected to be employed. This graphite grade, however, is lacking enough database that is needed for design. The present study aims to enhance the database with experimental data focusing on the low temperature regime (90–210 °C) by using 120–200 MeV protons to irradiate the IG-430 graphite to peak fluence of ~1.2 10 25 m –2 . It is anticipated that radiation-induced changes in the graphite properties and damage to be more pronounced in this low temperature regime than in elevated temperatures where damage annealing is taking place simultaneously. IG-430 graphite was characterized following irradiation for mechanical property changes (modulus and strength), dimensional stability and irradiation-induced growth as well as microstructural changes using high energy X-rays and different X-ray diffraction techniques. In assessing proton irradiation effects on the IG-430 graphite grade, comparison of radiation effects was made with the IG-43 grade, the un-purified version of IG-430, as well as other isotropic graphite grades. IG-430 was shown in this study to be better graphitized than other isotropic graphite grades. The study also revealed that during proton irradiation at low temperatures (~100 °C) the IG-430 exhibits stored energy release.
36 MATERIALS SCIENCE↗
Dislocation Loops in Proton Irradiated Uranium-Nitrogen-Oxygen System
Here in this study, we investigated the dislocation loop types formed in the proton-irradiated uranium-nitrogen-oxygen (U-N-O) system, which involves uranium mononitride (UN), uranium sesquinitride (a-U2N3), and uranium dioxide (UO2) phases. The dislocation loop formation is examined using specimens irradiated at 400°C and 710°C. Based on the detailed transmission-based electron microscopy characterization with i) the morphology-based on-zone and ii) the invisibility-criterion based two-beam condition imaging techniques, only a single type of dislocation loop in each phase is found: a/2?110?, a/2?111?, or a/3?111? dislocation loops in UN, a-U2N3, and UO2 phases, respectively. Molecular statics calculations for the formation energy of perfect and faulted dislocation loops in UN phases indicate a critical loop size of ~ 6 nm, above which perfect loops are energetically favorable. This could explain the absence of faulted loops in the experimental observation of the irradiated UN phase at two temperatures. This work will enhance the understanding of irradiation induced microstructural evolution for uranium nitrides as advanced nuclear fuels for the next-generation nuclear reactors.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗