Thermal Annealing of Radiation-Induced Trapped Charge in Simox and Thermal Oxide Thin Films

1992 ◽  
Vol 284 ◽  
Author(s):  
D. Herve ◽  
Ph. Paillet ◽  
J. L. Leray
Keyword(s):  
Thermal Annealing ◽  
Low Dose ◽  
Charge Trapping ◽  
High Dose ◽  
X Ray ◽  
Charge Densities ◽  
Large Bulk ◽  
Thermal Oxide ◽  
Radiation Induced ◽  
Trapped Charge

ABSTRACTThe results of charge trapping and thermal annealing in X-ray irradiated SiO2 are presented. A comparative study is made between thermal oxide and SIMOX buried oxide behavior. At low dose (10 krad(SiO2)), X-ray induced charge trapping is found to be very different in thermal and SIMOX oxides. Results are interpreted in terms of a relatively large bulk trapping in SIMOX whereas thermal oxide behavior is dominatedby interface trapping. However, at high dose, both oxides behave similarly and are dominated by interface trapping. Etch-back experiments performed on SIMOX irradiated at 10krad (SiO2) and 1 Mrad (SiO2) reveal these two trapping regimes. Isochronal annealings have been performed up to 300°C on irradiated samples. Recovery data are interpreted assuming an energy distribution of trapped charge densities. Detrapping energies located at about 1.05 eV and 1.35 eV have been obtained in SIMOX whereas the thermal oxide exhibits a unique peak at 1.35 eV. Based on these data, SIMOX and thermal oxides are demonstrated to differ significantly.

scholarly journals Space Charge Accumulation and Decay in Dielectric Materials with Dual Discrete Traps

2019 ◽  
Vol 9 (20) ◽  
pp. 4253 ◽  
Author(s):  
Zhaoliang Xing ◽  
Chong Zhang ◽  
Haozhe Cui ◽  
Yali Hai ◽  
Qingzhou Wu ◽  
...  
Keyword(s):  
Space Charge ◽  
Analytical Solutions ◽  
Charge Injection ◽  
Charge Trapping ◽  
Dielectric Materials ◽  
Dynamic Processes ◽  
Charge Accumulation ◽  
Charge Densities ◽  
Short Period ◽  
Trapped Charge

Charge trapping and de-trapping properties can affect space charge accumulation and electric field distortion behavior in polymers. Dielectric materials may contain different types of traps with different energy distributions, and it is of interest to investigate the charge trapping/de-trapping dynamic processes in dielectric materials containing multiple discrete trap centers. In the present work, we analyze the charge trapping/de-trapping dynamics in materials with two discrete traps in two cases where charges are injected continuously or only for a very short period. The time dependent trapped charge densities are obtained by the integration of parts in the case of continuous charge injection. In the case of instantaneous charge injection, we simplify the charge trapping/de-trapping equations and obtain the analytical solutions of trapped charge densities, quasi-free charge density, and effective carrier mobility. The analytical solutions are in good agreement with the numerical results. Then, the space charge dynamics in dielectric materials with two discrete trapping centers are studied by the bipolar charge transport (BCT) model, consisting of charge injection, charge migration, charge trapping, de-trapping, and recombination processes. The BCT outputs show the time evolution of spatial distributions of space charge densities. Moreover, we also achieve the charge densities at the same position in the sample as a function of time by the BCT model. It is found that the DC poling duration can affect the energy distribution of accumulated space charges. In addition, it is found that the coupling dynamic processes will establish a dynamic equilibrium rather than a thermodynamic equilibrium in the dielectric materials.

scholarly journals Low dose ionizing radiation induced acoustic neuroma: A putative link?

2012 ◽  
Vol 01 (01) ◽  
pp. 078-079
Author(s):  
Sachin Borkar ◽  
Deepak Agrawal
Keyword(s):  
Ionizing Radiation ◽  
Brain Tumors ◽  
Acoustic Neuroma ◽  
Cumulative Dose ◽  
Low Dose ◽  
High Dose ◽  
Atomic Reactor ◽  
Radiation Induced

Abstract Although exposure to high dose ionizing radiation (following therapeutic radiotherapy) has been incriminated in the pathogenesis of many brain tumors, exposure to chronic low dose ionizing radiation has not yet been shown to be associated with tumorigenesis. The authors report a case of a 50-year-old atomic reactor scientist who received a cumulative dose of 78.9 mSv over a 10-year period and was detected to have an acoustic neuroma another 15 years later. Although there is no proof that exposure to ionizing radiation was the cause for the development of the acoustic neuroma, this case highlights the need for extended follow-up periods following exposure to low dose ionizing radiation.

Re-examining mechanisms of radiation damage in organic specimens

1990 ◽  
Vol 48 (4) ◽  
pp. 812-813
Author(s):  
David A. Armstrong ◽  
Suichu Luo ◽  
David C. Joy
Keyword(s):  
Mass Loss ◽  
Radiation Damage ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Limiting Factor ◽  
High Dose ◽  
X Ray ◽  
Resolution Electron ◽  
Significant Mass Loss ◽  
Significant Mass

Radiation damage to organic specimens is the major limiting factor in high resolution electron microscopy studies of biological systems. Electron beam irradiation compromises resolution by altering chemical microstructure, resulting in local mass loss and volume shrinkage in a specimen. All significant mass loss is thought to occur prior to a total incident dose of 50 electrons/ square angstrom If this is the case it is hard to reconcile the observation that images must be recorded at doses of less than 100 el/Å in order to avoid excessive mass loss and shrinkage while microanalytical (EDS and EELS) studies of the same tissue are routinely carried out at doses of 104 - 105el/Å2. Also, since most workers typically use either low dose (for imaging) or high dose (for microapalysis) there are apparently no studies in the literature which attempt to follow the process of radiation damage between these two extremes.We have chosen to investigate mass loss in polymer embedding resins such as are routinely used for TEM imaging as well as for X ray microanalytical applications.

Effect of Proton Irradiation Induced Defects on 4H-SiC Schottky Diode X-Ray Detectors

2011 ◽  
Vol 679-680 ◽  
pp. 547-550
Author(s):  
Rupert C. Stevens ◽  
Konstantin Vassilevski ◽  
John E. Lees ◽  
Nicolas G. Wright ◽  
Alton B. Horsfall
Keyword(s):  
Schottky Diode ◽  
Nuclear Power ◽  
Proton Irradiation ◽  
Deep Level ◽  
High Dose ◽  
X Ray ◽  
Power Stations ◽  
Radiation Induced ◽  
Transient Spectroscopy ◽  
Induced Defects

Detectors capable of withstanding high radiation environments for prolonged periods of exposure are essential for the monitoring of nuclear power stations and nuclear waste as well as for space exploration. Schottky diode X-ray detectors were exposed to high dose proton irradiation (1013 cm-2, 50 MeV) and changes in the detection resolution (spectroscopic full width half-maximum) have been observed. Using Deep Level Transient Spectroscopy (DLTS) and the degradation of the electrical characteristics of the diode, we have shown that radiation induced traps located in the upper half of the bandgap have reduced the concentration of carriers.

Ion Beam Mixing and Thermal Demixing of Co/Cu Multilayers

1997 ◽  
Vol 504 ◽  
Author(s):  
M. Cai ◽  
T. Veres ◽  
R. W. Cochrane ◽  
S. Roorda ◽  
R. Abdouche ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Giant Magnetoresistance ◽  
Low Dose ◽  
Ion Beam ◽  
Ion Bombardment ◽  
Ex Situ ◽  
Ion Beam Irradiation ◽  
X Ray ◽  
Interlayer Structure ◽  
Subsequent Thermal Annealing

ABSTRACTX-ray reflectivity and magnetotransport studies have been used to probe the effects of ion-beam irradiation and subsequent thermal annealing on the structure and giant magnetoresistance (GMR) in Co/Cu multilayers. Low-dose ion bombardment produces interfacial mixing which is accompanied by a systematic suppression of the anti ferromagnetic (AF) coupling and the GMR. For ion doses not exceeding 5 × 1014 ions/cm2, subsequent thermal annealing restores the abrupt interlayer structure as well as the GMR. The combination of low-dose ion bombardment and thermal annealing provides an ex situ technique to modify interface structure reversibly over a gnificant range.

scholarly journals Indications of radiation damage in ferredoxin microcrystals using high-intensity X-FEL beams

2015 ◽  
Vol 22 (2) ◽  
pp. 225-238 ◽  
Author(s):  
Karol Nass ◽  
Lutz Foucar ◽  
Thomas R. M. Barends ◽  
Elisabeth Hartmann ◽  
Sabine Botha ◽  
...  
Keyword(s):  
Electron Density ◽  
Structural Changes ◽  
Atomic Displacement ◽  
High Dose ◽  
X Ray ◽  
Density Maps ◽  
Linac Coherent Light Source ◽  
Radiation Induced ◽  
Metal Cofactors ◽  
Molecular Bonding

Proteins that contain metal cofactors are expected to be highly radiation sensitive since the degree of X-ray absorption correlates with the presence of high-atomic-number elements and X-ray energy. To explore the effects of local damage in serial femtosecond crystallography (SFX),Clostridium ferredoxinwas used as a model system. The protein contains two [4Fe–4S] clusters that serve as sensitive probes for radiation-induced electronic and structural changes. High-dose room-temperature SFX datasets were collected at the Linac Coherent Light Source of ferredoxin microcrystals. Difference electron density maps calculated from high-dose SFX and synchrotron data show peaks at the iron positions of the clusters, indicative of decrease of atomic scattering factors due to ionization. The electron density of the two [4Fe–4S] clusters differs in the FEL data, but not in the synchrotron data. Since the clusters differ in their detailed architecture, this observation is suggestive of an influence of the molecular bonding and geometry on the atomic displacement dynamics following initial photoionization. The experiments are complemented by plasma code calculations.

scholarly journals Ultrafiltration Extract of Radix Angelica Sinensis and Radix Hedysari Attenuates Risk of Low-Dose X-Ray Radiation-Induced Myocardial Fibrosis In Vitro

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Juan Chang ◽  
Chengxu Ma ◽  
Huan Guo ◽  
Haiqiong Ran ◽  
Guolian Chen ◽  
...  
Keyword(s):  
Myocardial Fibrosis ◽  
Low Dose ◽  
Cardiac Fibroblasts ◽  
Pathological Condition ◽  
Cardiovascular Complications ◽  
Angelica Sinensis ◽  
X Ray ◽  
X Irradiation ◽  
Radiation Induced

The risk of radiation-induced heart damage (RIHD) is a growing concern since recent advances in radiation therapy (RT) for cancer treatments have significantly improved the number of survivors. Radiation-induced myocardial fibrosis (RIMF) is the final pathological condition of RIHD and main change leading to serious cardiovascular complications following RT. The aim of this study was to investigate the effect of ultrafiltration extract of Radix Angelica Sinensis and Radix Hedysari (RAS-RH) on the proliferation, apoptosis, and reactive oxygen species (ROS) of cardiac fibroblasts after X-irradiation in vitro. The RAS-RH extract was from the Danggui Buxue decoction (DBD) in TCM. Primary cardiac fibroblasts were irradiated with 1 Gy X-ray to evaluate the effect of RAS-RH on the expression levels of cell proliferation, apoptosis, ROS, and fibrotic molecules. Our data demonstrated that X-irradiation at 1 Gy resulted in the proliferation of cardiac fibroblasts; RAS-RH attenuated the myocardial fibrosis. Furthermore, X-ray radiation reduced the apoptosis of cardiac fibroblasts; RAS-RH accelerated the apoptosis of these cells after irradiation. In addition, the damage driven by ROS in primary cardiac fibroblasts after irradiation was weakened by RAS-RH and the expression of TGF-β1, Col1, and α-SMA increased after irradiation; RAS-RH decreased the expression of these makers. Overall, these data indicate that low-dose X-ray irradiation boosts myocardial fibrosis, and the effect of RAS-RH protects against fibrosis via attenuating the proliferation and accelerating the apoptosis of myocardial fibroblasts after X-irradiation.

scholarly journals X-ray radiation damage to biological samples: recent progress

2019 ◽  
Vol 26 (4) ◽  
pp. 907-911 ◽  
Author(s):  
Elspeth F. Garman ◽  
Martin Weik
Keyword(s):  
Radiation Damage ◽  
Structural Damage ◽  
Low Dose ◽  
Theoretical Calculations ◽  
Relevant Literature ◽  
Radiation Chemistry ◽  
Tissue Samples ◽  
High Quantum Efficiency ◽  
X Ray ◽  
Radiation Induced

With the continuing development of beamlines for macromolecular crystallography (MX) over the last few years providing ever higher X-ray flux densities, it has become even more important to be aware of the effects of radiation damage on the resulting structures. Nine papers in this issue cover a range of aspects related to the physics and chemistry of the manifestations of this damage, as observed in both MX and small-angle X-ray scattering (SAXS) on crystals, solutions and tissue samples. The reports include measurements of the heating caused by X-ray irradiation in ruby microcrystals, low-dose experiments examining damage rates as a function of incident X-ray energy up to 30 keV on a metallo-enzyme using a CdTe detector of high quantum efficiency as well as a theoretical analysis of the gains predicted in diffraction efficiency using these detectors, a SAXS examination of low-dose radiation exposure effects on the dissociation of a protein complex related to human health, theoretical calculations describing radiation chemistry pathways which aim to explain the specific structural damage widely observed in proteins, investigation of radiation-induced damage effects in a DNA crystal, a case study on a metallo-enzyme where structural movements thought to be mechanism related might actually be radiation-damage-induced changes, and finally a review describing what X-ray radiation-induced cysteine modifications can teach us about protein dynamics and catalysis. These papers, along with some other relevant literature published since the last Journal of Synchrotron Radiation Radiation Damage special issue in 2017, are briefly summarized below.

scholarly journals A New Insight on the Radioprotective Potential of Epsilon-Aminocaproic Acid

Medicina ◽  
2020 ◽  
Vol 56 (12) ◽  
pp. 663
Author(s):  
Timur Saliev ◽  
Dinara Baiskhanova ◽  
Dmitriy Beznosko ◽  
Dinara Begimbetova ◽  
Bauyrzhan Umbayev ◽  
...  
Keyword(s):  
Low Dose ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Aminocaproic Acid ◽  
Free Radical Scavengers ◽  
Peripheral Blood Mononuclear ◽  
X Ray ◽  
Radiation Induced ◽  
Induced Apoptosis ◽  
Epsilon Aminocaproic Acid

Background and objectives: The aim of the study was to scrutinize the ability of epsilon-aminocaproic acid (EACA) to prevent radiation-induced damage to human cells. Materials and Methods: Human peripheral blood mononuclear cells (PBMCs) were exposed to ionizing radiation at three low doses (22.62 mGy, 45.27 mGy, and 67.88 mGy) in the presence of EACA at the concentration of 50 ng/mL. Results: EACA was able to prevent cell death induced by low-dose X-ray radiation and suppress the formation of reactive oxygen species (ROS). EACA also demonstrated a capacity to protect DNA from radiation-induced damage. The data indicated that EACA is capable of suppression of radiation-induced apoptosis. Comparative tests of antioxidative activity of EACA and a range of free radical scavengers showed an ability of EACA to effectively inhibit the generation of ROS. Conclusions: This study showed that the pretreatment of PBMCs with EACA is able to protect the cells from radiation-elicited damage, including free radicals’ formation, DNA damage, and apoptosis.

scholarly journals The microstructure of Si surface layers after plasma-immersion He+ion implantation and subsequent thermal annealing

2017 ◽  
Vol 50 (2) ◽  
pp. 539-546 ◽  
Author(s):  
Andrey Lomov ◽  
Kirill Shcherbachev ◽  
Yurii Chesnokov ◽  
Dmitry Kiselev
Keyword(s):  
High Resolution ◽  
Ion Implantation ◽  
Thermal Annealing ◽  
Structural Changes ◽  
Layer Structure ◽  
Characteristic Size ◽  
High Dose ◽  
X Ray ◽  
P Type ◽  
Subsequent Thermal Annealing

The structural changes in the surface layer of p-type Cz-Si(001) samples after high-dose low-energy (2 keV) He+plasma-immersion ion implantation and subsequent thermal annealing were studied using a set of complementary methods: high-resolution X-ray reflectometry, high-resolution X-ray diffraction, transmission electron microscopy and atomic force microscopy. The formation of a three-layer structure was observed (an amorphous a-SiOxlayer at the surface, an amorphous a-Si layer and a heavily damaged tensile-strained crystalline c-Si layer), which remained after annealing. Helium-filled bubbles were observed in the as-implanted sample. The influence of annealing on the evolution of the three-layer structure and the bubbles is considered. The bubbles are shown to grow after annealing. Their characteristic size is determined to be in the range of 5–20 nm. Large helium-filled bubbles are located in the amorphous a-Si layer. Small bubbles form inside the damaged crystalline Si layer. These bubbles are a major source of tensile strain in the c-Si layer.

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