Nature Of Radiation-induced Defects Research Articles

Total Dose Testing Methodology for Bipolar Circuits Operating in the Jovian Radiation Environment

A total dose testing methodology for qualifying bipolar analog circuits for the Europa Clipper (EC) mission is presented. The method leverages the unique mission dose rate profile to bound device performance and reduces qualification test time from 1 year to 80 days. In addition, a new testing approach that simulates the mission dose profile revealed interesting information about the nature of radiation-induced defects in these “rad-hard” bipolar process lines. Results show that unlike bipolar parts from older generations (very sensitive to enhanced low dose rate sensitivity), these new processes seem to be dominated by oxide traps ( $\text{N}_{\mathrm {ot}}$ ) and not interface traps ( $\text{N}_{\mathrm {it}}$ ). This appears to be consistent with the mitigation used by vendors for reducing hydrogen (H2) contamination in their processing steps.

Nature of radiation-induced defects in quartz.

Although quartz (α-form) is a mineral used in numerous applications wherein radiation exposure is an issue, the nature of the atomistic defects formed during radiation-induced damage has not been fully clarified. Especially, the extent of oxygen vacancy formation is still debated, which is an issue of primary importance as optical techniques based on charged oxygen vacancies have been utilized to assess the level of radiation damage in quartz. In this paper, molecular dynamics simulations are applied to study the effects of ballistic impacts on the atomic network of quartz. We show that the defects that are formed mainly consist of over-coordinated Si and O, as well as Si-O connectivity defects, e.g., small Si-O rings and edge-sharing Si tetrahedra. Oxygen vacancies, on the contrary, are found in relatively low abundance, suggesting that characterizations based on E' centers do not adequately capture radiation-induced structural damage in quartz. Finally, we evaluate the dependence on the incident energy, of the amount of each type of the point defects formed, and quantify unambiguously the threshold displacement energies for both O and Si atoms. These results provide a comprehensive basis to assess the nature and extent of radiation damage in quartz.

Formation and bleaching of induced colour centres in gamma-irradiated vanadium-containing alkali-borate glasses

The nature of radiation-induced defects and defect generation process in glasses of the base composition B 2O 3 and R 2O+0.5g V 2O 5, where R is Li 2O, Na 2O or K 2O were studied. The glasses were exposed to successive irradiation doses up to 17 k Gy and their optical absorption spectra were measured in the range 200–1100 nm. Three factors were investigated: the role of V 2O 5, the effect of chemical composition, irradiation doses and the decay of colour centres by heat treatment at 200°C. The optical spectra have been shown to reveal the presence of V 3+, V 4+ and V 5+ ions altogether in varying proportions. The response of the glass to irradiation is related to the competition between formation and annihilation of induced defects and hence the observed characteristic colour centres. The rate of thermal bleaching at interval times was discussed.

Trapping of deuterium injected in austenitic stainless steel at elevated temperatures

The nature of radiation-induced defects and their roles in deuterium trapping in deuterium-ion injected austenitic stainless steel JPCA2 were studied by the complementary use of transmission electron microscopy (TEM) and thermal desorption spectroscopy (TDS). By irradiation with deuterium ions of keV energy at temperatures between 100 and 500 °C, platelet-like deuterium clusters and interstitial loops are formed. The former defects are the major trapping sites of deuterium in JPCA2 irradiated at elevated temperatures and, corresponding to their dissociation, noticeable desorption of deuterium gas occurs in the wide temperature range above 300 °C.

Radiation damage and deuterium trapping in deuterium ion irradiated austenitic stainless steel

The nature of radiation-induced defects and their roles in deuterium trapping in deuterium-ion-irradiated austenitic stainless steel, JPCA2, were studied by the complementary use of transmission electron microscopy (TEM) and thermal desorption spectroscopy (TDS). By irradiation with deuterium ions of keV energy at room temperature, very small dislocation loops and platelet-like deuterium clusters were formed. The comparison of the results of TEM and TDS showed that deuterium atoms trapped by the dislocation loops and by deuterium clusters dissociated at around 220°C and 300°C, respectively. Major trapping sites in JPCA2 are radiation-induced point defect clusters and some kind of imperfection in the matrix. Most of the deuterium atoms trapped by these sites are released at relatively low temperatures (< 180°C).

The nature and distribution of radiation-induced defects in silicon along the range of protons and alpha particles

Abstract The variation in the resistivity of the n-type silicon along the range of protons and α-particles with an energy of 6.3 MeV/nucleon has been studied experimentally over a wide interval of irradiation doses. The initial rate of removal of majority carriers as a function of the distance from the surface of a sample has been determined. The spatial distribution of radiation-induced defects, resulting from elastic collisions between the incident particles and the silicon atoms and the subsequent cascade multiplication, has been calculated by a computer simulation technique. The nature of radiation-induced defects in silicon, which are stable at room temperature, has been examined on the basis of the data obtained, in various segments of the range of heavy charged particles. Both the point defects, containing impurity atoms of oxygen or phosphorus, and the defects proper, which contain no impurity atoms, have been shown to form in the cases under consideration. The relation of electrically active defe...