Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 61 for “"point defect"”.
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Point defect engineering in germanium
… compared to silicon, little is known about the point defects in germanium. The goal of the present doctoral work is to remedy this gap. To this end, we have used radiation (gamma rays, alpha particles, and neutrons) to controllably introduce point defects in crystalline germanium, which were …
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Effect of point defect generation on transient enhanced diffusion
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.
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Hydrogen effects on the point defect spectrum in Fe-C alloys
… methods, the stability and concentrations of the point defect clusters present in metastable Fe-C-H alloys with vacancies. The defect spectrum is found to be strongly dependent on the local vacancy concentration, and for low hydrogen levels sharp highly non-linear changes in the defect cluster …
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Studies of point defect control in liquid-encapsulated czochralski growth of GaAs
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987.
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The mutual influence of strain fields and point defect distributions in krypton implanted polycrystalline titanium
Stress migration of point and open-volume defects in materials is an important problem in a wide variety of applications, such as degradation of metallic interconnects in semiconductor devices, metal fatigue, and radiation damage profiles in ion implantation and surface modification. From a …
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Annealing for intrinsic point-defect control and enhanced solar cell performance : the case of H₂S and tin sulfide (SnS)
… vacancy mid-gap states. Using the Kröger-Vink defect equilibria model of defect concentrations and DFT-calculated enthalpy of formations for intrinsic defects, predictions are made for how a particular anneal temperature and sulfur partial pressure will affect the carrier concentration in SnS. …
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Radiation-Induced Segregation and Precipitation in Ion-Irradiated Molybdenum-Rhenium Alloys
… of Re atoms in the same direction as the defect fluxes, that is, toward the external surface, was measured during irradiation by in situ Rutherford backscattering spectrometry (RBS). The results of the segregation measurements were in agreement with theoretical models based on point-defect …
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Modeling the effect of boron on microdefect formation
… demand larger diameter wafers and reduced microdefect concentration and size, one of the most crucial issues in the semiconductor industry becomes the understanding of defect formation in silicon crystal growth by the Czochralski crystal growth method. Microdefect patterns in the crystal are …
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The effect of Niobium on the defect chemistry and corrosion kinetics of tetragonal ZrO₂ : a density functional theory study
… 48, 201. Even the charge state of Nb as a defect in zirconia is debated. Experimental findings of Froideval et al [5] indicate charge state between +2 and +4 whereas other authors assume it to be +5 [21, 31, 34]. In order to uncover the role of Nb on the local oxide protectiveness we …
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Impact of grain boundary character on the radiation-induced segregation morphology in proton-irradiated 316L austenitic stainless steel
… to the local depletion or enrichment of atoms at point-defect sinks such as grain boundaries and dislocation loops in metallic alloys. This segregation can be so strong that it leads to radiation-induced precipitation at these sinks. Segregation and precipitation at these microstructural features …
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Extraordinary Temperature Amplification in Ion-Stimulated Surface Diffusion
… strong tradeoff between the energy threshold for point defect formation and substrate temperature. Experimental measurements of Ge and In surface diffusion on Si(111) by optical second harmonic microscopy (SHM) confirmed major aspects of the predicted temperature amplification. The work may offer …
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Modeling microdefects formation in crystalline silicon : the roles of point defects and oxygen
… demand for control of size and density of microdefects in the silicon for control of quality and uniformity of the fabricated microelectronic devices. This thesis is aimed at developing a fundamental understanding of the mechanisms for formation of such microdefects through the development of …
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Stress effects on atomistic kinetic transitions
… applied to transitions of increasing complexity: point defect generation in a perfect copper crystal, and grain boundary transitions in the [Sigma] 5 [210] grain boundary in copper.
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A new age of fuel performance code criteria studied through advanced atomistic simulation techniques
… damage displacement results in a multitude of defects that influence the fuel performance. Nuclear reactions are coupled, in that changing one variable will alter others through feedback. In the field of fuel performance modeling, these difficulties are addressed through the use of empirical …
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Heavy-ion damage in copper, nickel and dilute nickel alloys
… at temperatures where there is no long-range point defect mobility and the examination of the same area of sample at different dose levels.
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Optical and Interface-Based Methods of Defect Engineering in Silicon
… of the Si-SiO 2 interface affect diffusion of defects during annealing. The optical method elucidates the origin of a nonthermal influence of illumination on boron diffusion. The results show that photostimulated changes in diffusion stem primarily from light interacting with interstitial …
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Optical characterization of copper indium gallium diselenide thin films
… tolerance to off-stoichiometry and intrinsic defects. Film conductivity and recombination losses are controlled by intrinsic point defect concentrations, especially in the near-surface space-charge region of the heterojunction. Despite the amount of research already performed on CIGS alloys, …
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The production and annealing of point defects produced by quenching and by tensile deformation in pure gold and silver
… energy is 0.70 ± .04 eV. The identity of defects taking part in stage III in silver is not clear at the present time.
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Novel precipitate structures in alloys under irradiation
… and sink elimination of irradiation-induced point defects, as well as ballistic mixing. With this tool we explore the possibility of using point-defect sinks to alter the temperature range where compositional patterns are stable. This novel approach for optimizing radiation-resistant …
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Low Energy Ion Bombardment Effects in Supersaturated Copper-Indium Alloys
… enhanced diffusion to ion bombardment-created point defect sinks resulted in the volume precipitation of randomly dispersed In-rich (delta) phase ((TURN) 30at%In) particles in the near-surface region. Thermally induced precipitates, on the other hand, nucleated only at grain boundaries and were …
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