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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 81 for “"defect formation"”.
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Electronic structure, defect formation and passivation of 2D materials
… carrier mobility. Then we consider the defect formation of 2D HfS2 and SnS2 which are candidates in the n-type part of a tunnel FET. We found that these two materials have high mobility but there are also intrinsic defects including the S vacancy, S interstitial, and Hf/Sn interstitial. …
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Investigation of defect formation and control in poly-crystalline anatase titanium dioxide
… native carrier concentration likely due to the formation of oxygen vacancies and their clustering at grain boundaries which impede hole mediated photocatalytic reactions. Previous efforts to defect engineer atomic layer (ALD) grown TiO2 were successful by varying film thickness, with the …
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Scanning tunneling microscopy and photoemission studies of surface growth and defect formation
Made available in DSpace on 2011-05-07T14:05:58Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9512395.pdf: 7578890 bytes, checksum: 1e974a62019a1be35253bc1ad2741ff9 (MD5) Previous issue date: 1994
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Gravitational effects on defect formation in melt grown photorefractive materials : bismuth silicate
… Its photorefractivity is due to a native defect whose exact nature and origin have not been unambiguously determined. Motivation for current research arose from unexplained optical variations observed in BSO that implicate convective interference as playing a role in native defect …
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Effect of pattern and coating properties on defect formation in aluminum lost foam castings
… focuses on some of the factors affecting defect formation and the characterization of these defects in aluminum lost foam castings. Several statistically designed experiments were used to evaluate the effects of various gating designs, aluminum alloy compositions, foam pattern properties, …
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An investigation of defect formation and growth in epoxy resin using light scattering methods
… possible existence of inhonogeneities and other defects in an epoxy resin system, and the role these defects play in the mechanical and electrical failure of the polymer. Mie Theory was used in the analysis of the data throughout this thesis. Ultra clean fully degassed samples were prepared to …
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The mechanisms of mold filling and casting defect formation in the lost foam casting process
… filling and provide additional insight into the formation of casting defects in the process.</p> <p>In Paper 1, castings were poured over a wide range of temperatures using different coating permeabilities. Higher pouring temperature led to faster fill velocity when using a high permeability …
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Positron annihilation spectroscopy to understand defect formation and evolution in neutron-irradiated Fe-Cr model alloys
… technique used to characterize the defect properties of materials. There are two major types of PAS, positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy (DBS). This work focused on the latter. DBS can be used to gain information on the various types of …
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A study of defect formation due to flow instability during mold filling in lost foam casting
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.
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Investigations into b-o defect formation-dissociation in cz-silicon and their effect on solar cell performance
… Czochralski silicon degrades due to the formation of metastable defects when excess electrons are created by illumination or minority carrier injection during forward bias. The recombination path can be removed by annealing the cell at about 200 C but recombination returns on exposure to …
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Application of the tight-binding electronic structure method to study defect formation and optical absorption in covalently bonded materials
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2016-03-02 without embargo terms
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Effects of a combined supercritical extraction/thermal cycle on binder removal cycle time, yield, residual carbon, and defect formation in multilayer ceramic capacitors
… also resulted in a decrease in cycle time and defects following the combined SCE/TC. Samples subjected to the combined SCE/TC also had 25-30% less residual carbon as compared to samples subjected to a thermal cycle alone. This work also presents the binder removal efficiencies from tape cast …
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Influence of Electronic Structure and Lattice Dynamics on Oxygen Ion Transport in Solid-State Ionic Conductors
… and phonons. The results are extended to the formation of oxygen vacancies and interstitials in perovskite and RuddlesdenPopper oxides. We find that defect formation energy rises with defect formation entropy, which is linked to electronic energy states interacting with phonons. In perovskite …
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Extraordinary Temperature Amplification in Ion-Stimulated Surface Diffusion
… 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 a new …
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Models for Yield Estimation of Multichip Module Ceramic Substrates
… range of printed patterns. We also enhance the defect geometry models that are commonly used today. We introduce a defect geometry model that is based on the physical process of defect formation. Our defect geometry model employs Markov random fields to represent more general defect shapes. …
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Density Functional Study of Hydrogen in Amorphous Silicon
… clarify the role of H during electronic defect formation. We calculate the energetics for H to move from a variety of Si-H bonds to the bulk chemical potential. For isolated Si-H bonds (i.e. in micro-cavities without any bond reconstruction) the energetics are not consistent with …
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The Effect of Hydrostatic Pressure on The Ionic Conductivity of Some Crystals With The Fluorite Structure
… of doped and oxygen contaminated samples. The formation volumes of intrinsic defects were calculated from measured activation volumes at high temperatures. The defect formation volumes are found to be uniformly small and consistent with the dominance of Frenkel defects in all cases except PbC …
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A Heat Transfer Modeling Study of Rail Thermite Welding
… on the development of fatigue-critical weld defects in rail thermite welds. Finite Element Modeling (FEM) was used to analyze the heat transfer behavior during the thermite welding process. The results of the thermal analyses were correlated to the development of various weld defects and …
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Low-Pressure Metalorganic Chemical Vapor Deposition of High-Gain InGaP/GaAs Heterojunction Bipolar Transistors
… removal from the base and carbon-related defect formation. This effect is caused by the amount of thermal stress applied to the device by either prolonging the anneal or going to a higher temperature. The findings from the annealing study were applied to varying the emitter and cap growth …
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Two non-specific indicators of stress: Enamel hypoplasia and Harris lines
… EH, by age of the individual at the time of the defect formation, showed a completely different distribution. The results indicate no correlation between these two indicators at any level. Instead, the distribution of Harris lines, by age of the individual at the time of their formation, show …
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