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Your search keyword '"Al-Moatasem El-Sayed"' showing total 2 results
Start Over Author "Al-Moatasem El-Sayed" Journal microelectronic engineering
2 results on '"Al-Moatasem El-Sayed"'

1. Identification of intrinsic electron trapping sites in bulk amorphous silica from ab initio calculations

Author

Al-Moatasem El-Sayed, Valeri Afanas'ev, Matthew Watkins, and Alexander L. Shluger

Subjects
Materials science, Band gap, 02 engineering and technology, Electron, Condensed Matter::Disordered Systems and Neural Networks, 01 natural sciences, Molecular physics, Condensed Matter::Materials Science, Ab initio quantum chemistry methods, 0103 physical sciences, Electrical and Electronic Engineering, 010306 general physics, Condensed Matter::Quantum Gases, H611 Microelectronic Engineering, Electron trapping, H610 Electronic Engineering, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Thermal conduction, Atomic and Molecular Physics, and Optics, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Amorphous solid, Density functional theory, Electron configuration, Atomic physics, 0210 nano-technology
Abstract

Display Omitted HighlightsWide O-Si-O angles in bulk amorphous silica are shown to trap electrons.Trapped electron levels appear 3.2eV below the bottom of the silica conduction band.Estimated concentration of electron trapping sites is 5i?1019. Using ab initio calculations we demonstrate that extra electrons in pure amorphous SiO2 can be trapped in deep band gap states. Classical potentials were used to generate amorphous silica models and density functional theory to characterise the geometrical and electronic structures of trapped electrons. Extra electrons can trap spontaneously on pre-existing structural precursors in amorphous SiO2 and produce ? 3.2eV deep states in the band gap. These precursors comprise wide ( ? 130 ? ) O-Si-O angles and elongated Si-O bonds at the tails of corresponding distributions. The electron trapping in amorphous silica structure results in an opening of the O-Si-O angle (up to almost 180 ? ). We estimate the concentration of these electron trapping sites to be ? 5 i? 10 19 cm - 3 .

Published
2013
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2. A computational study of Si–H bonds as precursors for neutral E′ centres in amorphous silica and at the Si/SiO2 interface

Author

Alexander L. Shluger, Valery V. Afanas'ev, Francisco Lopez-Gejo, Matthew Watkins, Sanliang Ling, and Al-Moatasem El-Sayed

Subjects
Silicon, Oxide, chemistry.chemical_element, 02 engineering and technology, 01 natural sciences, Dissociation (chemistry), law.invention, chemistry.chemical_compound, Electron transfer, law, 0103 physical sciences, Molecule, Electrical and Electronic Engineering, Electron paramagnetic resonance, 010302 applied physics, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Crystallography, Unpaired electron, chemistry, Amorphous silica, Atomic physics, 0210 nano-technology
Abstract

Display Omitted HighlightsHole-trapping on Si-H bond facilitates creation of neutral E ' centres.Proton released from Si-H bond has a dramatic effect on the defect's levels.A proton nearby the neutral E ' defect can facilitate electron transfer from Si substrate onto defect. Using computational modelling we investigate whether Si-H Bonds can serve as precursors for neutral E ' centre formation in amorphous silica and at the Si/SiO2 interface. Classical inter-atomic potentials are used to construct models of a-SiO2 containing Si-H bonds. We then investigate the mechanism of dissociation of a Si-H bond to create a neutral E ' defect, that is a 3-coordinated silicon with an unpaired electron localised on it. We show that the Si-H bond is extremely stable, but as a result of hole injection it is significantly weakened and may dissociate, creating a neutral E ' centre and a proton attached to one of the nearby oxygen atoms. The proton can diffuse around the E ' centre and has a profound effect on the defect levels. We show that at a Si/SiO2 interface, the position of the proton can facilitate electron transfer from the Si substrate onto the defect, making it negatively charged.

Published
2013
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