Hydrogen-related defects in irradiated SiO/sub 2/

The energetics of proton and hydrogen release from hydrogen-complexed defects in silicon dioxide are compared using first-principles density functional theory. These calculations are used to assess models of total dose buildup of interface traps and charge trapping in silicon dioxide. It is found that hydrogen-passivated oxygen vacancies are a likely source of hydrogen and that proton release is favored by at least 1.2 eV over the release of neutral hydrogen. It is also found that the formation energies of most defects do not depend strongly on the local environment in amorphous SiO/sub 2/. However, the energy of a proton bound to different bridging oxygen sites can vary by more than 1.0 eV. Even when this is taken into account, proton release still dominates over neutral hydrogen release by more than 0.5 eV. Calculations also show that one defect, the hydrogen bridge, may be a source of EPR inactive, trapped positive charge in the oxide.

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