Hydrogen-related defects in irradiated SiO2

The energetics of proton and hydrogen release from hydrogen-complexed defec ts in silicon dioxide are compared using first-principles density functiona l theory. These calculations are used to assess models of total dose buildu p of interface traps and charge trapping in silicon dioxide. It is found th at 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 neut ral hydrogen. It is also found that the formation energies of most defects do not depend strongly on the local environment in amorphous SiO2, However, the energy of a proton bound to different bridging oxygen sites can vary b y more than 1.0 eV, Even when this is taken into account, proton release st ill, dominates over neutral hydrogen release by more than 0.5 eV, Calculati ons also show that one defect, the hydrogen bridge, may be a source of EPR inactive, trapped positive charge in the oxide.