First-principles calculations for charged states of hydrogen atoms in SiO2

Charged states of H atoms in defect-free SiO2 have been proposed from first-principles total-energy bandstructure calculations within a framework of the local-density approximation. The polarities of the charged states are determined depending on the position of the Fermi level. A positively charged state forms an Si-(OH+)-Si complex, while a negatively charged state forms an Si-H- bond. Calculated vibrational frequencies of newly formed O-H+ and Si-H- bonds for each charge state are found to be lower than those for neutral O-H and Si-H bonds, so the H-originated charge traps are expected to be distinguishable by either Raman or infrared spectroscopies.