Defect-controlled carrier transport in amorphous SiO2

The defect-controlled transport properties of the photogenerated electrons in amorphous SiO2, the low-temperature mobility of approximately 40 cm2 V−1 s−1 and the lifetime of approximately l.4 × 10−8 s, are shown to be determined by interaction with neutral intimate-valence-alternation pairs, defects consisting of charged, and over- and under-coordinated oxygen atoms, C3 + and C1 − respectively. The holes move by small-polaron hopping, and a dispersive character in their transport may be associated with trapping at the same defects.