Defect Structure and Irradiation Behavior of Noncrystalline SiO2

Various phenomena occuring during ionizing or particle irradiation of vitreous silica and Si-SiO2 interface structures are explained. Densification and changes in bond polarizability are due to the basic trend of maximizing π-bonding between Si and O atoms with minimum bond strain. Hole trapping in SiO2, as exhibited, e.g., in irradiated MOS devices, is an intrinsic property of the Si-O bond. Irradiation generates trivalent Si and non-bridging O defects. These interact with impurities, especially SiOH and SiH groups, as well as with interstitial H. These defects determine the radiation behavior of vitreous silica and Si-SiO2 interfaces, as well as the stability of MOS devices.