Effects of stoichiometry on the radiation response of SiO2

Defect center production in irradiated silica is shown to exceed that found in stoichiometric SiO2. The defect centers observed are the E′ type which are associated with oxygen vacancies. It is suggested that a large concentration of E′ centers is expected near the oxygen deficient Si-SiO2 interface of irradiated MOS devices and that the presence of these defects is one source of positive space charge buildup within the first hundred Angstroms of the oxide. In addition, the 4500Å emission band observed in irradiated SiO2 has been shown to be associated with the decay of E′ centers.