The E′ center and oxygen vacancies in SiO2

The E′ centers in crystalline and amorphous SiO2 trace their history to 1956 when Robert A. Weeks first used electron paramagnetic resonance (EPR) to study radiation-induced defects in quartz. Since then the primary defect responsible for the E′ family of EPR signals has been identified as a positively charged oxygen vacancy with asymmetric relaxations of the two neighboring Si atoms. In the last 15 years, two E′ centers, known as E γ ′ and E δ ′ have been found to play a key role in the dynamics of charged trapped caused by irradiation in Si metal–oxide–semiconductor (MOS) structures. In this paper, we give a brief overview of E′ centers and highlight recent theoretical results that have elucidated many experimental observations in MOS structures and other forms of SiO2, as presented in an invited talk at the XI Conference on the Physics of Non-Crystalline Solids.