Characterization of defects in amorphous SiO2 implanted with oxygen ions

Electron paramagnetic resonance (EPR) spectra of oxygen-implanted high-purity silica at temperatures ranging from 120 to 300 K have been measured at 9.7 GHz. Silica disks 2.0 cm in diameter and 0.1 cm thick were implanted with O+ ions at 140 keV with beam currents <3 μA/cm2 and doses that ranged from 8x1015 to 8x1016 ions/cm2. Paramagnetic defects have been observed, two of which are similar to defects formed by γ-ray irradiation of silica (E' center and the peroxy-radical (POR)). The POR shows several temperature-dependent features while the E' center has a dose-dependent annihilation cross section, as previously reported by Golanski, Devine, and Oberlin. Implantation of oxygen hinders defect formation of oxygen deficient defects such as the E' center while favoring production of oxygen-excessive defects such as the POR. (orig.)