Origins of optical absorption between 4.8 and 4.9 eV in silica implanted with Si and with O ions

We have determined some of the sources of the optical absorption bands between 4.8 and 4.9 eV in Si and O-implanted silica using several ion energies to produce layers of implanted ions with constant concentrations. The concentrations of implanted ions in the implanted layers ranged from >0.015 at.% to <3 at.%. Optical absorption was measured from 2.0 to 6.5 eV. Electron paramagnetic resonance measurements were made at ∼20.3 and 33 GHz for sample temperatures ranging from 77 to 100 K for most measurements. The components identified in the spectra, based on comparison with reported parameters, were, in the Si case, due to E′ centers and peroxy radicals. In the O case they were due to E′ centers, non-bridging oxygen hole centers, peroxy radical centers, and a newly appearing state which we labeled the OS center. By comparing the changes in the absorption at 4.83 eV with the changes in the concentrations of the various electron paramagnetic resonance components and with the reports in the literature, we conclude that there are at least four oxygen related centers and one Si related center absorbing between 4.8 and 4.9 eV.