Effects of multi-energy Si and O ion implantation on the optical properties of silica

Abstract Some effects on the optical bands produced by multi energy (highest energy 320 keV) Si and O implantations in (Type III) silica have been measured. We propose that in these samples bands due to the various combinations of oxygen vacancies will increase with increasing Si dose with related O related defects changing at a much smaller rates. In the absorption spectra of samples implanted with O, bands associated with oxygen related defects increase with increasing does, while those due to various forms of O vacancies will change at much smaller rates. Si ions were implanted using implant energies ranging from 35 to 320 keV. O ions were implanted using energies ranging from 35 to 250 keV. The doses at each energy were varied to maintain an approximately constant implanted-species concentration. The implanted layer has an approximately constant concentration for the Si ions that starts 40 nm below the surface and extends to 640 nm, while for the O implanted samples the constant concentration region starts at ∼80 nm from the surface and extend to 640 nm. The Si concentration in the implanted region ranges from ∼0.025 to 0.5 at.% (atomic percent) while the O concentration ranged from 0.035 to 0.7 at.%. The optical absorption was measured from 2.8 to 6.5 eV. We fit the observed spectra for the as implanted samples to the minimum number of bands attributed to intrinsic states in SiO 2 required to fit the data within ±2%. The intensities of these absorption bands were a function of dose and ion species. Bands at 5.01, 5.8 and 6.75 eV increased with increasing Si dose and changed at much smaller rates with increasing O dose, confirming that these bands are related to oxygen vacancies. The band at 4.8 eV increased with increasing O dose confirming that it is due to oxygen related defects, which we attribute to an oxygen molecular ion or peroxy radical.