Effects of coimplantation of silicon and nitrogen on structural defects and Si-N bond formation in silica glass

Effects of coimplantation of Si and N ions on structural defects in ${\mathrm{SiO}}_2$ glass are reported. Silicon-silicon bonds are formed as the predominant defect and their concentrations are almost the same as those of the implanted ions in Si-implanted samples but only about 1/10 those in the case of N-implanted samples. The bond concentrations in the coimplanted samples are approximately 50% of the sum of the concentrations in samples implanted with either Si or N. No difference was observed in the concentrations between specimens coimplanted in two different sequences. Paramagnetic nitrogen dioxide molecules are found to be formed in N-implanted samples but are not detected in the coimplanted samples. These results show that coimplantation is highly effective in combining implanted silicon with nitrogen, resulting in the formation of Si-N bonds. The importance of a Si-Si bond is suggested as an active reaction intermediate in coimplantation in ${\mathrm{SiO}}_2$.