Trapping of diffusing germanium by silicon excess co-implanted into fused silica

The trapping of germanium by silicon atoms, successively implanted into fused silica, is evidenced after thermal annealing at 1150 ° C. Rutherford backscattering spectroscopy and Raman measurements reveal a linear increase of remaining Ge concentration with the co-implanted Si fluence, accompanied by an increase of the Ge-Ge bond density, respectively. Comparison of Ge concentration profiles with scanning electron microscopy images shows the formation of nanoclusters, resulting from the accumulation of Ge within the region containing a greater concentration of co-implanted Si, whereas nanocavities, indicative of Ge release from nanostructures, are dominant in deeper sample region of lower Si excess concentration.