Ion-beam formation of nanopores and nanoclusters in SiO 2

Abstract

We studied nanopores and nanoclusters formation in thermally oxidized silicon wafers (SiO 2/Si) by means of ion-beam technique. RBS, SEM, TEM and TED were used to characterize the SiO 2 layers after the ion-beam processing. Nanopores were formed by high-energy Kr ions irradiation followed by chemical etching of latent tracks zones in SiO 2 matrix. Holes with diameters of ∼10–15 nm and length/diameter ratios of up to 22 have been etched through the SiO 2 film. The results of computer simulation of the track formation processes in SiO 2 based on the modified thermal spike model are also presented. Calculated radiuses of molten regions along swift Kr ion trajectories in fused silica have been compared with etched tracks dimensions. Nanoclusters were formed by co-implantation of As and In ions followed by high-energy Kr ions irradiation and thermal annealing. The high-energy Kr ions irradiation as a thermal annealing alternative was carried out to induce nanoclusters formation in swift ions tracks zones. TEM investigations of annealed samples demonstrate the presence of amorphous nanoclusters located at the depth of 40–190 nm. Their sizes vary from ∼2.5 to ∼6 nm. No influence of swift ion irradiation on the oriented precipitation of dopants (In+As) in the tracks region was revealed.