Observation of Sb2O3 nanocrystals in SiO2 after Sb ion implantation

Antimony nanocrystals were formed in thin SiO2 films using low-energy ion implantation of Sb followed by annealing. Using Fourier transform laser microprobe mass spectrometry (FT LMMS), we observed for the first time the presence of antimony oxide in the intermediate phase (as-implanted layer of Sb) by means of signals referring to the intact Sb2O3 molecules. Only SbO+ fragments, but no adduct ions of Sb2O3 could be detected in annealed samples. The size and the distribution of the nanocrystals formed around the initial depth of implantation were studied in the as-implanted samples by high-resolution electron microscopy (HREM). The crystalline structure of these nanocrystals was also studied and the presence of antimony trioxide Sb2O3 in the form of valentinite was proven. After the annealing step, the implanted material had spread into a wider band. The method introduced here, based on combining TEM (transmission electron microscopy) and FT LMMS results, offers the possibility of studying the evolution of the phases in Sb nanocrystal formation. (author)