Mechanisms of He bubble and void formation were investigated, with regard to single and multiple He implantation, using photoluminescence, Rutherford proton back-scattering, transmission electron microscopy and atomic force microscopy. When secondary implantation was carried out, a systematic enlargement of the bubble band revealed the importance of interactions between He atoms and the point defects which were generated during implantation. The size effects of implanted-region protrusions reflected He diffusion, and its interaction with vacancies and divacancies during bubble formation. The photoluminescence spectra indicated the presence of complexed He divacancies at the same temperature where self-interstitials annihilated at the sample surface. The interaction of He atoms with divacancies permitted an inversion of the vacancy-interstitial balance; thus producing a supersaturation of vacancies in the bulk. This vacancy supersaturation caused the annihilation of interstitial-type defects which was observed after suitable annealing.

He-Vacancy Interactions in Si and their Influence on Bubble Formation and Evolution V.Raineri, S.Coffa, F.Szilágyi, J.Gyulai, E.Rimini: Physical Review B, 2000, 61[2], 937-45