Atomistic simulation of interstitial cluster migration in silicon


Atomistic simulation of interstitial cluster migration in silicon

Posselt, M.

The state-of-the-art interpretation of physical processes during post-implantation annealing, such as defect evolution and transient-enhanced boron diffusion assumes that ion implantation produces a supersaturation of single vacancies and self-interstitials. They are supposed to be mobile and may recombine or may form immobile clusters. On the other hand, atomistic simulations demonstrated that implantation may generate not only single vacancies and self-interstitials but also more complex defects. Furthermore, recent theoretical studies showed that small interstitial clusters may be mobile as well. The present work gives an overview on the latter investigations. Due to the complex structure of the interstitial clusters, methods based on the estimation of migration barriers by considering the potential energy surface at 0 K are hardly applicable. Molecular dynamics (MD) simulations must be used to get a thorough understanding of the migration mechanisms. Ab-initio MD simulations are presently not practicable since they require a tremendous computational effort. Therefore atomic-level MD simulations are applied. The diffusivity of the small interstitial clusters, the self-diffusion coefficient per defect, and the corresponding effective migration barriers are determined. The implications of the present results for the explanation of experiments on post-implantation annealing and on room-temperature migration of implantation-induced self-interstitial defects are discussed.

Keywords: defects; diffusion; silicon; atomistic simulation; interstitial clusters

  • Invited lecture (Conferences)
    E-MRS IUMRS ICEM Spring Meeting 2006, 29.05.-02.06.2006, Nice, France

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Publ.-Id: 8529