Depending on the conditions, the implantation of noble gas atoms in silicon may lead to the formation of bubbles. To understand how bubbles are formed, we have investigated the stability and the migration of single noble gas atoms (He, Ne, Ar, Kr, Xe) in bulk silicon in presence or not of vacancies, by performing first-principles calculations. Our results indicate that, in the case where vacancies are present, all noble gas atoms were found to be preferentially located in a divacancy site. If no vacancies are present, small noble gas atoms like He prefer to be located in a tetrahedral interstitial site, whereas for large atoms like Xe, lowest energy configurations are obtained by forming vacancies in the silicon lattice. Using nudged elastic band technique, we have determined the minimum energy path for migration, and the associated energies. Several migration mechanisms are possible depending on the type of the noble gas atom and its location site in the crystal lattice. Our results are discussed and compared to other works. The energy required for a He atom to escape from a large bubble was estimated too, by considering a Si slab with surfaces. Our calculated value for He is in agreement with experimental results.

Azzam Charaf Eddin*, Institut Pprime. UPR 3346, CNRS, Université de Poitiers, France
Marie-France Beaufort, Institut Pprime. UPR 3346, CNRS, Université de Poitiers, France
Laurent Pizzagalli, Institut Pprime. UPR 3346, CNRS, Université de Poitiers, France

*presenting author