Molecular dynamics simulations were made of ion damage in silicon, with emphasis being placed on the effects of the ion mass and energy. The Stillinger-Weber potential was used; suitably modified so as to account for high-energy collisions between dopant- Si and Si-Si pairs. The computational cells contained up to 106 atoms, and these were bombarded with B and As atoms having incident energies that ranged from 1 to 15keV. It was shown that displacement cascades resulted in the production of amorphous pockets, as well as isolated point defects and small clusters with populations which exhibited a strong dependence upon ion mass, and a weaker relationship with regard to the ion energy. It was demonstrated that the total number of displaced atoms agreed with the predictions of binary collision calculations for low-mass ions, but was a factor of 2 larger in the case of heavy-ion masses. The results of the simulations were compared with experimental data, and it was shown that these results provided a clear and consistent physical picture of damage production in Si under ion bombardment. A study was also made of the stability of the damage that was produced by heavy ions at various temperatures, and of the nature of the recrystallization mechanism. It was pointed out that the inhomogeneous nature of the damage made characterization of the process, in terms of a single activation energy, very difficult. An effective activation energy was found which depended upon the pocket size. The results were considered in terms of the Spaepen-Turnbull recrystallization model for an amorphous/crystalline planar interface.

M.J.Caturla, T.Díaz de la Rubia, L.A.Marqués, G.H.Gilmer: Physical Review B, 1996, 54[23], 16683-95