Ion induced surface pattern evolution described by combined TRIM and kinetic Monte-Carlo simulation

Ion induced surface pattern evolution described by combined TRIM and kinetic Monte-Carlo simulation

Liedke, B.; Heinig, K.-H.; Facsko, S.; Möller, W.

Atomistic understanding of surface morphology evolution induced by ion beam sputtering is still strongly limited. Available continuum models cannot explain microscopic processes during ion beam irra-diation. On the other hand, so far atomistic simula-tions could not describe pattern dynamics in the spa-tiotemporal scales of experiments.
However, combined atomistic single ion impacts with continuum equations [1] gives a better under-standing of additional smoothing mechanisms, like an effective mass ‘downhill’ current induced by ballistic atomic drift [2][3].
We developed a novel program package which unifies the collision cascade with kinetic Monte-Carlo simulations. The 3D atom relocations were calculated in the Binary Collision Approximation (BCA), whereas the thermally activated relaxation of ener-getic atomic configurations as well as diffusive proc-esses were simulated by a very efficient bit-coded kinetic 3D Monte Carlo code.
Effects like ballistic mass drift or dependence of local morphology on sputtering yield are automati-cally included in the BCA approach. Distributions presented in Figure 1 show the mean preferential lo-cation of ad-atoms creation and the sputtering re-gions.
Low energy (up to 5 keV) ion a sputtering simula-tions have been performed on the simulation cell of about 17 million atoms, where irradiation fluence goes up to few 1018 cm-2. The pattern topography has been study by means of various intensive parameters like incidence angle (Fig. 2), ion beam energy, ion fluence, and migration energy of defects. Moreover, the scaling behaviour of surface roughness and pat-tern periodicity has been analysed.
Finally, we compare our results with experiments as well as with continuum theory.
[1] S. A. Norris and M. P. Brenner and M. J. Aziz J. Phys. Condens. Matter 21 (2009) 224017.
[2] G. Carter and V. Vishnyakov PRB 54 (1996) 17647.
[3] M. Moseler and P. Gumbsch and C. Casiraghi and A. C. Ferrari and J. Robertson Science 309 (2005) 1545.

Keywords: TRIM; kinetic Monte-Carlo; ion irradiation; ripple formation; scaling; crater function; surface mass current

  • Poster
    Workshop Ion Beam Physics, 29.-31.03.2010, FZD, Germany

Publ.-Id: 14798