Dresden 2011 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

DS: Fachverband Dünne Schichten

DS 49: Ion Interactions with Nano Scale Materials IV (Focused Session -- Organisers: Diesing, Facsko)

DS 49.3: Talk

Thursday, March 17, 2011, 18:30–18:45, GER 37

Surface patterning by ion bombardment: predictions of large-scale atomistic simulations — •Bartosz Liedke, Karl-Heinz Heinig, Stefan Facsko, and Wolfhard Möller — Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany

Despite of intense studies in recent years, atomistic understanding of surface evolution during ion irradiation is still under discussion. Continuum models, like the Bradley and Harper theory, cannot explain microscopic processes during ion irradiation. So far, atomistic simulations could not describe pattern dynamics on spatiotemporal scales of experiments.

We present a novel program package that unifies the simulation of collision cascades with kinetic Monte-Carlo simulations. The 3D atom relocations were calculated in the Binary Collision Approximation (BCA), whereas the thermally activated relaxation of energetically unstable atomic configurations as well as diffusive processes were simulated by a very efficient bit-coded kinetic 3D Monte Carlo code.

Our studies show that: (i) bulk defects continuously created within the collision cascade are responsible for local surface topography fluctuations and induce surface mass currents. These currents smooth the surface from normal incidence up to θ=40^∘, whereas at θ>40^∘ ripple patterns appear; (ii) sputtering is not the dominant driving force for the ripple formation at non-grazing incidence angles. Surface patterning is caused by processes like bulk and surface defect migration, recombination, bulk and surface diffusion and ion induced diffusion.