Molecular dynamics simulation of silicon surface smoothing by low-energy argon cluster impact

The molecular dynamics simulation method was employed to study the mechanis m of silicon (001) surface smoothing by impact of Ar-16 or Ar-40 clusters w ith energy at or below 20 eV per constituent atom. Smoothing of a pyramid o n top of an otherwise "flat" silicon surface was used as a model system to elucidate the mechanism of cluster-substrate interaction. Surface smoothing is achieved by lateral displacement of substrate atoms during cluster impa ct. There exists an optimum energy of around 4-5 eV per constituent atom of the cluster for efficient surface smoothing; this implies that a proper en ergy is required for effective lateral displacement. Cluster size also affe cts surface smoothing because lateral displacement depends on the nonlinear effect of multiple collisions in the near surface region. As anticipated, damage in the substrate increases with cluster energy. (C) 1999 American In stitute of Physics. [S0021-8979(99)08324-3].