Capacity of graphite's layered structure to suppress the sputtering yield: A molecular dynamics study
JT Tian and T Zheng and JY Yang and SY Kong and JM Xue and YG Wang and K Nordlund, APPLIED SURFACE SCIENCE, 337, 6-11 (2015).
120-20 keV C-60 bombardment on graphite and 20 keV C-60 impact on diamond are studied by classical molecular dynamics (MD) simulations. The number of atoms ejected from graphite after a 20 keV C-60 impact is found to be much smaller than that from diamond. By analyzing the microscopic sputtering process, we find this difference is due to the combined effects of graphite's low number density and layered structure. These two features of graphite make the pressure waves during the spike stage much weaker and the crater rim much more stable, compared to the case of diamond. While the role of atomic density on sputtering has been discussed in previous studies, effect of layered structure has not gained much attention yet. To affirm this effect and exclude the influence of density, we have also simulated C-60 impact on an amorphous carbon (a-C) target whose density is very close to that of graphite. The yield of a-C is higher than that of graphite, certifying the capacity of graphite's layered structure to suppress the sputtering yield. (C) 2015 Elsevier B.V. All rights reserved.
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