Molecular Dynamics Simulation Study of Small Scale Surface Defects upon Atom Ejection Processes

摘要

A molecular dynamics simulation has been used to investigate the sensitivity of atom ejection processes, from a single crystal target, to surface roughness (in the form of single and multiple surface vacancies and adatoms). A Rhodium (111)/Argon system was examined for normally incident ions at energies of 500 eV and 2 keV, using a modified Moliere/Morse atom-atom potential function. Comparisons are made between the effects of vacancies and adatoms on sputtering yield, ejection times, layer yield ratios, and ejected atom energy and angular distributions. Clean surface results are compared to those of a Born-Mayer/Morse potential function. Calculations show that the effects of vacancies exceed those of adatoms, requiring a surface density of 0.0153 vacancies/ A squared (at 500 eV) to produce a 5% change in the yield. The choice of the potential function affects the sputtering properties to the same degree as the surface defects, and tends to cast some doubt on quantitative results from this type of simulation.