Molecular dynamics simulation of nonlinear effects in sputtering - Au(100) and Au(111) targets

Abstract

Nonlinear effects in sputtering from Au(100) and Au(111) targets have been simulated with the multiple-interaction molecular dynamics code SPUT2. Both dimer and single-ion (monomer) impacts were studied for Kr, Xe, Au, and U ions normally incident on Au(100) and Au(111) with energies of 5 keV/atom. Statistically significant nonlinear dimer-to-monomer yield ratios were found in all cases. For each case studied the dimer-to-monomer nonlinear yield ratio from the Au(111) target was greater than from the Au(100) target. However, this ratio decreased as the mass of the incident projectile increased. Our simulations suggest that this was the result of significant nonlinear effects that occured when the heavier single-ions impacted the Au(100) and Au(111) surfaces. The nonlinear effects observed at these bombarding energies appear to be due primarily to collisional spikes involving moving atoms, and only secondarily to the lowering of the surface binding energy that results from damage to the surface.

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