Molecular dynamics simulations of ion self-sputtering of Ni and Al surfaces

We present results of molecular dynamics simulations of Ni+ impacting Ni(11 1) and Al+ impacting Al(111) and amorphous Al surfaces. Sputter yields and sticking probabilities were calculated as a function of ion fluence, impact angle (0-90 degrees) and energy (25-150 eV). We find that the simulated sp utter yields are in reasonable agreement with experiments and a commonly us ed empirical formula. For Al+ impacting at normal incidence, sputter yields were approximately the same for both Al(111) and amorphous Al. The initial penetration depth exhibited a linear dependence with velocity, and was app roximately the same for both Al+/Al(111) and Ni+/Ni(111) if the distances w ere scaled by the lattice constants. The average calculated time between io n impact and atom ejection was less than 25 fs for 100 eV Ni+/Si(111) sputt er events. (C) 2001 American Vacuum Society.