Molecular dynamics simulation of the damage production in Al (110) surface with slow argon ions

We have developed a molecular dynamics simulation program to gain more insight into the sputtering process, especially the damage produced by it. We have studied the sputtering of aluminium (110) surface with argon ions. The Morse pair potentail was used for Al-Al interaction, the Lennard-Jones potential for Ar-Ar interaction and both the Molière potential and the universal potential of Ziegler et al. for Ar-Al interaction. An electronic friction term proportional to the particle velocities was also used. The studied incident argon ion energies and angles were 200 and 400 eV and 0° (normal), 25°, 45° and 75°, respectively. The calculated sputtering yield and the overall shape and the mean depth of the vacancy profiles agree with the experimental results. The obtained profiles contain a narrow peak within the topmost atomic layers, followed by a weak tail deeper in the material. The intersitial and argon ion distributions are much more spread out at larger depths. The total number of vacancies per incident Ar⁺ ion varies from 0 to 7, increasing as function of Ar⁺ ion energy.