Simultaneous Calculation of Reflection, Physical Sputtering and Secondary Electron Emission from a Metal Surface due to Impact of Low-Energy Ions

Abstract

A computer simulation code which treats elastic and inelastic collision processes of low-energy ions in solids is presented. In the code, the direct excitation of electrons by a penetrating ion and recoiling atoms is simulated using the Monte Carlo technique, in addition to the simulation of elastic collisions of the moving particles with solid atoms. Electron cascades of the excited electrons and collision cascades of the recoil atoms are also taken into account, and as a result, the code allows us to simulate ion-solid interactions such as ion reflection, physical sputtering and secondary electron emission from the solids. This code is applied to calculations of the energy and angular distributions of emitted particles and the total particle yields of aluminum by impact of ions with the atomic numbers Z1 of 1 to 17 and energies Ei of 10 eV to 10 keV at normal incidence. The calculated sputtering yield and ion reflection coefficient are in reasonable agreement with empirical formulae which have been recently presented. The calculated electron yield shows the clear dependence on Z1 and Ei, but the Ei-dependence is different from that of the electronic stopping power at such low impact energies. The energy and angular distributions of emitted particles indicate the similarities of the secondary electron emission and the physical sputtering, as observed in recent experiments.