Atomic excitations in sputtering as functions of the projectile energy

Abstract

We have bombarded Mg, MgO, Al, and Si with Ar ions from 10 to 160 keV and measured yields of sputtered excited neutrals and ions as functions of the projectile energy. The yield curves for different levels within the same charge state and also the same element are essentially proportional. The curves for excited ions are steeper than those for excited neutral atoms. The steepness increases with increasing charge state, and is element dependent. This is presumably related to different velocity distributions for different charge states. The data seem to indicate a difference in excitation mechanism between the jellium-like metals Mg and Al and the semiconductor Si, which can be related to the different bonds (metals and covalent, respectively) of the solids.