Sputtering of silicon by multiply charged ions

We report on the sputtering of Si by 20 keV multiply charged Ar ions with primary charge state q ⩽ 9. To investigate the role of “electronic” sputtering, both the yield of positively charged secondary ions and the total sputtering yield (i.e. ions + neutrals) have been measured versus q. The secondary ion yield increases with increasing q, but the total sputtering yield remains however unaffected. From the comparably small effect observed we conclude that “electronic” sputtering does not contribute significantly to the ejection process