Transmission sputtering by heavy ions

Transmission sputtering yields of single and polycrystalline gold foils have been measured as a function of thickness in the range 250-5000 Å for bombardments with 560-keV Bi, 400-keV Ag, 200- and 400-keV Ar, and 50-keV He ions. Good agreement is found between the yield curves for polycrystalline and single-crystalline targets oriented in a high-index (random) direction. Calculated distributions of energy deposition in an amorphous target compare well with regard to the position of the maximum in the sputter yield. Absolute yields in the vicinity of the peak are generally in better agreement with yields calculated by Monte Carlo simulation for finite targets than with yields calculated on the basis of transport theory in an infinite solid. Compared with theory, all measured yield curves exhibit considerable enhancement at great depths. Sputter-yield distributions for a beam of 560-keV Bi ions along $〈100〉$ are in qualitative agreement with channeling theory. From a comparison with the random sputter-yield distributions, it can be concluded that channeling of such heavy projectiles causes a relatively minor reduction (≲ 40%) in the total amount of energy that goes into nuclear motion.