Experiments on the sputtering of group VI elements

Abstract At the last REI ∗ conference, we reported that 30…300 keV He + ions impinging on elemental solid sulfur cause tremendous erosion, corresponding to sputtering yields of 10 4 to 10 6 sulfur atoms per incident He ion. In the present work, these experiments were repeated at various temperatures to test our previously proposed model of a radiation enhanced sublimation. The measured temperature dependence indicates a thermally activated process. Further experiments on sulfur were performed with 3–9 keV Ar + ions for analysis of the masses and energies of the sputtered sulfur species. In contrast to thermal sublimation with predominantly S 2 , S 4 , and S 8 molecules, there is a preference for smaller clusters in sputtering by 3–9 keV Ar + ions. The other chalcogenes, selenium and tellurium, were irradiated with 50…300 keV He and Li for sputtering yield measurements. No special features or abnormally high sputtering yields were observed with these targets. Subsequent checks on the implanted helium and lithium revealed some unique features: the implanted helium is found to be extremely mobile in selenium at room temperature in contrast to the helium behaviour in metals. In the case of lithium implantation into selenium and tellurium, at least a major fraction shows mobility at room temperature, whereas the residual lithium is distributed in the targets according to theoretical predictions of range and damage distributions (TRIM calculations).