STM study of Ar⁺-induced defects produced by near-threshold energy collision

We have investigated graphite surfaces impacted with Ar⁺ ions of near-threshold energies (40-100 eV) using STM. In order to understand the effect of Ar atoms trapped between the graphite basal planes on STM image, the trapped atoms are evaporated by heating the surface at 600°C after 50 eV Ar⁺ impact. Ion impact creates hillocks of various size in STM images, which originate from the enhanced charge density at vacancy and interstitial defect sites. The yields for total defect production, vacancy production and Ar trapping upon ion impact are determined at an energy of 50-100 eV. The threshold energies for vacancy production and trapping are deduced from these data.