STM observation of cluster size dependence of HOPG surface damages induced by energetic Sin and Gen clusters

Samples of highly oriented pyrolytic graphite (HOPG) were irradiated by Sin (n = 1, 2, 3, 4, 5) with energy of 300 keV/atom and Gen (n = 1, 2, 3) with energy of 500 keV/atom at perpendicular incidence and at a fluence of 5 × 1012 projectiles/cm2, respectively. The observations by scanning tunneling microscopy (STM) clearly show a non-linear effect of the average damage area on the surface induced by clusters of different size. The dependence of the relative radiation damage on the cluster size follows a n1.47 law for Sin irradiation and a n1.1 law for Gen irradiation, respectively.