The surface changes which were produced in sapphire single crystals with 4 different orientations, by irradiation with 305MeV Kr ions, 595MeV Xe ions and Bi ions (710, 557, 269 or 151MeV), were studied by using atomic force microscopy and thermostimulated exo-electron emission. It was observed that individual surface defects with a density which corresponded to the ion fluence could be detected only for Bi ion energies higher than 269MeV. At the highest surface ionizing densities (41 and 35keV/nm), these defects had a complicated structure: a hillock surrounded by a bordering ring or a hillock with a cavity at its top. The thermostimulated exo-electron emission measurements showed that all of the crystals could be characterized by curves which depended upon the crystallographic orientation and irradiation dose. Nevertheless, some general features of the thermostimulated exo-electron emission data were observed for all of the crystallographic orientations.

Swift Heavy Ion Irradiation Effect on the Surface of Sapphire Single Crystals. V.A.Skuratov, D.L.Zagorski, A.E.Efimov, V.A.Kluev, Y.P.Toporov, B.V.Mchedlishvili: Radiation Measurements, 2001, 34[1-6], 571-6