Patterning of insulating surfaces by electronic excitation

The interaction of swift heavy ions with any material is governed by a strong electronic excitation. In insulators this often leads to permanent modifications. We have irradiated various insulating materials (SrTiO3,TiO2,Al2O3,CaF2,SrF2,BaF2,andLiF) with swift heavy ions and have studied the irradiated surfaces by means of scanning force microscopy. For all materials used in this study we find one nanosized hillock per incident ion if the beam is oriented perpendicular with respect to the surface. Under oblique angles we find elongated chains of discontinuous nanodots on all crystalline materials investigated here.