Electronic excitation induced mass transport on 200 MeV F107+14 ion irradiated Si surface

Abstract

Modification on Si (111) surface resulting from 200 MeV Ag107+14 ion irradiation at an incidence angle of 15° with respect to the surface normal has been investigated by atomic force microscope (AFM) and x-ray diffraction techniques. Root mean square roughness measured using AFM was found to increase from 0.96 nm in the pristine sample to 18.33 nm in the sample irradiated with an ion fluence of 5×1013 ions/cm2. This spectacular increase in surface roughness is ascribed to the displacement of Si atoms driven by the creation of unsaturated dangling bonds on the Si surface during swift heavy ion irradiation. At a fluence of 5×1013 ions/cm2, a new type of ditch and dike structure was observed. These structures were distributed over the irradiated surface. Each ditch is followed by a dike. This is attributed to the cumulative effect of ion irradiation arising due to overlapping of ion-induced damaged zones and electronic excitation-induced shear motion of the atoms towards the surface.