Characterisation by various microscopic techniques of the damage created by MeV C-60 ions in amorphous Ni3B

In the work presented here, we study the damage resulting from the high rat es of energy deposition in electronic processes during the slowing down of energetic projectiles in amorphous Ni3B. More precisely, we study the struc tural modifications of the targets irradiated at 300 K in a wide range of f luences (10(9)-5 x 10(11) cm(-2)) with 30 MeV C-60 ions. The experimental r esults mainly concern the surface features and were obtained by Transmissio n Electron Microscopy (TEM) using in particular phase contrast and topograp hical contrast imaging. In the case of C-60 ions, TEM reveals that surface damage consists of approximatively 20 nm diameter hollows, which are surrou nded by protuding rims. This seems to indicate that the anisotropic growth process, which is specific of amorphous structures, is induced by each indi vidual C-60 cluster. ion. Previous results obtained using GeV heavy monoato mic projectiles showed that the plastic deformation of the targets started only above an incubation fluence, i.e. after a significant spatial overlap of the damaged regions. (C) 1998 Elsevier Science B.V. All rights reserved.