Craters, bumps and onion structures in MoS2 irradiated with MeV C60 ions

In the scope of a general study of damage creation under high energy deposition by electronic excitation in various types of materials, we present here results relative to irradiations of a lamellar compound with energetic cluster ions. The projectiles are 20-40 MeV C-60 ions delivered by the tandem accelerator located in Orsay (France). Thin samples suitable for Transmission Electron Microscopy (TEM) are irradiated at 300 K. The damage is characterised by various TEM techniques, in particular Topographical Contrast Imaging. We study the influence of the angle of incidence of the projectiles (varied from normal to grazing incidence) on the morphology of the surface features (craters and bumps). We also characterise the structural modifications occurring in the vicinity of the projectile path. We observe in particular the formation of "onion like structures" either inside the latent tracks or deposited on the surface of the specimens. (C) 1998 Elsevier Science B.V. All rights reserved.