The annealing effects of crystalline silicon (Si) implanted with argon (Ar) ions at a dose of 2 x 10(16) Ar+/cm(2) at room temperature and subsequently annealed at 400-1100 degrees C for 30 min were investigated. The samples were analyzed by transmission electron microscopy and Raman spectroscopy. Before and after annealing up to 600 degrees C, an amorphous layer is formed but Ar bubbles are not observed in the damage layer. After annealing at 800 degrees C, argon bubbles are observed together with extended defects. The damage layer evolves into a polycrystalline structure. After annealing at 1100 degrees C; exfoliation occurs on the sample surface, and microtwin lamellas form in the damage layer. Raman scattering revealed that a strong recrystallization occurs from 600 degrees C to 800 degrees C. The results were compared with the case of helium implantation, with particular focus on bubble formation mechanisms. (C) 2011 Elsevier B.V. All rights reserved.