Résumé : The mechanical behavior of thin films of gallium nitride GaN, irradiated with swift heavy uranium ions, has been investigated by nanoindentation. Results show a decrease of the mechanical properties of the material due to irradiation, correlated to the increase of the fluency of the U ions. The growing disturbance of the GaN crystalline lattice caused by irradiation results in a change in the deformation mechanisms of the material. Highly disordered zones obstruct the dislocation motion, leading to the dislocations pile-up at the film/substract interface, and a consecutive increase of the hardness. Up to a fluency of 10(13) ions/cm(2), the recovering of the latent tracks created along the paths of the rapidly moving ions brings a significant drop of the mechanical properties of the GaN films, correlated with a homogenization of the behavior of the materials irradiated with elevated fluencies.
