Caractérisation par nanoindentation du GaN irradié par des ions uranium de grande énergie

Abstract

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 1013 ions/cm2, 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.