Positron Annihilation Study on Nanocrystalline Copper Thin Films Doped with Nitrogen

In the last decade a strong development in the nanomaterials field has been observed due to the unique and specific mechanical and physical properties of these nanomaterials comparatively to their coarser grain size materials [1–3]. On the other hand, thin metallic films play also an important role in many areas of the electronic industry for different applications, such as protective coatings [4], sensors [5] and contacts [6, 7]. Particularly, nanocrystalline copper is a promising material for automotive and electronic industries. Among different fabrication processes, sputtering is well known for producing nanocrystalline thin films. However, maintaining the nanocrystalline character during processes or applications is still not an easy task due to the tendency towards grain growth exhibited by nanomaterials (copper presents a low tendency for nanocrystallity due to the high adatoms mobility). On the other hand, the addition of solutes with a strong affinity for grain boundary segregation can inhibit grain growth, particularly during the manufacturing process, but it is still not well known the effects of impurities and dopants on the mechanical and physical properties of the nanomaterial. The presence of doping elements during the formation of sputtered metallic films could have an important role on the grain size decrease,