Metallic-layer morphology and nanoparticle creation during low-energy irradiation (<5 MeV): A review

In this paper, ion irradiation of thin metallic layers is reviewed. The main phenomena occurring are dewetting of the layer into spheres, alongside diffusion, ballistic ejection and precipitation of satellite nanoparticles. When irradiation is pursued long enough, the nanoparticle population created by dewetting reduces its mean size due to ballistic mixing. Eventually, if the dose rate is high enough, this population size will stabilize with the satellite precipitate size. The resulting mean radius depends on the balance between retro diffusion and ballistic ejection. As the ballistics effects could be scaled by ion beam parameters (intensity, ion type, energy, …) these phenomena could technically be used to tailor the size of the nanoparticles. This would have applications in the plasmonic field as nanoparticles’ optical properties are determined, among other things, by their size. Next, different models concerning nanoparticle size evolution during irradiation are discussed. Among these models, one is compared to experimental data from the literature. Our model is then added to increase compliance with experimental data.