Ion-beam-induced structure fragmentation and dewetting in Au/Ti films

• Published in: Materialia 2021-12, Vol.20, p.101214, Article 101214
• Main Authors: Codeço, C.F.S., Mello, S.L.A., Magnani, B.F., Sant'Anna, M.M.
• Format: Article
• Language: English
• Subjects: Fragmentation; Gold thin films; Ion beam processing; Microstructure formation; Solid-state dewetting
• ISSN: 2589-1529; 2589-1529
• DOI: 10.1016/j.mtla.2021.101214

We investigate the formation of Au structures by continuing fragmentation of a Au film separated from Si (100) substrate by a Ti adhesion layer. The ion-beam processing uses 2 keV Cs+ projectiles. It induces the formation of a large variety of structures with dimensions from tens of microns down to a few nanometers, and shapes that include flat Au islands and clusters of Au nanoparticles. We identify different fragmentation mechanisms. In one pathway, Au structures are formed as pinch-off droplets detached from large Au islands undergoing solid-state dewetting. In a second pathway, a continuing cracking fragmentation produces Au structures with a wide range of sizes and shows self-similarity, expressed in a power law for volume distribution of fragments Vα with α = −2.03 ± 0.05. The measured α value is consistent with theoretical results in the literature modeling strong impact fragmentation. In the last stage of fragmentation evolution, Au nanostructures are spread over a texturized Si background. They assume shapes close to hemispherical, reflecting the increasing relevance of surface tension as dimensions decrease. [Display omitted]