Tomography of thin-film interfaces by using random-pulse picosecond sonar Project ID: GA23-08020S Provider: Czech Science Foundation Period: Jan 01, 2023 - Dec 31, 2025 Principal Investigator: RNDr. Petra Veselá Ph.D. Co-investigators P. Mokrý, J. Budasz, M. Hlubučková, M. Guesmi, K. Žídek, K. Hlinomaz, V. Kanclíř Aims of the project: A buried interface between two solid-state materials is a specific species with distinct properties from the adjacent materials. Such interfaces are hard to study with contemporary methods in anon-destructive way. Therefore, many fields, including the deposition of optical coatings, suffer from limited knowledge about the interfaces. To understand processes governing the formation of interfaces, the project will develop a new approach to ultrafast acoustics based on random picosecond pulses and computational data reconstruction. It will allow us to reliably retrieve the response of the studied system with a high signal-to-noise ratio and link it to the interface morphology. We will use computational ultrafast acoustics to study interface formation and morphology in standard systems (SiO2-Si interface), and samples with a controlled interface. By using the developed techniques, we will study processes, such as oxidation, thermal diffusion, or ion bombardment, which are governing the formation of interfaces in thin-film systems for optical coating (incl. SiO2-Si3N4, SiO2-Ta2O5).