Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 12: Nanostructures at Surfaces II: Designer Structures and Surfaces
O 12.5: Vortrag
Montag, 1. April 2019, 16:15–16:30, H15
Femtosecond laser generation of microbumps and nanojets on single and bilayer Cu/Ag thin films — •Aida Naghiou1, Miao He2, Jasmin S. Schubert1, Leonid V. Zhigilei1,2, and Wolfgang Kautek1 — 1University of Vienna, Department of Physical Chemistry, Vienna, Austria — 2University of Virginia, Department of Materials Science and Engineering, Charlottesville, Virginia, USA
Femtosecond laser ablation of metal thin films has been of vivid interest since decades. The generation of microbumps and nanojets have been observed in many studies. It is generally accepted that frozen nanojets are produced through rapid melting. However, the mechanism for the formation of microbumps, is still under discussion. Subsurface boiling and pressure of the vapor released at the substrate-film interface, melting and redistribution of molten material, and plastic deformation of the irradiated film have been suggested as the processes responsible for the generation of the microbumps. In this study, the mechanisms of the formation of microbumps and nanojets on Ag/Cu thin films and double layers irradiated by a single 60 fs laser pulse are investigated experimentally and with atomistic simulations. The composition of the laser-modified bilayers is probed with the energy dispersive X-ray spectroscopy. The simulations reveal the important role of the difference in the electron-phonon coupling factor of the two metals in the mechanism of bump formation and breaching. The computational predictions of the threshold fluences for the formation of microbumps exposing different component of the bilayer targets, and the conditions for the bump breaching, agree well with experimental observations.