21 pags., 9 figs., 1 tab. -- This article belongs to the Special Issue Advanced Pulse Laser Machining TechnologySuperficial amorphization and re-crystallization of silicon in and orientation after irradiation by femtosecond laser pulses (790 nm, 30 fs) are studied using optical imaging and transmission electron microscopy. Spectroscopic imaging ellipsometry (SIE) allows fast data acquisition at multiple wavelengths and provides experimental data for calculating nanometric amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. For a radially Gaussian laser beam and at moderate peak fluences above the melting and below the ablation thresholds, laterally parabolic amorphous layer profiles with maximum thicknesses of several tens of nanometers were quantitatively attained. The accuracy of the calculations is verified experimentally by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). Along with topographic information obtained by atomic force microscopy (AFM), a comprehensive picture of the superficial re-solidification of silicon after local melting by femtosecond laser pulses is drawn.C.F. acknowledges the support from the European Commission through the Marie Curie Individual Fellowship—Global grant No. 844977 and funding from the Horizon 2020 CellFreeImplant European project. D.F., M.D., S.S., A.H. and U.B. gratefully acknowledge the funding from the German Central Innovation Program (AiF-ZIM) under grants No. ZF4044219AB7 and ZF4460401AB7. K.F., M.R. and A.U. acknowledge support by the German Research Foundation (grant Nos. UN 341/3-1 and Inst 275/391-1). J.B. acknowledges the projects CellFreeImplant and LaserImplant. These two projects have received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreements No. 800832 (CellFreeImplant) and No. 951730 (LaserImplant).Peer reviewe
