Bonn 2025 – wissenschaftliches Programm

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K: Fachverband Kurzzeit- und angewandte Laserphysik

K 5: Laser-Beam Matter Interaction – Light and Radiation Sources II

K 5.2: Vortrag

Dienstag, 11. März 2025, 11:30–11:45, HS XI ITW

Investigations on the ablation and the irreversible material changes of single-crystalline silicon irradiated with ultrashort pulsed laser radiation — •Andy Engel, Markus Olbrich, Theo Pflug, and Alexander Horn — Laserinstitut Hochschule Mittweida, Hochschule Mittweida, Technikumplatz 17, 09648 Mittweida, Germany

In this study the irradiation of single-crystalline, <111> -oriented silicon is investigated by varying the fluence of the applied ultrashort pulsed laser radiation (pulse duration 40 fs, wavelength 800 nm) and the number of single pulses per spot. The resulting irreversible material changes due to the laser radiation-matter interaction are presented and discussed. These material changes were observed by measuring the spatial- and spectral-resolved refractive index using ex-situ ellipsometry and SEM analyses. Comparative analyses of the topography of the irradiated surfaces were performed using confocal laser scanning microscopy and atomic force microscopy. Additional information about the depth of the thermally induced material phase changes have been obtained by downstream wet chemical etching. The ex-situ analyses were supported by ultrafast metrology, pump-probe imaging reflectometry and interferometry as well as optical modeling and simulations of the laser-matter interaction. This complementary approach enables a more accurate description of the physical processes induced by ultrashort pulsed laser irradiation, starting from changes in crystallinity up to ablation.

Keywords: ellipsometry; laser matter interaction; ultrashort pulsed laser radiation; phase changes; pump-probe