Physico-Chemical characterization of D-LIPSS formation by femtosecond laser beam on N-doped (100) silicon under controlled atmospheres

Abstract

In this work, the formation of deep laser-induced periodic surface structures (D-LIPSS) on N-type silicon (100) was investigated using femtosecond laser pulses (pulse duration = 350 fs; wavelength = 1030 nm; repetition rate = 100 kHz) with linear polarization. Experiments were performed at atmospheric pressure and at 1 mbar under various atmospheres, including oxygen, nitrogen, argon, and ambient air, in both static mode (accumulation of successive pulses) and scanning mode (sample displacement under the beam). The study aimed to better understand the mechanisms involved in ultrashort laser-induced surface structuring by examining the influence of atmospheric pressure and gas composition on the morphology, topography, chemical composition, and wettability of the fabricated structures. Morphological characterization using SEM, AFM, and TEM revealed the formation of D-LIPSS with amplitudes around 650 ± 50 nm, significantly exceeding typical values reported in the literature. Material redeposition was markedly reduced under low-pressure conditions compared to atmospheric pressure, leading to cleaner and more well-defined surface structures.