Influence near-infrared ultrashort laser pulse duration on silicon ablation

N. R. Lebedev^ab, N. V. Minaev^a, V. I. Yusupov^a, E. I. Mareev^a, S. I. Tsypina<sup>a

a</sup> Kurchatov Complex Crystallography and Photonics, NRC "Kurchatov Institute", Moscow
^b National Engineering Physics Institute "MEPhI", Moscow

Abstract: By varying the duration and energy of ultrashort near-infrared laser pulses, it wasdemonstrated that the size of microstructuring on silicon surfaces, as well as the optical breakdown threshold, are primarily determined by the effects of avalanche ionization. The laser-induced microstructure consists of two zones: a central zone, which size logarithmically depends on the laser pulse energy $E$, and a peripheral area, whose size is proportional to $E^{1/2}$. These regions are characterized by different amounts of the crystalline phase of silicon. Using rate equations, it has been shown that this dependence is due to the increased contribution of avalanche ionization as the pulse duration changes from 200 fs to 2 ps (the breakdown threshold varies from 0.2 to 0.22 J/cm$^2$).

Keywords: femtosecond laser ablation, rate equations, silicon.

Received: 28.11.2024
Revised: 12.03.2025
Accepted: 20.03.2025

DOI: 10.61011/PJTF.2025.12.60609.20201

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