CC BY
4The 30th International Conference on Advanced Laser Technologies ALT'23
LM-0-20
Investigation of the short pulse laser ablation of porous silicon targets
with molecular dynamics simulation.
M. Grigoryeva1'2, I. Kutlubulatova12, A. Kanavin1, V. Timoshenko1'2'3, and I.N.
Zavestovskaya12
1-P. N. Lebedev Physical Institute of the Russian Academy of Sciences, 53 Leninskiy Prospekt, Moscow 199991,
Russian Federation
2- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31 Kashirskoe shosse,
Moscow 115409, Russian Federation 3- Lomonosov Moscow State University, GSP-1 Leninskie Gory, Moscow 119991, Russian Federation
grigorevams@lebedev. ru
The interaction of high-power laser radiation with matter is represented by a complex of processes, such as absorption of light by electrons, diffusion of hot electrons, thermionic emission, heat transfer by hot electrons to the lattice, heating of the crystal lattice, detachment of atoms or ions from the lattice, interaction of radiation with detached particles, cooling and recrystallization [1,2]. Taking into account all the processes leads to difficulties in the creation of a universal laser ablation model, and the effects caused by the above mentioned processes are often studied separately [3].
The laser ablation of a silicon (Si) target was widely studied because of the great practical importance of Si-based nanomaterials [4-6]. The modeling has been mostly performed for single-crystalline Si (c-Si), while interaction with a nano- structured substrate, such as porous silicon (PS), may be of particular interest. In this work, we simulated the ablation of PS substrates with various degrees of porosity and pore size under laser radiation with wavelengths in ultraviolet (UV), visible and infrared (IR) spectral ranges and various fluences using a one-temperature molecular dynamics model. The number of ablated atoms and ablation threshold are calculated.
It is found that for UV and visible irradiation an increase of the porosity to 80% leads to a 1.5-3 times decrease of the ablation threshold compared to the bulk silicon. For IR irradiation, the maximum drop in the ablation threshold was observed for the porosity of 60-65%. In addition, a decrease of pores size from 5 to 1 nm leads to the ablation threshold drop almost 40%.
Despite the reduction of the ablation threshold, the ablation rate of PS substrates is significantly lower than that of crystalline targets. Reducing the ablation threshold can be important in the laser ablation synthesis of nanoparticles due to lowering the laser requirements for the ablation. However, a decrease in the ablation rate with an increase in porosity leads to the need to optimize the treatment regimes and the initial porous target for each specific synthesis process.
This work was financially supported by Ministry of Science and Higher Education of Russian Federation (project No 075-15-2021-1347).
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