Influence of Impact Ionization on the Laser Ablation of Silicon Surface by Ultrashort Pulses in the Near and Mid-IR Range

IF 0.5 Q4 PHYSICS, CONDENSED MATTER
E. I. Mareev, A. V. Pushkin, F. V. Potemkin
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引用次数: 0

Abstract

We investigated the influence of impact ionization on the laser ablation of silicon using ultrashort pulses in the near and mid-infrared ranges. Using electron microscopy and numerical modeling of the ionization process based on dynamical rate equations, we demonstrated that the transition to the mid-IR range significantly changes the mechanisms of plasma generation. In the near-IR range, photoionization (both multiphoton and tunneling) predominates, while the contribution of avalanche ionization becomes dominant for pulse durations exceeding 500 fs. Consequently, the smallest size of microstructures on the silicon surface during laser ablation is achieved for picosecond pulses, where the electron concentration in the generated plasma is low and laser beam defocusing is negligible. In contrast, in the mid-IR range, impact ionization becomes the dominant mechanism for increasing the electron density of the plasma, enabling high spatial resolution during the ablation process at the shortest pulse durations, as impact ionization proves to be more effective. The results of this study contribute to a better understanding of the mechanisms of laser radiation interaction with material surfaces and can be applied to optimize laser processing techniques in various fields.

Abstract Image

我们研究了冲击电离对使用近红外和中红外超短脉冲激光烧蚀硅的影响。利用电子显微镜和基于动力学速率方程的电离过程数值建模,我们证明了过渡到中红外范围会显著改变等离子体的生成机制。在近红外范围内,光离子化(多光子和隧道)占主导地位,而当脉冲持续时间超过 500 fs 时,雪崩电离的贡献则占主导地位。因此,在激光烧蚀过程中,硅表面微结构的最小尺寸是在皮秒脉冲下实现的,在皮秒脉冲下产生的等离子体中电子浓度较低,激光束偏焦可以忽略不计。相反,在中红外范围内,撞击电离成为增加等离子体电子密度的主要机制,在最短脉冲持续时间的烧蚀过程中实现了高空间分辨率,因为撞击电离被证明更为有效。这项研究的结果有助于更好地理解激光辐射与材料表面相互作用的机制,并可用于优化各个领域的激光加工技术。
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来源期刊
CiteScore
0.90
自引率
25.00%
发文量
144
审稿时长
3-8 weeks
期刊介绍: Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques publishes original articles on the topical problems of solid-state physics, materials science, experimental techniques, condensed media, nanostructures, surfaces of thin films, and phase boundaries: geometric and energetical structures of surfaces, the methods of computer simulations; physical and chemical properties and their changes upon radiation and other treatments; the methods of studies of films and surface layers of crystals (XRD, XPS, synchrotron radiation, neutron and electron diffraction, electron microscopic, scanning tunneling microscopic, atomic force microscopic studies, and other methods that provide data on the surfaces and thin films). Articles related to the methods and technics of structure studies are the focus of the journal. The journal accepts manuscripts of regular articles and reviews in English or Russian language from authors of all countries. All manuscripts are peer-reviewed.
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