Relaxation dynamics of femtosecond-laser-induced temperature modulation on the surfaces of metals and semiconductors
Relaxation dynamics of femtosecond-laser-induced temperature modulation on the surfaces of metals and semiconductors
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DOI：
10.1016/j.apsusc.2015.10.159
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发表时间：
2016-06-30
影响因子：
6.7
通讯作者：
Mocek, Tomas
中科院分区：
文献类型：
--
作者：
Levy, Yoann;Derrien, Thibault J. -Y.;Mocek, Tomas
激光诱导周期表面结构（LIPSS）的形成是一种复杂的现象，涉及到被照射表面激光能量吸收的周期性空间调制、光响应的瞬态变化、表层熔化和/或烧蚀。所列出的过程在很大程度上取决于激光通量和脉冲持续时间以及材料特性。本文旨在研究金属（Ti）和半导体（Si）表面辐照后沉积的激光能量一旦形成周期调制的时空演变。假设入射激光脉冲干扰表面电磁波，将吸收激光能量的正弦调制引入钛和硅的二维双温度模型。模拟结果表明，在激光脉冲后，两种材料表面的晶格温度调制在调制吸收后的50 ps以上仍然显著。在这里考虑的情况下，部分熔融相在Ti中存在10 ps，在Si中存在50 ps以上，这表明由于材料表面的温度分布被调制，熔融物质可能受到温度驱动向LIPSS形成的重新定位。纳米距离下的熔融相（纳米熔化）也被揭示出来。(C) 2015 Elsevier B.V.版权所有
Formation of laser-induced periodic surface structures (LIPSS) is a complicated phenomenon which involves periodic spatial modulation of laser energy absorption on the irradiated surface, transient changes in optical response, surface layer melting and/or ablation. The listed processes strongly depend on laser fluence and pulse duration as well as on material properties. This paper is aimed at studying the spatiotemporal evolution of a periodic modulation of the deposited laser energy, once formed upon irradiation of metal (Ti) and semiconductor (Si) surfaces. Assuming that the incoming laser pulse interferes with a surface electromagnetic wave, the resulting sinusoidal modulation of the absorbed laser energy is introduced into a two-dimensional two-temperature model developed for titanium and silicon. Simulations reveal that the lattice temperature modulation on the surfaces of both materials following from the modulated absorption remains significant for longer than 50 ps after the laser pulse. In the cases considered here, the partially molten phase exists 10 ps in Ti and more than 50 ps in Si, suggesting that molten matter can be subjected to temperature-driven relocation toward LIPSS formation, due to the modulated temperature profile on the material surfaces. Molten phase at nanometric distances (nano-melting) is also revealed. (C) 2015 Elsevier B.V. All rights reserved.