Femtosecond-laser-induced quasiperiodic nanostructures on TiO2 surfaces
Femtosecond-laser-induced quasiperiodic nanostructures on TiO2 surfaces
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DOI：
10.1063/1.3117509
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发表时间：
2009-04-15
影响因子：
3.2
通讯作者：
Grunwald, Ruediger
中科院分区：
文献类型：
--
作者：
Das, Susanta Kumar;Dufft, Daniela;Grunwald, Ruediger
高空间频率，准周期性结构（HSFL，纳米波纹）的特征尺寸为170 nm的诱导在金红石型二氧化钛表面聚焦150 fs钛：蓝宝石激光脉冲在波长约800 nm。对于N=100-1000的脉冲数，涟漪形成是明显可见的。在较低的脉冲数（N=10），一个显着的表面粗糙化出现，而不是波纹，其特征在于随机曲折的纳米结构。这些观察结果证实了早期阶段的不规则材料修改的准周期性涟漪形成的动力学的重要贡献。涟漪产生的阈值通量估计的基础上，激光诱导的表面结构的传统理论。当脉冲数从N=100增加到N=1000时，发现阈值注量从0.34 J/cm（2）降低到0.24 J/cm（2），这归因于损伤累积效应。通过在优化的能量和激光脉冲的重复率下利用受控的样品平移来实现空间延伸区域的纳米结构化。通过对扫描电子显微镜数据的二维傅里叶变换，证实了纳米结构的周期性的显著增强。在约400 nm的二次谐波波长下，证明了甚至在亚100 nm尺度上的纳米波纹的产生。(C)2009年美国物理学会。[DOI：10.1063/1.3117509]
High-spatial frequency, quasiperiodic structures (HSFL, Nanoripples) of 170 nm feature size were induced in rutile-type titanium dioxide surfaces by focused 150 fs Ti:sapphire laser pulses at wavelengths around 800 nm. The ripple formation is distinctly visible for numbers of pulses of N=100-1000. At lower number of pulses (N=10), a significant surface roughening appears instead of ripples which is characterized by randomly meandering nanostructures. These observations confirm an essential contribution of early stage irregular material modifications to the dynamics of quasiperiodic ripple formation. The threshold fluence for ripple generation is estimated on the basis of the conventional theory of laser-induced surface structuring. The decrease in the threshold fluence from 0.34 to 0.24 J/cm(2), as it was found for an increase in the number of pulses from N=100 to N=1000, is attributed to a damage accumulation effect. Nanostructuring of spatially extended regions was enabled by utilizing a controlled sample translation at optimized energy and repetition rate of the laser pulses. A significant enhancement of the periodicity of the nanostructures was confirmed by two-dimensional Fourier transform of scanning electron microscopy data. At second harmonic wavelengths around 400 nm, the generation of nanoripples even on the sub-100 nm scale was demonstrated. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3117509]