Abstract In this paper interaction of a different number of femtosecond laser pulses and various fluences with silicon wafer has been studied. Effects of the pulse number and the laser fluence on self-organized structures created during femtosecond laser pulses processing are investigated. The scanning electron microscopy images of the sample show that by increasing the number of laser pulses, spike-like structures form on the surface, which gradually transform to hills and holes structure. The increment of the laser fluence causes the microstructures to grow in diameter. However, the increase in diameter is limited by surface stability. When the micro-structures are at their maximum size and a stable geometrical shape, further fluence increment can cause new self-organized nanostructures to be created over the microstructures’ surface. The hierarchical micro and nanostructures created after femtosecond laser pulse interaction have a similar shape. Thus fractal-like structures formed in the femtosecond pulse laser processing can be useful in the surface nano-structuring applications.

中文翻译：

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使用飞秒激光脉冲在硅片表面形成自组织分形结构

摘要 本文研究了不同数量的飞秒激光脉冲和各种能量密度与硅片的相互作用。研究了脉冲数和激光能量密度对飞秒激光脉冲加工过程中产生的自组织结构的影响。样品的扫描电镜图像显示，随着激光脉冲数量的增加，表面形成尖峰状结构，逐渐转变为丘陵和孔洞结构。激光能量密度的增加导致微结构直径增大。然而，直径的增加受到表面稳定性的限制。当微结构处于其最大尺寸和稳定的几何形状时，进一步的注量增量会导致在微结构表面上产生新的自组织纳米结构。飞秒激光脉冲相互作用后产生的分层微米和纳米结构具有相似的形状。因此，在飞秒脉冲激光加工中形成的分形结构可用于表面纳米结构化应用。