不同气氛下飞秒激光诱导硅表面微结构

利用钛宝石飞秒激光脉冲对单晶硅在SF6、空气和真空环境中进行了累积脉冲辐照,研究了硅表面微结构的演化。在SF6气氛中,在激光辐照的初始阶段,硅表面形成了1维的波纹结构,随着辐照脉冲数的增加,波纹结构演化成了2维凹凸结构。累积600个脉冲后,硅表面产生了准规则排列且具有大纵横比的锥形尖峰结构。该结构呈现高度相对较低、锥形尖端小球不明显的特征,分析认为主要与环境气压的大小有关。对比空气、SF6和真空中的微结构发现,尖峰的数密度依次减小;SF6中形成的尖峰高度最大,其次为真空,再次为空气。研究结果表明,真空、SF6和空气3种环境下微结构的形成及表面形貌主要由激光烧蚀、化学刻蚀和氧化决定。

Silicon surface microstructures induced by femtosecond laser pulses in different background gases

The single crystal silicon wafers are irradiated by the cumulative Ti: sapphire femtosecond laser pulses in SF6, air or vacuum atmosphere. The evolution of silicon surface microstructures formed in SF6 is investigated. The one-dimensional ripple structures induced by laser pulses are formed on silicon on early stages of irradiation. With increasing number of pulses, the structures gradually evolve into two-dimensional concave-convex structures. The quasi-ordered arrays of spikes with high aspect ratio are formed on silicon after six hundred laser shots irradiation. Compared with the reported results, the spikes show the characteristics of relatively low height and non obvious ball on their tips. It is believed that gas pressure is primarily responsible for the results. The number density