纳秒激光脉冲诱导硅表面微结构

Nanosecond laser pulses-induced surface microstructures on silicon

利用Nd:YAG纳秒激光脉冲,在能量密度为1～10 J/cm2范围内辐照单晶硅,形成了表面锥形微结构,在SF6气氛和空气环境下均形成了锥形尖峰表面微结构。SF6气氛下产生的锥形尖峰顶端都有小球,部分锥形上还有二次尖峰形成,空气中纳秒激光诱导的锥形尖峰微结构顶端和边缘有由液滴固化形成的粒状物质,不同于利用准分子纳秒激光诱导的细长须状结构和飞秒激光辐照下产生的具有表面枝蔓状纳米结构的锥形微结构。实验结果表明,这种尖峰微结构的形成与辐照激光的波长和脉冲持续时间有关。对空气中微构造硅的辐射反射的初步研究表明,在500～2 400 nm范围内的光辐射反射率不高于20%。

The surface spike microstructures are formed by Nd：YAG nanosecond laser pulses irradiating single crystal silicon wafers with energy densities within the ablation regime, in SF4 or air atmosphere. All the tops of the spikes created in SF6 atmosphere have small spheres, there are still the secondary tips on some spikes. There is granular material on the top and the edge of the spikes indueed by nanosecond laser pulses in air atmosphere, which is formed by solidification of the droplets. The microstructures formed in air are different from the slender whiskerlike structures created by excimer laser and also different from the conical microstruetures with dendritie nanostructures formed under femtosecond laser irradiation. The experimental results suggest that both the laser wavelength and the pulse duration are involved in the formation of the spike mierostructures. The preliminary experiment in air shows that the radiation reflectivity is not more than 20% at the wavelength range of 500-2 400 nm.