Spontaneous formation of nanospiked microstructures in germanium by femtosecond laser irradiation
Spontaneous formation of nanospiked microstructures in germanium by femtosecond laser irradiation
复制标题
DOI：
10.1088/0957-4484/18/19/195302
复制
发表时间：
2007-05-16
期刊：
影响因子：
3.5
通讯作者：
Kolasinski, Kurt W.
中科院分区：
文献类型：
--
作者：
Nayak, Barada K.;Gupta, Mool C.;Kolasinski, Kurt W.
我们报告了一种新现象，即通过在 SF6 环境中将锗表面暴露于飞秒激光脉冲，在圆锥形微结构顶部自发形成近乎规则的纳米尖峰阵列。硅激光纹理化已有报道，但尚未发表有关Ge激光微纹理化的信息，特别是圆锥形微结构顶部纳米尖峰的观察。纳米尖峰高约 2 μm，尖端半径为 100 nm，形成于宽约 5 μm、高约 10 μm 的圆锥形微结构顶部。通过简单的化学蚀刻，尖端半径可以锐化至大约 10 nm。较高的激光能量密度和较少的发射次数有利于纳米尖峰的形成。通过增加更高注量下的发射次数，表面形态从圆锥形微结构变为高直壁柱状结构，并且纳米尖峰消失。已将锗的表面形态与硅进行了比较。激光处理后，锗样品完全变黑，即它们在整个可见光谱范围内的反射率大大降低。
We report a novel phenomenon of spontaneous formation of nearly regular arrays of nanospikes atop conical microstructures by exposing a germanium surface to femtosecond laser pulses in an environment of SF6. Silicon laser texturing has been reported, but no information has been published on laser microtexturing of Ge and in particular the observation of nanospikes atop conical microstructures. The nanospikes are around 2 mu m high having a tip radius of 100 nm and are formed atop conical microstructures that are around 5 mu m wide and 10 mu m tall. The tip radius could be sharpened down to similar to 10 nm by brief chemical etching. A higher laser fluence and fewer shots favour the formation of nanospikes. By increasing the number of shots at higher fluence the surface morphology changes from conical microstructures to tall straight-walled pillar-like structures and the nanospikes disappear. The surface morphology of germanium has been compared with silicon. The germanium samples turn completely black after laser processing, i.e. they exhibit greatly reduced reflectivity throughout the visible spectrum.