皮秒激光功率变化对激光诱导晶体硅变化的影响

Influence of laser power variation on laser-induced changes of crystalline silicon

为了深入了解皮秒激光烧蚀对晶体硅所造成的影响,使用不同平均功率下的皮秒脉冲激光辐照晶体硅,然后使用X射线光电子能谱仪和透射电子显微镜,分别对被烧蚀晶体硅的化学成分与微观组织结构进行观察与分析。研究发现:随着激光脉冲平均功率的增加,烧蚀产物中晶体硅的相对含量不断下降,而Si O2的相对含量则逐步上升;与此同时,材料的无定形化程度也随之加剧。最终认为:因激光脉冲平均功率增加而逐渐升高的激光能量密度是诱导上述实验结果出现的主要原因,并最终不断扩大并加剧着材料所受到热与机械损伤的范围与程度。

In order to understand the influence of picosecond laser irradiation on crystalline silicon, laser- induced changes of crystalline silicon by picosecond laser ablation with different average laser powers were studied. Then X-ray photoelectron spectroscopy and transmission electron microscope were used to analyze the influence of average laser power variation on final chemical composition and microstructure of the ablated silicon, respectively. It is concluded that, with the increase of average laser power, the relative content of Si in ablation product keeps falling, by contrast, the relative content of Si02 gradually rises. At the same time, the increase of average laser power intensifies the amorphization degree of microstructure of ablated silicon. Finally, it is deduced that the increased laser fluence resulted from average laser power increasing is the main reason for all of above experimental results, and also to enlarge and deepen the thermal and mechanical damages in ablated silicon.