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利用Nd∶YAG纳秒脉冲激光(波长为532 nm)分别在空气中和水下对单晶硅进行单脉冲辐照,研究了在介质/硅片界面产生的激光等离子冲击波对硅表面形貌的影响。通过压电传感器对辐照过程中冲击波力学信号进行采集,利用扫描电子显微镜(SEM)对辐照后的硅片进行表征。结果表明:在相同能量强度下,水下辐照硅表面所产生的冲击波平均速度为空气中的1.5~2倍,力学强度约为空气中的10倍;水下硅表面的熔坑中心处出现了许多凸起的球状物以及下凹的孔洞,边缘处没有沉积物且具有波纹状结构,而空气中硅表面熔坑中心处较为光滑,边缘处具有一圈圈的沉积物。研究表面,在介质/硅片界面产生等离子冲击波所引起的热-力学效应是硅表面形貌形成的主要原因。与空气介质相比,在水下由于水的约束作用而引起更大的冲击波力学强度,以及由于水的存在而发生爆发式沸腾的热学现象共同导致了在水下和空气中硅表面形成了截然不同的形貌。
Single-pulsed Nd: YAG nanosecond pulsed laser (532 nm wavelength) was used to mononuclear single-pulse irradiation in air and underwater respectively. The effect of laser plasma shock wave on the surface morphology of silicon influences. Piezoelectric sensors were used to acquire shock wave mechanics signals during irradiation, and the irradiated silicon wafers were characterized by scanning electron microscopy (SEM). The results show that under the same energy intensity, the average velocity of shock waves generated on the surface of underwater irradiated silicon is 1.5 ~ 2 times that of air and the mechanical strength is about 10 times that of air; A large number of raised globes and concave holes, no deposits on the edges and a corrugated structure, while the surface of the silicon in the air is smoother at the center of the crater and has a circle of deposits at the edges. Studying the surface, the thermo-mechanical effect caused by the plasma shock wave at the media / silicon interface is the main reason for the formation of silicon surface topography. Compared with the air medium, the greater shock wave mechanics strength due to the confinement of water under water and the thermal phenomena of explosive boiling due to the presence of water lead to the complete formation of the silicon surface under water and in the air Different appearances.