Growth of high spatial frequency periodic ripple structures on SiC crystal surfaces irradiated with successive femtosecond laser pulses
Growth of high spatial frequency periodic ripple structures on SiC crystal surfaces irradiated with successive femtosecond laser pulses
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DOI：
10.1364/oe.21.026323
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发表时间：
2013-11-04
期刊：
影响因子：
3.8
通讯作者：
Obara, Minoru
中科院分区：
文献类型：
--
作者：
Obara, Go;Shimizu, Hisashi;Obara, Minoru
本文从理论上和实验上研究了飞秒激光脉冲在真空室中辐照SiC晶体表面制备的高频周期波纹的演化过程。在早期阶段，种子缺陷主要由激光脉冲辐照引起，导致烧蚀阈值的降低。通过观察这些表面结构在连续激光脉冲照射下的演变，采用纳米烧蚀法在SiC表面缺陷处制备了纳米晶圆。纳米蚀坑的米氏散射产生周期性波纹。随着脉冲数的增加，HSFL的数量增加。在激光光斑边缘，Mie散射过程仍然占主导地位，导致HSFL的制备。在光斑SiC衬底的外围保持半导体状态，这是因为激光照射导致SiC中的电子密度很低。用多个激光脉冲照射，观察到的高通量荧光在碳化硅表面非常深。通过三维时域有限差分（FDTD）仿真可以很好地解释这些实验结果。(C) 2013年美国光学学会
We present experimentally and theoretically the evolution of high spatial frequency periodic ripples (HSFL) fabricated on SiC crystal surfaces by irradiation with femtosecond laser pulses in a vacuum chamber. At early stages the seed defects are mainly induced by laser pulse irradiation, leading to the reduction in the ablation threshold fluence. By observing the evolution of these surface structures under illumination with successive laser pulses, the nanocraters are made by nanoablation at defects in the SiC surface. The Mie scattering by the nanoablated craters grows the periodic ripples. The number of HSFL is enhanced with increasing pulse number. At the edge of the laser spot the Mie scattering process is still dominant, causing the fabrication of HSFL. On the periphery of the spot SiC substrate remains a semiconductor state because the electron density in the SiC induced by laser irradiation is kept low. The HSFL observed is very deep in the SiC surface by irradiating with many laser pulses. These experimental results are well explained by 3D FDTD (three-dimensional finite-difference time-domain) simulation. (C) 2013 Optical Society of America