Zhong Yaoyu, Shi Feng, Tian Ye, Dai Yifan, Song Ci, Zhang Wanli, Lin Zhifan
Opt Express. 2019 Apr 15;27(8):10826-10838. doi: 10.1364/OE.27.010826.
Near-surface nanoscale damage precursor generated from the fabrication process has great influence on laser-induced damage threshold improvement of fused silica. In this work, high-resolution transmission electron microscopy (HRTEM) is used to characterize the arrangement of material particles near surface. The nanoscale defects in the Beilby layer could be clearly distinguished. And we find ion beam etching (IBE) has little effect on the arrangement of material particles. This microscopic phenomenon makes IBE a promising technique for the detection of nanoscale near-surface damage precursors. To further investigate the nanoscale near-surface damage after chemical mechanical polishing, a trench is generated by ion sputtering to contain the nature and characteristics of nanoscale precursors in different depths. The evolutions of chemical structure defects and nanoparticles are measured and their laser-induced absorption performance are tested. The results show that there is a nanoscale defect layer (~360nm) beneath the Beilby layer. A model for nanoscale defect layer of fused silica after CMP is offered. In the model, the quantitative density of nanoparticles falls exponentially with increasing the depth and the contents of ODC and NBOHC decreases linearly, respectively. Research results can be a reference on characterizing nanoscale defects near surface and conducting post-processing technologies to improve the laser damage resistance property of fused silica.
制造过程中产生的近表面纳米级损伤前驱体对熔融石英激光诱导损伤阈值的提高有很大影响。在这项工作中，使用高分辨率透射电子显微镜（HRTEM）来表征近表面材料颗粒的排列。可以清楚地分辨出拜耳层中的纳米级缺陷。并且我们发现离子束蚀刻（IBE）对材料颗粒的排列影响很小。这种微观现象使IBE成为检测纳米级近表面损伤前驱体的一种有前途的技术。为了进一步研究化学机械抛光后的纳米级近表面损伤，通过离子溅射产生一个沟槽，以包含不同深度处纳米级前驱体的性质和特征。测量化学结构缺陷和纳米颗粒的演变，并测试它们的激光诱导吸收性能。结果表明，在拜耳层下方存在一个纳米级缺陷层（约360nm）。给出了化学机械抛光后熔融石英纳米级缺陷层的模型。在该模型中，纳米颗粒的定量密度随深度增加呈指数下降，而ODC和NBOHC的含量分别呈线性下降。研究结果可为表征近表面纳米级缺陷和进行后处理技术以提高熔融石英的抗激光损伤性能提供参考。
