Xu Liye, Geng Jiao, Shi Liping, Cui Weicheng, Qiu Min
College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310058, China.
Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, 310024, China.
Front Optoelectron. 2023 Jun 20;16(1):16. doi: 10.1007/s12200-023-00071-6.
We report self-organized periodic nanostructures on amorphous silicon thin films by femtosecond laser-induced oxidation. The dependence of structural periodicity on the thickness of silicon films and the substrate materials is investigated. The results reveal that when silicon film is 200 nm, the period of self-organized nanostructures is close to the laser wavelength and is insensitive to the substrates. In contrast, when the silicon film is 50 nm, the period of nanostructures is much shorter than the laser wavelength, and is dependent on the substrates. Furthermore, we demonstrate that, for the thick silicon films, quasi-cylindrical waves dominate the formation of periodic nanostructures, while for the thin silicon films, the formation originates from slab waveguide modes. Finite-difference time-domain method-based numerical simulations support the experimental discoveries.
我们报道了通过飞秒激光诱导氧化在非晶硅薄膜上形成的自组织周期性纳米结构。研究了结构周期性对硅膜厚度和衬底材料的依赖性。结果表明，当硅膜厚度为200nm时，自组织纳米结构的周期接近激光波长，且对衬底不敏感。相比之下，当硅膜厚度为50nm时，纳米结构的周期远短于激光波长，且依赖于衬底。此外，我们证明，对于厚硅膜，准圆柱波主导周期性纳米结构的形成，而对于薄硅膜，其形成源于平板波导模式。基于时域有限差分法的数值模拟支持了实验发现。
