物理学报2017，Vol.66Issue(6)：331-339,9.DOI:10.7498/aps.66.067902
飞秒激光脉冲能量累积优化对黑硅表面形貌的影响
Femtosecond laser pulse energy accumulation optimization effect on surface morphology of black silicon
摘要
Abstract
Arrays of sharp conical spike microstructures are created by repeatedly irradiating silicon surfaces with focused femtosecond laser pulses in SF6. The absorbance of light is increased to approximately 90%in a wavelength range from the near ultraviolet (0.25 μm) to the near infrared (2.5 μm) by the microstructured silicon surface. The microstructured surface presents pitch-black because of enhanced absorption with a broad wavelength range, which is called black silicon. The unique microstructure morphology of black silicon surface formed by femtosecond laser can also bring a lot of other surface functions, for example, self-cleaning and field emission. These functions make black silicon highly desirable in solar energy, detectors and other fields. Therefore, the forming mechanism and conditions of fabrication optimization for black silicon microstructure have always been the focus of research. In our work, the sample is moved by motor-controlled stage while the laser beam is fixed. In the case of laser beam scanning, arrays of sharp conical spikes on the silicon are manufactured in 70 kPa SF6. The aim of the experiment is to find how to optimize the distribution of the laser energy in a number of laser accumulation pulses (the combination of single pulse energy and pulse number) to control the surface morphology of the black silicon. Experimental results show that there appears a bottleneck effect of morphology size growth with the increase of laser irradiation (improving the single pulse energy or increasing pulse accumulation number). Excessive energy accumulation brings no extra effect on optimizing and controlling of microstructure morphology on the surface. Based on theoretical results obtained from a physical model we proposed, we find that the reason for this phenomenon is that the microstructure morphology induced by former sequence pulse modulates the laser energy absorption of current laser pulse, and changes the laser ablation efficiency of the current pulse. According to this physical mechanism, we propose a new way of optimizing surface morphology, with fixing the total laser irradiation energy. And the size and distribution of surface morphology can be achieved by optimizing the distribution of the laser energy in a number of laser accumulation pulses. This approach can not only improve the efficiency of silicon surface preparation of microstructures but also reduce the surface defects and damage. Furthermore, the proposed method can reduce the energy consumption in the process of femtosecond machining. It is of great significance for the engineering application of black silicon.关键词
飞秒激光/微结构/黑硅/表面形貌Key words
femtosecond laser/microstructures/black silicon/surface topography引用本文复制引用
陶海岩,陈锐,宋晓伟,陈亚楠,林景全..飞秒激光脉冲能量累积优化对黑硅表面形貌的影响[J].物理学报,2017,66(6):331-339,9.基金项目
国家自然科学基金(批准号:61605017)、长春市科技计划(批准号:14KP007)、长春理工大学青年科学基金(批准号:XQNJJ-2015-01)和光电信息控制和安全技术重点实验室基金资助的课题. Project supported by the National Natural Science Foundation of China (Grant No. 61605017), the Science and Technology Planning Project of Changchun, China (Grant No. 14KP007), the Young Scientists Fund of Changchun University of Science and Technology, China (Grant No. XQNJJ-2015-01), and the Foundation of the Science and Technology on Electro-Optical Information Security Control Laboratory, China. （批准号:61605017）
