飞秒激光硅表面微纳结构制备及其光学特性研究

发布时间：2018-06-13 16:06

本文选题：飞秒激光 + 微结构形貌　；参考：《长春理工大学》2016年硕士论文

【摘要】：利用飞秒激光对硅材料进行微处理后,表面会形成一层微纳米复合尺寸的圆锥状柱形结构,这层结构使半导体硅材料具备优异的光学性能,对紫外到红外波段光的吸收效率高达90%,我们称这种材料为“黑硅”。这种微结构表面在光电探测领域、太阳能光伏产业和场致发射器等方面都具有广阔的应用前景。黑硅这些新颖的功能特性与它表面的微结构形貌是密不可分的,自黑硅诞生以来,对黑硅微纳结构形貌控制和优化的研究从来没有间断过。本论文主要研究激光能量的不同累积方式以及激光波长对结构尺寸的影响,从而实现黑硅表面微结构的优化与调控,提升其应用潜力。在飞秒激光制备硅表面微纳结构过程中,首先进行了激光能量的累积方式(调节激光辐照的脉冲数和调节单脉冲的激光能量)对表面形貌影响的研究。实验发现相同的累积能量条件下表面形貌并不相同,而且过多的激光脉冲数和过高的激光功率对微结构尺寸的增长没有明显效果,存在一个最佳的能量累积方式使结构尺寸达到最大的同时还能减少激光能量的消耗和加快黑硅的制备速度,同时也避免过多能量沉积对硅表面造成的缺陷和损伤。通过模拟计算证明,产生这一现象的原因是表面形貌演化过程中微结构表面对激光的吸收能力发生变化所导致。最后对优化参数后制备出的黑硅样品光吸收效率进行了测试,测试结果表明对250nm—2500nm波段光吸收率大于95%,并分析了其光吸收机理。进一步我们又进行了800nm和400nm飞秒激光制备硅表面微结构的对比研究,实验发现,在激光能量累积较少时,400nm激光在硅表面形成微结构需要的激光总能量要比800nm激光少;但是在激光辐照能量较大时,800nm激光制备出微结构的最终尺寸要比400nm激光大。这是由于激光对硅材料穿透深度的不同。
[Abstract]:After microtreating silicon material by femtosecond laser, the surface will form a conical cylindrical structure with micro and nano composite size, which makes the semiconductor silicon material have excellent optical properties. UV-to-infrared light absorption efficiency is as high as 90%, we call this material "black silicon." The microstructural surface has a wide application prospect in the field of photoelectricity detection, solar photovoltaic industry and field emitter. These novel functional properties of black silicon are closely related to the microstructure and morphology of its surface. Since the birth of black silicon, the control and optimization of the morphology of black silicon microstructures have never been interrupted. In this paper, the effects of different accumulative modes of laser energy and the influence of laser wavelength on the structure size are studied, so as to optimize and regulate the microstructure of black silicon surface and enhance its application potential. In the fabrication of silicon surface microstructures by femtosecond laser, the effect of laser energy accumulation (adjusting the number of pulses irradiated by laser and the laser energy of single pulse) on the surface morphology was studied. The experimental results show that the surface morphology is not the same under the same cumulative energy, and the excessive number of laser pulses and the excessive laser power have no obvious effect on the increase of the microstructure size. The existence of an optimal energy accumulation method can not only maximize the structure size, but also reduce laser energy consumption and speed up the preparation of black silicon, while avoiding the defects and damage caused by excessive energy deposition on the surface of silicon. The simulation results show that the reason for this phenomenon is the change of the absorption ability of the microstructure surface to the laser during the evolution of the surface morphology. Finally, the optical absorption efficiency of the black silicon samples prepared by optimizing the parameters is tested. The results show that the optical absorption rate of the 250nm-2500nm band is greater than 95, and the optical absorption mechanism of the black silicon sample is analyzed. Furthermore, we have made a comparative study on the fabrication of Si surface microstructures by 800nm and 400nm femtosecond laser. The experimental results show that the total energy required for the formation of Si surface microstructure by 400nm laser is less than that by 800nm laser. However, the final size of microstructures prepared by 800 nm laser is larger than that by 400nm laser. This is due to the different depth of laser penetration into silicon.
【学位授予单位】：长春理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN249;TN304.12

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