硅片绒面形貌影响光线反射的数值研究

Numerical Study on Effect of Silicon Texture Structure on Reflectance of Light

太阳能硅片表面绒面的光陷阱可以使光在其中经历多次反射,从而尽量减少光的反射损耗。不同光陷阱的形貌决定了光的不同多次反射路径而具有不同的反射效果。为了研究光陷阱形貌及光线入射角对减反射效果的影响,提出了数值仿真计算的方法跟踪每一条光线的反射过程计算加权出射系数,从而可以计算分析复杂形貌绒面的减反射效果并给出合理的优化方法,为制备高性能绒面结构提供理论依据。当光陷阱尺寸小于入射光线波长时,发生镜反射,将该尺寸的结构平滑处理。然后从光陷阱的深径比、高度、密度等方面计算分析光在不同入射角的情形下的加权出射系数。提出了理想的绒面光陷阱形貌,及获得最佳反射效果的入射角度。最后计算碱腐蚀及电火花加工产生的两种典型绒面的加权出射系数,并利用实验测量值验证了该计算方法。

The light trap on texture of silicon wafer surface makes the light reflect many times when it enters, and declines energy loss of light, and different structure of light trap produces different transmission path which makes a different effect of light reflectance. To study how structure of light trap and incident angle affect reflectance of light, a numerical method was proposed. Every light transmission process was tracked and then the weighted coefficient of reflectance of all lights was calculated. Subsequently the anti-reflection of complex texture with different incident angle was obtained, and a reasonable advice for change of process parameter was given, providing a theoretical basis for fabricating efficient texture. If the size of light traps is less than the wavelength of incident light, the reflection is specular, and the light trap is seen as smooth. Weighted coefficient of reflectance was got by calculating and analyzing different incident angle on light trap with aspect ratio, depth, and density of light trap, then ideal structure on fabric surface was proposed, and the incident angle with the best reflection effect was got. At the end, weighted coefficients of reflectance of two classic textures by alkaline corrosion and electrical discharge machining were calculated, and the validity of this method was proved by experimental measurement.