Reduction of surface reflection loss is crucial for high efficiency next generation Si solar cells. Surface texturing provides a viable method to reduce loss over the full solar bandwidth. Previous studies have concentrated on simple moth-eye silicon pillar arrays protruding from the surface. Using FDTD simulation methods, we undertake a systematic investigation into performance benefits provided by complex semi-random photonic quasi-crystal surface patterning methodologies whereby arrays of air holes are etched deep into the solar cell surface. In contrast to other studies we carefully investigate the effect of lattice symmetry, systematically comparing performance of simple 6-fold symmetric triangular photonic crystal patterning to 12 fold symmetry photonic quasicrystal patterning and infinitely symmetric 2D Fibonacci patterning. We optimize key geometric parameters such as lattice pitch, hole size and etch depth to maximize optical performance for each lattice type. 12 fold photonic quasi crystal lattice is found to provide best overall anti-reflectance performance providing a solar-corrected average reflectance of 8.3% for a hole depth of 1.5 µm and 300 nm diameter, in comparison to 36.4% for a bare silicon solar cell surface. Practical feasibility of the optimal designs is demonstrated by fabrication of physical prototypes consisting of arrays of nm scale air-holes etched into the surface of a silicon slab fabricated Using e-beam lithography and ICP/RIE etching. FDTD Simulation methodology is validated by convergence studies as well as comparison to optical measurements on these fabricated devices. Furthermore, in contrast to previous studies we provide an in depth analysis of the physical mechanisms responsible for reduction in surface reflection, determining the parameter space where conventional Gaussian optical processes such as effective refractive index, refraction and Fresnel reflection dominate, vs parameter space where sub wavelength photonic crystal scattering effects play the main role. We finish up with an analysis of electrical performance for the optimal designs to further validate real world performance. Taking electrical performance into account we determine that infinite-symmetry 2D Fibonacci patterning far outperforms lower symmetry 12 fold and triangular arrangement. We believe that this is the first in depth investigation into 2D Fibonacci patterning in silicon solar cells.

表面反射损耗的减少对于高效下一代Si太阳能电池至关重要。表面纹理化提供了一种可行的方法来减少整个太阳能带宽上的损耗。先前的研究集中在从表面突出的简单蛾眼硅柱阵列上。使用FDTD模拟方法，我们对复杂的半随机光子准晶体表面构图方法所提供的性能益处进行了系统研究，从而将气孔阵列蚀刻到太阳能电池表面深处。与其他研究相比，我们仔细研究了晶格对称性的影响，系统地比较了简单的6倍对称三角光子晶体图案与12倍对称光子准晶体图案和无限对称2D斐波那契图案的性能。我们优化关键的几何参数，例如晶格间距，孔尺寸和蚀刻深度，以最大化每种晶格类型的光学性能。发现12倍的光子准晶格可提供最佳的整体抗反射性能，对于1.5 µm的孔深度和300 nm的直径，经太阳能校正的平均反射率为8.3％，相比之下，裸硅太阳能电池表面的平均反射率为36.4％ 。最佳设计的实际可行性由物理原型的制造证明，该物理原型包括蚀刻到使用电子束光刻和ICP / RIE蚀刻制成的硅片表面的纳米级气孔阵列。FDTD仿真方法已通过收敛性研究以及与这些制造设备上的光学测量结果的比较得到了验证。此外，与以前的研究相比，我们提供了减少表面反射的物理机制的深入分析，确定了传统高斯光学过程（例如有效折射率，折射和菲涅耳反射）占主导地位的参数空间与亚波长光子的参数空间晶体散射效应起主要作用。最后，我们对电气性能进行了分析，以优化设计，以进一步验证实际性能。考虑到电气性能，我们确定无限对称2D斐波那契图案远胜于较低的对称12倍和三角形排列。我们相信，这是对硅太阳能电池中2D斐波那契图案的首次深入研究。