Origin of Strong and Tunable Polarization-Independent Light-Trapping in Asymmetric Silicon Nanostructures

Polarization-independent light trapping is a cornerstone for advancing both solar energy harvesting and spectroscopic technologies. Using finite element method (FEM) simulations, the interplay of geometry, polarization, and leaky mode resonances (LMR) in modulating the absorption and reflection characteristics of different morphologies of silicon nanopillars (SiNPs) is investigated. Here, nanopillars with kinked morphology are introduced, a hybrid design combining features of straight and slanted SiNPs in detail, and demonstrate exceptional polarization insensitivity and superior absorption efficiency. The results reveal that kinked SiNPs outperform their counterparts by sustaining high absorption efficiency across both transverse electric (TE) and transverse magnetic (TM) polarizations, leveraging their structural discontinuities to excite hybridized guided and leaky modes. These modes enhance light trapping by increasing the optical path length and promoting stronger light-matter interactions. Parametric studies further emphasize the critical role of geometric factors in optimizing light absorption, including diameter, inclination angle, and interpillar distance. The kinked SiNPs may be utilized for exceptional performance as light-trapping substrates because of the enhanced localized electric fields in their surroundings that can enhance the signal sensitivity. This enhanced functionality underscores the potential of kinked SiNPs for a variety of uses, from spectroscopy to renewable energy technologies.