Optical Properties of Thin Crystalline Silicon Nanostructures for Photovoltaic Applications

The optical performance of four lattice crystalline silicon nanostructures, i.e., cylinder nanowire arrays, cylinder nanohole arrays, square nanowire arrays and square nanohole arrays is numerically investigated in this paper. The method of rigorous coupled-wave analysis (RCWA), an efficient and accurate computational tool, is used to calculate the optical absorption for the lattice constant from 100 nm to 1500 nm. The results indicate that the lattice constant is the foremost structure parameter to determine the ultimate efficiency, and the ultimate efficiencies are reached at the lattice constant around 600 nm. The optimal filling ratio of square nanowire arrays is the lowest among the four nonostructures, whereas the cylinder nanohole arrays exhibit a broad range of optimal filling ratios. Lower optimal filling ratios implies that the nanostructures cost less raw material while maintain the high ultimate efficiencies. The high ultimate efficiency of all structures can be achieved over a large range of incident angles, even the efficiency will slowly decrease as the incident angle increases.