Application of Si Nanowires Fabricated by Metal-Assisted Etching to Crystalline Si Solar Cells

Abstract

Reflection and transmission through a solar cell can be significantly reduced using light-trapping structures. This approach can be applied to both crystalline and thin-film solar cells to improve the light absorption and conversion efficiency of the cell. In this study, vertically aligned Si nanowires were fabricated over a large area via a metal-assisted etching technique. Following a detailed parametric study, nanowires were applied to industrial-size (156 mm × 156 mm) Si solar cells. The reflectivity from the device surface was reduced to less than 5% for the entire visible spectrum (350-750 nm), including the blue-violet region. Standard solar cell fabrication procedures were employed to fabricate cells with and without Si nanowires, and the results showed that the efficiencies of solar cells with nanowires were similar to those of standard pyramid-textured cells, revealing the potential of the proposed concept. A systematic study of the dependence of the solar cell parameters on the length of the nanowires was performed. The quantum efficiency of the cells exhibited relatively poor performance in the blue-ultraviolet range of the spectrum, and enhancement in carrier generation was observed in the red-infrared region especially for shorter nanowires.