SiN_x layers on nanostructured Si solar cells: Effective for optical absorption and carrier collection

We compared nanopatterned Si solar cells with and without SiN_x layers. The SiN_x layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiN_x layer played a crucial role in the improved carrier collection of the nanostructured solar cells.