Formation of Nanotextured Surfaces on Microtextured Si Solar Cells by Metal-Assisted Chemical Etching Process

We investigated a nanotexturization process on the microtextured surface of monocrystalline Si solar cells which utilized a metal assisted chemical etching process. P-type Si solar cell wafers were used for nanotexturing followed by saw damage removal and a microtexturing process. As the nanotexturing time was increased, green and red-orange photoluminescence spectra at wavelengths of 506, 507, and 637 nm were observed from the nanotextured cells, indicating that the quantum size effect caused the confinement of charge carriers in nanocrystalline silicon. The nanotextured cells showed a low photoreflectance of 4.5% in the visible spectral region of 400–600 nm. However, the reduced quantum efficiency from the nanotextured samples suggests that a shallow nanopore depth and density are required to prevent surface-related phenomena of charge recombination and surface current leakage.