Surface Quality Optimisation of Monocrystalline and Polycrystalline Silicon Wafers through Cleaning, Etching and Texturisation Processes for Si Solar Cell Applications

Silicon (Si) wafers, critical substrates for semiconductor and photovoltaic (PV) device fabrication, require surface cleaning and damage removal to ensure high-quality performance. This study investigates the surface morphology and contamination levels of monocrystalline silicon (c-Si) and multicrystalline silicon (mc-Si) wafers before and after cleaning. Scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX) analysis revealed that, before cleaning, both wafer types exhibit micro-roughness and contain contaminants such as iron (Fe), oxygen (O), nitrogen (N), carbon (C) and fluorine (F). For the as-cut c-Si wafer, EDX data reveals a Si content of 85.08%, with contamination levels of C (9.38%), O (2.41%), N (1.45%) and F (0.68%). In mc-Si wafers, slicing introduces surface roughness and leaves residues, with the surface characterised by particulates and metallic contaminants. Following the damage removal process using nitric acid/hydrofluoric acid (HNO₃/HF) etching, the contamination levels on mc-Si wafers reduce significantly, with Si content increasing to 90.8%. In comparison, C decreases to 7.5%, and O drops to 1.7%. The wet-chemical etching removes ~5 µm–12 µm of wafer thickness, effectively eliminating surface defects and contaminants. The cleaning process reduces particulate contamination by over 90%, and a smooth, defect-free surface is observed in SEM images post-cleaning. These results demonstrate that adequate cleaning and damage removal are essential for improving solar cell efficiency by enhancing carrier lifetime, reducing surface recombination, and minimising leakage currents.