ABSTRACT

Silicon (Si) wafers, critical substrates for semiconductor and photovoltaic (PV) device fabrication, require surface cleaning and damage removal to ensure high- quality performance. Th is 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 fl uorine (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/hydrofl uoric acid (HNO₃/HF) etching, the contamination levels on mc-Si wafers reduce signifi cantly, with Si content increasing to 90.8%. In comparison, C decreases to 7.5%, and O drops to 1.7%. Th e wet-chemical etching removes ~5 μm–12 μm of wafer thickness, eff ectively eliminating surface defects and contaminants. Th e cleaning process reduces particulate contamination by over 90%, and a smooth, defect-free surface is observed in SEM images post-cleaning. Th ese results demonstrate that adequate cleaning and damage removal are essential for improving solar cell effi ciency by enhancing carrier lifetime, reducing surface recombination, and minimising leakage currents. 

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