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Khalifa M.,Photovoltaic Laboratory Research and Technology Center on Energy | Atyaoui M.,Photovoltaic Laboratory Research and Technology Center on Energy | Hajji M.,University of Sfax | Ouertani R.,Photovoltaic Laboratory Research and Technology Center on Energy | Ezzaouia H.,Photovoltaic Laboratory Research and Technology Center on Energy
Materials Science in Semiconductor Processing | Year: 2013

We investigated a novel process for purifying metallurgical-grade silicon (MG-Si). MG-Si powder was first treated to form a thin porous silicon layer. This was heated at 900 C under oxygen to weaken impurity-Si bonds. Samples were then chemically etched with dilute aqueous hydrofluoric acid. To understand the mechanisms in this purification process, structural, chemical composition and optical properties of MG-Si powder before and after treatment were characterized using Fourier-transform infrared (FTIR), inductively coupled plasma-atomic emission (ICP-AES), and photoluminescence (PL) spectroscopy techniques. FTIR studies of treated MG-Si powder revealed the formation of a thin porous silicon layer on the top surface, as evidenced by SiHx vibration peaks. PL spectra show that 30-min HF etching of MG-Si led to an increase in red emission, indicating the formation of porous silicon and suggesting a decrease in impurities. ICP-AES revealed that the process led to significant decreases in the concentrations of 15 different elemental impurities. © 2013 Elsevier Ltd. Source

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