Growth of n-type multicrystalline silicon ingots from recycled CZ silicon feedstock

5 Ω·cm recycled n-type CZ silicon feedstock is used to grow n-type multicrystalline silicon to investigate the possibilities of using other feedstock resources available from the rejected silicon of the semiconductor industry. High diffusion lengths were realized near the bottom region due to the less impurity contamination and relatively high resistivity. The heavy accumulation of metal impurities and lower resistivity at the top of the ingot resulted in a poor diffusion length. The edges have lower diffusion lengths due to the different metallic contaminations diffused from the silicon nitride coating layer during the growth cycle. The response of the wafers to p-gettering was ascertained and carrier lifetimes improved further especially at the bottom of the ingot. The improvement was realized for a total of 80% of the ingot height with higher lifetimes exceeding values above 250 μs at Δn = 10¹⁵ cm⁻³ and 400 ·s at Δn = 10¹⁴ cm⁻³.