Bulk Si production from Si–Fe melts by directional-solidification, part II: Element distribution

Abstract

Abstract Bulk Si was grown from Si–Fe alloy using the directional-solidification technique. Some metal and oxide impurity particles, such as Fe–Si–Al and Si–Al–Ca–O, formed in the Si–Fe melts. These particles were captured by the bubbles in the melt and finally aggregated in the bubbles or/and floated as a slag layer. Some impurities with a low segregation coefficient segregated in the solid Si/liquid Si–Fe interface and were finally enriched in the alloy phase. According to the distribution characteristics of impurity and impurity particles, a potential production technology for bulk Si based on purifying alloy melts and growing bulk Si is proposed. This technology mainly consists of two steps: a pre-purification treatment of Si–Fe alloy and a directional-solidification treatment of bulk Si.