The development of a purification technique of metallurgical silicon to silicon of the solar brand

Abstract

The experimental results that show the possibility of obtaining silicon of the solar brand by the recrystallization of metallurgical silicon in fusible metals, e.g., tin, and growing monocrystalline silicon ingots from the obtained silicon scales by the Czochralski method are presented. The experiments on purifying fusible metal (tin) after ending a cycle to obtain silicon scales for the purpose of its repeated use were made. Tin purification was carried out by the method of vacuum decontamination of tin melt, its filtration, and then zone recrystallization. The qualitative and quantitative analysis of the initial materials (silicon and tin) and their structure after various stages of the technological process was carried out by the method of the roentgen-fluorescent analysis on the Elvax light device. The structural features of the obtained silicon scales were considered by means of raster electronic microscopy on the REMMA106I device. The conductivity type and the specific electric resistance of the obtained silicon monocrystalline ingot were measured by the fourprobe method on the PIUS-1UM-K device. It was shown that the grown monocrystalline silicon ingot has silicon content of at least 99.999% weight, n-type conductivity, and specific electric resistance of at least 2.0 Оhm сm. The described parameters correspond to the silicon the solar brand and confirm the possibility of obtaining it from metallurgical silicon by recrystallization in fusible metals, for example, tin.