Investigating boron and phosphorus removal from silicon by Si-Ti and Si-Ti-Fe alloying systems

B and P content of purified Si through alloying refining by Ti was investigated. 65-75% P removal and 39-80% B removal were obtained by the addition of 5-20 wt% Ti to silicon. The reduction of impurities was recognized to be attributable to the formation of Ti5P3.16 and TiB2. The iron addition (up to 20 wt%) to the Si-Ti system increased B removal from 63 to 83% and 74 to 92% in the presence of 10 wt% and 15 wt% Ti, respectively. Nevertheless, iron addition did not make any noticeable improvement in P removal. Phosphorus removal in the Fe containing samples may be ascribed by the formation of the TiFeP phase. Overall, the best impurity removal was obtained for the sample containing 15 wt% Ti + 20 wt%Fe that showed 75% P and 92% B reduction in the purified Si. The directional solidification of a sample containing 20 wt% Ti slightly improved the removal rates compared to its corresponding furnace cooled sample. Also, it resulted in the enhancement of (220) plane of silicon in the solidified alloy. At last, boron removal as a result of TiB2 formation was studied from the thermodynamic point of view.