Effects of Co-Doped B and Al on the Improvement of Electrical Properties of Ga and P Contaminated Upgraded Metallurgical-Grade Silicon Materials

摘要

High-performance p-type silicon target materials of Co-doped B and Al elements were produced using Ga and P contaminated upgraded metallurgical-grade silicon (UMG-Si) at the industrial scale. The purity of silicon ingots is above 5.5 N after the directional solidification process, which meets market demand. The segregation behavior of elements and compensation effect on the resistivity are discussed. The effective segregation coefficients of B, Al, Ga, and P for ingot No. 1 were approximately 0.66, 0.14, 0.38, and 0.49, respectively. The segregation coefficients of P, Ga, and Al become larger, the segregation effect tends to become smaller, which is attributed to the doped and contaminated elements that have the recombination effect on the holes and electrons. The distribution of resistivity can be regulated precisely by the compensation difference [N-A-N-D] along the solidified fraction. The mean resistivity of the ingots is approximately 0.013 omega cm. Prolonging melting time is conducive to the uniform distribution of doping elements.