溶融シリコン中のボロンの活量

抄録

In order to develop economical production methods for high purity silicon used in solar cells, thermodynamic properties of boron, the most difficult element to remove, in molten silicon were measured by equilibrating Si-B melts with solid BN and/or solid Si3N4 at 1,723 K and 1,773 K. Based on the results, (a) the free energy change for the nitrogen dissolution into molten silicon, (b) the activity coefficient of boron at infinite dilution referred to pure solid, and (c) the interaction parameters related to boron in molten silicon were determined to be: (a) 1/2 N2(g) = (mass %, H, in Si melt): Δ (b) (at 1,723 K) (at 1,773 K) (c) (at 1,723 K) (at 1,773 K) (at 1,723 K) (at 1,773 K), respectively, for 1,723 ∼ 1,773 K. Finally, the stability diagram of the Si-B-N system was established.