VAPOUR-SOLID PHASE-EQUILIBRIUM OF BI2(SE1-XSX)3 TERNARY CRYSTALS

With the objective of analyzing the relations between the concentration of free carriers in Bi//2(Se//1// minus //xS//x)//3 ternary crystals and the vapour pressures of selenium and/or sulfur, a model describing the equilibrium between the vapour and the solid phase of a ternary crystal has been worked out by adopting the simplification that the ternary system can be taken for an ideal solid solution where the activity of Bi//2S//3 is equal to its concentration. The proposed model explains well the experimentally observed variation of the concentration of free carriers in Bi//2(Se//1// minus //xS//x)//3 crystals with increasing value of x(x equals 0. 00-0. 16) under identical growth conditions.