Activity of Ga2O3 in B2O3 flux and standard free energies of formation of GaBO3 and InBO3

The equilibrium between liquid III group metal and B2O3 flux was investigated thermodynamically as a fundamental study on impurity control in single crystal growth of III-V group compound semiconductors. The oxygen distribution ratio between gallium melt and B2O3 flux and the activity of Ga2O3 in B2O3 Bur were clarified at 1373 and 1273 K by measuring oxygen contents in gallium melt and Ga(2)O(3)contents in B2O3 flux. The standard free energies of formation of GaBO3 and InBO3 were determined by measuring oxygen content of liquid Ill group metal (gallium or indium) equilibrated with B2O3 flux and GaBO3 or InBO3: Delta G degrees(GaBO3) = -1.14 x 10(6) + 251T (J) (T : 1123 similar to 1173 K) Delta G degrees(InBO3) = -1.02 x 10(6) + 220T (J) (T : 1223 similar to 1373 K).