Distribution of impurity elements between flux and melt during the growth of III-V compound semiconductor single crystals.

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1. Phase diagrams of III group oxide-B_2O_3 binary systems.No phase diagrams has been reported in Ga_2O_3-B_2O_3 and In_2O_3-B_2O_3 systems, and one phase diagram in Al_2O_3-B_2O_3 system. In the present work, solubility of III group oxide (Ga_2O_3, In_2O_3, Al_2O_3) in B_2O_3 melt and the solid phase equilibrated with the melt were determined. The phase diagrams of Ga_2O_3-B_2O_3, In_2 O_3-B_2O_3, and Al_2O_3-B_2O_3 binary systems were constructed with high accuracy using these data.2. Oxygen solubility in liquid gallium and liquid indium.The oxygen solubility in liquid gallium or liquid indium equilibrated with solid Ga_2O_3 or In_2O_3, respectively was determined as follows :log (O/mass% in liquid gallium) =-6200/T+2.61 (T : 1123-1523 K)log (O/mass% in liquid indium) =-6600/T+3.77 (T : 1073-1373 K)Using the temperature dependence of the oxygen solubility, the standard free energy change for oxygen dissolution in liquid gallium or liquid indium could be represented as follows :1/20O_2 (g) =O (mass% in liquid gallium) , DELTAGﾟ=-2.45x10^5+59.6T (J)1/20O_2 (g) =O (mass% in liquid indium) , DELTAGﾟ=-1.79x10^5+33.8T (J)3. Oxygen distribution between flux and meltOxygen distribution between III group metal oxide (Ga_2O_3 or In_2O_3) -B_2O_3 binary flux and liquid III group metal (Ga or In) was investigated in the view point of fundamental study for LEC method. Distribution ratio of oxygen for the Ga system at 1423 K and the In system at 1373 to 1473 K were determined. The activity of Ga_2O_3 and In_2O_3 in B_2O_3 flux were found to be small, which suggested that oxygen content in III-V compound melts might be suppressed to be lower level in the LEC process.