Phase relation in Ga-Al-N2 systems and nitrogen solubilities in Ga-Al melts equilibrated with aluminum nitride

The liquid phase epitaxial method has been applied using Ga-Al solutions to grow single-crystalline aluminum nitride (AlN). Understanding the solubility of nitrogen in such solutions is essential for improving the growth process; however, no solubility data have been reported. Therefore, we have developed two methods (a crucible method and a levitation method) that can be used to determine the nitrogen solubility in Ga-Al melts equilibrated with AlN. It was determined that the nitrogen solubilities in the Ga-Al melts were much lower than that in pure molten Al. Using the levitation method, the nitrogen solubility in pure molten Al was measured at 1282 and 1403 K. By combining the data obtained from both methods, the equilibrium constant and standard enthalpy of nitrogen dissolution reaction in molten Al were determined. Thermodynamic analysis of the nitrogen dissolution in Ga-Al melts was also performed to determine the activity coefficients of nitrogen in the melts.