Ca3N2 as a flux for crystallization of GaN

In this work Ca3N2 was investigated as a potential flux for crystallization of GaN. Melting temperature of the potential flux at high N2 pressure evaluated by thermal analysis as 1380 °C is in good agreement with the theoretical prediction. It is shown that Ca3N2 present in the liquid gallium in small amount (1 at%) dramatically accelerates synthesis of GaN from its constituents. On the other hand, it does not influence significantly the rate of GaN crystallization from solution in gallium in temperature gradient for both unseeded and seeded configurations. However the habit and color of the spontaneously grown GaN crystals change drastically. For 10 mol% Ca3N2 content in the liquid Ga it was found that the GaN thick layer and GaN crystals (identified by micro-Raman scattering measurements) were grown on the substrate. For growth from molten Ca3N2 (100%) with GaN source, the most important observations were (i) GaN source material was completely dissolved in the molten Ca3N2 flux and (ii) after experiment, GaN crystals were found on the sapphire substrate.