Temperature dependent control of the solubility of gallium nitride in supercritical ammonia using mixed mineralizer.

Using a mass-loss method, we investigated the solubility change of gallium nitride (GaN) in supercritical ammonia with mixed mineralizers [ammonium chloride (NH4 Cl) + ammonium bromide (NH4 Br) and NH4 Cl + ammonium iodide (NH4 I)]. The solubilities were measured over the temperature range 450-550 °C, at 100 MPa. The solubility increased with NH4 Cl mole fraction at 450 °C and 100 MPa. The temperature dependence of the solubility curve was then measured at an equal mole ratio of the two mineralizers. The slope of the solubility-temperature relationship in the mixed mineralizer was between those of the individual mineralizers. These results show that the temperature dependence of the solubility of GaN can be controlled by the mineralizer mixture ratio. The results of the van't Hoff plot suggest that the solubility species were unchanged over the investigated temperature range. Our approach might pave the way to realizing large, high-quality GaN crystals for future gallium-nitride electronic devices, which are increasingly on demand in the information-based age.