Physico-chemical features of the acid ammonothermal growth of GaN

Growth of GaN crystals by the ammonothermal route is both challenging and promising. We discuss the impact of the chemical environment on the nucleation of GaN through the acidic ammonothermal route at temperatures ⩽550 °C. The solubility of GaN in supercritical ammonia containing the acidic mineralizer ammonium chloride (NH4Cl) is investigated. Low-temperature photoluminescence shows that improved supersaturation yields ammonothermal GaN with high-optical quality comparable to hydride vapor-phase epitaxy (HVPE)-grown GaN.