Thermogravimetric analysis and microstructural observations on the formation of GaN from the reaction between Ga2O3 and NH3

Thermogravimetric analysis (TGA) and microstructural observations were carried to investigate the nitridation mechanism of β-Ga2O3 powder to GaN under an NH3/Ar atmosphere. Non-isothermal TGA showed that nitridation of β-Ga2O3 starts at ∼650 °C, followed by decomposition of GaN at ∼1100 °C. Isothermal TGA showed that nitridation follows linear kinetics in the temperature range 800–1000 °C. At an early stage of nitridation, small GaN particles (∼5 nm) are deposited on the β-Ga2O3 crystal surface and they increase with time. We proposed a mechanism for the nitridation of Ga2O3 by NH3 whereby nitridation of β-Ga2O3 proceeds via the intermediate vapor species Ga2O(g).