Thermogravimetric analysis (TGA) and microstructural observations were carried to investigate the nitridation mechanism of β-Ga2O 3 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 8001000 °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).
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