Thermogravimetric analysis (TGA) and microstructural observations were carried to investigate the nitridation mechanism of β-Ga 2 O 3 powder to GaN under an NH 3 /Ar atmosphere. Non-isothermal TGA showed that nitridation of β-Ga 2 O 3 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-Ga 2 O 3 crystal surface, and they increase with time. We proposed a mechanism for the nitridation of Ga 2 O 3 by NH 3 whereby nitridation of β-Ga 2 O 3 proceeds via the intermediate vapor species Ga 2 O ( g).

Nitridation of β-Ga 2 O 3 to GaN in an atmosphere of NH 3 /Ar was investigated from the view points of kinetic results by thermogravimetric analysis (TGA) and microstructural observation. TGA and X-ray powder diffraction results showed that the nitridation of Ga 2 O 3 to GaN starts at about 650°C and decomposition of GaN formed occurs from 870°C. Isothermal TGA results showed that the nitridation proceeds linearly with time at 800 -1000°C. Microstructural observation of the samples nitrided at 800°C showed that fine GaN particles (~50 nm size) deposit on surfaces of Ga 2 O 3 particles at an early stage, and the deposits grow with progress of the nitridation.