Microstructural observation of beta-gallium oxide nanostructures after ammonolysis

The reaction mechanism of beta-gallium oxide (beta-Ga2O3) to gallium nitride (GaN) under flowing ammonia was examined by observing the change in morphology according to the conversion of nanostructured beta-Ga2O3 to GaN by ammonolysis. The morphology of the beta-Ga2O3 nanostructures after ammonolysis was dependent on the experimental conditions (i.e. oxygen-rich and -deficient gas flow) for their growth. The surface of the beta-Ga2O3 nanostructures grown in the oxygen-rich gas flow was striated after ammonolysis. On the other hand, the morphology of the beta-Ga2O3 nanostructures grown in the oxygen-deficient gas flow was changed remarkably and diversely with maintaining their contour. These microstructural observations can be explained by the reaction mechanism, in which the ammonolysis of beta-Ga2O3 to GaN consists of two successive reactions, the reduction of beta-Ga2O3 to gaseous Ga2O and the nitridation of Ga2O(g) to GaN. The relative rates of the two reactions affect the morphology of the nitridated beta-Ga2O3 nanostructures. (C) 2015 The Ceramic Society of Japan. All rights reserved.