Synthesis of GaN cauliflowers by ammoniating Ga2O3

The properties of GaN semiconductors are strongly dependent on the shapes, sizes, and dimensionalities. So it would be interesting to synthesize GaN with various morphologies for different applications. In this article, Ga2O3 cauliflowers were obtained by a solvothermal process at 180 °C for 36 h, which was further converted into wurtzite GaN cauliflowers by calcinations in the flow of NH3 gas at 800 °C for 100 min. The synthesized Ga2O3 and GaN microspheres were characterized using FESEM, TEM, TGA, Raman and PL. The FESEM and TEM observations suggest that the GaN product retained essentially the same basic topological morphology in contrast to that of the Ga2O3 precursor. The initial Ga2O3 structural motifs were unaffected by the subsequent high temperature chemical transformations process. The TGA tests indicate that the as-prepared GaN has excellent thermal stability and anti-oxidation property that will make it particularly useful for high temperature applications. The Raman and PL results indicate that GaN cauliflowers prepared in our experiment have excellent optical properties.

► GaN cauliflowers were obtained from Ga2O3 cauliflowers by calcinations in the flow of NH3 gas at 800 °C.
► The initial Ga2O3 structural motifs were unaffected in the transformations process.
► Reaction temperature has a dramatic effect on the formation of GaN.
► The as-prepared GaN has excellent thermal stability and anti-oxidation property.
► The GaN cauliflowers prepared in our experiment have good optical properties.