Controlled transformation and characteristics of GaN hollow nanostructures via Carbon@Ga(OH)CO₃ by hydrothermal method

Gallium nitride (GaN) hollow nanostructures were successfully produced from carbon@Ga(OH)CO₃ core-shell nanostructrures under calcination in air atmosphere and nitridation using ammonia gas. The pure carbon and core-shell nanostructures have a uniform spherical shape with a diameter of about 150~200 nm and a shell thickness of about 20 nm. The highly crystalline β-Ga₂O₃ hollow nanostructures with diameters of approximately 200 nm were obtained. The effects of transformation from β-Ga₂O₃ to GaN hollow nanostructures as a function of nitridation temperatures and NH₃ flow rates were characterized using scanning electron microscopy. Uniform GaN hollow nanostructures were obtained under a flowing NH₃ (100 sccm) atmosphere at 800 °C for 1 hour. Two prominent IR absorption bands at 584 cm^-1 and 615 cm^-1 were attributed to the formation of GaO_xN_y and GaN intermediates. The broad symmetric four peaks at 224, 415, 571 E₂(high), and 723 A₁(LO) cm^-1 correspond to the Raman selection rules for wurtzite GaN.