Thermal stability of GaN powders investigated by XRD, XPS, PL, TEM, and FT-IR

Thermal stability of gallium nitride (GaN) powders was investigated using X-ray diffraction (XRD), low-temperature photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and transmission electron microscopy (TEM). The results indicated that GaN powders annealed in nitrogen ambient for 30 min became unstable above 900 °C. Annealing at 1050 °C resulted in the degradation of the crystalline quality of the GaN powders. Ga metal was formed on the surface of GaN particles, but annealing at 1200 °C leaded to the improvement of the GaN crystalline quality that was indicated by strong diffraction peaks of the GaN powders and strong PL peak (352 nm) not being attributed to the structure defects and quantum confinement effects, respectively.