Zinc doping of Ga-rich GaN powders obtained by nitridation of the Ga-Zn liquid metallic solution

Zn-doped GaN powders were obtained by supersaturation of the Ga-Zn liquid metallic solution at 440 °C, followed by a nitridation process in ammonia flow at 1000 °C for two hours. Photoluminescence spectrum measured at room temperature for Zn-doped GaN powders, showed an emission band with a maximum energy of 2.89 eV (429 nm), which might be related to the excitons binding to the Zn acceptors. The Raman spectra agree with the incorporation of Zn as dopant into GaN powders, demonstrating a shoulder at 651.89 cm⁻¹ and a slight shift (1.55 cm⁻¹) to low frequency of the vibration mode A₁(TO) with respect to undoped GaN powders. The Raman spectra showed a separation between the E₁(TO) and E₂(High) modes, confirming that Ga-rich GaN was obtained. X-ray diffraction patterns did not show any shift of the peaks of the Zn-doped GaN with respect to the undoped GaN powders. Scanning electron microscopy micrographs demonstrated that the surface morphology of the Zn-doped GaN powders was composed of platelets of irregular structure with an average length of 2.80 μm. Finally, x-ray photo-electron spectroscopy spectra did not show an important elemental contribution of zinc due to the small amount of the dopant element (1.05 mol%).