Hexagonal Nanocrystal Growth of Mg or Zn from Incorporation in GaN Powders Obtained through Pyrolysis of a Viscous Complex Compound and Its Nitridation

Hexagonal nanocrystals were obtained from Zn-doped GaN powders and Mg-doped GaN powders, which were synthesized via pyrolysis of a viscous complex compound, followed by its nitridation. XRD showed well-defined peaks for hexagonal GaN with an average crystal size of 21.3 nm. Scanning electron microscopy showed an amorphous and porous appearance in surface morphology, which could be related to the combustion process. Energy-dispersive spectroscopy characterization showed contributions of gallium, nitrogen, and small traces of Zn and Mg in the GaN samples. TEM showed the presence of well-defined hexagonal nanocrystals with an area of 75.9 nm(2) for the Zn-doped GaN powders and an area of 67.7 nm(2) for the Mg-doped GaN powders. The photoluminescence spectra showed an emission energy of 2.8 eV (431.5 nm) for the Zn-doped GaN powders, while the Mg-doped GaN powders showed energies in the range from 2.7 eV to 2.8 eV (460.3 nm-443.9 nm). The Raman scattering showed spectra where the vibration modes A(1)(TO), E1(TO), and E-2(High) could be observed, which are characteristic of hexagonal GaN.