Crystalline and luminescence changes due to nitridation of undoped GaN powders obtained by pyrolysis from an organometallic complex

Abstract Unannealed GaN material was synthesized by pyrolysis from an organometallic complex, where after a nitridation process at 1000 °C in ammonia flow during 2 h, undoped GaN powders were obtained. X-ray diffraction pattern and Raman spectrum for unannealed GaN material did not show well-defined peaks. After the nitridation process, x-ray diffraction pattern and Raman spectrum, demonstrated defined peaks with reflection planes and vibration modes, characteristics of hexagonal GaN. Scanning electron microscopy showed an amorphous superficial morphology for both materials. On the other hand, energy dispersive spectroscopy showed a higher elemental contribution of oxygen for unannealed GaN material, with respect to undoped GaN powders. Photoluminescence spectrum for unannealed GaN material only showed an energy emission band at 1.8 eV (688 nm), while photoluminescence spectrum for undoped GaN powders demonstrated an emission with a maximum energy of 3.44 eV (360 nm), which was associated to the band-to-band transition for the hexagonal GaN.