摘要
Black-coloured GaN nanoparticles with an average grain size of 50 nm have been obtained by annealing GaN nanoparticles under flowing nitrogen at 1200 ℃ for 30 min. XRD measurement result indicates an increase in the lattice parameter of the GaN nanoparticles annealed at 1200 ℃, and HRTEM image shows that the increase cannot be ascribed to other ions in the interstitial positions. If the as-synthesised GaN nanoparticles at 950 ℃ are regarded as standard, the thermal expansion changes nonlinearly with temperature and is anisotropic; the expansion below 1000 ℃ is smaller than that above 1000 ℃. This study provides an experimental demonstration for selecting the proper annealing temperature of GaN. In addition, a large blueshift in optical bandgap of the annealed GaN nanoparticles at 1200 ℃ is observed, which can be ascribed to the dominant transitions from the C（FT） with the peak energy at 3.532 eV.
Black-coloured GaN nanoparticles with an average grain size of 50 nm have been obtained by annealing GaN nanoparticles under flowing nitrogen at 1200 ℃ for 30 min. XRD measurement result indicates an increase in the lattice parameter of the GaN nanoparticles annealed at 1200 ℃, and HRTEM image shows that the increase cannot be ascribed to other ions in the interstitial positions. If the as-synthesised GaN nanoparticles at 950 ℃ are regarded as standard, the thermal expansion changes nonlinearly with temperature and is anisotropic; the expansion below 1000 ℃ is smaller than that above 1000 ℃. This study provides an experimental demonstration for selecting the proper annealing temperature of GaN. In addition, a large blueshift in optical bandgap of the annealed GaN nanoparticles at 1200 ℃ is observed, which can be ascribed to the dominant transitions from the C（FT） with the peak energy at 3.532 eV.
基金
Project supported by the Excellent Young Scientist Awarding Fund of Shandong Province,China(Grant No.2008BS04005)
the China Postdoctoral Science Foundation(Grant No.20080441141)
the Postdoctoral Innovation Program Special Fund of Shandong Province,China(Grant No.200803054)
