Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Cathodoluminescence (CL) spectrum imaging and grazing incidence X-ray diffraction (GIXRD) are employed to investigate nitride three-dimensional (3D) gallium structures. The metallic precursors are naturally obtained on a large variety of substrates by metal-organic chemical vapor deposition (CVD) with different shape/size controlled by the growth conditions, especially the temperature. These 3D metallic structures are subsequently exposed to a nitridation process in a conventional CVD reactor to form GaN nanocrystals, as confirmed by GIXRD measurements. CL spectroscopy shows visible light emission (2.5-2.8 eV) excited from the GaN in the 3D structures. (C) 2008 Elsevier B.V. All rights reserved.1293176180ANR-Filemon 3-5 FranceConseil Regional de Bourgogne-FranceConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Department of Energy [DE-AC36-99GO10337]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Department of Energy [DE-AC36-99GO10337]