This work presents the selective growth of three-dimensional metallic gallium nitride structures on silicon substrates by chemical beam epitaxy (CBE) with a subsequent plasma nitridation process. The use of titanium pre-deposited stripes over silicon (100) is shown to provide high selectivity where spherical and semi-spherical structures are obtained only over the metal. These structures have diameters ranging from 100 nm to 3 mu m depending on the growth conditions. The nitridation process was performed on an electron cyclotron resonance (ECR) plasma system. Raman micro-spectroscopy results showed GaN formation with zinc blend crystal structure and photoluminescence emission in the visible spectrum in a range between 350 and 650 nm. (C) 2007 Elsevier B.V. All rights reserved.