We demonstrate the growth of alpha-Si3N4 nanowires with GaN branching on a (100) Si substrate via metal-organic chemical vapor deposition. Transmission electron microscopy and energy disperse spectroscopy results reveal that the well-aligned Si3N4 nanowires are grown on a (100) Si substrate, and GaN branches are epitaxially formed on the side walls of Si3N4 nanowires. The possible growth mechanism of Si3N4 nanowires was attributed to the melt-back phenomenon originating from the reaction of Ga-metal and Si substrates. (C) 2012 Elsevier B.V. All rights reserved.