Gallium nitride nanowires (GaN NWs) are traditionally fabricated using foreign metal catalysts. with an accompanying risk of increased contamination of the grown material and associated electrical and optical device degradation. Catalyst-free growth suffers from the inability to direct NW growth into predefined device architectures. In the present work, GaN NWs were fabricated by atmospheric CVD with a Ga-based catalyst, thus avoiding the dangers of foreign metal contamination while retaining the ability to spatially control NW growth. The effect of the total gas flow rate on wire morphology was examined and explained as a consequence of increasing Ga concentration with gas flow. Transmission electron microscopy was used to compare the crystalline structure of NWs grown from Ga(NO3)(3)-derived catalysts to that of the more conventional, Ni-catalyzed wires. Electron diffraction confirmed that both NW types exhibited the wurtzite crystal structure. The single crystal Ni-catalyzed NWs showed predominantly a [0 1 1] growth direction, whereas the Ga-based catalyst resulted in wires composed of single crystal segments with predominantly [0 0 1] or [1 1 1] growth directions. (c) 2006 Elsevier B.V. All rights reserved.