We have studied the vapour-liquid-solid (VLS) growth of free-standing GaN wires on various III-V substrates using metalorganic vapour phase epitaxy. The low-temperature deposition including in situ droplet formation was investigated applying 1,1-dimethylhydrazine and trimethylgallium. In particular, the Surface structure of BP and CaN intermediate layers on the growth of GaN wires is discussed. Furthermore, the GaN growth was examined with a special focus on the influence of triethylboron on the droplet formation and wire growth. Additionally, the Au-initiated VLS growth on c-plane Al2O3 is reported, where NH3 and triethylgallium have been used at Usual growth conditions. Depending on the growth conditions used, the wires have hexagonal (h-GaN) wurtzite or Cubic (c-GaN) zinc blende Structure. The resulting nanowire diameters range from 50 to 300 nm and they are up to 2 mu m in length. (C) 2008 Elsevier B.V. All rights reserved.