GaAs nanowires (NWs) were grown by Ga-assisted chemical beam epitaxy on Si(111) substrates covered by a thin oxide layer using different substrate temperatures and growth times. Ga droplet terminated NWs with hexagonal footprint and cross section were observed by scanning electron microscopy, with diameters and lengths in the range of 40-65 nm and 0.3-1.2 mu m, respectively. Transmission electron microscopy (TEM) images show evidences of vapor-liquid-solid growth mechanisms which lead to different droplet-nanowire interface quality depending on Ga-catalyst wetting area of NW sidewalls. TEM and Raman spectroscopy demonstrates the existence of a single zincblende phase in the NW body, without any evidence of wurtzite phase domains. (C) 2013 Elsevier B.V. All rights reserved.