Epitaxial growth of Au-assisted InAs nanowires using metal organic vapour phase epitaxy is investigated. The growth rate and morphology of nanowires as a function of growth temperature, substrate material and precursor flows are discussed. It is observed that tapering increases with both In and As precursor flows, but decreases with temperature. Finally, we report growth of InAs nanowires on both InAs and InP substrates, with those grown on InAs substrates exhibiting more tapered shape. (c) 2006 Elsevier B.V. All rights reserved.