We report the self-catalysed growth of InAs1-xSbx nanowires directly on bare Si substrates. Vertically aligned and non-tapered InAs1-xSbx nanowires were realized via indium-assisted nucleation without using nanowire stems. The compositions of the InAs1-xSbx nanowires were determined by high resolution X-ray diffraction (HRXRD). It is observed that the geometry of the nanowires is modified by the Sb flux resulting in an almost doubling of the lateral dimension and a corresponding suppression in the axial growth of the InAs1-xSbx nanowires. This observation unravels a method to modify the geometry of InAs nanowire and open up a promising route for the direct integration of InAs1-xSbx nanowires with the well-established Si platform. (C) 2014 Elsevier Ltd. All rights reserved.