Plissard, SebastienDick, Kimberley A.Larrieu, GuilhemGodey, SylvieAddad, AhmedWallart, XavierCaroff, Philippe2015-12-130957-4484http://hdl.handle.net/1885/79523We report growth by molecular beam epitaxy and structural characterization of gallium-nucleated GaAs nanowires on silicon. The influences of growth temperature and V/III ratio are investigated and compared in the case of oxide-covered and oxide-free substrates. We demonstrate a precise positioning process for Ga-nucleated GaAs nanowires using a hole array in a dielectric layer thermally grown on silicon. Crystal quality is analyzed by high resolution transmission electron microscopy. Crystal structure evolves from pure zinc blende to pure wurtzite along a single nanowire, with a transition region.Keywords: Crystal qualities; Dielectric layer; Gaas nanowires; Hole arrays; Polytypism; Precise positioning; Pure zinc; Single nanowires; Structural characterization; Transition regions; V/III ratio; Wurtzites; Crystal structure; Epitaxial growth; Gallium alloys; G201010.1088/0957-4484/21/38/3856022016-02-24