title: Single-Crystalline Hexagonal Silicon-Germanium.
abstract: Group IV materials with the hexagonal diamond crystal structure have been predicted to exhibit promising optical and electronic properties. In particular, hexagonal silicon-germanium (Si1-xGex) should be characterized by a tunable direct band gap with implications ranging from Si-based light-emitting diodes to lasers and quantum dots for single photon emitters. Here we demonstrate the feasibility of high-quality defect-free and wafer-scale hexagonal Si1-xGexgrowth with precise control of the alloy composition and layer thickness. This is achieved by transferring the hexagonal phase from a GaP/Si core/shell nanowire template, the same method successfully employed by us to realize hexagonal Si. We determine the optimal growth conditions in order to achieve single-crystalline layer-by-layer Si1-xGexgrowth in the preferred stoichiometry region. Our results pave the way for exploiting the novel properties of hexagonal Si1-xGexalloys in technological applications.
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.
authors.forename: Håkon Ikaros T
authors.initials: HI
authors.lastname: Hauge
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands.
authors.forename: Sonia
authors.initials: S
authors.lastname: Conesa-Boj
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.|Philips Innovation Laboratories, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands.
authors.forename: Marcel A
authors.initials: MA
authors.lastname: Verheijen
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.
authors.forename: Sebastian
authors.identifier: 0000-0002-6606-9110
authors.initials: S
authors.lastname: Koelling
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands.
authors.forename: Erik P A M
authors.identifier: 0000-0002-8264-6862
authors.initials: EP
authors.lastname: Bakkers
keywords: Silicon−germanium; core/shell nanowire; growth rate; hexagonal crystal structure; kinetics; single-crystalline