title: Hexagonal Silicon Realized.
abstract: Silicon, arguably the most important technological semiconductor, is predicted to exhibit a range of new and interesting properties when grown in the hexagonal crystal structure. To obtain pure hexagonal silicon is a great challenge because it naturally crystallizes in the cubic structure. Here, we demonstrate the fabrication of pure and stable hexagonal silicon evidenced by structural characterization. In our approach, we transfer the hexagonal crystal structure from a template hexagonal gallium phosphide nanowire to an epitaxially grown silicon shell, such that hexagonal silicon is formed. The typical ABABAB... stacking of the hexagonal structure is shown by aberration-corrected imaging in transmission electron microscopy. In addition, X-ray diffraction measurements show the high crystalline purity of the material. We show that this material is stable up to 9 GPa pressure. With this development, we open the way for exploring its optical, electrical, superconducting, and mechanical properties.
authors.affiliation: Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.
authors.forename: Håkon Ikaros T
authors.initials: HI
authors.lastname: Hauge
authors.affiliation: Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.|Philips Innovation Services, 5656 AE Eindhoven, The Netherlands.
authors.forename: Marcel A
authors.initials: MA
authors.lastname: Verheijen
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands.
authors.forename: Sonia
authors.initials: S
authors.lastname: Conesa-Boj
authors.affiliation: Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria.
authors.forename: Tanja
authors.initials: T
authors.lastname: Etzelstorfer
authors.affiliation: Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria.
authors.forename: Marc
authors.initials: M
authors.lastname: Watzinger
authors.affiliation: Department of Condensed Matter Physics, Charles University in Prague , Ke Karlovu 5, 121 16 Prague 2, Czech Republic.
authors.forename: Dominik
authors.initials: D
authors.lastname: Kriegner
authors.affiliation: Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Zardo
authors.affiliation: CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy.|Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia , V.le Regina Elena, 291-00185, Rome, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Fasolato
authors.affiliation: CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Capitani
authors.affiliation: CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy.|Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia , V.le Regina Elena, 291-00185, Rome, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Postorino
authors.affiliation: Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kölling
authors.affiliation: Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.
authors.forename: Ang
authors.initials: A
authors.lastname: Li
authors.affiliation: Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.
authors.forename: Simone
authors.initials: S
authors.lastname: Assali
authors.affiliation: Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria.
authors.forename: Julian
authors.initials: J
authors.lastname: Stangl
authors.affiliation: Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands.
authors.forename: Erik P A M
authors.initials: EP
authors.lastname: Bakkers
keywords: Core/Shell Nanowire; Hexagonal Crystal Structure; Raman Spectroscopy; Silicon; Single-Crystalline; X-ray Diffraction