title: Controlled growth of hexagonal gold nanostructures during thermally induced self-assembling on Ge(001) surface.
abstract: Nano-sized gold has become an important material in various fields of science and technology, where control over the size and crystallography is desired to tailor the functionality. Gold crystallizes in the face-centered cubic (fcc) phase, and its hexagonal closed packed (hcp) structure is a very unusual and rare phase. Stable Au hcp phase has been reported to form in nanoparticles at the tips of some Ge nanowires. It has also recently been synthesized in the form of thin graphene-supported sheets which are unstable under electron beam irradiation. Here, we show that stable hcp Au 3D nanostructures with well-defined crystallographic orientation and size can be systematically created in a process of thermally induced self-assembly of thin Au layer on Ge(001) monocrystal. The Au hcp crystallite is present in each Au nanostructure and has been characterized by different electron microscopy techniques. We report that a careful heat treatment above the eutectic melting temperature and a controlled cooling is required to form the hcp phase of Au on a Ge single crystal. This new method gives scientific prospects to obtain stable Au hcp phase for future applications in a rather simple manner as well as redefine the phase diagram of Gold with Germanium.
authors.affiliation: Marian Smoluchowski Institute of Physics Jagiellonian University, Lojasiewicza 11, PL-30348 Krakow, Poland.
authors.forename: B R
authors.initials: BR
authors.lastname: Jany
authors.affiliation: EMAT University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Gauquelin
authors.affiliation: EMAT University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Willhammar
authors.affiliation: Marian Smoluchowski Institute of Physics Jagiellonian University, Lojasiewicza 11, PL-30348 Krakow, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Nikiel
authors.affiliation: EMAT University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium.
authors.forename: K H W
authors.initials: KH
authors.lastname: van den Bos
authors.affiliation: Marian Smoluchowski Institute of Physics Jagiellonian University, Lojasiewicza 11, PL-30348 Krakow, Poland.
authors.forename: A
authors.initials: A
authors.lastname: Janas
authors.affiliation: Marian Smoluchowski Institute of Physics Jagiellonian University, Lojasiewicza 11, PL-30348 Krakow, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Szajna
authors.affiliation: EMAT University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Verbeeck
authors.affiliation: EMAT University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Van Aert
authors.affiliation: EMAT University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Van Tendeloo
authors.affiliation: Marian Smoluchowski Institute of Physics Jagiellonian University, Lojasiewicza 11, PL-30348 Krakow, Poland.
authors.forename: F
authors.initials: F
authors.lastname: Krok