title: The Synergic Effect of Atomic Hydrogen Adsorption and Catalyst Spreading on Ge Nanowire Growth Orientation and Kinking.
abstract: Hydride precursors are commonly used for semiconductor nanowire growth from the vapor phase and hydrogen is quite often used as a carrier gas. Here, we used in situ scanning electron microscopy and spatially resolved Auger spectroscopy to reveal the essential role of atomic hydrogen in determining the growth direction of Ge nanowires with an Au catalyst. With hydrogen passivating nanowire sidewalls the formation of inclined facets is suppressed, which stabilizes the growth in the ⟨111⟩ direction. By contrast, without hydrogen gold diffuses out of the catalyst and decorates the nanowire sidewalls, which strongly affects the surface free energy of the system and results in the ⟨110⟩ oriented growth. The experiments with intentional nanowire kinking reveal the existence of an energetic barrier, which originates from the kinetic force needed to drive the droplet out of its optimum configuration on top of a nanowire. Our results stress the role of the catalyst material and surface chemistry in determining the nanowire growth direction and provide additional insights into a kinking mechanism, thus allowing to inhibit or to intentionally initiate spontaneous kinking.
authors.affiliation: Institute of Physical Engineering, Brno University of Technology , Technická 2, 616 69 Brno, Czech Republic.|CEITEC BUT, Brno University of Technology , Purkyňova 123, 616 69 Brno, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Kolíbal
authors.affiliation: CEITEC BUT, Brno University of Technology , Purkyňova 123, 616 69 Brno, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Pejchal
authors.affiliation: FEI Company, Vlastimila Pecha 1282/12, 627 00 Brno, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Vystavěl
authors.affiliation: Institute of Physical Engineering, Brno University of Technology , Technická 2, 616 69 Brno, Czech Republic.|CEITEC BUT, Brno University of Technology , Purkyňova 123, 616 69 Brno, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Šikola
keywords: Nanowire; faceting; germanium; hydrogen; nanowire kinking; vapor−liquid−solid growth