title: Abrupt Schottky Junctions in Al/Ge Nanowire Heterostructures.
abstract: In this Letter we report on the exploration of axial metal/semiconductor (Al/Ge) nanowire heterostructures with abrupt interfaces. The formation process is enabled by a thermal induced exchange reaction between the vapor-liquid-solid grown Ge nanowire and Al contact pads due to the substantially different diffusion behavior of Ge in Al and vice versa. Temperature-dependent I-V measurements revealed the metallic properties of the crystalline Al nanowire segments with a maximum current carrying capacity of about 0.8 MA/cm(2). Transmission electron microscopy (TEM) characterization has confirmed both the composition and crystalline nature of the pure Al nanowire segments. A very sharp interface between the ⟨111⟩ oriented Ge nanowire and the reacted Al part was observed with a Schottky barrier height of 361 meV. To demonstrate the potential of this approach, a monolithic Al/Ge/Al heterostructure was used to fabricate a novel impact ionization device.
authors.affiliation: †Institute for Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Kral
authors.affiliation: †Institute for Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Zeiner
authors.affiliation: ‡Universitäre Service-Einrichtung für Transmissionselektronenmikroskopie, Vienna University of Technology, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Stöger-Pollach
authors.affiliation: †Institute for Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Vienna, Austria.
authors.forename: E
authors.initials: E
authors.lastname: Bertagnolli
authors.affiliation: §Institut Néel, CNRS/UJF, UPR2940, Univ. Grenoble Alpes, 25 rue des Martyrs, 38042 Grenoble, France.
authors.forename: M I
authors.initials: MI
authors.lastname: den Hertog
authors.affiliation: ∥CEA-INAC/UJF-Grenoble 1 UMR-E, SP2M, LEMMA, Univ. Grenoble Alpes, Minatec, Grenoble F-38054, France.|⊥FEI Company, KA 5600 Eindhoven, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Lopez-Haro
authors.affiliation: ∥CEA-INAC/UJF-Grenoble 1 UMR-E, SP2M, LEMMA, Univ. Grenoble Alpes, Minatec, Grenoble F-38054, France.
authors.forename: E
authors.initials: E
authors.lastname: Robin
authors.affiliation: §Institut Néel, CNRS/UJF, UPR2940, Univ. Grenoble Alpes, 25 rue des Martyrs, 38042 Grenoble, France.
authors.forename: K
authors.initials: K
authors.lastname: El Hajraoui
authors.affiliation: †Institute for Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Lugstein
keywords: Nanowire; Schottky contact; aluminum; germanium; heterostructure; impact ionization