title: Tensile strained germanium nanowires measured by photocurrent spectroscopy and X-ray microdiffraction.
abstract: Applying tensile strain in a single germanium crystal is a very promising way to tune its bandstructure and turn it into a direct band gap semiconductor. In this work, we stress vapor-liquid-solid grown germanium nanowires along their [111] axis thanks to the strain tranfer from a silicon nitride thin film by a microfabrication process. We measure the Γ-LH direct band gap transition by photocurrent spectrometry and quantify associated strain by X-ray Laue microdiffraction on beamline BM32 at the European Synchrotron Radiation Facility. Nanowires exhibit up to 1.48% strain and an absorption threshold down to 0.73 eV, which is in good agreement with theoretical computations for the Γ-LH transition, showing that the nanowire geometry is an efficient way of applying tensile uniaxial stress along the [111] axis of a germanium crystal.
authors.affiliation: †Université Grenoble Alpes, INAC-SP2M, SINAPS, F-38000 Grenoble, France.|‡CEA, INAC-SP2M, SINAPS, F-38000 Grenoble, France.
authors.forename: Kevin
authors.initials: K
authors.lastname: Guilloy
authors.affiliation: †Université Grenoble Alpes, INAC-SP2M, SINAPS, F-38000 Grenoble, France.|‡CEA, INAC-SP2M, SINAPS, F-38000 Grenoble, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pauc
authors.affiliation: †Université Grenoble Alpes, INAC-SP2M, SINAPS, F-38000 Grenoble, France.|‡CEA, INAC-SP2M, SINAPS, F-38000 Grenoble, France.
authors.forename: Alban
authors.initials: A
authors.lastname: Gassenq
authors.affiliation: †Université Grenoble Alpes, INAC-SP2M, SINAPS, F-38000 Grenoble, France.|‡CEA, INAC-SP2M, SINAPS, F-38000 Grenoble, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Gentile
authors.affiliation: §Université Grenoble Alpes, INAC-SP2M, NRS, F-38000 Grenoble, France.|∥CEA, INAC-SP2M, NRS, F-38000 Grenoble, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Tardif
authors.affiliation: §Université Grenoble Alpes, INAC-SP2M, NRS, F-38000 Grenoble, France.|∥CEA, INAC-SP2M, NRS, F-38000 Grenoble, France.
authors.forename: François
authors.initials: F
authors.lastname: Rieutord
authors.affiliation: †Université Grenoble Alpes, INAC-SP2M, SINAPS, F-38000 Grenoble, France.|‡CEA, INAC-SP2M, SINAPS, F-38000 Grenoble, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Calvo
keywords: Germanium; Laue; XRD; nanowire; photocurrent; tensile strain