title: Fast Strain Mapping of Nanowire Light-Emitting Diodes Using Nanofocused X-ray Beams.
abstract: X-ray nanobeams are unique nondestructive probes that allow direct measurements of the nanoscale strain distribution and composition inside the micrometer thick layered structures that are found in most electronic device architectures. However, the method is usually extremely time-consuming, and as a result, data sets are often constrained to a few or even single objects. Here we demonstrate that by special design of a nanofocused X-ray beam diffraction experiment we can (in a single 2D scan with no sample rotation) measure the individual strain and composition profiles of many structures in an array of upright standing nanowires. We make use of the observation that in the generic nanowire device configuration, which is found in high-speed transistors, solar cells, and light-emitting diodes, each wire exhibits very small degrees of random tilts and twists toward the substrate. Although the tilt and twist are very small, they give a new contrast mechanism between different wires. In the present case, we image complex nanowires for nanoLED fabrication and compare to theoretical simulations, demonstrating that this fast method is suitable for real nanostructured devices.
authors.affiliation: †Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Tomaš
authors.initials: T
authors.lastname: Stankevič
authors.affiliation: †Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Emelie
authors.initials: E
authors.lastname: Hilner
authors.affiliation: ‡Technische Universität Dresden, D-01062 Dresden, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Seiboth
authors.affiliation: §Glo AB, Scheelevägen 17, Betahuset 6, 223 70 Lund, Sweden.
authors.forename: Rafal
authors.initials: R
authors.lastname: Ciechonski
authors.affiliation: §Glo AB, Scheelevägen 17, Betahuset 6, 223 70 Lund, Sweden.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Vescovi
authors.affiliation: ⊥Glo-USA, Inc., 1225 Bordeaux Drive, Sunnyvale, California 94089, United States.
authors.forename: Olga
authors.initials: O
authors.lastname: Kryliouk
authors.affiliation: ∥Lund University, 22100 Lund, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Johansson
authors.affiliation: ∥Lund University, 22100 Lund, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Samuelson
authors.affiliation: ¶Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Wellenreuther
authors.affiliation: ¶Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Falkenberg
authors.affiliation: †Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Robert
authors.initials: R
authors.lastname: Feidenhans'l
authors.affiliation: ∥Lund University, 22100 Lund, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Mikkelsen
keywords: core−shell nanowires; nanofocused X-rays; scanning X-ray diffraction microscopy; strain mapping