Measurement of strain in InGaN/GaN nanowires and nanopyramids

Tomas Stankevic, Simas Mickevicius, Mikkel Schou Nielsen, Olga Kryliouk, Rafal Ciechonski, Giuliano Vescovi, Zhaoxia Bi, Anders Mikkelsen, Lars Samuelson, Carsten Gundlach, Robert Krarup Feidenhans'l

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The growth and optoelectronic properties of core-shell nanostructures are influenced by the strain induced by the lattice mismatch between core and shell. In contrast with planar films, nanostructures contain multiple facets that act as independent substrates for shell growth, which enables different relaxation mechanisms. In this study, X-ray diffraction data are presented that show that InGa1-N shells grown on GaN cores are strained along each of the facets independently. Reciprocal space maps reveal multiple Bragg peaks, corresponding to different parts of the shell being strained along the individual facet planes. The strained lattice constants were found from the positions of the Bragg peaks. Vegard's law and Hooke's law for an anisotropic medium were applied in order to find the composition and strain in the InGaN shells. A range of nanowire samples with different InGaN shell thicknesses were measured and it is concluded that, with an In concentration of around 30%, major strain relaxation takes place when the thickness reaches 23nm. InGaN shells of 6 and 9nm thickness remain nearly fully strained biaxially along each of the facets of the nanowires and the facets of the nanopyramids.
Original languageEnglish
JournalJournal of Applied Crystallography
Volume48
Issue number2
Pages (from-to)344-349
Number of pages6
ISSN0021-8898
DOIs
Publication statusPublished - 2015

Keywords

  • core-shell nanostructures
  • GaN
  • InGaN
  • nanopyramids
  • nanowires
  • optoelectronics
  • Anisotropic media
  • Gallium nitride
  • Lattice constants
  • Lattice mismatch
  • Nanostructures
  • Nanowires
  • Optoelectronic devices
  • X ray diffraction
  • Core shell nano structures
  • Nano-pyramids
  • Optoelectronic properties
  • Reciprocal space maps
  • Relaxation mechanism
  • X-ray diffraction data
  • Shells (structures)
  • CRYSTALLOGRAPHY
  • CORE-SHELL NANOWIRES
  • SCIENCE BEAMLINE
  • SOLAR-CELLS
  • NITRIDE

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