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Title: Polarity characterization by anomalous x-ray dispersion of ZnO films and GaN lateral polar structures

We demonstrate the use of anomalous x-ray scattering of constituent cations at their absorption edge, in a conventional Bragg-Brentano diffractometer, to measure absolutely and quantitatively the polar orientation and polarity fraction of unipolar and mixed polar wurtzitic crystals. In one set of experiments, the gradual transition between c+ and c− polarity of epitaxial ZnO films on sapphire as a function of MgO buffer layer thickness is monitored quantitatively, while in a second experiment, we map the polarity of a lateral polar homojunction in GaN. The dispersion measurements are compared with piezoforce microscopy images, and we demonstrate how x-ray dispersion and scanning probe methods can provide complementary information that can discriminate between polarity fractions at a material surface and polarity fractions averaged over the film bulk.
Authors:
; ; ; ; ; ; ;  [1]
  1. Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)
Publication Date:
OSTI Identifier:
22275604
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; CATIONS; COMPARATIVE EVALUATIONS; CRYSTALS; CUBIC LATTICES; EPITAXY; GALLIUM NITRIDES; LAYERS; MAGNESIUM OXIDES; SAPPHIRE; THIN FILMS; X RADIATION; X-RAY DIFFRACTION; ZINC OXIDES