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

Christopher T. Shelton, Edward Sachet, Elizabeth A. Paisley, Marc P. Hoffmann, Joseph Rajan, Ramón Collazo, Zlatko Sitar, Jon-Paul Maria

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Abstract

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.

Original languageEnglish (US)
Article number044912
JournalJournal of Applied Physics
Volume115
Issue number4
DOIs
StatePublished - Jan 1 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Shelton, C. T., Sachet, E., Paisley, E. A., Hoffmann, M. P., Rajan, J., Collazo, R., Sitar, Z., & Maria, J-P. (2014). Polarity characterization by anomalous x-ray dispersion of ZnO films and GaN lateral polar structures. Journal of Applied Physics, 115(4), [044912]. https://doi.org/10.1063/1.4863120