Direct observation of threading dislocations in GaN by high-resolution Z-contrast imaging

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Wide gap nitride semiconductors have attracted significant attention recently due to their promising performance as short-wavelength light emitting diodes (LEDs) and blue lasers. One interesting issue concerning GaN is that the material is relatively insensitive to the presence of a density of dislocations which is six orders of magnitude higher than that for III-V arsenide and phosphide based LEDs. Although it is well known that these dislocations originate at the film-substrate interface during film growth, thread through the whole epilayer with line direction along <0001> and are perfect dislocations with Burgers vectors of a, c, or c+a, the reason why ... continued below

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5 p.

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Xin, Y.; Browning, N.D.; Sivananthan, S.; Pennycook, S.J.; Nellist, P.D.; FAurie, J.P. et al. February 1, 1998.

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  • Xin, Y. Univ. of Illinois, Chicago, IL (United States). Dept. of Physics
  • Browning, N.D.
  • Sivananthan, S. Univ. of Illinois, Chicago, IL (United States). Dept. of Physics
  • Pennycook, S.J. Oak Ridge National Lab., TN (United States). Solid State Div.
  • Nellist, P.D. Cambridge Univ. (United Kingdom). Cavendish Lab.
  • FAurie, J.P. Univ. of Illinois, Chicago, IL (United States). Dept. of Physics
  • Gibart, P. CRHEA-CNRS, Valbonne (France)

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Description

Wide gap nitride semiconductors have attracted significant attention recently due to their promising performance as short-wavelength light emitting diodes (LEDs) and blue lasers. One interesting issue concerning GaN is that the material is relatively insensitive to the presence of a density of dislocations which is six orders of magnitude higher than that for III-V arsenide and phosphide based LEDs. Although it is well known that these dislocations originate at the film-substrate interface during film growth, thread through the whole epilayer with line direction along <0001> and are perfect dislocations with Burgers vectors of a, c, or c+a, the reason why they have such a small effect on the properties of GaN is unclear. To develop a fundamental understanding of the properties of these dislocations, the core structures are studied here by high resolution Z-contrast imaging in a 300kV VG HB603 scanning transmission electron microscope (STEM) with a resolution of 0.13 nm. As the Z-contrast image is a convolution between the probe intensity profile and the specimen object function, it is possible to obtain more detailed information on the specimen object function, i.e. the structure, through maximum entropy analysis (the maximum entropy technique produces the ``most likely`` object function which is consistent with the image).

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5 p.

Notes

OSTI as DE98004962

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  • Microscopy and microanalysis 1998, Atlanta, GA (United States), 12-16 Jul 1998

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  • Other: DE98004962
  • Report No.: ORNL/CP--97022
  • Report No.: CONF-980713--
  • Grant Number: AC05-96OR22464
  • DOI: 10.2172/650358 | External Link
  • Office of Scientific & Technical Information Report Number: 650358
  • Archival Resource Key: ark:/67531/metadc709815

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Creation Date

  • February 1, 1998

Added to The UNT Digital Library

  • Sept. 12, 2015, 6:31 a.m.

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  • Jan. 25, 2016, 12:25 p.m.

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Xin, Y.; Browning, N.D.; Sivananthan, S.; Pennycook, S.J.; Nellist, P.D.; FAurie, J.P. et al. Direct observation of threading dislocations in GaN by high-resolution Z-contrast imaging, report, February 1, 1998; Tennessee. (digital.library.unt.edu/ark:/67531/metadc709815/: accessed June 23, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.