CBED study of grain misorientations in AlGaN epilayers

S. L. Sahonta, D. Cherns, R. Liu, Fernando Ponce, H. Amano, I. Akasaki

Research output: Contribution to journalArticle

Abstract

Large angle convergent beam electron diffraction (LACBED) has been used to examine AlGaN epilayers grown by facet-controlled epitaxial lateral overgrowth on GaN/(0 0 0 1) sapphire substrates in prototype UV laser structures. The substrates, defined by masks with seed openings along a 〈10-10〉 stripe direction, had GaN seed columns with {11-22} surfaces. Studies were carried out on cross-sectional samples cut perpendicular to the stripe axis. An LACBED analysis of the orientation of (0 0 0 2) planes, and of the (11-20) planes parallel to the stripe axis, revealed that the AlGaN wings were both rotated by angles of 1-2×10-2 radians about the 〈10-10〉 stripe axis with respect to the underlying GaN, and distorted due to misfit strains. It is shown that the results are consistent with the observed structure of the AlGaN/GaN and the wing/wing boundaries, and with a new model for the generation of a-type misfit dislocations at the AlGaN/GaN interface.

Original languageEnglish (US)
Pages (from-to)23-32
Number of pages10
JournalUltramicroscopy
Volume103
Issue number1
DOIs
StatePublished - Apr 1 2005

Keywords

  • AlGaN/GaN interface
  • Grain rotation
  • LACBED
  • Misfit dislocations
  • Misfit strain

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

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    Sahonta, S. L., Cherns, D., Liu, R., Ponce, F., Amano, H., & Akasaki, I. (2005). CBED study of grain misorientations in AlGaN epilayers. Ultramicroscopy, 103(1), 23-32. https://doi.org/10.1016/j.ultramic.2004.11.013