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 2005

Fingerprint

Epilayers
misalignment
wings
Electron diffraction
Seed
seeds
electron diffraction
Substrates
ultraviolet lasers
Dislocations (crystals)
Sapphire
Aluminum Oxide
Masks
flat surfaces
sapphire
masks
prototypes
Lasers
aluminum gallium nitride

Keywords

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

ASJC Scopus subject areas

  • Materials Science(all)
  • Instrumentation

Cite this

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

CBED study of grain misorientations in AlGaN epilayers. / Sahonta, S. L.; Cherns, D.; Liu, R.; Ponce, Fernando; Amano, H.; Akasaki, I.

In: Ultramicroscopy, Vol. 103, No. 1, 04.2005, p. 23-32.

Research output: Contribution to journalArticle

Sahonta, SL, Cherns, D, Liu, R, Ponce, F, Amano, H & Akasaki, I 2005, 'CBED study of grain misorientations in AlGaN epilayers', Ultramicroscopy, vol. 103, no. 1, pp. 23-32. https://doi.org/10.1016/j.ultramic.2004.11.013
Sahonta, S. L. ; Cherns, D. ; Liu, R. ; Ponce, Fernando ; Amano, H. ; Akasaki, I. / CBED study of grain misorientations in AlGaN epilayers. In: Ultramicroscopy. 2005 ; Vol. 103, No. 1. pp. 23-32.
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