Document Type


Original Publication Date


Journal/Book/Conference Title

Journal of Applied Physics





DOI of Original Publication



Originally published at

Date of Submission

October 2015


We report a void defect in gallium nitride (GaN) and InGaN, revealed by aberration-corrected scanning transmission electron microscopy (STEM). The voids are pyramids with symmetric hexagonal {0001} base facets and {101¯1} side facets. Each pyramid void has a dislocation at the peak of the pyramid, which continues up along the [0001] growth direction to the surface. Some of the dislocations are hexagonal open core screw dislocations with {101¯0} side facets, varying lateral widths, and varying degrees of hexagonal symmetry. STEM electron energy loss spectroscopy spectrum imaging showed a large C concentration inside the void and on the void surfaces. There is also a larger C concentration in the GaN (or InGaN) below the void than above the void. We propose that inadvertent carbon deposition during metal organic chemical vapor deposition growth acts as a mask, stopping the GaN deposition locally, which in combination with lateral overgrowth, creates a void. Subsequent layers of GaN deposited around the C covered region create the overhanging {101¯1} facets, and the meeting of the six {101¯1} facets at the pyramid’s peak is not perfect, resulting in a dislocation.


Yankovich, A. B., Kvit, A. V., & Li, X., et al. Hexagonal-based pyramid void defects in GaN and InGaN. Journal of Applied Physics, 111, 023517 (2012). Copyright © 2012 American Institute of Physics.

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VCU Electrical and Computer Engineering Publications