Kathleen A Dunn, Sue Babcock, Donald S Stone, Richard J Matyi, Ling Zhang
University of Wisconsin - Madison
Thomas F. Kuech
University of Wisconsin
This article was presented as part of Symposium W, "Gallium Nitride and Related Alloys" at the 1999 Fall Meeting of the Materials Research Society held in Boston, Massachusetts, November 28-December 3
Diffraction-contrast TEM, focused probe electron diffraction, and high-resolution
X-ray diffraction were used to characterize the dislocation arrangements in a 16xm thick
coalesced GaN film grown by MOVPE LEO. As is commonly observed, the threading
dislocations that are duplicated from the template above the window bend toward (0001).
At the coalescence plane they bend back to lie along [0001] and thread to the surface. In
addition, three other sets of dislocations were observed. The first set consists of a wall of
parallel dislocations lying in the coalescence plane and nearly parallel to the substrate,
with Burgers vector (b) in the (0001) plane. The second set is comprised of rectangular
loops with b = 1/3 [11
0] (perpendicular to the coalescence boundary) which originate
in the coalescence boundary and extend laterally into the film on the (1
00). The third
set of dislocations threads laterally through the film along the [100] bar axis with
1/3<110>-type Burgers vectors These sets result in a dislocation density of ~109 cm-2 .
High resolution X-ray reciprocal space maps indicate wing tilt of ~0.5°.
Full text of this article is available.
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 5S1, W2.11 (2000).
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