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Dislocation Arrangement in a Thick LEO GaN Film on Sapphire

Published online by Cambridge University Press:  03 September 2012

Kathleen A. Dunn
Affiliation:
Materials Science and Engineering;Chemical Engineering University of Wisconsin – Madison, Madison, WI 53706
Susan E. Babcock
Affiliation:
Materials Science and Engineering;Chemical Engineering University of Wisconsin – Madison, Madison, WI 53706
Donald S. Stone
Affiliation:
Materials Science and Engineering;Chemical Engineering University of Wisconsin – Madison, Madison, WI 53706
Richard J. Matyi
Affiliation:
Materials Science and Engineering;Chemical Engineering University of Wisconsin – Madison, Madison, WI 53706
Ling Zhang
Affiliation:
Chemical Engineering University of Wisconsin – Madison, Madison, WI 53706
Thomas F. Kuech
Affiliation:
Chemical Engineering University of Wisconsin – Madison, Madison, WI 53706
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Abstract

Diffraction-contrast TEM, focused probe electron diffraction, and high-resolution X-ray diffraction were used to characterize the dislocation arrangements in a 16[.proportional]m 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 20] (perpendicular to the coalescence boundary) which originate in the coalescence boundary and extend laterally into the film on the (1 100). The third set of dislocations threads laterally through the film along the [1 100] bar axis with 1/3<11 20>-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°.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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