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Tem Study of Defects in Laterally Overgrown GaN Layers

Published online by Cambridge University Press:  15 February 2011

Z. Liliental-Weber
Affiliation:
Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, 62/203
M. Benamara
Affiliation:
Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, 62/203
W. Swider
Affiliation:
Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, 62/203
J. Washburn
Affiliation:
Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, 62/203
J. Park
Affiliation:
Microelectronics Research Center, The University of Texas at Austin, Austin TX 78712-1100
P. A. Grudowski
Affiliation:
Microelectronics Research Center, The University of Texas at Austin, Austin TX 78712-1100
C. J. Eiting
Affiliation:
Microelectronics Research Center, The University of Texas at Austin, Austin TX 78712-1100
R. D. Dupuis
Affiliation:
Microelectronics Research Center, The University of Texas at Austin, Austin TX 78712-1100
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Abstract

Transmission electron microscopy was applied to study defects in laterally overgrown GaN layers, with initial growth on A12O3 substrates followed by further growth over SiO2 masks. Dislocations found in the overgrown areas show changes in line direction. Most dislocations propagate along c-planes. In the overgrown material planar defects (faulted loops) are present on c-planes and their presence is most probably related to segregation of excess point defects and impurities present in this material. They appear to be initiated by the fast lateral growth. Some dislocations with screw orientation become helical resulting from climb motion.

Formation of voids and also a high dislocation density was observed at the boundaries where two overgrowing fronts meet. Tilt and twist components were observed for these boundaries that were different for different overgrown strips grown in the same crystallographic direction suggesting that the GaN subgrain orientations on the two sides of a SiO2 mask are responsible for the final tilt and twist value.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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