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Effect of the polar surface on GaN nanostructure morphology and growth orientation

Published online by Cambridge University Press:  01 February 2011

C. Y. Nam
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104–6272
D. Tham
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104–6272
J. E. Fischer*
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104–6272
*
* E-mail address: fischer@seas.upenn.edu Corresponding author
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Abstract

Wurtzite gallium nitride nanostructures were synthesized by catalyst-free thermal reaction of gallium oxide and ammonia. Depending on ammonia flow rate the resulting morphology varied. At 75 sccm only nanowires were obtained, while polyhedral crystals and nanobelts were observed at 175 sccm. From scanning electron microscopy and transmission electron microscopy, both thin smooth and thick corrugated nanowires were observed. The growth orientations of most of the smooth ones, as well as the nanobelts, were perpendicular to the c-axis (<0001>), while the corrugated nanowires and the large polyhedra grew parallel to <0001>. We propose a model to explain these variations of morphology and growth orientation in terms of the Ga/N ratio and the different characteristic length of {0001} polar surface in each morphology.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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References

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