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Transmission Electron Microscopy Study of Room Temperature Lasing Epitaxial ZnO Films on Sapphire

Published online by Cambridge University Press:  10 February 2011

N. Wang ,
K. K. Fung ,
P. Yu ,
Z. K. Tang ,
G. K. L. Wong ,
M. Kawasaki ,
A. Ohtomo ,
H. Koinuma  and
Y. Segawa
N. Wang
Affiliation:
Department of Physics, Hong Kong University of Science and Technology, Hong Kong
K. K. Fung
Affiliation:
Department of Physics, Hong Kong University of Science and Technology, Hong Kong
P. Yu
Affiliation:
Department of Physics, Hong Kong University of Science and Technology, Hong Kong
Z. K. Tang
Affiliation:
Department of Physics, Hong Kong University of Science and Technology, Hong Kong
G. K. L. Wong
Affiliation:
Department of Physics, Hong Kong University of Science and Technology, Hong Kong
M. Kawasaki
Affiliation:
Research Laboratory of Engineering Materials, Tokyo Institute of Technology, Japan
A. Ohtomo
Affiliation:
Research Laboratory of Engineering Materials, Tokyo Institute of Technology, Japan
H. Koinuma
Affiliation:
Research Laboratory of Engineering Materials, Tokyo Institute of Technology, Japan
Y. Segawa
Affiliation:
Photodynamics Research Center, RIKEN, Sendai 980, Japan
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Abstract

We have studied the microstructures of lasing and non-lasing ZnO films on sapphire in plan-view and cross-section by transmission electron microscopy (TEM). While ZnO films in general are made up of cloumnar close-packed c-axis misoriented nanocrystals, the misorientation in nonlasing film, typically 5°, is considerably larger than lasing film, typically less than 1°. A rather high density of pinholes or nanotubes is associated with the highly misoriented films. The misorientation between adjacent grains is taken up by grain boundary dislocations. Room temperature lasing films contain a high density of threading boundary edge dislocations, in excess of 1010 cm−2. But faceting in the columnar nanocrystals is not well developed so that the grain boundaries are not clearly visible. Tilting of (0001) lattice planes between grains originating from substrate surface step and growth fault step, however, has been observed in high resolution electron microscopy (HREM) images.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 482 , 1997 , 423
Copyright
Copyright © Materials Research Society 1998

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Footnotes

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Department of Physics and Materials Science, City University of Hong Kong.

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