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Core Structures of Dislocations within CdTe Grains

Published online by Cambridge University Press:  02 May 2013

Chen Li
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831USA Department of Chemistry, Vanderbilt University, Nashville, TN 37235USA
Timothy J. Pennycook
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831USA Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235USA
Donovan N. Leonard
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831USA
Kim Jones
Affiliation:
The Measurements and Characterization Group, National Renewable Energy Laboratory, Golden, CO 80401USA
Zhiwei Wang
Affiliation:
The Measurements and Characterization Group, National Renewable Energy Laboratory, Golden, CO 80401USA
Mowafak Al-Jassim
Affiliation:
The Measurements and Characterization Group, National Renewable Energy Laboratory, Golden, CO 80401USA
Naba Paudel
Affiliation:
Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606USA
Yanfa Yan
Affiliation:
Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606USA
Stephen J. Pennycook
Affiliation:
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831USA
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Abstract

CdTe is well known as an excellent photovoltaic material for high efficiency solar cell applications because it has a direct band-gap, low fabrication cost and high optical absorption coefficient. However, the nonradiative recombination and low average minority carrier lifetime caused by the defects in CdTe solar cells limit its efficiency. So far, grain boundaries (GB) have been considered to be the major origin of the nonradiative recombination. However, we show that CdTe grains contain many dislocations that could limit device efficiency. Scanning transmission electron microscopy (STEM) was used to determine the atomic structure of intrinsic and extrinsic stacking faults and their terminating partial dislocation cores. Z-contrast images are sensitive to atomic number and are able to distinguish Cd and Te atomic columns. Unpaired Cd and Te atomic columns were found to form the partial dislocation cores, suggesting the presence of dangling bonds. These defects are likely to be electrically active, and may be the origin of the low minority carrier lifetime.

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Articles
Copyright
Copyright © Materials Research Society 2013

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