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Characterization of Sputtered CdTe Thin Films with Electron Backscatter Diffraction and Correlation with Device Performance

Published online by Cambridge University Press:  16 June 2015

Matthew M. Nowell ,
Michael A. Scarpulla ,
Naba R. Paudel ,
Kristopher A. Wieland ,
Alvin D. Compaan  and
Xiangxin Liu
Matthew M. Nowell
Affiliation:
EDAX-TSL, 392 East 12300 South Suite H, Draper, UT 84020, USA
Michael A. Scarpulla
Affiliation:
Departments of Materials Science and Engineering and Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA
Naba R. Paudel*
Affiliation:
Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA
Kristopher A. Wieland
Affiliation:
Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA
Alvin D. Compaan
Affiliation:
Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA
Xiangxin Liu
Affiliation:
Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA
*
*Corresponding author.naba.paudel@utoledo.edu
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Abstract

The performance of polycrystalline CdTe photovoltaic thin films is expected to depend on the grain boundary density and corresponding grain size of the film microstructure. However, the electrical performance of grain boundaries within these films is not well understood, and can be beneficial, harmful, or neutral in terms of film performance. Electron backscatter diffraction has been used to characterize the grain size, grain boundary structure, and crystallographic texture of sputtered CdTe at varying deposition pressures before and after CdCl2 treatment in order to correlate performance with microstructure. Weak fiber textures were observed in the as-deposited films, with (111) textures present at lower deposition pressures and (110) textures observed at higher deposition pressures. The CdCl2-treated samples exhibited significant grain recrystallization with a high fraction of twin boundaries. Good correlation of solar cell efficiency was observed with twin-corrected grain size while poor correlation was found if the twin boundaries were considered as grain boundaries in the grain size determination. This implies that the twin boundaries are neutral with respect to recombination and carrier transport.

Keywords

CdTesputteringEBSDthin film
Type
Materials Applications and Techniques
Information
Microscopy and Microanalysis , Volume 21 , Issue 4 , August 2015 , pp. 927 - 935
Copyright
© Microscopy Society of America 2015 

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Footnotes

†

Current address: Corning Incorporated, One Riverfront Plaza, Corning, NY 14831 USA

‡

Current address: Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, P.R. China

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