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Effects of Mg Content on Zn1-xMgxO:Al Transparent Conducting Films

Published online by Cambridge University Press:  01 February 2011

Xiaonan Li ,
Hannah Ray ,
Craig L. Perkins  and
Rommel Noufi
Xiaonan Li
Affiliation:
xiaonan_li@nrel.gov, National renewable Energy Laboratory, 5200, 1617 Cole Blvd., Golden, CO, 80401, United States, 303-384-6428, 303-384-7600
Hannah Ray
Affiliation:
hannahlray@gmail.com, NREL, 5200, 1617 Cole Blvd., Golden, CO, 80401, United States
Craig L. Perkins
Affiliation:
Craig_Perkins@nrel.gov, NREL, 5200, 1617 Cole Blvd., Golden, CO, 80401, United States
Rommel Noufi
Affiliation:
rommel_noufi@nrel.gov, NREL, 5200, 1617 Cole Blvd., Golden, CO, 80401, United States
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Abstract

Conductive zinc oxide (ZnO) films are used extensively as transparent electrodes in thin-film photovoltaic solar cells. Compared with the widely used indium tin oxide (ITO) and tin oxide (SnO2), ZnO has a smaller optical bandgap. ZnO is commonly used as a front contact for copper indium gallium diselenide (CIGS) solar cells, but it forms a small, unfavorable conduction-band offset with the CdS layer. The optical bandgap of ZnO could easily be engineering by alloying with MgO or CdO. In this work, we try to optimize the ZnO for CIGS solar cells. The optical and electrical properties of Zn1-xMgxO:Al films fabricated by co-sputtering were studied. Two targets: ZnO:Al and MgO, were used. The ratio of ZnO/MgO was varied continuously on the 6”x6” glass substrate, and the effects of composition on the properties of the Zn1-xMgxO:Al films were investigated. The carrier concentration and mobility of the Zn1-xMgxO:Al films decreased quickly with increasing Mg content. However, the optical properties of the Zn1-xMgxO:Al films do not vary linearly with Mg content, as reported by most papers. The observed optical bandgap of Zn1-xMgxO:Al films is actually first narrowed, then increased with the Mg content. The shift in optical bandgap from narrow to wide occurs at around a composition of x = 0.07. After the point of x = 0.07, the bandgap width star increase but film sheet resistance already too low. Our result therefore suggests that the alloyed Zn1-xMgxO:Al does not benefit the CIGS solar cell.

Keywords

thin filmoxidesputtering
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1101: Symposium KK – Light Management in Photovoltaic Devices–Theory and Practice , 2008 , 1101-KK05-15
Copyright
Copyright © Materials Research Society 2008

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References

1 Schmid, D. Ruckh, M. and Schock, H.W. Solar Energy Materials and Solar Cells 41/42, 281, (1996).Google Scholar
2 Choopun, S. Vispute, R.D. Yang, W. Sharma, R. P. and Venkatesan, T. “Realization of band gap above 5.0 eV in metastable cubic-phase MgxZn1-xO films,” Appl. Phys. Lett. 80, 1529, (2002).Google Scholar
3 Matsubara, K. Tampo, H. Shibata, H. Yamada, A. Fons, P. Iwata, K. and Niki, S. “Band-gap modified Al-doped Zn1-xMgxO transparent conducting films deposited by pulsed laser deposition,” Applied Physics Letters 85, pp.1374–1376, 2004.Google Scholar
4 Li, X. Young, D.L. Moutinho, H. Yan, Y. Narayanswamy, C. Gessert, T.A. and Coutts, T.J. “Properties of CdO thin films produced by chemical vapor deposition,” Electrochemical and Solid-State Letters 4, pp. C43–C46, 2001.Google Scholar
5 Ohtomo, A. Kawasaki, M. Koida, T. Masubuchi, K. Koinuma, H. Sakurai, Y. Yoshida, Y. Tasuda, T. and Segawa, Y. Appl. Phys. Lett. 72, 2466, (1998).Google Scholar
6 Minemoto, T. Negami, T. Nishiwaki, S. Takakura, H. hamakawa, Y. Thin Solid Films, 372, 173, (2000).Google Scholar
7Sheng Li, S. Semiconductor Physical Electronics, 1993, Plenum Press, New York and London, ISBN 0-306-44157-8.Google Scholar
8 Baer, W.S. Physical Review 154, 785, (1967).Google Scholar
9 Burstein, E. Phys. Rev. 93, 632, (1954).Google Scholar
10 Moss, T.S. Proc. Phys. Soc. B67, 775 (1954).Google Scholar
11 Palankovski, V. Kaiblinger-Grujin, G., and Selberherr, S. Materials Science and Engineering B66 46, (1999).Google Scholar