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Screen-Printed Al Back Contacts on Si Solar Cells: Issues and Some Solutions

Published online by Cambridge University Press:  31 January 2011

Vishal Mehta ,
Bhushan Sopori ,
Robert Reedy ,
Bobby To ,
Helio Moutinho  and
Nuggehalli M. Ravindra
Vishal Mehta
Affiliation:
Vishal_mehta@nrel.gov, National Renewable Energy Laboratory, Golden, Colorado, United States
Bhushan Sopori
Affiliation:
Bhushan.Sopori@scholarone.net, National Renewable Energy Laboratory, Golden, Colorado, United States
Robert Reedy
Affiliation:
Bob.Reedy@nrel.gov, National Renewable Energy Laboratory, Golden, Colorado, United States
Bobby To
Affiliation:
Bobby.To@nrel.gov, National Renewable Energy Laboratory, Golden, Colorado, United States
Helio Moutinho
Affiliation:
helio.moutinho@nrel.gov, National Renewable Energy Laboratory, Golden, Colorado, United States
Nuggehalli M. Ravindra
Affiliation:
nmravindra@gmail.com, New Jersey Institute of Technology, Newark, New Jersey, United States
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Abstract

This paper identifies some mechanisms that lead to problems in back Al contact formation. Major issues are related to a basic problem that the Al melt has a large surface tension and tries to ball up during the firing step. Other issues arise from dissolution of the Si-Al interface and entrapment of glass within the Si-Al alloy. Si diffusion into Al can be applied to control the melt, while cooling rate can help improve the structure of various regions of the back contact for a favorable series resistance. We also discuss a modified time-temperature profile that can lead to a deep and uniform back-surface field.

Keywords

screen printingdiffusionalloy
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1210: Symposium Q – Photovoltaic Materials and Manufacturing Issues II , 2009 , 1210-Q05-02
Copyright
Copyright © Materials Research Society 2010

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References

1 Mehta, V. Sopori, B. Rupnowski, P. Moutinho, H. Shaikh, A. Khadilkar, C. Bennett, M. and Carlson, D. Mater. Res. Soc. Symp. Proc. 1123, Pittsburgh, PA, 2008, pp. 7–11.Google Scholar
2 Plekhanov, P.S. Negoita, M.D. and Tan, T.Y. J. App. Phys. 90, 5388 (2001).Google Scholar
3 Meemongkolkiat, V. Nakayashiki, K. Kim, D.S. Kopecek, R. and Rohatgi, A. J. Electrochem. Soc. 153, 1, G53 (2006).Google Scholar
4 Huster, F. Proc. 20th European Photovoltaic Solar Energy Conference, Barcelona, 2005, pp. 1466–1469.Google Scholar
5 Sopori, B. and Mehta, V. Back Al contact formation, to be published.Google Scholar
6 Sopori, B. Mehta, V. Rupnowski, P. Domine, D. Romero, M. Moutinho, H. To, B. Reedy, R., Al-Jassim, M., Shaikh, A. Merchant, N. and Khadilkar, C. Proc. 22nd European Photovoltaic Solar Energy Conference, Milano, 2007, pp. 841–848.Google Scholar
7 Murray, J.L. and McAlister, A.J. Bull. Alloy Phase Diagrams 5, 74 (1984).Google Scholar
8 Sopori, B. Mehta, V. Fast, N. Moutinho, H. Domine, D. To, B. and Al-Jassim, M., Proc.17th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, Vail, 2007, pp. 222–227.Google Scholar
9 Alamo, J.D. Eguren, J. and Luque, A. Solid-State Electron. 24, 415 (1981).Google Scholar
10 Narasimha, S. Rohatgi, A. and Weeber, A.W. IEEE Trans. on Electron Devices 46, 7, 1999, pp. 1363–1369.Google Scholar
11 Amick, J.A. Bottari, F.J. and Hanoka, J.I. J. Electrochem. Soc. 141, 6, 1577 (1994).Google Scholar
12 McCaldin, J.O. and Sankur, H. Appl. Phys. Lett. 19, 12, 524 (1971).Google Scholar
13 Sopori, B. Mehta, V. Guhabiswas, D. Reedy, R. Moutinho, H. To, B. Shaikh, A. and Rangappan, A., Proc 34th IEEE Photovoltaic Specialists Conference, Philadelphia, 2009, pp. 1963–1968.Google Scholar