Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-25T16:41:41.706Z Has data issue: false hasContentIssue false
  • English
  • Français

Studies on Backside Al-Contact Formation in Si Solar Cells: Fundamental Mechanisms

Published online by Cambridge University Press:  21 March 2011

Bhushan Sopori ,
Vishal Mehta ,
Przemyslaw Rupnowski ,
Helio Moutinho ,
Aziz Shaikh ,
Chandra Khadilkar ,
Murray Bennett  and
Dave Carlson
Bhushan Sopori
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401, USA
Vishal Mehta
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401, USA
Przemyslaw Rupnowski
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401, USA
Helio Moutinho
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401, USA
Aziz Shaikh
Affiliation:
Ferro Electronic Materials, Vista, CA 92083, USA
Chandra Khadilkar
Affiliation:
Ferro Electronic Materials, Vista, CA 92083, USA
Murray Bennett
Affiliation:
BP Solar, Frederick, MD 21703, USA
Dave Carlson
Affiliation:
BP Solar, Frederick, MD 21703, USA
Get access

Abstract

We have studied mechanisms of back-contact formation in screen-printed Si solar cells by a fire-through process. An optimum firing temperature profile leads to the formation of a P-Si/P+- Si/ Si-Al eutectic/agglomerated Al at the back contact of a Si solar cell. Variations in the interface properties were found to arise from Al-Si melt instabilities. Experiments were performed to study melt formation. We show that this process is strongly controlled by diffusion of Si into Al. During the ramp-up, a melt is initiated at the Si-Al interface, which subsequently expands into Al and Si. During the ramp-down, the melt freezes, which causes the doped region to grow epitaxially on Si, followed by solidification of the Si-Al eutectic. Any agglomerated (or sintered) Al particles are dispersed with Si. Implications on the performance of the cell are described.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1123: Symposium P – Photovoltaic Materials and Manufacturing Issues , 2008 , 1123-P07-11
Copyright
Copyright © Materials Research Society 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Alamo, J. D., Eguren, J., and Luque, A., Solid-State Electron. 24, 415 (1981).Google Scholar
2. Khadilkar, C., Kim, S., Shaikh, A., Sridharan, S., and Pham, T., Tech. Digest. of International PVSEC- 15, (2005).Google Scholar
3. Kaminski, A., Vandelle, B., Fave, A., Boyeaux, J.P., Nam, L. Q., Monna, R., Sarti, D., and Laugier, A., Solar Energy Materials & Solar Cells 72,373 (2002).Google Scholar
4. Narasimha, S., Rohatgi, A., and Weeber, A. W., IEEE Trans. on Electron Devices 46(7), 1363 (1999).Google Scholar
5. Huster, F. and Schubert, G., 20th European Photovoltaic Solar Energy Conference and Exhibition, Barcelona, 2DV2.48, 6–10 June (2005).Google Scholar
6. Lin, C.H., Tsai, S. Y., Hsu, S. P., and Hsieh, M. H., Solar Energy Materials & Solar Cells 92, 986 (2008).Google Scholar
7. Sopori, B., Mehta, V. R., 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, Milan, 841(2007).Google Scholar
8. Cudzinovic, M. and Sopori, B., Proc. 25th IEEE PVSC, 501 (1996).Google Scholar
9. 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, Colorado, 222 (2007).Google Scholar
10. Murray, J. L. and McAlister, A. J., Bull. Alloy Phase Diagrams 5, 74 (1984).Google Scholar