About this Journal Submit a Manuscript Table of Contents
International Journal of Photoenergy
Volume 2013 (2013), Article ID 724502, 6 pages
http://dx.doi.org/10.1155/2013/724502
Research Article

Material Properties of Laser-Welded Thin Silicon Foils

1Bavarian Center for Applied Energy Research (ZAE Bayern), Haberstraße 2a, 91058 Erlangen, Germany
2Institute Materials for Electronics and Energy Technology (i-MEET), University of Erlangen-Nuremberg, Martensstrße 7, 91058 Erlangen, Germany
3BLZ-Bavarian Laser Center, Konrad-Zuse-Straße 2–6, 91052 Erlangen, Germany
4University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07745 Jena, Germany
5Max-Planck-Institute for the Science of Light, Günther-Scharowsky-Straße 1, 91058 Erlangen, Germany

Received 22 May 2013; Accepted 30 June 2013

Academic Editor: Leonardo Palmisano

Copyright © 2013 M. T. Hessmann et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

An extended monocrystalline silicon base foil offers a great opportunity to combine low-cost production with high efficiency silicon solar cells on a large scale. By overcoming the area restriction of ingot-based monocrystalline silicon wafer production, costs could be decreased to thin film solar cell range. The extended monocrystalline silicon base foil consists of several individual thin silicon wafers which are welded together. A comparison of three different approaches to weld 50 μm thin silicon foils is investigated here: (1) laser spot welding with low constant feed speed, (2) laser line welding, and (3) keyhole welding. Cross-sections are prepared and analyzed by electron backscatter diffraction (EBSD) to reveal changes in the crystal structure at the welding side after laser irradiation. The treatment leads to the appearance of new grains and boundaries. The induced internal stress, using the three different laser welding processes, was investigated by micro-Raman analysis. We conclude that the keyhole welding process is the most favorable to produce thin silicon foils.