Characterization of Laser Doped Silicon and Overcoming Adhesion Challenges of Solar Cells with Nickel-Copper Plated Contacts

The combination of localized laser patterning and metal plating allows to replace conventional silver screen printing with nickel-copper plating to form inexpensive front contacts for crystalline silicon solar cells. In this work, a focus is put on effects that could cause inhomogeneous metal deposition and low metal contact adhesion. A descriptive model of the silicon nitride ablation mechanism is derived from SEM imaging and a precise recombination analysis using QSSPC measurements. Surface sensitive XPS measurements are conducted to prove the existence of a parasitic surface layer, identified as SiOxNy. The dense SiOxNy layer is an effective diffusion barrier, hindering the formation of a nickel silicide interlayer. After removal of the SiOxNy layer, cells show severe degradation caused by metal-induced shunting. These shunts are imaged using reverse biased electroluminescence imaging. A shunting mechanism is proposed and experimentally verified. New laser process sequences are devised and proven to produce cells with adhering Ni-Cu contacts. Conclusively the developed processes are assessed based on their industrial feasibility as well as on their efficiency potential.

Product details

• Authors: Christian Geisler
• Assisted by: Freiburg/Brsg. Fraunhofer ISE (Editor)
• Publisher: Fraunhofer Verlag
• Languages: English
• Product format: Paperback / Softback
• Released: 01.01.2015
• EAN: 9783839609163
• ISBN: 978-3-8396-0916-3
• No. of pages: 195
• Illustrations: num., mostly col. illus. and tab.
• Series: Solare Energie- und Systemforschung / Solar Energy and Systems Research,
• Subject: Natural sciences, medicine, IT, technology > Technology