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International Journal of Photoenergy
Volume 2013, Article ID 583867, 7 pages
Research Article

Isolation of III-V/Ge Multijunction Solar Cells by Wet Etching

1Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, QC, Canada J1K OA5
2Laboratoire Nanotechnologies Nanosystèmes (LN2)-CNRS UMI-3463, Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, QC, Canada J1K OA5
3Cyrium Technologies Inc., 50 Hines Road, Suite 200, Ottawa, ON, Canada K2K 2M5

Received 4 September 2013; Revised 31 October 2013; Accepted 31 October 2013

Academic Editor: Mahmoud M. El-Nahass

Copyright © 2013 A. Turala 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.


Microfabrication cycles of III-V multijunction solar cells include several technological steps and end with a wafer dicing step to separate individual cells. This step introduces damage at lateral facets of the junctions that act as charge trapping centers, potentially causing performance and reliability issues, which become even more important with today’s trend of cell size reduction. In this paper we propose a process of wet etching of microtrenches that allows electrical isolation of individual solar cells with no damage to the sidewalls. Etching with bromine-methanol, the solution that is typically used for nonselective etching of III-V compounds, results in the formation of unwanted holes on the semiconductor surfaces. We investigate the origin of holes formation and discuss methods to overcome this effect. We present an implementation of the isolation step into a solar cell fabrication process flow. This improved fabrication process opens the way for improved die strength, yield, and reliability.