By Dietmar Kohler, University of Konstanz; Sven Seren, ‘New Materials’ Group Leader, University of Konstanz; Bernd Raabe, 'Novel Silicon Solar Cell Concepts' Group Leader, University of Konstanz
Upgraded metallurgical-grade silicon (UMG-Si), once looked on as a cost-effective and energy-efficient alternative to Si produced via the Siemens route, has experienced a severe regression of late. This has been caused both by the market conditions and by specific physical properties of these materials. Meanwhile, the qualities and the rated influence of negative physical effects have changed partially. Hopes are again rising that these materials, which have to be compensated to meet the desired net doping specifications, might achieve an economical breakthrough instead of long-dreaded low breakdown voltages. In the following paper, we summarize a few of our results on multicrystalline UMG silicon as well as results published by other research groups in the last few years.