Square-shaped silicon crystal rod growth by the FZ method with special 3D shaped HF inductors

A. Muiżnieks¹ - A. Rudeviċs¹ - K. Lācis¹ - H. Riemann² - A. Ludge² - F. W. Schulze³ - B. Nacke⁴

¹ Faculty of Physics and Mathematics, University of Latvia 8 Zellu str., LV-1002 Riga, Latvia
² Institute for Crystal Growth, Max-Born-Str. 2, D-12489 Berlin, Germany
³ PV Silicon AG, Wilhelm-Wolff-Str. 25, D-99099 Erfurt, Germany
⁴ Institute for Electrothermal Processes University of Hannover, Wilhelm-Busch Str. 4, D-30167 Hannover, Germany

Abstract
The use of square-shaped silicon crystals instead of circular-shaped ones as a raw material for the production of solar cells can reduce material loss and save processing steps of cutting round rods to the quadratic shape. The experimental work carried out by the Silicon crystals group at the Institute for Crystal Growth (Berlin, Germany) has shown for the first time that it is possible to grow squared silicon crystals by using an especially shaped HF inductor in the FZ method without crystal rotation. To support the experimental work, a chain of mathematical models for 3D modelling of phase interfaces for the molten zone is created at the University of Latvia and implemented in a specialized software package Shape3D. This allows to study and analyze numerically the features of the squared crystal growth process. Figs 18, Refs 12.