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New improvements in industrial growth of silicon mono crystals for solar application by using Magnetic-Cz

Alexander Molchanov 1Frank Mosel 1Alexey V. Denisov 1Albrecht Seidl 2

1. PVA TePla AG, Im Westpark 10-12, Wettenberg 35435, Germany
2. Schott Technology Center Crystals, Ilmstr. 8, Jena 07749, Germany

Abstract

Solar industry requires further increasing of solar cell efficiency and reduction of production costs.

The quest for the improvement of solar cell efficiency is the intention for the Magnetic Czochralski (MCZ) growth of mono crystals for the PV industry. It is established that a steady magnetic field damps the convective melt flow and hence affects the oxygen concentration in the crystal which influences the cell efficiency.

A superconducting magnet in a CUSP configuration was installed on a Czochralski puller for the growth of silicon mono crystals. For investigation several boron-doped silicon crystals were grown. Different field configurations with respect to the field strength and the position of the symmetry line of the cusp field were applied. Additionally other growth parameters which affect the crystal quality were modified in order to find the best interaction of all these parameters for the production of high efficiency solar cells. Also importance was attached to high growth productivity.

We report in detail about the equipment configuration and the process parameters which were successfully applied resulting in high quality crystals. Complete characterisation of the ingots especially with respect to the oxygen distribution and finally to the cell efficiency is presented.

High quality crystals for the production of high efficiency cells can be grown by the application of a cusp magnetic field. It is shown that the additional investment and the operation costs of the superconducting magnet can be compensated by improved operational conditions and a high quality of the substrate material.

Further approaches and special tools to increase the productivity and to reduce the production costs of Cz-Si for PV will be presented and discussed.

 

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Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 5, by Alexander Molchanov
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-16 14:28
Revised:   2013-04-16 14:32