Low-Cost High Efficient Multicrystalline Silicon for Photovoltaics

Bayer AG / Bayer Solar is the largest commercial producer of multicrystalline silicon

wafers (Baysix) for photovoltaic applications. For fabrication of the wafers mainly the blockcasting

technology is employed. Baysix represents a material with outstanding quality

properties; several research groups already have achieved efficiencies well above 16 %. In

addition to the block-casting production facility a smaller casting unit is used for research

purposes concerning e.g. novel feedstock sources or improved processing sequences. A large

variety of characterisation techniques is used in the Bayer research labs at the Uerdingen site.

The characterisation tools are applicable to as-grown wafers (e.g. high resolution resistivity

and lifetime maps) as well as solar cells (e.g. electrical characterisation, locally resolved

measurements of all relevant solar cell parameters) and include a Bayer-own test solar cell

process as well.

In this paper we describe shortly the techniques used in the production of

multicrystallin Silicon (mc-Si) solar cells and the experimental techniques used in the solar

cell characterisation who will be used during the project.

Solar cell processes are designed for our wafers at independent research institutes

(FhG, ISE, Freiburg and UKN, Konstanz) and some results will be shown.