Multicrystalline silicon materials

Cast lead-calcium-tin alloys, 14 775 Cast-link belt furnaces, 12 289 Cast-mature process, in bar soap manufacture, 22 749 Cast multicrystalline silicon material, 23 40... 

As nearly all the developed ribbon silicon growth techniques result in multicrystalline material, crystal defects play a major role in the solar cell efficiencies obtained on ribbon silicon wafers. There is a general trend for higher defect concentrations with faster ribbon growth, but even within wafers of one growth technique, there is an inhomogeneous defect distribution. In this section, we will introduce the known relevant defects for the three materials under closer examination (EFG, SR and RGS) and their impact for solar cell processing. Especially, interaction between different types of defects must be taken into account to understand the behaviour of the different ribbon silicon materials within the cell process. 

Fabrication of solar cells using ribbon silicon wafers has to be adapted to the material needs to reach satisfactory conversion efficiencies. As for all multicrystalline silicon wafers, material quality should be improved during cell processing to cope with the defect structure present in the as-grown material. The implementation of gettering and hydrogenation steps into the solar cell process is, therefore, crucial, as the efficiency obtainable for solar cells from a given material is important for cost-effectiveness. 

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Ferrazza, F. Large size multicrystalline silicon ingots. Proc. E-MRS 2001, Spring Meeting, Symposium E on Crystalline Silicon Solar Cells. Solar Energy Material Solar Cells 2002, 72,77-81. 

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