Silicon Ribbons for Solar Cells

Multicrystalline silicon materials hold a dominant position in providing wafers for the solar cell manufacturing industry. These materials contain impurities and defects several orders of magnitude greater than those found in single crystal silicon because the methods of crystallization are chosen to achieve cost-effective products. Bulk lifetime in these materials is significantly compromised as a result. Over 10 % of multicrystalline silicon wafer production currently comes from silicon ribbon. Success in ribbon wafer commercialization has been achieved with the development of bulk material upgrading processes for the as-grown lifetime that allows competitive cell performance to be attained. This paper examines material issues related to achievement of good bulk properties and cell efficiencies in one such multicrystalline solar material- ribbon produced by the Edge-defined Film-fed Growth (EFG) method.