ABSTRACT
This chapter shows the properties of large grain polycrystalline materials which are strongly influenced by the presence of extended defects, which, in turn, are a consequence of the rather high growth rate of the casting processes. In spite of the presence of extended defects and of a great number of recombination centers due to the interaction between defects and impurities, large grain polycrystalline silicon is neverthess the best material to prepare low cost solar cells, and thanks to the use of simple upgrading techniques the way to achieve high conversion efficiencies is opened. Oxygen and carbon in various amounts which depend on the type of process used to cast it, are the major contaminants of polycrystalline silicon. In fact, depending on the relative concentration of oxygen and carbon, both the density and the recombination activity of intragrain defects could be very different.
