Ribbon Silicon

Ribbon Silicon
Although single-crystal silicon technology is well developed,the Czochralski and float-zone processes are complex and expensive (as are the ingot -casing processed discussed under multicrystalline silicon)Another group of crystal-producing processed,however ,goes by the general name of "ribbon growth" .The single crystal may cost less than other processes, because thy form the silicon directly into thin,usable wafers of single-crystal silicon.these methods involve forming .Thin crystalline sheets directly,thus avoiding the slicing step required of cylindrical rods.
One"ribbon growth"technique-edge-defined film-fed growth starts with two crystal seeds that grow and capture a sheet of meterials between them as they are pulled from a source of moltem silicon.A frame entrains a thin sheet of material when drawn from a melt .This technique does not waste much material,but the quality of the material is not as high as Cz and Fz silicon.

Mulyicrystalline Silicon
Multicrystalline Silicon devices are generally less efficient than those of single-crystal silicon,but they can be less expensive to produce .The multicrystalline silicon can be produced in variety of ways.The most popular commercial methods involve a casting process in which molten silicon is directly cast into a mold and allowed to solidify into an ingot.The starting material can be a refined lower-grade silicon,rether that the higher grade semiconductor grade required for single-crystal material .The cooling rate is one factor that determines the final size of crystals in the ingot and the distribution of impurities.The mold is usually square,producing an ingot that can be cut and sliced into square cells that fit more compactly into a pv module .(Round cells have spaces between them in modules ,but square cells fit together better with a minimum of wasted space)