1. Field of the Invention
The invention relates to the production of silicon bodies and somewhat more particularly to a process and apparatus for producing plate-shaped silicon bodies useful in solar cell manufacture.
2. Prior Art
In the production of solar cells comprised of large-surface silicon slabs or plates, the cheapest available silicon material is desired. The quality of the silicon material which is used in producing solar cells, especially the crystal quality thereof, is not overly critical, for example, as in instances where silicon material is used to manufacture electrical components.
A typical prior art process of producing silicon slabs for solar cells comprises growing a large cylindrical monocrystal of silicon by slowly withdrawing a seed crystal from a silicon melt and slicing this monocrystalline rod into thin slabs or the like. The flat surfaces of each slab is then polished or otherwise treated to remove surface irregularities.
German Pat. No. 1,555,916 suggests that plate-like silicon bodies may be produced by heating a silicon rod sufficiently to render such rod ductile and subjecting such ductile rod to a rolling or forging process so as to convert the rod into a flat sheet-like body from which silicon plates or the like may be severed. In this process, the starting rod is a monocrystal so that the ultimately produced silicon plates retain at least some monocrystalline characteristics during the transformation of the rod into a ductile condition and during the subsequent rolling or forging. While substantial crystal disorder in the so-processed structures occurs, such disorder is readily removed by subsequent annealing processes.