Process for producing large-size, self-supporting plates of silicon

A process for producing large-size, self-supporting plates of silicon deposited from the gaseous phase on a substrate body, comprising the steps of:

• heating a graphite substrate to the decomposition temperature of silicon;
• depositing silicon from a gaseous compound to which a dopant of a first conductivity has been added, upon said substrate, in solid form until a layer of about 200 to 600 .mu.m has formed;
• subsequently melting 40-100% of said layer from the free surface downward;
• resolidifying the molten silicon from the substrate body upwardly to the free surface of the molten silicon layer to effect an oriented growth of the resolidifying silicon from the substrate toward the free surface, said resolidifying step being effected by maintaining a vertically directed temperature gradient between the lower surface and the free surface of said molten layer until said molten layer is completely resolidified;
• and
• finally separating the silicon from said substrate.