Abstract: It is desirable to coat large area, thin sheets of large-grain polycrystalline silicon on an inexpensive ceramic substrate for use in solar cell applications and the like. Such ceramic substrate as are used are chosen from those having thermal expansion coefficients similar to those of silicon. The ceramics meeting these requirements, for example mulite, alumina and zirconia, when brought into contact with molten silicon, however, are not wet by the silicon and no coating takes place. In this invention the structure includes an interface layer comprising carbon on the surface of such a substrate to render the surface wettable by molten silicon. With this interface layer the ceramic of the type which is not wet by molten silicon can be successfully coated with silicon.

Abstract: When electrically insulating ceramic substrates are coated with silicon by any of a number of methods that brings the substrate into contact with molten silicon, electrical contact can only be made conveniently to the exposed surface of the silicon coating. This invention teaches an improvement for making electrical contact to the interface surface of the silicon. It was discovered that by providing narrow slits or small holes in the ceramic substrate that upon coating the substrate with molten silicon, molten slicon will wick through the slits or holes to the uncoated surface of the ceramic.

Abstract: It is desirable to coat large area, thin sheets of large-grain polycrystalline silicon on an inexpensive ceramic substrate for use in solar cell applications and the like. Such ceramic substrates as are used are chosen from those having thermal expansion coefficients similar to those of silicon. The ceramics meeting these requirements, for example mullite, alumina and zirconia, when brought into contact with molten silicon, however, are not wet by the silicon and no coating takes place. In this invention the method of coating includes the step of carbonizing the surface of such a substrate and then contacting the carbonized surface of the ceramic with the molten silicon, whereupon a large-grain silicon coating is produced wherever the ceramic is carbonized. In this way the ceramic of the type which is not wet by molten silicon can be successfully coated with silicon.