| 摘要 |
A photosensitive device of the face illumination type (see Group XL(b)) comprises a main body of p- or n-type material, having a thin film of the opposite type material on one face, the photo-voltaic barrier being between the body and the film. Electrical contact is provided by a metallic ring and a metallic film secured to opposite faces of the body, and the metallic film may be made from a heat cured silver paste comprising finely divided silver, a small amount of binder, and a volatile solvent. p The photo-cell element may be made from a piece of p-type silicon containing an acceptor impurity such as boron, by surface treatment with a donor impurity such as phosphorus, as by sealing the p-type silicon in an evacuated silica tube with some yellow phosphorus and heating. The body thus treated exhibits a bluish film which has n-type rectification properties. Alternatively p-type silicon containing boron and phosphorus is polished and heat treated in water saturated air or steam and the resulting oxide layer etched off with a hydrofluoric acid solution, boron being removed by selective oxidation from the surface of the material. Several such treatments may be required to produce an n-type film on the surface.
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