| 摘要 |
<PICT:0787394/III/1> A single crystal of silicon is obtained by melting and subsequently cooling silicon in a non-reactive atmosphere, while the silicon is supported in contact with substantially pure boron nitride. Specimens of silicon 24 are supported on a slab or boat 19 of alumina, beryllia or zirconia, having a layer 20 of boron nitride, which boat 19 moves along inside a quartz tube 10 through which is passed an inactive gas such as argon or helium. As the boat moves along it passes through a cylinder 16 of tantalum, molybdenum, tungsten, graphite, iridium, osmium, ruthenium or rhenium, which is heated by induction from a coil 15 around the quartz tube 10, to a temperature about 200 DEG C. above the melting point of silicon (1426 DEG C.). The silicon may be prepared by reacting silicon tetrachloride with zinc vapour, which produces polycrystalline silicon which is powdered and pressed into the shape required and sintered. Donor or acceptor metals may be added to the silicon powder before pressing, or the metals may be added to the silicon by exposure to the metal vapour in the melting zone of the tube.
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