| 摘要 |
853,365. Semi-conductor devices. WESTINGHOUSE ELECTRIC CORPORATION. May 20, 1959 [May 29, 1958], No. 17139/59. Class 37 A silicon-carbide semi-conductor device has a junction including iron as a significant N-type conductivity impurity. In an example a P-type silicon-carbide single crystal obtained by nucleation and growth from silicon vapour in an aluminium-containing argon atmosphere was used. The crystal was out to about #" diameter and to a thickness of between 0 À01 and 0 À03 inches. The side chosen for the junction was lapped with diamond powder to a symmetrical roughness, cleared in carbon tetrachloride and dilute hydrofluoric acid and laid in a graphite boat with the roughened side uppermost. A one mil thick iron wire was laid on this surface and the boat was placed in a vacuum furnace. The pressure was lowered to 10-4 mm. of mercury and a temp. of 1600 ‹C. maintained for half an hour. The temperature was then raised to 2000 ‹C. for one minute to evaporate excess iron. To avoid silicon carbide decomposition the furnace may be pressured with argon and a piece of silicon vapourised.
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