| 摘要 |
954,577. Semi-conductor devices. WESTERN ELECTRIC CO. Inc. Feb. 21, 1961 [Feb. 26, 1960], No. 6282/61. Heading H1K. A solid body of gallium arsenide is heated in the presence of a gaseous compound of germanium, silicon or tin to alter the conductivity or conductivity type of at least part of the body. Suitable gaseous compounds are silicon dichloride or tetrachloride, silicon difluoride or tetrafluoride, silane, disilane, and the tetrachlorides of germanium and tin. Apparatus used in the process is preferably made of alumina or molybdenum. Silica is unsuitable because it reacts with the gaseous compounds at the temperatures involved. In one method 5 ohm cm. P-type monocrystalline gallium arsenide slices 16 (Fig. 1) and silicon tetrachloride 13 are sealed into opposite ends of tube 10. After placing the end 12 of the tube in a mixture of acetone and dry ice at - 56‹ C. and allowing 2 minutes to attain equilibrium the narrow part 11 of the tube broken and part 15 is sealed off with silicon tetrachloride at a partial pressure of 8 mm. of mercury therein. The tube is then heated for 24 hours to 820‹ C. or 1100‹ C. to produce an N-type layer on the slices 2Á or 1 mil. thick respectively. Alternatively in a continuous flow method slices 26 (Fig. 2) of P-type gallium arsenide are placed after etching and polishing in tube 20 as shown. After raising the assembly to 600-1200‹ C. the tube is flushed with helium or nitrogen and then a mixture containing 2 vols. silicon tetrachloride to 100 vols. of helium is flowed through the tube for from 1 hour to several days. The resulting N layer may be selectively removed from the bodies to give the required device configurations. Use of the process to give low resistivity contact surfaces on N-type bodies is also suggested. |
