| 摘要 |
1,137,354. Semi-conductor devices. MULLARD Ltd. 28 March, 1966 [19 Aug., 1965], No. 35625/65. Heading H1K. A semi-conductor device comprises a layer of an A III B V compound epitaxially deposited on a layer of a substituted A III B V compound of narrower band gap formed by diffusing the substituent into an A III B V compound body. In one embodiment indium is diffused into the surface of a tin-doped N-type gallium arsenide wafer to convert it to indium gallium arsenide to a depth of up to 10Á. P-type zinc doped gallium arsenide is then epitaxially deposited from a reaction mixture of hydrogen and the chlorides of gallium and arsenic. Subsequently a silicon oxide layer is deposited by reaction of dry oxygen with tetraethyl silicate and the wafer heated to redistribute the impurities and the diffused-indium. As a result the PN junction is relocated in part of the epitaxial layer converted to indium gallium arsenide by out diffusion of the indium. Holes are etched in the oxide to the epitaxial layer using photoresist techniques and gold-zinc alloy electrode material vapour deposited over it. After covering the alloy in the holes with a cerric resist and removing the remaining alloy the assembly is heated to bond the alloy to the layer and the wafer diced to form individual photo-diodes. These are soldered to headers and encapsulated after removal, if desired, of the oxide masking. Photo-diodes may similarly be formed by deposition of gallium arseno-phosphide on the diffused wafer, or of gallium phosphide on a gallium arsenide wafer surface diffused with phophorus. The junctions may also be used as the collectors of opto-electronic transistors. Thus a P-type collector region may be formed by diffusing indium into the walls of a cavity in one face of a gallium arsenide wafer, the base by epitaxially growing the arsenide in the cavity and the emitter by diffusing acceptor into the base.
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