Semiconductor Devices

摘要

1,176,950. Electroluminescence. WESTERN ELECTRIC CO. Inc. 18 April, 1967 [26 April, 1966], No. 17722/67. Heading C4S. [Also in Divisions C1 and H1] A PN junction light-emitting diode is formed in a body of III-V compound material containing bismuth as an impurity with a concentration in the range 1016 to 1019 atoms/cm3. The material is of crystalline form grown from a melt containing one or more III-V compounds and an appropriate proportion of bismuth. The presence of the bismuth in the melt is found to increase the efficiency of crystal growth -e.g. for a quoted gallium phosphide crystal forming technique the presence of bismuth produces a five-fold increase in the volume of the resulting crystal. Conductivity determining impurities, e.g. group IV elements, may also be added to the melt, and the PN junction formed by diffusion of further impurity into the resulting crystal. The drawing (not shown) depicts successive stages in the manufacture of a lightemitting diode by diffusion of zinc into the surface of an N-type crystal of bismuth-doped gallium phosphide. The doped crystal is shaped by largely conventional techniques so as to constitute a plurality of mesa diodes. The III-V compounds from which the crystal may be made are the nitrides and phosphides of Ga, Al, In, B and III-V compound mixtures of which gallium arsenide-gallium phosphide alloy is quoted as an example. The preferred crystal-forming method is to form a first melt of elementary Ga Al, In, B or a mixture of them, add to this melt a III-V compound and crystallize out from the resulting mixed melt. The bismuth, whose proportion is 0À01 to 99% of the total quantity of bismuth plus first-melt elements, may be added to the melt either before or at the same time as the III-V compound. S, Se and Te may be used as additional dopants.