GB723808A - Signal translating devices utilizing semiconductive bodies - Google Patents

Abstract

723,808. Transistors. WESTERN ELECTRIC CO., Inc. May 2, 1952 [May 5, 1951], No. 11144/52. Class 37. In a transistor comprising a semi-conductive body of the same conductivity type throughout, noise effects are reduced by providing a zone or region of higher conductivity than in the remaining or bulk part and making the collector connection to the high conductivity region. It is stated that in such a transistor interference or noise component charge carriers of like sign to those injected at the emitter and generated sporadically in the bulk part or region are prevented from flowing to the collector by a barrier presented at the interface between or junction of the high/low conductivity regions. The invention is described with reference to N- type semi-conductive material with the high conductivity region denoted by N + and the low conductivity region by N so that interference or noise holes generated sporadically in N are prevented from reaching the collector by the N/N + interface barrier. The N + zone or region may be a crystal boundary. In the example, shown, Fig. 1, a germanium wafer 20 comprises N zones 21, 22 on opposite sides of a narrow N + zone 23 and the collector point 26 bears directly upon the N + zone and the emitter 25 upon N region 21. The ohmic or base electrode consists of coating 24 covering one face of wafer 20. In a second example, Fig. 4, an N-type block 200 has an N + top layer 32 which is receptive of both emitter 25 and collector 26 point contacts and the N region bears on ohmic base 24. An auxiliary point contact may be provided as at 33, Fig. 7, at the N/N + interface and is polarized to control the barrier magnitude. In a further modification to Fig. 4 the two-point contacts 25, 26 bear against the side of the block, as shown, Fig. 6, with 25 bearing against the N region and both adjacent the N/N + interface; an auxiliary connection on the interface as in Fig. 7 may be included. The invention may also be embodied in filamentary transistors as demonstrated in Figs. 8 and 9 wherein the N + zone 32 extends along the filament portion and into one enlarged end portion 35 ; the emitter is a point contact on N + in the filament portion and the collector is a coating on N + in enlarged end portion 35 and the base or ohmic connection is made to the wholly N end portion 34. The invention may be put into effect using silicon instead of germanium. The theory underlying the invention is explained utilizing Fermi-Level diagrams, Figs. 2 and 5 (not shown), and the noise improvements are illustrated with the aid of performance graphs, Figs. 10A and 10B and Figs. 11A and 11B (not shown). Specifications 694,021, 700,231, 700,236, 706,849 and 706,858 are referred to.