Patent GB-700232-A (GB)
Title: Electric circuit elements, devices and systems utilizing semiconductive bodies
IPC: H01L29/02
Filed: 1949-08-12
Abstract: 700,232. Semi-conductor amplifiers. WESTERN ELECTRIC CO., Inc. Aug. 12, 1949 [Aug. 14, 1948 ; Aug. 19, 1948], Nos. 21020/49 and 21021/49. Class 40 (4) [Also in Groups XXXVI and XL (c)] An electric circuit element for translating electrical signals comprises a semi-conductor body having an ohmic connection and two opposed faces each engaging a rectifying contact, the thickness of the material between the rectifying contacts being very small so that current emitted from one contact is collected by the other. The device may be used for amplifying or generating oscillations. In Fig. 1,  a wedge-shaped piece 11 of semi-conductive material is mounted on a rod 14, and wire contacts 12, 13 are mounted on rods 15, 16 for engagement with the faces of the semiconductor. The rods 14, 15 and 16 are slidable in bores in a block of insulating material 10 and are maintained in their adjusted position by set screws 17. Electrodes 12 and 13 may act as the emitter and collector electrodes and the rod 14 as the base electrode, whereby with suitable biassing conditions signals applied between the emitter and base electrode appear in amplified form in the collector electrode circuit. In a modification, the semiconductor wedge is mounted in and connected to a tubular metal housing, the rods supporting the rectifying electrodes being supported by insulator blocks fixed in the housing. Fig. 5 shows an alternative arrangement in which a semi-conductive disc 40 with two concave surfaces is mounted in a metal cylinder 43 and maintained in position by spring washer 44. Insulating members 45, 46 secure cylinder 43 in position with respect to the terminal members 47, 48 which support the rods bearing contacts 41 and 42. The semi-conductor disc may alternatively be of plano-concave formation or a thin slab. The device may be connected as an amplifier in some intermediate position in a coaxial line, the bias sources being located at the distant ends of the line. The device may also act as an oscillator, and if the resistance between the base electrode and the rectifying contact region of the semi-conductor is of proper value, positive feedback occurs without the need for any other intercoupling means. The semi-conducting material may consist of N or P-types of either germanium or silicon. A suitable etching and washing process and an electrical forming treatment are described. The collector is biased in the direction of difficult current flow and the emitter in the direction of easy current flow, but owing to potential variation in the body of the block this may mean that the emitter is biassed in the same direction as the collector with respect to the base electrode. The rectifying contact for the collector and the emitter may be provided by means of metallic point contacts, or by having ohmic contacts which engage a region of material of conductivity type opposite to that of the main block of semi-conductor, and this region may be produced by the exchange of material between the contact point and the body during current flow. The element of ;the device may be adjusted during assembly with the aid of an oscilloscope, and visual orifices in the housing or insulator blocks may also be provided for this purpose. Specfications 694,021 and 700,231, [Group XXXVI], are referred to.