Patent GB-694023-A (GB)
Title: Electric circuit devices utilizing semiconductive materials
IPC: H01L29/00
Filed: 1949-02-25
Abstract: 694,023. Semi-conductor amplifiers. WESTERN ELECTRIC CO., Inc. Feb. 25, 1949 [Feb. 26, 1948; Feb. 26, 1948], Nos. 5203/49 and 5204/49. Class 40 (iv). An electric signal translating device comprises a thin layer of semi-conductor having spaced connections between which a current is passed longitudinally through the layer, and a control electrode, which may comprise an electrolyte, situated so as to apply an electric field to the layer to control its conductivity. Various forms of semi-conductor amplifying arrangements are described. In Fig. 1, a positively-biased source electrode 5, consisting of a rectifier point contact, is placed in contact with a surface layer 2 of N-type silicon provided on a block 1 of P-type silicon material. A high resistance barrier 3 separates the P- and N-types of material. A low resistance contact is pro. vided by a metal film 4 on the block 1, the load circuit RL being connected between electrodes 5 and 4. A control electrode 7 consisting of a metal ring is separated from the surface layer 2 by a thin film 8 of insulating material such as polystyrene, and from electrode 5 by a layer of wax 9. A source of input signals 10 applied to the control electrode 7 results in amplified signals appearing between electrodes 4 and 5 due to the strong field across the layer 2 which control its conductivity. Due to the presence of the high resistance barrier 3, the current from the source electrode 5 tends to spread along the layer 2 before reaching electrode 4, and therefore is influenced by the control effect of electrode 7. In a modification, Fig. 3 (not shown), the control electrode 7 and insulating film 8 are replaced by an electrolyte, such as polymerized glycol borate, connection being established by a metal ring immersed in the electrolyte. Negat. tive bias may be applied, so that there is a strong field at the layer surface, due possibly to the formation of a thin oxide layer by electrolytic action. Positive bias and other electrolytes, such as water, may be used to achieve this effect. Alternatively, the insulating layer' 8 may be dispensed with, and electrode 7 formed by providing a metal film making a high resistance rectifier contact with the layer 2, the electrode then being biased in the reverse current direction. The control electrode 7 may also consist of a ring of semi-conductive material of the opposite conductivity type to that of the layer 2, Fig. 7 (not shown). In place of the block 1 of semi-conductive material, a metal block supporting a thin layer of P or N-type semi-conductor may be used, the large area contact between metal and semiconductor being of the rectifier junction type, which may be produced by pyrolytic deposition of silicon or germanium on to the metal block. Alternatively, as shown in Fig. 5, a block 31 of insulating material may be used, the low resistance contact then being in the form of a ring 32. The control electrode 7 may be placed below the electrode 5 in this arrangement. Fig. 8 shows another arrangement in which a thin layer 82 of semi-conductive material is supported on an insulating block 1, and two spaced electrodes 63, 64 in contact with the layer are interconnected through biasing means. The input signal is applied to a control electrode consisting of an electrolyte 67 which contacts the surface of the semi-conductor 2, and has an embedded grid-like conductor 70. Other arrangements, including alternative biasing conditions, and the use of either P- or N- type material are described. Specifications 592,260, 592,303, 595,601, 632,942, 669,399, 694,021 and 694,022, [all in Group XXXVI], are referred to.