GB1113442A - Electrical signal translating apparatus - Google Patents

Abstract

1,113,442. Semi-conductor devices. INTERNATIONAL BUSINESS MACHINES CORPORATION. 21 May, 1965 [12 June, 1964], No. 21756/65. Heading H1K. An electric field in excess of a threshold value applied to a body of Ga As or like polar semiconductor produces in the body an abrupt fall of conductance, in a time of the order of 10<SP>-10</SP> seconds, which can give rise to current fluctuations at microwave frequency as described in Specification 1,070,261. The fall in conductance is associated with the formation, adjacent the cathode terminal of such a body, of a localized region or domain of abnormally high electric field and this domain propagates towards the anode terminal where it is dissipated. The current fluctuations described in the abovementioned prior Patent are shown to be the consequence of successive transits of such domains through the body. The invention exploits this new understanding of the effect, and its claims relate to a system in which the body has at least three electrodes which are selectively energized to produce appropriate fields in the body. Other aspects of the subject matter are claimed in Specifications 1,113,443, 1,113,444, 1,113,445, 1,113,446 and 1,113,447. The description with respect to Figs. 1 to 3 (not shown) recapitulates the subject matter of Specification 1,070,261 and Figs. 4 to 7 (not shown) illustrate experiments which have been performed to establish the physical mechanism of the effect. Fig. 8 (not shown, but see Specification 1,113,444) depicts input voltage and output current pulse shapes related to the use of the effect to produce a single domain transit, i.e. pulsed operation. Figs. 9a to 9c (not shown) depict diagrammatically various electrode configurations and Figs. 10 and 11 (not shown) input and output pulse shapes obtainable by their use. In particular, a voltage less than that necessary to establish the required threshold field may be applied between two electrodes and a domain initiated by applying an appropriate potential to a third electrode. Fig. 12 shows a suitable three-electrode device consisting of a wafer 10 with a terminal 48 connected to a contact covering one surface of the wafer, and terminals 46, 47 connected to contacts on the opposite wafer surface which are made by covering this surface with metal and then cutting a slot 49 to separate this covering into two electrodes. Figs. 13 to 17 (not shown, but see Specifications 1,113,443, 1,113,445 and 1,113,446) depict bodies of irregular shape and/or non-uniform resistivity, and systems exploiting such bodies, e.g. as logic elements.