GB1242731A - Negative resistance element and its application - Google Patents

Abstract

1,242,731. Bulk negative reistance device. JAPAN, AGENCY OF INDUSTRIAL SCIENCE & TECHNOLOGY MINISTRY OF INTERNATIONAL TRADE & INDUSTRY. 22 Aug., 1968 [22 Aug., 1967; 27 Nov., 1967 (4); 29 Nov., 1967; 26 Dec., 1967; 8 March, 1968 (5); 21 March, 1968; 23 April, 1968; 5 July, 1968], No. 40199/68. Heading H1K. A bulk negative-resistance device consists of a two valley semi-conductor with ohmic electrodes adjacent its ends and a layer of high dielectric constant insulation disposed on the body between the ohmic electrodes. This serves to prevent the formation of high field domains in the body. Typically the body is of gallium arsenide and the insulation barium titanate. The body may be flat with insulation formed on or inset in one or both faces, a rod surrounded by a sleeve of insulation or a Y- or H-shaped member of circular or laminar cross-section with an ohmic contact at the end of each arm. Preferably the insulation extends into contact with the ohmic contacts and in this case to prevent the output being shunted through it the insulation may be divided by one or more lateral slots. Instead of extending the insulation in the above manner the cross-section of the ends of the body adjacent the cathode or both ohmic contacts may be increased by a gradual or stepwise increase in thickness or width of the body there. In all cases a fixed D.C. bias is applied between the terminal ohmic contacts and the input signal fed to one contact and output taken from the other. Alternatively capacitive or waveguide input and output arrangements are provided adjacent these contacts. For higher power a parallel-connected stack of devices with common electrodes is used. One or more control electrodes may be disposed on each discrete area of insulation in any of the above configurations. A device adapted for insertion between the conductors of a strip transmission line is also described. In this case, with the device acting as an amplifier the amplification is determined by the length of the body and electron density. To achieve higher amplification factors for a given applied voltage a plurality of devices may be mounted in series along the strip line, mutually spaced by layers of insulation. The ends of the body are preferably tapered to reduce reflections at the semiconductor air interfaces.