JPH0260177A - Superconductive transistor - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of a transistor of this design by a method wherein a source and a drain branch electrode are provided to a place where superconductors face each other, and a central part of an insulated non-superconductor penetrating through the superconductor and a control means which controls the current density of the central part are provided between the electrodes. CONSTITUTION:A superconductor film 1 and an insulating film 4 are formed on a substrate 7, the superconductor film 1 is removed from the part which is to be a central part 5, and non-superconductors is filled into the above part. And, openings of a source 2 and a drain 3 are bored in the insulating film 4 and electrodes are built after a coil 6 of superconductor has been formed on the insulating film. In this structure, the current, ramified off through the central part 5 to flow through the superconductive section 1, is affected by the interference action of a magnetic field potential induced by a flux of the central part 5 due to an Aharonov-Bohm effect, the current flowing between the source 2 and the drain 3 is made to vary periodically and repeatedly in quantity basing on each certain increase of the flux density of the central part 5, so that the current can be made to vary by controlling the flux which is induced by the control coil 6.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to the construction of a high-speed transistor having superconducting properties.

<Conventional technology> Conventionally, Si and G were used as current and voltage switching elements.
A transistor using a semiconductor such as aAs.

There are Josephson devices that use superconducting properties, and superconducting transistors that combine superconductors and normal semiconductors are also being developed.

<Problems to be solved by the invention> Semiconductor transistors are characterized by the fact that normally conductive semiconductors always have electrical resistance (R), and that the capacitance (C) can be increased by their junction or by the structure with an insulating film interposed. Motsukotokara RC
There was a delay in transmission due to this, which hindered speeding up.

Josephson devices capable of high-speed operation also have the drawbacks of requiring extremely advanced technology to fabricate an insulating film of several 1 OA that is interposed in a superconductor, that they are not easy to handle, and that their output level is low.

Various configurations have been considered for transistors that combine superconductors and normal conductor semiconductors, but it is difficult to create a Josephson junction in a superconductor and a junction between a superconductor and a semiconductor. In addition, the need for ultra-fine processing has hindered its practical application.

An object of the present invention is to provide a superconducting transistor that solves the above-mentioned problems of conventional switching elements such as superconducting transistors.

Means for Solving the Problems> The superconducting transistor of the present invention is a high-speed transistor that takes advantage of the zero electrical resistance property of a superconductor. An electrode is provided between the source and drain of the superconductor, and the central part of the non-superconductor is insulated from the superconductor, and a control means such as a coil that increases or decreases the magnetic flux density in the central part is provided. It has a long structure.

In the superconducting transistor with the above configuration, when an external power source is connected to the source and drain and the magnetic flux density of the non-superconducting part provided in the center is changed, the central part The shunted current flowing through the superconducting part is subject to the interference effect of the magnetic field potential due to the magnetic flux in the center due to the Ahranov-Bohm effect, and the current flowing between the source and drain has a periodicity every time the magnetic flux density in the center increases. Therefore, if the magnetic flux generated in the control coil is controlled between the maximum and minimum values of the current flowing between the source and drain, the current can change according to the magnetic flux, resulting in a super It can operate as a conductor transistor.

The above operation is shown in Figure 2, where the wave functions of the two superconducting electron streams separated at the central part made of non-superconducting material are denoted by 1 and φ2, respectively, and the wave function of the superconducting electron stream at the drain is Let Lp be Lp, and the magnetic flux penetrating the central part be Φ, then the superconducting electron flow flowing through the superconductor circuit will be in a state expressed by the following formula: Oh is the blank constant, e is the electron charge, and C is the speed of light.

Re is the real part symbol, and * is the el sheet conjugate symbol.

From the above equation, we can see that the drain current can be changed by the magnetic flux Φ controlled by the coil, and from this characteristic it can be used in the same way as a conventional transistor.

<Example> Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of one embodiment of the present invention, in which Yx Ba2Cu30y-y (0<, 5<+
) is formed, and the thin film 1 is
An insulating film 4 of alumina was formed thereon, and then the superconducting film in the portion that would become the central portion 5 was removed by photolithography and etching, and the hole was filled with alumina by the CVD method. Furthermore, a superconducting coil 6 is formed on the insulating film 4 by growing a superconducting film, photolithography and etching.
After forming Ti, which has good adhesion to the ceramic superconductor, openings for the source 2 and drain 8 are made in the insulating film 4.
A superconducting transistor 8 was completed by vaporizing the material to form electrodes and connecting lead wires with silver paint.

The fabricated superconducting transistor is cooled to below the critical temperature Tc of its superconductor portion, the current between its source and drain is set to such an extent that it can operate below the critical current Jc of the superconductor film 1, and the coil 6 is connected to the central When the magnetic flux of part 5 was changed, it was possible to measure that the drain current increased and decreased at a constant period as the magnetic flux density increased. This means that when the magnetic flux is decreased, periodic increases and decreases in the drain current can be measured in the same way as when the magnetic flux is increased.

The present invention has been described above according to examples, but the present invention
Not limited to the examples, superconductors may also be B i −
8r -Ca-Cu-0 series or T7? -Ba-Ca-Cu
Ceramic superconductors such as -0 series, the father is Pb.

Elemental superconductors such as Tc, Nb3Ge, Nb3
A compound superconductor such as Ga may be used, and the substrate may also be SrTiO.
3° Al t 03 or the like may be used, and the effects of the invention can be obtained even if the shape of the superconducting transistor 8 is arbitrarily modified within the scope of the operation of the invention.

<Effects of the invention> A high-speed operation transistor that controls superconducting electrons can be manufactured without using special technology by using magnetic flux control by the Ahranov-Bohm effect, and its use is also easy. It became 0

[Brief explanation of the drawing]

@ Figure 1 is a perspective view of an embodiment of the superconducting transistor of the present invention, and Figure 2 is a diagram for explaining the operating principle of the superconducting transistor of the present invention. ! ...superconductor, 2...source, 3...drain. 4... Insulating film, 5... Central part, 6... Coil. 7... Board. Agent Patent attorney Takeshi Sugiyama (and 1 other person) Figure 2

Claims (1)

[Claims] 1. A ring-shaped superconductor having a non-superconducting part formed at least around the center with an insulating film, with source and drain electrodes sandwiching the center part; A superconducting transistor characterized in that it is provided with means for controlling magnetic flux in a central portion. 2. The superconducting transistor according to claim 1, wherein the means for controlling the magnetic flux in the central portion comprises a coil formed of a superconductor.