JPH01202874A - Superconductor element - Google Patents

Abstract

PURPOSE:To obtain a circuit having high gains by forming an injection electrode injecting main carriers bearing the superconduction of a superconductor layer to the superconductor layer. CONSTITUTION:Two electrodes 4a, 4c are disposed at both ends of a ceramic superconductor layer 2 having low carrier concentration, and at least one injection electrode 3 injecting main carriers bearing superconduction is shaped along the superconductor layer 2. Consequently, when fixed bias voltage is applied between the two electrodes 4a, 4c and control voltage is applied between one electrode 4a and the injection electrode 3, currents flowing between both electrodes 4a, 4c are little first, and are increased based on injection carriers from injection voltage when control voltage exceeds a threshold, and switching operation is conducted. Accordingly, carrier density is changed by small control voltage, and a switching element controlling superconducting currents is acquired.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Field of Application Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems Action Embodiment An Embodiment of the Present Invention (Figures 1 to 3) Effects of the invention [Summary] A superconductor element that controls superconducting current with a small voltage to perform a switching action, and also makes it possible to create a high gain circuit and increase speed. Two electrodes are arranged at both ends of a ceramic superconductor layer with a low carrier concentration, and at least one electrode is injected along the superconductor layer to inject the main carrier responsible for superconductivity. An injection electrode is provided, and when a predetermined bias voltage is applied between the two electrodes, a current flowing between one electrode and the injection electrode has predetermined switching characteristics based on carriers injected from the injection electrode. Configure it as follows.

[Industrial application field]

The present invention relates to a superconductor element, and more particularly to a superconductor element that is used in logic circuits such as computers, memories, etc., and performs a switching action.

Examples of the switching element include a type that controls a superconducting current flowing between two electrodes by an electric signal applied to another electrode (such as an FET), a Yakyotron, a Josephson element, and the like. By controlling superconducting current using superconducting development, such switching elements can allow current to flow with almost zero voltage when conducting.
A superconducting state (the same state as having no electrical resistance) can be obtained. .

In recent years, switching elements have been required to have higher switching speeds as computers and the like have become faster.

[Conventional technology]

Here, a Josephson element will be explained as an example of a switching element that is advantageous for increasing speed.

Josephson elements are known for their Josephson effect (when two superconductors are brought very close together and electrically conductive, they exhibit superconductivity under conditions where there is a current flowing between them, but under other conditions). A typical structure is one in which a thin (several nanometer) insulating film that allows electron tunneling is sandwiched between electrodes made of super-flattened four bodies.

When this is cooled to an extremely low temperature and a current is passed between the electrodes, no voltage will be generated between the electrodes if the current is below the threshold value, but a voltage will be generated if the current is above the threshold value.

Therefore, it can be seen that the Josephson element has the property of switching from a superconducting state to a voltage state. An integrated circuit can be constructed by utilizing this superconducting state and voltage state.

-i Josephson elements are known to have a short switching time and are advantageous for extremely high speeds (the same applies to integrated circuits made of Josephson elements).

[Problem to be solved by the invention]

However, such conventional Josephson elements have the problem that it is difficult to obtain high gain circuits when used in highly integrated circuits, and with Talaiotrons, the switching speed is slow and high speed cannot be achieved. There was a problem.

In addition, in switching elements such as FET type that use field effect, when used in highly integrated circuits, a considerably large voltage (several volts) is applied to the gate voltage in order to control the superconducting current.
L is several tens of volts, which means it is too high for practical use. ), which is impractical.

Therefore, an object of the present invention is to provide a superconductor element that can control superconducting current with a small voltage to perform a switching action, as well as make it possible to create a high gain circuit and increase speed. .

[Means to solve the problem]

In order to achieve the above object, the superconductor element according to the present invention has two electrodes disposed at both ends of a ceramic-based superflat four-body layer with a low carrier concentration, and a superconductor that is responsible for superconductivity along the superconductor layer. When at least one injection electrode for injecting carriers is provided and a predetermined bias voltage is applied between the two electrodes, the current flowing between one electrode and the injection electrode is based on the carriers injected from the injection electrode. It is made to have predetermined switching characteristics.

[For production]

In the present invention, two electrodes are disposed at both ends of a ceramic superconductor layer with a low carrier concentration, and at least one injection electrode for injecting the main carriers responsible for superconductivity along the superconductor layer. provided. When a predetermined bias voltage is applied between the two electrodes and a control voltage is applied between one electrode and the injection electrode, the current flowing between the two electrodes is initially small and the control voltage exceeds the threshold. If you exceed
Due to the injected carriers from the injected voltage, a large (superconducting state B) switching action takes place.

Therefore, a small control voltage changes the carrier density,
A switching element that controls superconducting current can be realized.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a sectional view showing the structure of an embodiment of a superconductor element according to the present invention. The illustrated example shows a case where the present invention is applied to a voltage-controlled negative resistance element.

In this figure, 1 is a substrate made of, for example, 5rTiO, and 2 is a substrate made of, for example, (Lat-x Snx) z CuOa.
(x = 0.02), the layer thickness is, for example, 5,000 layers, and the carrier concentration is low. 3 is for example (L a l-X S
r X) z Cu Os (x = 0.075)
An injection electrode consisting of a film with a film thickness of, for example, 5000 @
4as4bs4c is an electrode made of, for example, Au.

Note that the emitter electrode here consists of an injection electrode 3 and an electrode 4b. In addition, ceramic-based superconductor layer 2
acts as a medium through which superconducting currents flow and are controlled.

The injection electrode 2 functions as an electrode for injecting the main carriers responsible for the superconductivity of the superconductor layer 2, and is used to increase the carrier density of the superconductor layer 2.

Next, its operation will be explained.

As shown in FIG. 2, the bias voltage (emitter voltage Vt,
Neemitter current by applying base voltage Vm)! . When flowing from the injection electrode 3 to the ceramic superconductor layer 2, the voltage-current characteristics of the emitter become as shown in FIG. When the emitter voltage ■E is the threshold voltage V of negative resistance, the emitter junction 5 between the injection electrode 3 and the ceramic superconductor layer 2 is reverse biased, and the ceramic superconductor layer Almost no injection of layer 2 carriers (holes) occurs. Therefore, the ceramic superconductor layer 2 appears to have high resistance. Furthermore, when the emitter voltage (■) exceeds the threshold voltage vP, the emitter junction 5 is forward biased and carriers are injected from the injection electrode 3 into the ceramic superconductor layer 2. The resistivity of the material decreases, and it finally becomes a superconducting state (section A in Figure 3).

That is, in the above embodiment, since the injection electrode 3 for injecting the main carriers responsible for the superconductivity of the superconductor layer 2 is provided in contact with the ceramic superconductor layer 2 having a low carrier concentration, a small voltage ( Specifically, it is possible to change the carrier density of the superconductor layer 2 to a greater degree than in the conventional case by changing the emitter voltage V (approximately several tens of mV), and the superconducting properties can also be changed significantly. Therefore, it is possible to obtain a so-called voltage-controlled switching element (a negative resistance element in this example) that can control superconducting current with a small voltage, and it is possible to obtain a high-gain circuit as well as a high-speed circuit. It becomes possible.

In the above embodiment, the ceramic superconductor layer has (Lat-x S rx ) t Cubs (x=
0°02), the present invention is not limited to this, and the present invention is not limited to this.
It only needs to contain both u and O, specifically, for example, Y+ B a ! It may also be Cus O6,9.

Further, in the above embodiment, a case was described in which carriers were injected from the injection electrode 3 into the ceramic superconductor layer 2 by current injection, but the present invention is not limited to this, and the carriers are injected by light. It may also be carried out by excitation.

Further, in the above embodiment, the case where one injection electrode 3 is provided on the ceramic superconductor layer 2 has been described, but the present invention is not limited to this, and two or more injection electrodes may be provided. Good too.

Further, in the above embodiment, the injection electrode 3 was constructed by directly joining the ceramic superconductor layer 2, but the present invention is not limited to this. A structure other than direct bonding to the layer 2 may be used, and specifically, the function of the injection electrode 3, that is, the injection of the main carriers responsible for the superconductivity of the superconductor layer 2, cannot be prevented, such as a semiconductor layer, etc. may be provided in between.

〔effect〕

According to the present invention, an injection electrode is provided in the ceramic superconductor layer for injecting the main carriers responsible for superconductivity in the superconductor layer, so a switching action is performed by controlling the superconducting current with a small voltage. This makes it possible to obtain a high-gain circuit and also to increase the speed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an embodiment of a superconductor element according to the present invention, FIG. 2 is a schematic diagram explaining the operation of the superconductor element shown in FIG. 1, and FIG. The emitter voltage of the superconductor element shown in the figure -
FIG. 3 is a diagram showing current characteristics. 1... Substrate, 2... Ceramic superconductor layer, 3...
... Injection electrode, 4a, 4C... Electrode. 1 palanquin price

Claims (1)

[Claims] Two electrodes are arranged at both ends of a ceramic superconductor layer with a low carrier concentration, and at least one injection of a main carrier responsible for superconductivity is carried out along the superconductor layer. electrodes are provided, and when a predetermined bias voltage is applied between the two electrodes, the current flowing between one electrode and the injection electrode has predetermined switching characteristics based on the carriers injected from the injection electrode. A superconductor element characterized by comprising: