JPH01170080A - Superconducting fet element - Google Patents

Abstract

PURPOSE:To enable an element of this design to be large in capacitance by a method wherein an electric field applied between a superconductive layer and an electrode is controlled to regulate the superconductor layer so as to be a superconductor or a non-superconductor and a current which flows through the superconductor layer is controlled. CONSTITUTION:An electrode 4 is formed on the front or the rear of a semiconductor substrate 1 provided with a superconductor layer 2 formed on it through the intermediary of a dielectric layer 3, the superconductor layer 2 is controlled to be a superconductor or a non-superconductor and a current which flows through the superconductor layer 2 is controlled by regulating an electric field applied between the superconductor layer 2 and electrode 4. That is, an electric field applied between the superconductor layer 2 and the electrode 4 is controlled to govern a number of carriers so as to control the superconductor layer 2 to be a superconductor or a non-superconductor, so that a high speed modulation can be realized. And, as a current flowing through a superconductor body is directly employed in this element differently from the conventional element which employs an effect such as a Josephson effect or a superconductivity proximity effect, a current as large in density as the critical current can be made to flow. By these processes, switching of a large capacitance can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a current switching element that is suitable for information processing and power fields and is capable of controlling high-speed, large-capacity current with low loss.

(Prior Art) Conventionally, switching elements have been proposed in which the superconducting characteristics of a superconductor are controlled by controlling minority carriers.

(Problems to be Solved by the Present Invention) However, conventional switching elements are mainly Josephson devices.
and S Q U I D (Super conduct
ing Quantum Interference
Most of the devices utilize the superconducting proximity effect, such as 2017-2013 (Device), and although they are capable of increasing speed, it has been difficult to increase the so-called large capacity by controlling large currents.

(Means for Solving the Problems) The present invention has been made in view of the above points, and an electrode is formed via a dielectric layer on the front or back surface of a semiconductor substrate on which a superconducting layer is formed. This is a superconducting FET device characterized by controlling the superconducting layer to be a superconductor or a non-superconductor by controlling the electric field applied between the superconducting layer and the electrode, and controlling the current flowing through the superconducting layer.

(Function) By controlling the electric field applied between the superconducting layer and the electrode, the majority carriers (I
(on the order of O"cm-"). That is, by applying an electric field, charges are charged at the interface between the superconducting layer and the dielectric layer, eliminating electron pairs within the superconducting layer, thereby making the superconducting layer a non-superconductor and reducing the amount of current flowing.

As the semiconductor substrate, it is preferable to use S1S GaAss InP or the like.

The dielectric layer is SrTiOs, MgOsTa
It is better to use xes etc.

(Example 1) Hereinafter, in Figure 0, which will be explained with reference to Figure 1, which illustrates one embodiment of the present invention, +11 is a semiconductor substrate made of a Si single crystal substrate, and (2) is a semiconductor substrate formed on the semiconductor substrate +11.
Superconducting layer such as BaxCusOi, s, (3) is 5rTi
A dielectric layer made of Os, (4) an electrode made of Au, (5) a gate terminal connected to the electrode (4), and (6) and (7) each sandwiching the electrode (4). These are a source terminal and a drain terminal connected to the superconducting layer (2).

The superconducting layer (2) has a thickness of about 2000 nm, has a critical temperature of about 89'', and has a dense C-axis orientation.

In addition, the superconducting layer (2) at the location where the dielectric layer (3) is to be formed is patterned using lithography technology, and dry etching is performed (RrBE=Reactive
(on beaa+ etching, C1, using gas) grooves were formed. As a result, the thickness of the ultra-N conductive layer (3) in this groove is 1200. The thickness of the dielectric layer (3) is 800 mm, and the thickness of the electrode (4) is 200 mm.
It is composed of 0 people.

The superconducting FET device of the above example configured in this way is cooled in a liquid temperature atmosphere, and the gate (5) and source (
When a voltage of 500μ is applied between the source (6) and the
) and the drain (7) changed to a non-superconducting state.

(Example 2) Next, in Figure 0, which will be explained with reference to Figure 2, which illustrates another example of the present invention, Ol) is a semiconductor substrate made of a Si single crystal substrate, @ is an MgO A dielectric layer composed of Al is on the dielectric layer (material).
Q4) (b) is an insulating layer of 5ft formed on the surface of the semiconductor substrate αυ, and (b) is an insulating layer (b) of YBa, Cu formed between αυ.
, Ohl are the superconducting layers, αe is the gate terminal connected to the electrode α, and α and α− are the source and gate terminals connected to the superconducting layer α on the insulating layers (B) and (B).

The back surface of the semiconductor substrate αD forming the dielectric layer (goods) is RI.
A groove is formed by the BE method, the thickness of the semiconductor substrate αD at the groove portion is approximately 1000 mm, and the dielectric layer (2) and the electrode side are laminated so as to straddle the groove. The insulators 041G are each 1500mm thick so as to straddle the grooves.
The superconducting layer a9 is formed on the surface of the semiconductor substrate αυ with a thickness of 1200 nm thick.

The superconducting FET device of the second embodiment configured in this way was cooled in a liquid temperature atmosphere, and
? When a voltage of 550V is applied between + and source 0η
And the superconducting state with the drain OI changed to a non-superconducting state.

(Effects of the Invention) As described in detail above, the present invention is characterized in that an electrode is formed on the front or back surface of a semiconductor substrate on which a superconducting layer is formed via a dielectric layer, and an electric field is applied between the superconducting layer and the electrode. This is a superconducting 4FET device characterized by controlling the superconducting layer to be a superconductor or a non-superconducting 7!1 conductor, and controlling the current flowing through the superconducting layer. Therefore, by controlling the electric field applied between the superconducting layer and the electrode, majority carriers can be controlled and Since the IT conductive layer is controlled to be a superconductor or a non-superconductor, high-speed modulation is possible.Also, unlike the conventional Gisefson effect and superconducting proximity effect, it directly utilizes the conduction current within the superconductor. It has the excellent effect of allowing current to flow up to a critical current density and performing large-capacity switching.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view showing another embodiment of the invention. (l) 0υ is the semiconductor substrate, (2) α is the superconducting layer, (3
) side is a dielectric layer, +41 G31 is an electrode. Patent applicant Furukawa Electric Co., Ltd. Figure 1 Figure 2

Claims (5)

[Claims] (1) An electrode is formed via a dielectric layer on the front or back surface of a semiconductor substrate on which a superconducting layer is formed, and by controlling the electric field applied between the superconducting layer and the electrode, the superconducting layer can be transformed into a superconductor. A superconducting FET element characterized in that it is controlled to be a non-superconductor and that current flowing through a superconducting layer is controlled. (2) The superconducting FET element according to claim 1, wherein the superconducting layer is composed of an RE-Ba-Cu-O system (RE is a rare earth element). (3) The superconducting FET element according to claim 1 or 2, wherein the C-axis of the superconducting layer is perpendicular to the plane of the semiconductor substrate. (4) Claim 1, characterized in that the semiconductor substrate is made of Si, GaAs, or InP.
The superconducting FET device according to any one of items 1 to 3. (5) Dielectric layer is SrTiO_3, MgO, Ta_2O
The superconducting FET element according to any one of claims 1 to 4, characterized in that the superconducting FET element is made of any one of _5SiO_2.