JPH07235700A - Superconductive super-lattice crystal device - Google Patents

Abstract

PURPOSE:To provide a superconductive super-lattice crystal device, in which a tunnel junction type Josephson element using a copper oxide high-temperature superconductor is constituted by utilizing a peculiar multilayer structure by which the crystal structure of the superconductor is characterized. CONSTITUTION:A superconductive super-lattice crystal device comprises a ceramic substrate 11 having small distortion at a cryogenic temperature and a small thermal expansion coefficient, a superconductive super-lattice crystal 12 which is formed on the board and to which fine processing is carried out, an insulating layer formed on a crystal layer, a piezoelectric element working as a control terminal mounted on the crystal layer, a ceramic cover 14 so fitted as to cover these elements and board and having the same quality as the substrate material and a spring clip 15 for fixing the ceramic cover. Control electrodes formed on the crystal layer and the insulating layer respectively are connected to the control electrodes by leads respectively, and the electronic coupling between superconductive layers in the vertical direction to the multilayer structure of the superconductive layer and the semiconductor or of the insulating layer and the superconductive layer can be controlled mechanically, electrically and magnetically from the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a tunnel junction type Josephson device using a copper oxide high temperature superconductor, which has a peculiar laminated structure which characterizes the crystal structure of the superconductor regardless of the thin film manufacturing technique. The present invention relates to a superconducting superlattice crystal device in which a series connection tunnel junction type Josephson device is constructed by utilizing. The present invention relates to an electronic element manufacturing technique using a superconductor, and an object thereof is to provide a multifunctional Josephson element which can be widely used in electronic devices, communication devices and information devices.

Products to which the present invention can be applied are electromagnetic wave detectors,
It is an electromagnetic wave oscillator, a voltage standard, an electronic computer element, a super-sensitive SQUID magnetometer (superconducting quantum interferometer), and the like.

[0003]

2. Description of the Related Art Superconducting electronic devices developed and used up to now are Josephson devices, and as shown in FIG. 1, (a) tunnel junction type, (b) point contact type and (c)
It is represented by three types of bridge shapes.

The Josephson device is a device that utilizes the weak interaction of superconducting electrons (or holes) between two superconductors, and is generally composed of two superconductors (or superconducting thin films). It is composed of a weakly coupled portion provided between them. Heretofore, practical Josephson devices have been realized by using metal Nb (niobium) (superconducting transition temperature: 9.2 K) as a superconducting material. Therefore, first, an outline and a problem of a typical manufacturing method of a metal-based Josephson device using Nb as a superconducting electrode will be described. The tunnel junction element shown in FIG. 1A is a sandwich (lamination) in which two superconducting thin film electrodes 1A and 1B sandwich an insulating layer (tunnel barrier) 2 having a thickness of about 2 nm.
It has a structure. First, a Nb thin film having a thickness of 100 to 100 is formed on a Si (silicon) substrate 4 by a sputtering method.
Fabricate to 150 nm and form the lower superconducting electrode 1A. An Al (aluminum) thin film having a thickness of several nm is formed thereon, and the surface thereof is thermally oxidized to form an Al ₂ O ₃ (aluminum oxide) layer to form the tunnel barrier 2. An Nb / Al.Al ₂ O ₃ / Nb tunnel junction device is completed through a step of forming an Nb thin film again to a thickness of 100 to 150 nm and forming an upper superconducting electrode 1B on this. This element manufacturing technology is almost completed at present, and stable elements are manufactured.

Furthermore, in order to realize a more stable element,
Sputtered NbN (niobium nitride) thin film (superconducting transition temperature:
16K) for both upper and lower electrodes 1A and 1B and a MgO (magnesium oxide) layer as a tunnel barrier 2 NbN / MgO
/ NbN tunnel junction element is also being developed. Figure 1
In the point contact element shown in (b), one of the superconductors 1C is formed into a needle shape (the tip has a diameter of about 1 μm) through steps such as machining and chemical polishing, and the other superconductor is formed. Flat plate 1D
Press to configure. This element usually uses bulk Nb as a superconducting material, and has a weak point that it is weak against mechanical vibration because its needle-shaped contact portion is a weakly coupled portion.

The bridge type device shown in FIG. 1 (c) uses a single superconducting thin film 1 or a two-layer film consisting of a superconducting thin film and a normal conducting thin film formed on a substrate 4, and these are used as weak coupling portions 3. A part of the thin film is narrowed down to about 1 μm by a microfabrication technique, and the length in the current direction is processed to a size of 200 nm to 1 μm, and the superconductivity of this part is weakened. Normally, Nb is used for the superconducting thin film and Ta is used for the normal conducting thin film.
(Tantalum) is used. However, this element has a drawback that it is easily destroyed by an electric shock because current concentrates on the weakly coupled portion.

[0007]

The characteristic features of these three types of elements are that, as shown in FIG. 2, in the current-voltage characteristic, the tunnel junction type element basically includes a junction capacitance. Although it has a large hysteresis (see FIG. 2A), the other two elements do not have a hysteresis because the junction capacitance can be ignored (see FIG. 2B). In the figure,
I is current (axis), V is voltage (axis), I ₀ is critical current (maximum DC Josephson current), Δ is superconductor (electrode)
, The energy gap, and e is the electronic charge. But,
The former element can realize the latter element characteristics by devising the circuit configuration, is multifunctional, and has good controllability in its manufacture.
Also, due to the stability of characteristics and good controllability, it is the mainstream of Josephson devices, such as switching devices and memory devices for superconducting electronic computers, and super-sensitive magnetometers (SQ).
UID magnetometer), electromagnetic wave mixer / detector, voltage standard element, etc. are widely studied for application to electronic devices related to information processing, communication and electronic measurement (including biological measurement), and superconducting electronic circuits in communication devices. Is coming. However, the current problem of this device is that the superconducting electrode material Nb has a transition temperature of 9.2 K, so its operation is limited to very low temperatures. Therefore, cooling with liquid helium (boiling point: 4.2 K) is essential. That is.

However, since a copper oxide high temperature superconductor having a superconducting transition temperature higher than the liquid nitrogen temperature (77K) was recently discovered, the same superconductor was used as an electrode and operated at the liquid nitrogen temperature. A possible tunnel junction type Josephson device (Fig. 1 (a)) is under development. In this case, the central superconducting material is a YBa ₂ Cu ₃ O ₇ compound thin film (transition temperature: about 90 K), which can be manufactured by the reactive sputtering method or the reactive vapor deposition method. Based on this thin film manufacturing technology, Y
After forming the Ba ₂ Cu ₃ O ₇ thin film upper electrode 1A (FIG. 1A), SrTiO ₃ or Y ₂ which becomes a tunnel barrier is formed on the upper electrode 1A.
O ₃ insulating layer 2 of the thin film or the like to prepare a (FIG. 1 (a)), then again YBa ₂ Cu ₃ O ₇ thin upper electrode 1B (Fig 1
It has been proposed to form (a)) to fabricate a tunnel junction type element, but an element having hysteresis and reliable tunnel characteristics has not been realized so far. The cause is that there are many kinds of constituent elements of the copper oxide high temperature superconductor and the crystal structure is complicated, so that the quality and characteristics of the thin film cannot be sufficiently controlled from its surface or interface to the inside, and This is based on the fact that high-quality insulating layers that serve as tunnel barriers have not been obtained.

On the other hand, an element whose operation as a Josephson element has been confirmed to date is PrB as an insulating layer.
YBa ₂ Cu ₃ O ₇ / Pr using a ₂ Cu ₃ O ₇ thin film
Although it is a Ba ₂ Cu ₃ O ₇ / YBa ₂ Cu ₃ O ₇ laminated junction type element, since the PrBa ₂ Cu ₃ O ₇ layer actually acts as a normal conductor, its current-voltage characteristic is shown in FIG. 2 (b). It shows the characteristics without hysteresis as shown in. As an element exhibiting similar _{characteristics, Bi 2 Sr 2 CaCu 2 O} x superconducting thin film (transition temperature: 80K) and Bi ₂ Sr ₂ CuO _y Bi ₂ by a combination of normal-conducting thin film Sr ₂ CaCu ₂ O _x / B
An i ₂ Sr ₂ CuO _y / Bi ₂ Sr ₂ CaCu ₂ O _x laminated junction device has also been manufactured. As another type of element, a grain boundary junction type Josephson element utilizing Josephson coupling at the crystal grain boundary of a YBa ₂ Cu ₃ O ₇ epitaxial (crystal orientation) thin film is also manufactured, but its current-voltage characteristic is The characteristics are the same as described above.

As described above, a tunnel junction type Josephson device having a copper oxide high temperature superconductor as an electrode (see FIG. 1).
When (a)) is realized, not only can the multi-functionality be applied, but it can also be used at liquid nitrogen temperature (77K), so the applicable range is metal-based superconductors. Compared with the Josephson device, which is said to be, it can be expected to spread greatly. However, with the current thin film manufacturing and processing technology,
It is difficult to fabricate a tunnel junction type Josephson device by artificially stacking thin films.

According to the present invention, a tunnel junction type Josephson device using a copper oxide high temperature superconductor is characterized not by artificially forming it by a thin film manufacturing technique but by characterizing the crystal structure of the superconductor. The purpose is to realize a multifunctional Josephson device that can be widely used in electronic, communication, and information devices.

The copper oxide high temperature superconductor generally has an alternating laminated structure of a metallic CuO ₂ layer responsible for superconductivity and a nonmetallic charge storage layer for injecting carriers (holes or electrons) into the CuO ₂ layer. Characterized by. Therefore, its superconducting property exhibits strong anisotropy. In particular, (Bi _1-x Pb _x ) ₂ Sr
₂ C _n-1 C _n O _{2n + 4} (where 0 ≦ X ≦ 0.5, n =
2 or 3) and _{Tl 2 Ba 2 Ca n-1} Cu n O 2n + 4 ( however, n = 1 to 3) and the superconducting layer, each single crystal, such as a compound containing a metallic CuO ₂ layers, the insulator manner Alternatively, a superconducting layer / insulating layer (semiconductor layer) / superconducting layer / which is formed of an alternating laminated structure of charge storage layers including semiconducting {(Bi _1-x Pb _x ) O} ₂ or {TlO} ₂ layers _- a superlattice (multi-junction series) structure spontaneously formed by the crystal growth process entailment of.

The superconducting crystal including the natural superlattice structure (hereinafter referred to as a superconducting superlattice crystal) has a unique superconducting layer / insulating layer (semiconductor layer) / superconducting layer junction. It has a tunnel-junction-like Josephson characteristic, and since the whole crystal shows the characteristic that multiple junctions are connected in series, it has an element function itself. However, since the interlayer coupling of the insulating or semiconducting {(Bi _1-x Pb _x ) O} ₂ and {TlO} ₂ layers of the same crystal is weak due to the Van der Waals force, the intrinsic Josephson It gives uncertainty and instability to the electronic coupling (interaction) of the junction. For this reason,
Since the junction is accompanied by the stochastic operation in the whole crystal, it is problematic in terms of stability and reliability to form the element only with the crystal.

[0014]

A superconducting superlattice crystal device according to the present invention comprises a ceramic substrate having a low strain and a small coefficient of thermal expansion at an extremely low temperature, and a microfabricated superconducting film formed on the substrate. Superlattice crystal, insulating layer provided on the crystal layer, piezoelectric element provided on the crystal layer as a control terminal, and ceramic of the same material as the substrate material fitted to cover these elements and the substrate A control cover electrode and a ceramic cover (auxiliary) fixing spring clip. Control electrodes provided on the crystal layer and the insulating layer are connected to control electrodes provided on the substrate by lead wires. And a structure in which electronic coupling between superconducting layers in a direction perpendicular to the structure of the superconducting layer / semiconductor or insulating layer / superconducting layer stack can be mechanically, electrically and magnetically controlled from the outside. It is an butterfly.

The superconducting superlattice crystal of the superconducting superlattice crystal device of the present invention is fixed to a substrate by a suitable resin,
On the upper surface of the crystal, a convex portion to be an element portion is formed by microfabrication by ion etching, and these convex portions constitute a Josephson tunnel junction connected in series, and the upper surface of the concave portion other than the convex portion constituting the Josephson tunnel junction is formed. To form an insulating layer, and connecting the gold electrode formed on the upper surface of the superconducting superlattice crystal and the gold electrode formed on the insulating layer to the gold electrode formed on the substrate side portion by a lead wire, The ceramic cover is provided with electrodes for piezoelectric elements, and the piezoelectric elements are used as control terminals for mechanically controlling electronic coupling due to interaction between superconducting layers existing in the crystal, and individual piezoelectric elements from the outside. This structure is configured to control the synchronization and resonance phenomena of the Josephson tunnel junction of the conductive layer / insulating layer / superconducting layer junction structure.

The superconducting superlattice crystal of the present invention uses a copper oxide type high temperature superconductor.

[0017] The copper oxide-based high temperature superconductor of the present invention _{(Bi 1-x Pb x)} 2 Sr 2 Ca n-1 Cu n O 2n + 4 ( however, 0 ≦ x ≦ 0.5, n = 2~ 3) and Tl ₂ Ba ₂ C
Any one selected from a _n-1 Cu _n O _{2n + 4} (where n = 1 to 3) is used.

The copper oxide type high temperature superconductor of the present invention comprises:
A superconducting layer containing metallic CuO ₂ and an insulator or semiconductor {(Bi _1-x Pb _x ) O} ₂ or {T
those harboring lO} superconductive layer / insulating layer or semiconductor layer / made of superconducting layer multijunction series of superlattice structure constituted by alternating lamination structure of the charge storage layer comprising _two layers in the crystal structure .

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows the basic structure of a superconducting superlattice crystal device according to the present invention. The device of the present invention is composed of a microfabricated superconducting superlattice crystal and a control terminal for controlling electronic coupling (interaction) between superconducting layers in the crystal. Reference numeral 11 denotes a ceramic substrate made of, for example, alumina, beryllia or the like, which has a low coefficient of thermal expansion and a small strain at extremely low temperature, and 12 denotes, for example, (Bi _1-x Pb _x ) ₂ Sr ₂ CaCu ₂
A superconducting superlattice crystal subjected to fine processing such as O _y , 13
Is a piezoelectric element acting as a control terminal, 14 is a ceramic cover of the same material as the substrate material, 15 is a ceramic substrate 11, piezoelectric element 13
And a spring clip (for example, Be—Cu alloy) for auxiliary fixing of the ceramic cover 14. The superconducting superlattice crystal 12 and the ceramic cover 14 are bonded and fixed to the ceramic substrate 11 with a soft epoxy resin (for example, bisphenol A type epoxy resin or the like) having a small thermal expansion coefficient and which can be used at low temperature.

FIG. 4 (a) is a top view of the device of the present invention,
FIG. 4 (b) shows an internal top view thereof, and FIG. 4 (c) shows a longitudinal sectional view thereof. Reference numeral 21 is a ceramic substrate, and gold electrodes 22, 22 are provided on both sides of the ceramic substrate 21. 23 is a superconducting superlattice crystal, and this crystal 23 is bonded and fixed to the ceramic substrate 21 with an epoxy resin. On the crystal 23, a 23A convex portion to be an element portion is formed by fine processing by ion etching. The convex portion 23A constitutes a series connection Josephson tunnel junction which is the center of the device of the present invention. The 23B convex portion is an unprocessed portion of the crystal 23, has a larger area than the 23A convex portion, and does not operate as an element. Reference numeral 24 denotes an insulating layer provided on the recess 23C of the crystal 23.
Reference numeral 24 is for preventing a short circuit between the current injection / signal extraction terminal 25 (gold electrode) in contact with the convex portion 23A and the concave portion 23C. For example, SrTiO ₃ (strontium titanate) or the like is used. use. Reference numeral 26 is a lead wire connecting between the gold electrodes 22 and 25. Reference numeral 27 denotes a piezoelectric element, which acts as a control terminal that mechanically controls electronic coupling (interaction) between superconducting layers in the crystal. As a result, the Josephson tunnel junction characteristics of the individual superconducting layer / insulating layer (semiconductor layer) / superconducting layer junction structure and the Josephson effect synchronization / resonance phenomenon due to the series connection of a plurality of junctions can be facilitated from the outside. Can be controlled.
Also, these phenomena can be selected depending on the shape of the crystal convex portion 23A. Furthermore, by adding a coaxial cable as shown in FIG. 19 to the basic device shown in FIG. 3 and irradiating with an electromagnetic wave, the Josephson effect synchronization phenomenon of the series connection junction can be controlled. Also, by applying a weak magnetic field to this, the resonance phenomenon of the Josephson effect and the interaction with the magnetic flux quantum can be controlled. Reference numeral 28 is a ceramic cover of the same quality as the substrate 21, and is used for protecting the crystal and fixing the piezoelectric element 27. Reference numeral 29 is a piezoelectric element electrode provided on the ceramic cover.

The manufacturing process of the device of the present invention is shown in FIG. First, a ceramic substrate 31 having a gold electrode 32 attached thereto is made of epoxy resin and has a thickness of about 100 μm to 1 mm.
Fix 33 as shown in FIG. Next, a photoresist (eg, negative type) photoresist 34 is applied on the crystal 33 to a thickness of about 2 μm as shown in FIG. After drying, a glass mask 35 having a device-shaped pattern is placed on the resist film 34,
Irradiate with ultraviolet rays (see FIG. 7). By developing this resist film 34, a desired resist pattern is formed as shown in FIG. This sample is ion-etched using a gas such as Ar (argon) to etch the crystal 33 by a desired thickness as shown in FIG. The maximum number of synchronous Josephson junctions is determined by this process. Here, the depth per 100 Josephson junctions is 300.
equivalent to nm.

Next, in order to flatten the crystallized portion, an insulating film (for example, SrTiO ₃ ) 36 having the same thickness as the height of the convex portion is vapor-deposited on the resist pattern (see FIG. 10). Then, it is dipped in a resist solvent such as acetone, and the photoresist and the insulating film adhered thereon are removed by a lift-off method (see FIG. 11). Flattened crystal
For example, a negative photoresist 37 is applied again on 33 (see FIG. 12), and the resist is exposed and developed using a glass mask 38 having a metal electrode pattern, and the electrode-shaped resist pattern is shown in FIGS. 13 and 14. To form. Next, a metal film 39 (gold, silver, etc.) for the electrode is formed on the resist pattern.
As shown in FIG. 15, vacuum evaporation is performed and a lift-off process is performed to form electrodes as shown in FIG. After connecting the metal electrode 39 on the crystal 33 and the metal electrode 32 on the ceramic substrate 31 with the metal wire 40 (see FIG. 17), the crystal 33 is fixed on the ceramic cover 42 to which the control terminal piezoelectric element 41 is attached. It is completed by attaching and fixing to the existing substrate 31. In this case, a recess is provided in a part of the ceramic cover 42, and the piezoelectric element 41 is fixed by inserting and adhering in the recess (see FIG. 18). At this time, the control terminal is attached so as to overlap the crystal convex portion (serial connection Josephson tunnel junction). The piezoelectric element 41 for control terminal is adjusted by the electrode 43 on the ceramic cover. Further, a series connection Josephson junction is also formed in the crystal 33 below the metal electrode 39 on the left side of FIG. 18, but since the area of this portion is larger than the area of the crystal convex portion, this portion is Josephson. Shows bulk (crystalline) behavior instead of tunnel-junction behavior,
No problem occurs due to device characteristics. On the contrary, by reducing the area of this portion, it is possible to positively utilize the Josephson junction characteristic of this region.

[Application Example] The superconducting superlattice crystal device according to the present invention has a single Josephson tunnel junction characteristic, a series connection multi-Josephson tunnel junction characteristic and a synchronization / resonance characteristic, a magnetic flux flow device characteristic, a soliton device characteristic, and the like. The above characteristics can be freely selected in the same device by external control, and the invention can be applied to the following devices. Application example 1 Voltage standard device

Currently, the voltage standard device is shown in FIG.
A tunnel junction type Josephson device as shown in FIG.
About 1000 pieces are connected in series. In this case, since the Josephson elements are arranged in a plane (two-dimensional), there is a limit to miniaturize the device. Since the device of the present invention has the Josephson tunnel junctions arranged three-dimensionally in the height direction, the device area is equivalent to that of a single Josephson tunnel junction and can be miniaturized. Therefore, FIG. 19 shows a configuration diagram when the device is used as a voltage standard device. In this case, in order to introduce an electromagnetic wave into the device by a coaxial cable 52 such as a semi-rigid cable, as shown in FIG. 3, a terminal 51 for introducing an electromagnetic wave into the basic device (the length corresponds to 1/4 of the wavelength of the applied electromagnetic wave) Is added, and the core wire of the coaxial cable 52 is in direct contact with this terminal 51. A filter 53 for cutting high frequencies is connected to the current injection terminal 22A and the output signal extraction terminal 22B. When used as a voltage standard device, the area of the Josephson tunnel junction is set so that the electromagnetic wave is efficiently biased to the series-connected Josephson junction in the crystal 23.
_{In the case of 1-x} Pb _x ) ₂ Sr ₂ CaCu ₂ O _y ), about 100
Fine processing to μm or less. When an alternating current such as an electromagnetic wave is biased to the Josephson tunnel junction, a constant voltage step with a voltage interval (about 20 μV at 10 GHz) that is proportional to the frequency of the alternating current appears on the current-voltage characteristics. The voltage standard utilizes this constant voltage step. Since the device of the present invention operates with multiple Josephson tunnel junctions in synchronism, the constant voltage step interval is several times larger than the synchronised junctions, allowing large voltage standards. Further, in the device of the present invention, the number of junctions that are synchronized from the outside can be freely changed, so that a variable voltage standard device can be configured.

Application Example 2 High Speed and High Output Switching Device A Josephson tunnel junction having a hysteresis in current-voltage characteristics is a high speed switching device by using a zero voltage state (“0”) and a finite voltage state (“1”). Can be used as The device of the present invention also has hysteresis in current-voltage characteristics, and thus can be used as a switching device. Since the device of the present invention includes a large number of Josephson tunnel junctions connected in series as described above, a high output of volt order is possible, which is about the same as the operating voltage of current semiconductor devices. Therefore, a superconducting device-semiconductor / optical device hybrid circuit can be configured. Further, since the device of the present invention can freely adjust the number of joints synchronized by the control terminal,
The output voltage can be changed.

Application Example 3 Electromagnetic Wave Mixing / Detecting Device Since the copper oxide high temperature superconductor used in the present invention has a large superconducting energy gap of 10 to 30 meV and is capable of super high frequency response such as millimeter wave and submillimeter wave. It can also be used as an ultra-high frequency electromagnetic wave mixing / detection device. in this case,
The basic device shown in FIG. 3 can be used by mounting it in a waveguide. Also in this case, high conversion efficiency can be obtained by using the synchronization phenomenon of the device of the present invention.

Application Example 4 Ultra High Frequency Oscillation Device In order to realize the ultra high sensitivity electromagnetic wave mixing / detecting device described in Application Example 3, a low noise ultra high frequency oscillator is required as a local oscillator. Since the device of the present invention has magnetic flux flow characteristics, it can be used as an ultra-high frequency oscillation device. In this case, the length of the junction is several times the length of the Josephson magnetic field penetration (about 1 m to generate the magnetic flux flow).
m), width is about Josephson magnetic field penetration length (about 100 μm)
It is processed into and used. At this time, in the device of the present invention, high output oscillation becomes possible by using the synchronization phenomenon of the Josephson tunnel junction in the crystal. An integrated electromagnetic wave detection device can be realized by using the device of Application Example 3 together.

FIG. 20 shows a sectional view of this integrated electromagnetic wave detection device. In FIG. 20, 61 is an ultra-high frequency oscillation device, 62 is an electrode for an oscillation device, 63 is an electromagnetic wave detection device, 64 is an electrode for an electromagnetic wave detection device, and the device
The electromagnetic wave generated at 61 is transmitted to 63 by the insulator 65 between the device 61 and the device 63. The insulator 65 is made of a dielectric material, that is, a material having a high dielectric constant in this case (for example, SrTi).
By using O ₃ ), a microminiature electromagnetic wave detector can be realized by the device of the present invention.

Application Example 5 Ultra-sensitive SQUID magnetometer The above-mentioned superconducting superlattice crystal used in the present invention operates as a Josephson weak coupling element having no hysteresis in current-voltage characteristics by inserting an impurity layer. To do. Therefore, two protrusions including one such junction are formed on the crystal 23 of FIG. 4 and, for example, YBa ₂ Cu ₃ O ₇ and Bi ₂ Sr are formed.
SQUID is formed by connecting in parallel with a superconducting wire made of ₂ CaCu ₂ O _y, etc.
It can be used for an ID magnetometer. In this case, there is an advantage that a high output can be obtained because the superconducting energy gap of the crystal is large.

[0030]

The superconducting superlattice crystal device of the present invention comprises:
Since the series connection Josephson tunnel junction that is inherent in the single crystal of the copper oxide high temperature superconductor is used, it is possible to operate at liquid nitrogen temperature (77K),
It also has features such as high integration and high output. Further, conventionally, a device designing dedicated to each of the devices utilizing the single Josephson tunnel junction characteristic, the multi-Josephson junction characteristic, the magnetic flux flow characteristic, etc. was required. Device has these characteristics, and it can be a multifunctional superconducting device that can be controlled by selecting each characteristic from the outside as needed, facilitating device design. effective.
Furthermore, by applying a voltage from the control terminal of the basic device of the present invention to the crystal element portion through the insulating film, it is possible to extend the application to a superconducting transistor.

The superconducting superlattice crystal device of the present invention has an advantage that it can provide an electronic device having the following effects. (1) Copper oxide high temperature superconductor (Bi _1-x Pb _x ) ₂ Sr
₂ Ca _n-1 Cu _n O _y and Tl ₂ Ba ₂ Can _n-1 Cu _n
Between the superconducting layer of the natural superlattice (multijunction series) structure of superconducting layer / insulating layer (semiconductor layer) / superconducting layer / ---- which is naturally formed during the growth of the single crystal such as O _y Since the electronic coupling (interaction) is directly controlled and used, it is possible to provide a device having a series connection tunnel junction type Josephson element.

(2) Since the device portion is obtained by finely processing the above-mentioned superlattice crystal, the device portion is provided with a control terminal for controlling electronic coupling (interaction) between the superconducting layers. The Josephson effect and the synchronous resonance phenomenon can be easily controlled from the outside.

(3) The device of the present invention is configured so that it can be mechanically, electrically and magnetically controlled from the outside. Single Josephson tunnel junction characteristics Series-connected multi-Josephson tunnel junction characteristics and synchronization・
Resonance characteristics Both the magnetic flux flow device characteristics and the soliton device characteristics are selected and controlled, and there is an industrially great effect that a device having characteristics that can be used for multiple purposes can be provided.

[Brief description of drawings]

1A, 1B, and 1C show a typical example of a conventional superconducting Josephson device. FIG. 1A is a tunnel junction type, and FIG. 1B is a point. The contact type and FIG. 1C are explanatory views showing an example of three typical superconducting Josephson devices of the bridge type.

2 (a) and 2 (b) are current-voltage characteristic diagrams of the Josephson device of FIG.

FIG. 3 is a perspective view showing a basic configuration of a superconducting superlattice crystal device of the present invention.

4 (a), (b), and (c) are drawings respectively showing a top view, an internal top view, and a vertical cross-sectional view of the device of the present invention.

FIG. 5 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 6 is a sectional view showing a manufacturing process of the device of the present invention.

FIG. 7 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 8 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 9 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 10 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 11 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 12 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 13 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 14 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 15 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 16 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 17 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 18 is a cross-sectional view showing the manufacturing process of the device of the present invention.

FIG. 19 is a perspective view showing an exploded basic configuration of the device of the present invention when applied to a device for a voltage standard.

FIG. 20 is a sectional view showing an example of the basic configuration of an integrated electromagnetic wave detection device to which the device of the present invention is applied.

[Explanation of symbols]

1,1A, 1B Superconducting thin film 1C, 1D Superconductor 2 Tunnel barrier 3 Weak coupling part 4 Substrate I Current (axis) V Voltage (axis) I ₀ Critical current (maximum DC Josephson current) Δ Superconductor Energy gap of (electrode) e Electronic charge 11 Ceramic substrate 12 Superconducting superlattice crystal 13 Piezoelectric element for control terminal 14 Ceramic cover 15 Ceramic cover (auxiliary) fixing spring clip 21 Ceramic substrate 22 Gold electrode 23 Superconducting superlattice crystal 23A convex part 23B convex part 23C concave part 24 insulating layer 25 gold electrode 26 lead wire 27 piezoelectric element 28 ceramic cover 29 piezoelectric element electrode 31 ceramic substrate 32 gold electrode 33 superconducting superlattice crystal 34 photoresist 35 photomask 36 insulating layer 37 Photoresist 38 Photomask 39 Gold electrode 40 Metal Wire 41 Piezoelectric element 42 Ceramic cover 43 Piezoelectric element electrode 51 Electromagnetic wave introduction terminal 52 Coaxial cable 53 Filter 61 Ultra high frequency oscillation device 62 Oscillation device electrode 63 Electromagnetic wave detection device 64 Electromagnetic wave detection device electrode 65 Insulator

Claims (5)

[Claims] 1. A superconducting superlattice crystal device comprises a ceramic substrate having a low strain and a small coefficient of thermal expansion at a cryogenic temperature, a microfabricated superconducting superlattice crystal formed on the substrate, and the crystal. An insulating layer provided on the layer, a piezoelectric element provided on the crystal layer as a control terminal, a ceramic cover of the same quality as a substrate material fitted to cover the element and the substrate, and the ceramic cover ( (Auxiliary) fixing spring clips, and connecting the control electrodes respectively provided on the crystal layer and the insulating layer to the control electrodes provided on the substrate by lead wires,
A superconducting superlattice characterized in that the electronic coupling between the superconducting layers in the direction perpendicular to the structure of the semiconductor or the insulating layer / superconducting layer stack can be controlled mechanically, electrically and magnetically from the outside. Crystal device. 2. The superconducting superlattice crystal is fixed to a substrate with a suitable resin, and a convex portion to be an element portion is formed on the upper surface of the crystal by fine processing by ion etching. A Son tunnel junction is formed, and an insulating layer is formed to cover the upper surfaces of the recesses other than the protruding portions that form the Josephson tunnel junction, and the gold electrode is formed on the upper surface of the superconducting superlattice crystal, and is formed on the insulating layer. A gold electrode is connected to a gold electrode formed on the side of the substrate by a lead wire respectively, and a piezoelectric element electrode is provided on the ceramic cover, and the piezoelectric element is provided between the superconducting layers existing in the crystal. A control terminal that mechanically controls electronic coupling due to interaction, and controls the synchronization and resonance phenomena of the Josephson tunnel junctions of individual superconducting layer / insulating layer / superconducting layer junction structures from the outside. The superconducting superlattice crystal device according to claim 1, which is configured to be controlled. 3. The superconducting superlattice crystal device according to claim 1, wherein the superconducting superlattice crystal is a copper oxide high-temperature superconductor. 4. The copper oxide high temperature superconductor is (Bi
_1-x Pb _x ) ₂ Sr ₂ Can _n-1 Cu _n O _{2n + 4} (however,
0 ≦ x ≦ 0.5, n = 2 to 3) and Tl ₂ Ba ₂ C an _-1.
The superconducting superlattice crystal device according to claim 3, which is any one selected from Cu _n O _{2n + 4} (where n = 1 to 3). 5. The copper oxide high-temperature superconductor comprises a superconducting layer containing metallic CuO ₂ and an insulating or semiconducting {(Bi _1-x Pb _x ) O} ₂ or {TlO}.
_A multi-junction series superlattice structure composed of a superconducting layer / insulating layer or a semiconductor layer / superconducting layer constituted by an alternating laminated structure of charge storage layers including _two layers is included in the crystal structure. The superconducting superlattice crystal device according to any one of 1 to 4.