CN116209343A - Field effect superconducting Josephson junction device and preparation method thereof - Google Patents
Field effect superconducting Josephson junction device and preparation method thereof Download PDFInfo
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Abstract
The invention provides a field effect superconducting Josephson junction device and a preparation method thereof, wherein the field effect superconducting Josephson junction device comprises: the device comprises a substrate, a bridging left-bank electrode, a bridging right-bank electrode, an insulating channel, a nanobridge, an insulating medium layer and a voltage electrode; the insulating channel isolates the bridging left bank electrode and the bridging right bank electrode from each other; the nanobridge spans the insulating channel to connect the bridging left bank electrode with the bridging right bank electrode; the insulating medium layer coats the nano bridge; the voltage electrode is positioned on the upper side of the insulating medium layer, and a modulation electric field is applied to the nanobridge. The field effect superconducting Josephson junction device and the preparation method thereof can solve the problems that the critical current of the traditional Josephson field effect transistor is low, the working temperature is too low, and the device cannot be applied to superconducting integrated circuits.
Description
Technical Field
The invention relates to the field of superconducting electrons, in particular to a field effect superconducting Josephson junction device and a preparation method thereof.
Background
In integrated circuit technology of semiconductor materials, field effect transistors are the basic unit of all logic circuits. The field effect, i.e., the control of the conductivity of the cell device by the application of an electric field, the magnitude of the carrier concentration in the semiconductor material allows the electric field to pass through to control the concentration of the carriers.
However, the carriers in the superconductor material exist in the form of electron-cooper pairs, the distribution of which decays exponentially from the surface to the inside of the superconductor, and the superconducting penetration depth is small, so that the difficulty of regulating the carrier concentration in the superconductor directly through an electric field is high in theory.
The basic component of the superconducting integrated circuit is a Josephson junction, and the phase difference between the current flowing through the superconducting Josephson junction and the superconducting wave function at two ends of the junction is in the form of a sine function, and the effect is called as direct current Josephson effect.
The superconductive Josephson junction is similar to PN junction in semiconductor integrated circuit, and is a key element for constituting superconductive integrated circuit. Therefore, the superconductive Josephson junction with the electric field effect greatly simplifies the design complexity of the superconductive integrated circuit and improves the integrated level of the whole circuit.
To solve this problem of electric field regulation, scientists have tried to achieve control of the supercurrent in the structure of superconductor-normal metal-superconductor josephson junctions (SNS) as early as the 60 th century by applying a voltage to the normal metal layer to modify the quasi-particle distribution. Another technique for controlling the josephson supercurrent is to introduce a semiconductor nanowire whose carrier concentration can be tuned by the effect of an electric field, so that the josephson field effect transistor is realized by constructing a small hybrid superconductor-semiconductor structure.
Although the field effect in the mixed semiconductor-superconductor structure accords with theoretical prediction and is proved in experiments, the critical current of the mixed semiconductor-superconductor Josephson junction is in nanoampere level, the environment temperature required by the operation is below 3K, and the critical current and the operation temperature of the structure are too low to be applied in a superconducting integrated circuit.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a field effect superconducting josephson junction device and a method for manufacturing the same, which are used for solving the problems that the critical current of the conventional josephson junction transistor is low, the working temperature is too low, and the device cannot be applied to a superconducting integrated circuit.
To achieve the above and other related objects, the present invention provides a field effect superconducting josephson junction device as described, comprising:
the device comprises a substrate, a bridging left-bank electrode, a bridging right-bank electrode, an insulating channel, a nanobridge, an insulating medium layer and a voltage electrode;
the bridge left bank electrode, the insulating channel and the bridge right bank electrode are positioned on the upper side of the substrate, and the insulating channel isolates the bridge left bank electrode and the bridge right bank electrode from each other;
the nanobridge spans the insulating channel to connect the bridging left bank electrode with the bridging right bank electrode and is positioned on at least part of the upper surface of the bridging left bank electrode and part of the upper surface of the bridging right bank electrode;
the insulating medium layer coats the nano bridge and is arranged on the upper sides of the left bridge electrode, the insulating channel and the right bridge electrode;
the voltage pole is positioned on the upper side of the insulating medium layer, and the projection of the voltage pole at least covers the area where the nanobridge and the insulating channel overlap in the top view direction.
Optionally, the thickness of the nanobridge is less than the thickness of the bridging left-bank electrode, while being less than the thickness of the bridging right-bank electrode.
Optionally, the field effect superconducting josephson junction device further comprises an isolation layer, wherein the isolation layer is located on the upper side of the substrate and located on the lower side of the bridge right bank electrode, and the bridge right bank electrode and the substrate are isolated from each other.
Optionally, the bridge length of the nanobridge is less than the coherence length of the superconducting material employed by the nanobridge.
Optionally, the nanobridge has a thickness less than a penetration depth of the superconducting material employed by the nanobridge.
Optionally, the superconducting materials adopted by the nanobridge, the left-bank electrode of the bridge and the right-bank electrode of the bridge are the same.
Optionally, the material of the substrate comprises at least one of MgO, sapphire, si3N4, al2O3 and SiO 2; the material of the bridged left bank electrode comprises at least one of Nb, nbN, nbTi and NbTiN; the material of the right bank electrode of the bridge comprises at least one of Nb, nbN, nbTi and NbTiN.
Optionally, changing the critical current magnitude of the field effect superconducting josephson junction device by adjusting the voltage magnitude of the voltage pole;
by the formula θ=arcsin (I C /I S )+2πL J I S /Ф 0 Modulating the current-phase relationship of said field effect superconducting Josephson junction device, wherein I C Expressed as the critical current, I S Superconducting current represented as the field effect superconducting Josephson junction device, θ is represented as a phase difference between the bridge left-side shore electrode internal wave function and the bridge right-side shore electrode internal wave function, L J Equivalent inductance denoted as the field effect superconducting josephson junction device, Φ 0 Represented as a flux quantum.
The invention also provides a preparation method of the field effect superconducting Josephson junction device, which comprises the following steps:
s1), providing a substrate, and forming a first superconducting material layer on the upper surface of the substrate;
s2), forming a patterned mask layer on the upper surface of the first superconducting material layer, and etching the first superconducting material layer based on the mask layer to form a bridge left bank electrode, a bridge right bank electrode and a groove, wherein the groove is positioned between the bridge left bank electrode and the bridge right bank electrode;
s3), filling the groove to form an insulating channel;
s4), forming a nano bridge on the upper surfaces of the bridge left bank electrode, the insulating channel and the bridge right bank electrode, wherein the nano bridge spans the insulating channel to connect the bridge left bank electrode with the bridge right bank electrode;
s5), forming an insulating medium layer on the upper surfaces of the nanobridge, the bridge left bank electrode, the insulating channel and the bridge right bank electrode;
and S6) forming a voltage pole on the upper surface of the insulating medium layer, wherein the projection of the voltage pole at least covers the overlapping area of the nano bridge and the insulating channel in the overlooking direction.
Optionally, the thickness of the nanobridge is less than the thickness of the first superconducting material layer.
As described above, the field effect superconducting Josephson junction device and the preparation method thereof of the invention realize the weak connection of the left side electrode of the bridge junction and the right side electrode of the bridge junction through the insulating channel isolation bridge left side electrode and the right side electrode of the bridge junction, and change the critical current of the junction through applying an electric field to the voltage electrode above the bridge, so as to obtain large critical current.
Drawings
Fig. 1 shows a schematic diagram of the front view of a field effect superconducting josephson junction device according to the present invention.
Fig. 2 shows a schematic top view of a field effect superconducting josephson junction device according to the present invention.
Fig. 3 is a schematic front view of a device with a larger contact area between the nanobridge and the left bank electrode of the bridge structure according to an embodiment.
Fig. 4 shows a schematic front view of a field effect superconducting josephson junction device with isolation layer according to the present invention.
Fig. 5 shows a schematic perspective view of a josephson junction with a 2-dimensional nanobridge according to an embodiment.
Fig. 6 shows an electron micrograph of a field effect superconducting josephson junction device according to the invention.
Fig. 7 shows the critical current as a function of voltage for a field effect superconducting josephson junction device according to the invention.
Fig. 8 shows a graph of current-phase relationship for a field effect superconducting josephson junction device according to the invention at different voltages.
Fig. 9 shows a schematic front view of a field effect superconducting josephson junction device according to the present invention after trench formation.
Fig. 10 shows a schematic diagram of the front view of the field effect superconducting josephson junction device after formation of the nanobridge according to the present invention.
Description of the component reference numerals
10. Field effect superconducting Josephson junction device
110. Substrate and method for manufacturing the same
120. Bridge left bank electrode
130. Bridging right bank electrode
140. Insulated trench
141. Groove(s)
150. Nano bridge
151. Two-dimensional nanobridge
160. Insulating dielectric layer
170. Voltage pole
180. Isolation layer
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Referring to fig. 1 to 10, the drawings provided in the present embodiment are only schematic to illustrate the basic concept of the present invention, and only the components related to the present invention are shown in the drawings, rather than the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
Example 1
The present embodiment provides a field effect superconducting josephson junction device 10, as shown in fig. 1, 2 and 6, the field effect superconducting josephson junction device 10 comprising:
the substrate 110 is made of at least one material selected from MgO, sapphire, si3N4, al2O3 and SiO 2.
The left bridge shore electrode 120, the right bridge shore electrode 130 and the insulating trench 140 are formed on the upper side of the substrate 110, the insulating trench 140 isolates the left bridge shore electrode 120 and the right bridge shore electrode 130 from each other, the left bridge shore electrode 120 and the right bridge shore electrode 130 are respectively used as two superconductors of the josephson junction, wherein the materials of the left bridge shore electrode 120 and the right bridge shore electrode 130 comprise at least one of, but not limited to, nb, nbN, nbTi, nbTiN, and the materials of the left bridge shore electrode 120 and the right bridge shore electrode 130 can be different.
The nanobridge 150 is located above the left bridge shore electrode 120, the insulating trench 140 and the right bridge shore electrode 130, and spans the insulating trench 140 to connect the left bridge shore electrode 120 and the right bridge shore electrode 130, so as to form a weak connection between two superconductors (the left bridge shore electrode 120 and the right bridge shore electrode 130), wherein materials adopted by the nanobridge 150 include, but are not limited to, nb, nbN, nbTi, nbTiN.
An insulating dielectric layer 160 positioned on the left bank electrode 120 of the bridge junction and the insulating trench 140 and the upper side of the right bank electrode 130, and cover the nanobridge 150 to protect and electrically isolate the nanobridge 150, wherein the insulating dielectric layer 160 is made of a material including but not limited to SiO 2 Layer, hfO 2 Layers or Al 2 O 3 At least one of the layers.
And a voltage pole 170, which is located on the upper side of the insulating medium layer 160, and the formed electric field applies a modulation electric field to the nanobridge through the insulating medium layer 160, so as to change the critical current of the josephson junction.
In this embodiment, the nanobridge 150 is formed on the upper surfaces of two superconductors (the left-bank electrode 120 and the right-bank electrode 130), and the thickness thereof is much smaller than that of the left-bank electrode 120 (or the right-bank electrode 130), because the thickness of the nanobridge 150 can be thinner than that of the left-bank electrode 120 (or the right-bank electrode 130), for example, the thickness thereof is smaller than the penetration depth of the superconducting material used, the modulation electric field applied by the voltage electrode 170 can effectively penetrate the nanobridge 150, so as to realize effective modulation of the josephson junction critical current; meanwhile, as shown in fig. 5, the three-dimensional structure of the josephson junction is a schematic diagram of a conventional 2-dimensional nano bridge, in the structure, because the two-dimensional nano bridge and the two superconductors are in the same structural layer, the thickness of the two-dimensional nano bridge is equivalent to that of the two superconductors, when the 2-dimensional nano bridge josephson junction shown in fig. 3 is adopted to prepare a field effect superconducting josephson junction device, a modulation electric field applied by the voltage pole 170 cannot effectively penetrate the two-dimensional nano bridge, that is, the critical current of the josephson junction cannot be effectively modulated by the voltage, and the relation of the wave function phase difference and the superconducting current at two ends of the junction (current-phase relation, CPR) cannot be ensured to be nonlinear; while the nanobridge 150 in this application connects two superconductors across the insulating channel 140, forming a 3-dimensional nanobridge josephson junction with a more excellent current-phase relationship (only slightly deviating from the sine function curve) than a 2-dimensional nanobridge josephson junction with the same bridge length L.
In some embodiments, as shown in FIG. 1, the upper surface of the insulating channel 140, the upper surface of the bridging left bank electrode 120, andthe upper surface of the bridging right bank electrode 130 is flush; in this embodiment, the upper surfaces of the insulating channel 140, the left-bank electrode 120 and the right-bank electrode 130 are controlled to be level, which is helpful for controlling the bridge length of the nanobridge 150 bridging the left-bank electrode 120 and the right-bank electrode 130, the bridge length L of the nanobridge 150 affects the current-phase relationship of Josephson junction, and the method is described in the DC Josephson equation I C ＝I S sin (θ) is a sine, but this sine exists only when the bridge length (L) of the nanobridge 150 is smaller than the coherence length (ζ) of the superconducting material, and when L/ζ is greater than 1, the current-phase relationship of the josephson junction gradually deviates from the sine function, so that it is preferable that the bridge length L of the nanobridge 150 is smaller than the coherence length of the superconducting material used by the nanobridge.
In some embodiments, as shown in fig. 2, since the bridge length L and the width of the nanobridge 150 are respectively determined by the thickness of the insulating channel 140 and the width of a length of the nanobridge 150 covered on the insulating channel 140, in order to make good contact between two ends of the nanobridge 150 and the left and right bridge shore electrodes 120 and 130, respectively, the contact area between two ends of the nanobridge 150 and the left and right bridge shore electrodes 120 and 130 is not limited by the width and the length of the nanobridge 150, and can be made wider and the contact area is made larger.
In some embodiments, as shown in fig. 4, the field effect superconducting josephson junction device 10 further comprises an isolation layer 170, the isolation layer 170 being located on the upper side of the substrate 110 and on the lower side of the bridge right bank electrode 130, isolating the bridge right bank electrode 130 from the substrate 110; since the thickness of the insulating channel 140 determines the bridge length L of the nanobridge 150, in order to make the bridge length L of the nanobridge 150 smaller than the coherence length (ζ) of the superconducting material used by the nanobridge, the thickness of the insulating channel 140 should also be smaller than the coherence length (ζ) of the superconducting material used by the nanobridge, and even smaller than 10nm when some superconducting materials with extremely short coherence length are used, in some process paths, after the formation of the left bank electrode of the bridge, an insulating layer 170 is formed on the surface of the substrate not covered by the left bank electrode of the bridge while depositing the insulating channel 140 on the sidewall thereof, and then the right bank electrode of the bridge is prepared.
In some embodiments, for effective, sensitive control of the critical current of the josephson junction, the thickness of the nanobridge 150 is less than the penetration depth of the superconducting material employed by the nanobridge to ensure that an electric field can enter the interior of the nanobridge 150 and act on the coumaron pairs.
In some embodiments, the bridge left bank electrode 120 and the bridge right bank electrode 130 are made of the same superconducting material, so that they have the same critical current under the same structural morphology and environmental conditions; in some embodiments, the superconducting materials used for the left bridge shore electrode 120 and the right bridge shore electrode 130 and the nanobridge 150 are the same, so that the three have the same working temperature, for example, nb is used, the critical temperature of the superconducting state is about 9K, the device based on Nb superconducting material can work in a liquid helium environment, the working temperature condition is easy to reach, the penetration depth of Nb superconducting material is higher than that of other superconducting metals, and the critical current of the josephson junction can be effectively controlled by the electric field formed by the voltage electrode 170.
To further illustrate the beneficial effects of the field effect superconducting josephson junction device 10 of the present embodiment, the present embodiment also illustrates the operation of the field effect superconducting josephson junction device 10:
in operation of the field effect superconducting josephson junction device 10, the voltage electrode 170 applies a voltage forming an electric field acting on the nanobridge 150, the superconducting critical current I of the field effect superconducting 10 being varied by adjusting the magnitude of the voltage C Is of a size of (a) and (b).
Specifically, as shown in FIG. 7, when a voltage V is applied to the voltage pole 170 gate Critical current I of josephson junction C Can be regulated and controlled by voltage in a certain voltage range, and when the applied voltage is smaller, the critical current I C Does not change when the applied voltage V gate Exceeding a certain threshold range (e.g. V g1 ) Critical current I of josephson C Will be gradually suppressed to zero, wherein,I C0 the maximum critical current expressed as field effect superconducting josephson junction device; voltage V gate ＝V g1 When I C ＝I C0 The method comprises the steps of carrying out a first treatment on the surface of the Voltage V gate ＝V g2 When I C ＝3I C0 4; voltage V gate ＝V g3 When I C ＝I C0 2; voltage V gate ＝V g4 When I C ＝I C0 Statistical critical current I C And V is equal to gate Can be obtained as a function of the junction and the voltage of Josephson C ＝I C0 f(V gate )。
In actual operation, it is desirable that critical current I of field effect superconducting Josephson junction device 10 C Larger (to make the device on-current larger), but at the same time it is desirable to obtain a better current-phase relationship (better nonlinearity current-phase relationship), in order to better reveal the current-phase relationship of the present embodiment of the field effect superconducting josephson junction device 1, the field effect superconducting josephson junction device 1 is understood as a physical model consisting of an ideal josephson junction (no inductance) in series with an equivalent inductance (inductance of the field effect superconducting josephson junction device 10), and then the functional relation of the current-phase relationship of the field effect superconducting josephson junction device 10 is expressed as: θ=arcsin (I C /I S )+2πL J I S /Ф 0 Wherein I C Expressed as the critical current, I S Superconducting current represented as said field effect superconducting josephson junction device, θ being represented as phase θ of superconducting wave function in the left bank electrode of said bridge junction L Phase theta of the wave function in the right bank electrode of the bridge junction R Phase difference of phi 0 Expressed as a flux quantum, L J Represented as the equivalent inductance of the field effect superconducting josephson junction device, and the longer the two superconducting bulk weak link length (the longer the bridge length of nanobridge 150), L J The larger.
Specifically, as shown in FIG. 8, when the voltage V gate When the magnitude is different, the relation curve of the current-phase relation represents different linearity, when the voltage V gate ＝V g4 At the time, current I S The relation with the phase theta is approximately sinusoidal, when the voltage V gate ＝V g1 At the time, current I S The phase θ relationship is approximately linear. By applying different voltages V gate The current I can be S The phase θ relationship is modulated to the desired curve.
Example two
The present embodiment provides a method for manufacturing a field effect superconducting josephson junction device 10, the method comprising: step S1) to step S6).
Step S1): a substrate 110 is provided, and a first superconducting material layer is formed on an upper surface of the substrate 110.
In this embodiment, the substrate 110 is made of MgO, sapphire, or Si 3 N 4 、Al 2 O 3 SiO (silicon oxide) 2 At least one of (a) or other material that allows the growth of a superconducting thin film; methods of forming the first superconducting material layer include, but are not limited to, magnetron sputtering, chemical vapor deposition, and the like.
Step S2), a patterned mask layer is formed on the upper surface of the first superconducting material layer, and the first superconducting material layer is etched based on the mask layer, as shown in fig. 9, to form a bridge left bank electrode 120, a bridge right bank electrode 130, and a trench 141 between the bridge left bank electrode 120 and the bridge right bank electrode 130.
In this embodiment, a photoresist layer may be formed on the upper surface of the first superconducting material layer by a coating process, then, the photoresist layer is patterned by an exposure developing method, and then, the patterned photoresist layer is used as a mask to etch (e.g. plasma etch) the first superconducting material layer to form the trench 141, where the first superconducting material layer is cut into the bridge left bank electrode 120 and the bridge right bank electrode 130 by the trench 141, and the bridge left bank electrode 120 is not in contact with (not electrically connected to) the bridge right bank electrode 130.
Step S3), filling the trench 141 to form an insulating trench 140 isolating the bridging left and right shore electrodes 120 and 131 from each other.
In this embodiment, a layer of insulating material is deposited in the left and right bridge electrodes 120, 130 and the trench 141 by chemical vapor deposition, for example, and then thinned by chemical mechanical polishing until the upper surfaces of the left and right bridge electrodes are exposed, and the thinned insulating material is located in the trench and has an upper surface flush with the upper surfaces of the left and right bridge electrodes, i.e., an insulating channel sandwiched between the left and right bridge electrodes is formed.
Step S4), as shown in fig. 10, a nanobridge is formed on the upper surfaces of the left bridge shore electrode, the insulating trench and the right bridge shore electrode, and the left bridge shore electrode and the right bridge shore electrode are connected across the insulating trench.
In this embodiment, a second superconducting material layer is deposited and patterned to obtain a nanobridge, where the thickness of the second superconducting material layer is far smaller than that of the first superconducting material layer, for example, the thickness of the second superconducting material layer is within 30% of that of the first superconducting material layer, so that the superconducting current of the josephson junction is not only related to the critical current (density), but also related to the cross-sectional areas of two superconductors (the left bridge shore electrode and the left bridge shore electrode), and the thicker left bridge shore electrode and the left bridge shore electrode (the first superconducting material layer) can enable the device to have larger superconducting current circulation under the condition that the critical current is limited; while a thinner nanobridge (second superconducting material layer) helps to ensure that the josephson junction has a better non-linear current-phase relationship.
And S5), forming an insulating medium layer on the upper surfaces of the nanobridge, the bridge left bank electrode, the insulating channel and the bridge right bank electrode.
In this embodiment, the insulating dielectric layer may be formed by a chemical vapor deposition process, and the insulating dielectric layer coats the nanobridge to isolate the nanobridge from a voltage electrode formed subsequently.
Step S6), as shown in fig. 1, of forming a voltage pole 170 on the upper surface of the insulating dielectric layer, and, as shown in fig. 2, the projection of the voltage pole covers at least the overlapping area of the nanobridge and the insulating channel in the top view direction.
In this embodiment, a physical sputter deposition process may be used to form a voltage pole that is used to apply a modulating electric field to the nanobridge to change the magnitude of the critical current and modulate the current-phase relationship.
In summary, according to the field effect superconducting josephson junction device and the preparation method thereof, the bridge left bank electrode and the bridge right bank electrode are isolated through the insulating channel, weak connection between the bridge left bank electrode and the bridge right bank electrode is realized through the nanobridge, the critical current of the junction is changed through applying an electric field to the voltage pole above the nanobridge, so that large critical current is obtained, the nanobridge with a smaller thickness, the bridge left bank electrode with a thicker thickness and the bridge right bank electrode are positioned on different structural layers, the device can have a current-phase relation with better nonlinearity, meanwhile, the nanobridge also adopts superconducting materials, the working temperature of the device is equal to that of the left (or right) bank superconducting electrode, and the working temperature is not too low.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (10)
1. A field effect superconducting josephson junction device, the field effect superconducting josephson junction device comprising: the device comprises a substrate, a bridging left-bank electrode, a bridging right-bank electrode, an insulating channel, a nanobridge, an insulating medium layer and a voltage electrode;
the bridge left bank electrode, the insulating channel and the bridge right bank electrode are positioned on the upper side of the substrate, and the insulating channel isolates the bridge left bank electrode and the bridge right bank electrode from each other;
the nanobridge spans the insulating channel to connect the bridging left bank electrode with the bridging right bank electrode and is positioned on at least part of the upper surface of the bridging left bank electrode and part of the upper surface of the bridging right bank electrode;
the insulating medium layer coats the nano bridge and is arranged on the upper sides of the left bridge electrode, the insulating channel and the right bridge electrode;
the voltage pole is positioned on the upper side of the insulating medium layer, and the projection of the voltage pole at least covers the area where the nanobridge and the insulating channel overlap in the top view direction.
2. The field effect superconducting josephson junction device of claim 1, wherein the thickness of the nanobridge is less than the thickness of the bridge left bank electrode and less than the thickness of the bridge right bank electrode.
3. The field effect superconducting josephson junction device of claim 1, further comprising an isolation layer,
the isolation layer is positioned on the upper side of the substrate and on the lower side of the right bank electrode of the bridge, and the right bank electrode of the bridge and the substrate are isolated from each other.
4. The field effect superconducting josephson junction device of claim 1, wherein the bridge length of the nanobridge is less than the coherence length of the superconducting material employed by the nanobridge.
5. The field effect superconducting josephson junction device of claim 1, wherein the thickness of the nanobridge is less than the penetration depth of the superconducting material employed by the nanobridge.
6. The field effect superconducting josephson junction device of claim 1, wherein the superconducting materials used for the nanobridge, the bridge left bank electrode, and the bridge right bank electrode are the same.
7. The field effect superconducting josephson junction device of claim 1, wherein the material of the substrate comprises at least one of MgO, sapphire, si3N4, al2O3 and SiO 2; the material of the bridged left bank electrode comprises at least one of Nb, nbN, nbTi and NbTiN; the material of the right bank electrode of the bridge comprises at least one of Nb, nbN, nbTi and NbTiN.
8. The field effect superconducting josephson junction device according to any of claims 1-7, characterized in that,
changing the critical current of the field effect superconducting Josephson junction device by adjusting the voltage of the voltage pole;
by the formula θ=arcsin (I C /I S )+2πL J I S /Ф 0 Modulating the current-phase relationship of said field effect superconducting Josephson junction device, wherein I C Expressed as the critical current, I S Superconducting current represented as the field effect superconducting Josephson junction device, θ is represented as a phase difference between the bridge left-side shore electrode internal wave function and the bridge right-side shore electrode internal wave function, L J Equivalent inductance denoted as the field effect superconducting josephson junction device, Φ 0 Represented as a flux quantum.
9. A method for fabricating a field effect superconducting josephson junction device, the method comprising:
s1), providing a substrate, and forming a first superconducting material layer on the upper surface of the substrate;
s2), forming a patterned mask layer on the upper surface of the first superconducting material layer, and etching the first superconducting material layer based on the mask layer to form a bridge left bank electrode, a bridge right bank electrode and a groove, wherein the groove is positioned between the bridge left bank electrode and the bridge right bank electrode;
s3), filling the groove to form an insulating channel;
s4), forming a nano bridge on the upper surfaces of the bridge left bank electrode, the insulating channel and the bridge right bank electrode, wherein the nano bridge spans the insulating channel to connect the bridge left bank electrode with the bridge right bank electrode;
s5), forming an insulating medium layer on the upper surfaces of the nanobridge, the bridge left bank electrode, the insulating channel and the bridge right bank electrode;
and S6) forming a voltage pole on the upper surface of the insulating medium layer, wherein the projection of the voltage pole at least covers the overlapping area of the nano bridge and the insulating channel in the overlooking direction.
10. The field effect superconducting josephson junction device of claim 9, wherein the thickness of the nanobridge is less than the thickness of the first layer of superconducting material.
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| CN116887663A (en) * | 2023-09-06 | 2023-10-13 | 量子科技长三角产业创新中心 | Superconducting quantum circuit and superconducting quantum device |
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2023
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116887663A (en) * | 2023-09-06 | 2023-10-13 | 量子科技长三角产业创新中心 | Superconducting quantum circuit and superconducting quantum device |
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