DE102019106508A1 - Method for adjusting the electrical resistance of a nanowire and method for adjusting the electrical resistance of the nanowire and of at least one additional nanowire or additional nanowires - Google Patents

Abstract

A method (100) for adjusting the electrical resistance of a nanowire comprising: providing at least (110) one nanowire, an electrical energy supply and a measuring device; Applying a measuring pulse to determine an actual electrical resistance value of the nanowire (120); Acquiring the measured value for the current flowing through the nanowire and the measured value for a voltage (130) dropping across the nanowire; Determining an actual electrical resistance value (140); Comparing whether the actual electrical resistance value is greater than or equal to a previously determinable, desired electrical resistance value (150); Applying a subsequent electrical pulse if the actual resistance value is greater than the desired resistance value (160); and repeating the preceding method steps as long as the actual electrical resistance value is greater than the previously determinable, desired electrical resistance value (170).

Description

The invention relates to a method for adjusting the electrical resistance of a nanowire and a method for adjusting the electrical resistance of the nanowire and of at least one additional nanowire or additional nanowires by applying at least one electrical pulse.

Electrical resistances can be implemented in the most varied of ways, whereby a fundamental distinction can be made between fixed and adjustable resistances (for an overview of various implementations and production methods, see e.g. bibliography [1] and [2]).

In connection with the present method, implementation with the aid of metallic thin-film layers, which have a characteristic sheet resistance, is of particular relevance. Here, the target resistance is usually determined via the geometry (width and length), assuming a constant surface resistance. Thus, the resistor produced in this way is subject to the tolerances that result from the inhomogeneity of the sheet resistance and the production-related deviation from the planned geometry. Depending on the material used and the size of the structure, for example, nanowires can easily deviate from the target resistance by up to several hundred percent. Subsequent adaptation, for example by reducing the surface resistance by means of an etching process / laser trimming, is possible, but difficult or technically complex and therefore cost-intensive. In the special case that the resistor is to be integrated directly into a circuit and manufactured in the same process step as the rest of the structure, subsequent treatment for adaptation is particularly difficult, since other elements of the circuit are also uncontrollably changed or affected by any processes can be.

This invention is based on the objective technical problem of providing a method for adjusting the electrical resistance of a nanowire and a method for adjusting the electrical resistance of a nanowire and of at least one additional nanowire or additional nanowires, which makes it possible to reduce the resistance of one or more adapt prefabricated nanowires in such a way that an abrasive or chemical post-treatment of the nanowire or the additional nanowires to adjust the electrical resistance is avoided and the electrical resistance of the nanowire or of the at least one additional nanowire or the additional nanowires can be adjusted independently of their respective wire geometry.

This objectively technical problem mentioned above is achieved with the method disclosed herein according to the subject matter of the first independent claim 1. Related secondary claims or subclaims reproduce advantageous configurations or embodiments. Advantageous developments, which can be implemented individually or in any combination, are presented in the dependent claims.

In the following, the terms “have”, “comprise” or “include” or any grammatical deviations therefrom are used in a non-exclusive manner. Accordingly, these terms can relate to situations in which, besides the features introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the expression "A has B", "A comprises B" or "A includes B" can refer to the situation in which, apart from B, there is no other element in A (i.e. a situation in which A consists exclusively of B), as well as the situation in which, in addition to B, one or more further elements are present in A, for example element C, elements C and D or even further elements.

Furthermore, it should be noted that the terms “at least one” and “one or more” as well as grammatical modifications of these terms, if these are used in connection with one or more elements or features and are intended to express that the element or feature is provided once or several times can be used, as a rule, only once, for example when the feature or element is introduced for the first time. If the feature or element is subsequently mentioned again, the corresponding term “at least one” or “one or more” is generally no longer used, without restricting the possibility that the feature or element can be provided once or several times.

Furthermore, the terms “preferably”, “in particular”, “for example (for example)” or similar terms are used below in connection with optional features, without this limiting alternative embodiments. Features introduced by these terms are optional features, and it is not intended to use these features to restrict the scope of protection of the claims and in particular of the independent claims. So can the Invention, as those skilled in the art will recognize, can also be carried out using other embodiments. In a similar way, features which are introduced by “in one embodiment” or by “in a further embodiment” are understood as optional features, without this being intended to restrict alternative configurations or the scope of protection of the independent claims. Furthermore, by means of these introductory expressions, all possibilities of combining features introduced in this way with other features, be it optional or non-optional features, remain untouched.

In a first embodiment, the method for adjusting the electrical resistance of a nanowire between at least two electrically conductive connection points comprises: providing at least: one nanowire; an electrical energy supply, wherein the electrical energy supply is electrically conductively connected with two electrical poles at the electrically conductive connection points with the nanowire, wherein the electrical energy supply is set up in such a way that an electrical pulse with a predeterminable pulse height and pulse is applied to the nanowire between the connection points. can be applied permanently, wherein the electrical pulse is formed by means of a specifiable electrical current and a specifiable electrical voltage and its pulse height is regulated by means of the specifiable electrical current or the specifiable electrical voltage, and the output from the electrical energy supply to the nanowire during the pulse duration electrical power is formed from the electrical current flowing during the pulse duration and the electrical voltage dropping across the nanowire; and a measuring device, wherein the measuring device is set up in such a way that when the electrical pulse is applied, a measured value for the current flowing through the nanowire or a measured value for a voltage drop across the nanowire can be recorded, and from the measured value for a current flowing through the nanowire Current and the measured value for a voltage dropping across the nanowire, an actual resistance value of the nanowire can be determined; Applying an electrical measuring pulse by means of the electrical energy supply with a predeterminable, first pulse height and duration to the nanowire between the connection points for determining an actual electrical resistance value of the nanowire; Detecting the measured value for the current flowed through the nanowire and the measured value for a voltage drop across the nanowire by means of the measuring device; Determining an actual electrical resistance value of the nanowire between the two connection points from the measured values; Comparing whether the actual electrical resistance value of the nanowire is greater than or equal to a previously determinable, desired electrical resistance value; Applying a subsequent electrical pulse with a predeterminable, second pulse height and / or duration to the nanowire between the connection points to adjust the resistance of the nanowire if the actual resistance value of the nanowire is greater than the target resistance value, the predeterminable second pulse height and / or duration of the electrical subsequent pulse is increased or longer by a previously determinable, first value compared to the specifiable, first pulse height and / or duration of the measurement pulse; and repeating the preceding method steps as long as the actual electrical resistance value of the nanowire is greater than the previously determinable, nominal electrical resistance value, with the predeterminable second pulse height and / or duration of the subsequent electrical pulse by a previously determinable second value in each iteration is increased or longer than the predeterminable, second pulse height and / or duration.

Such a method thus makes it possible to adapt the resistance of one or more prefabricated nanowires in such a way that an abrasive or chemical post-treatment of the nanowire or the additional nanowires to adapt the electrical resistance is avoided and the electrical resistance of the nanowire or the at least one additional nanowire or the additional nanowires can be adapted independently of their respective wire geometry.

In a second embodiment, the method for adapting the electrical resistance of the nanowire and of at least one additional nanowire or additional nanowires, which has / have a common functional relationship between the voltage drop across the nanowire and the current flowing through the nanowire : Carrying out the previously described method steps of the first embodiment of the method for adapting the electrical resistance of the nanowire, this nanowire serving as a reference nanowire; Detection of a common functional relationship between the applied electrical follow-up pulses and the respective change in the electrical resistance of the reference nanowire; Determination of a reference curve, which is based on the common functional relationship, by means of the preceding method step; and applying the electrical follow-up pulse with a predeterminable, second pulse height and / or duration to the nanowire between the connection points for adapting the resistance of the nanowire, the specifiable, second electrical pulse height and / or duration of the electrical follow-up pulse (eFP) being taken from the reference curve becomes.

This enables the electrical resistance of a class of nanowires that have a common functional relationship to be adjusted without any intermediate steps.

In a further embodiment of the method for adapting the electrical resistance of a nanowire or of a nanowire and of at least one additional nanowire or of additional nanowires, the nanowire and / or the at least one additional nanowire or the additional nanowires at least partially comprise aluminum oxide (Al ₂ O ₃ ) on or is / are formed from it.

For granular aluminum oxide (AlO _x ), the composition of metallic nano-crystallites and insulating barriers of different thicknesses has been well studied and can be precisely adjusted during the evaporation process (e.g. by means of sputtering / thermal evaporation). Granular aluminum oxide (AlO _x ) is therefore particularly suitable for the process described.

In a further embodiment of the method for adapting the electrical resistance of a nanowire or of a nanowire and of at least one additional nanowire or of additional nanowires, the nanowire and / or the at least one additional nanowire or the additional nanowires have a diameter of approximately 10 Nanometers up to about 200 nanometers.

In a further embodiment of the method for adjusting the electrical resistance of a nanowire or of a nanowire and of at least one additional nanowire or of additional nanowires, the nanowire and / or the at least one additional nanowire or the additional nanowires have a length in one area from about 10 nanometers to about 10 micrometers.

Choosing a sufficient length ensures that self-averaging of the intrinsic structure takes place, which ensures the change or variability of the resistance over a wide range.

In a further embodiment of the method for adapting the electrical resistance of a nanowire or of a nanowire and of at least one additional nanowire or additional nanowires, the electrical measurement pulse with a current strength in a range from approximately 10 ^-8 amperes to approximately 10 ^-7 Amps applied.

The use of measuring pulses with said low current strengths (see current strengths in the above paragraph) prevents unwanted changes to the nanowire and ensures that the nanowire is not heated up, which could otherwise lead to unwanted changes in its material properties.

In a further embodiment of the method for adapting the electrical resistance of a nanowire or of a nanowire and of at least one additional nanowire or additional nanowires, the subsequent electrical pulse is applied with a pulse duration in a range from approximately 1 millisecond to approximately 300 milliseconds.

This prevents the nanowire from being heated up.

In a further embodiment of the method for adapting the electrical resistance of a nanowire and / or of a nanowire and of at least one additional nanowire or additional nanowires, the subsequent electrical pulse with an amplitude of the voltage pulse in a range of approximately 10 ^-3 volts up to about 10 ⁺² volts applied.

For suitable nanowires, a change in resistance can take place over several orders of magnitude with voltage pulses in the range described. Commercially available devices can generate the required voltage pulses in this area very precisely.

In a further embodiment of the method for adapting the electrical resistance of a nanowire or of a nanowire and of at least one additional nanowire or of additional nanowires is / are the nanowire and / or the at least one additional nanowire or the additional nanowires to a temperature in one Cooled range from about 10 millikelvin to about 77 Kelvin.

This leads to a better controllability of the change in resistance, since the thermally activated charge transport is largely suppressed.

In a further exemplary embodiment, use of the method as voltage protection is described below:

Since the amplitude of the applied voltage or the current flowing through the nanowire is primarily decisive for reducing the electrical resistance of the nanowire, a use z. B. imaginable as voltage protection in an electrical circuit. Reached the above Nanowire dropping voltage has a wire-specific value (this can be determined via the geometry and the sheet resistance (material)), so the resistance is reduced and the current can flow through the nanowire. This mechanism can also be used to specifically activate individual “current paths” by applying a voltage pulse to the nanowire integrated in the circuit in order to reduce its resistance.

The following general terms used herein are defined:

The term “electrical resistance” (also referred to as ohmic resistance) defines here what current flows through a component for a specific voltage under otherwise identical conditions (Ohm's law U = R * I).

The term “nanowire” defines the physical object whose electrical resistance is to be changed by means of the method. The exact shape and geometry can vary and is not fixed. For the sake of simplicity, wires are used synonymously, which are characterized by a specifiable length, width and thickness, their length in a range from approximately 5 nm to approximately 100 μm and their width or thickness in a range from approximately 5 nm to approximately 10 µm. There are of course other forms - such as B. A nanowire that narrows over a specific length - conceivable. Manufacturing-related deviations can also lead to the thickness and width of the nanowire varying in other ways over its length.

The term “dimension / dimensions” defines in particular the spatial extent of the nanowire (width, height, length).

The term “electrically conductive” defines here that the respective element / device has a measurable, finite electrical resistance.

Explanation of suitable materials:

Particularly suitable films for producing the nanowires are high-resistance (> 100 Ohm / square) metallic films. This is e.g. B. given by films with a film thickness which is in a range from approximately 10 nm to approximately 100 nm, so-called cermets, which are composed of metallic nano-crystals and an insulating ceramic component. It is also important for the method that the metallic nano-crystals are separated from one another by insulating barriers, the spatial extent of which is in a range from approximately 0.05 nm to approximately 10.00 nm. Possible materials are e.g. B. Al-SiO ₂ , Ni-SiO ₂ , Au-SiO ₂ , W-AlO ₂ and many more and also films made of granular aluminum oxide (AlO _x ). The sheet resistances of the materials can be adjusted in the growth process of the films via the proportion of the insulating component. This changes both the size of the metallic crystallites and the thickness of the insulating barriers.

The mechanism of drag reduction using one of the methods according to the invention is essentially based on the following physical principles / processes:

The film contains - due to the growth process - before and after structuring into a nanowire a disordered distribution of metallic nano-crystallites and insulating barriers of different thickness between them. Applying a voltage to the nanowire creates local electrical fields that drive the tunneling of electrons and therefore lead to an "increased" electrical conductivity, ie a relative increase compared to the conductivity without the applied voltage. If the effective local voltage across an inner barrier is increased above its critical value, the barrier is broken down (breakdown voltage) and the neighboring metallic crystallites are connected with low resistance. This process lowers the overall resistance of the nanowire. Since the local voltage drops across a large number of parallel barriers in a wire with a wide cross-section (>> 1 µm ² ), the method of reducing the resistance becomes increasingly impractical, since it also increases the overall conductivity and the wire heats up, as does the mechanism described above is suppressed.

The term “energy supply” here defines a voltage or current source. Depending on which of the two physical quantities of the pulse is regulated (current or voltage), a voltage or current source is required. Many devices offer both options, i.e. they are DC voltage or current sources.

The term “measuring device” defines a device which is set up in such a way that an electrical voltage that drops across the nanowire and / or an electrical current that flows through the nanowire, or a voltage or current source, can be detected a previously described electrical voltage or a previously described current can be detected. It can of course also be a combination device that enables control both with regard to a previously selected voltage and with regard to a specific current. It is too possible to use the same device for power supply and as a measuring device.

The term “connection points” here define electrically conductive structures which are themselves electrically connected to the nanowire and enable electrical contacting (e.g. contacting surfaces that are made from the same material as the nanowire and connect to it).

Alternatively, the ends of the nanowire can also be contacted directly, if this is possible without destroying the nanowire.

The term “pole” as used herein defines the outputs of the voltage source (i.e. electrical positive and negative poles).

The term “electrical measuring pulse” defines the voltage and current pulse (regardless of whether it is regulated with regard to a previously specified current or a voltage, the pulse always has a current and a voltage component) that is generated by the measuring device to determine the resistance and from which the resistance of the nanowire can be determined using Ohm's law (U = R * I see above).

The term “follow-up pulse” here defines at least one voltage and current pulse that is emitted by the energy supply.

The term “measured value” here defines a current or a measured voltage measured with the energy supply or measuring device.

The term “common functional relationship” defines a characteristic relationship between the pulses applied to change the resistance (e.g. amplitude of the voltage component) and the change in resistance of the nanowire. Mathematically this can e.g. B. can be described by a straight line slope or a constant factor in an exponential function. Such a connection can e.g. B. be found by one or more reference curves for a class of wires.

In order to clarify the above term “common functional relationship”, an exemplary experiment is used, which is described below, in which the electrical resistance of nanowires made of granular aluminum oxide was changed in a controlled manner using the method disclosed herein. The nanowires used are, for example, 50 nm wide and 20 nm thick. The following functional relationship can be found empirically for the electrical resistance of the nanowire as a function of the amplitude of the applied current pulse: $$\text{R.}=m_2\text{/}\left(m_1+{\mathrm{I.}}_{puls}\right)+m_3$$

The parameters m ₁ , m ₂ and m ₃ depend on the material properties and the wire geometry and are therefore nanowire-specific. I _puls represents the pulse current that flows through the nanowire while the voltage pulse required for a change in resistance is applied.

1 shows an exemplary curve of the wire resistance as a function of the pulse current for the nanowires described in this example. The nanowire has a length of 750 nm (sheet resistance 2.5 kΩ) and was produced using the method described in the explanations on the vapor deposition process. The method disclosed in this application was used at a wire temperature of 4 K (Kelvin). For the example shown, the following values result for the parameters m ₁ , m ₂ and m ₃ : $$m_1=-{2.48}^{-\mathrm{6th}},m_2=\mathrm{7.1,}{m}_3={9.66}^{\mathrm{4th}}.$$

Based on the functional relationship (1) and the parameters m ₁ , m ₂ and m ₃ , it can thus be determined for nanowires of the same class which electrical pulse is necessary to achieve a desired change in resistance.

Since the change in resistance as a function of the applied voltage (or current) can have very different curves, depending on the temperature at which the disclosed method is used, which resistance range is considered and what the intrinsic properties of the nanowires (i.e. material / geometry) are, Suitable functions for different wire classes can differ greatly from one another.

$$\text{R}=m_2\text{*exp}\left(-m_1*I_{puls}\right)+m_3$$

$$\text{R}=m_1*I_{puls}+m_2$$

wobei typischer Weise bei einer Variation der Drahtlänge mit ansonsten gleichen Drahteigenschaften (d. h. Dicke, Material und/oder Breite) einer der Parameter m_i (i=1,2,3) mit der Drahtlänge skaliert.In our experiments with wires made of granular aluminum oxide, the following functions (A, B and C) have proven to be particularly suitable (whereby the pulse voltage can also be viewed as a controlled variable instead of the pulse current): $$\text{R.}=m_2\text{/}\left(m_1+{\mathrm{I.}}_{puls}\right)+m_3$$

$$\text{R.}=m_2\text{* exp}\left(-m_1*{\mathrm{I.}}_{puls}\right)+m_3$$

$$\text{R.}=m_1*{\mathrm{I.}}_{puls}+m_2$$

with a variation of the wire length with otherwise the same wire properties (ie thickness, material and / or width), one of the parameters m _i (i = 1, 2, 3) typically being scaled with the wire length.

1. 1. Bereitstellen:
   • mindestens eines exemplarischen Nanodrahts aus granularem Aluminiumoxid mit näherungsweise gleicher Dicke und Breite wie die zu verändernden Nanodrähte,
   • mindestens einer Spannungs- und Stromversorgung derart eingerichtet, um damit einen Spannungs- und Strompuls zu erzeugen,
   • mindestens einer Messvorrichtung, die eine gleichzeitige elektrische Kontaktierung beider Drahtenden ermöglicht und mit welcher mittels der Spannungsquelle aus (b.) eine Spannung über dem Nanodraht angelegt werden kann.
2. 2. Mit Hilfe der Messvorrichtung werden beide Enden des exemplarischen Nanodrahts mit der Spannungs- und Stromversorgung elektrisch kontaktiert.
3. 3. Anlegen einer Messspannung mit Hilfe der Spannungs- und Stromversorgung zur Bestimmung des Ausgangswiderstands des Nanodrahts. Unter Berücksichtigung des ohmschen Gesetzes U = R · I und der gewählten Drahtgeometrie sowie des Flächenwiderstands kann der zu erwartende Widerstand des Nanodrahts abgeschätzt werden. Ausgehend von diesem sollte die verwendete Messspannung so gewählt werden, dass der zu erwartende Messstrom 0.1 Mikroampere (µA) nicht überschreitet, um so eine ungewollte Widerstandsveränderung zu vermeiden.
4. 4. Anlegen eines gegenüber der Messspannung größeren Spannungs- und somit Strompulses zur Widerstandsveränderung mittels der Spannungs- und Stromversorgung. Die Differenz ΔU zwischen der Messspannung und der Spannung, die zur Widerstandsveränderung angelegt wird, kann beliebig klein gewählt werden. Für diese Beispiele lag die Pulsdauer typischerweise bei einigen 10 Millisekunden und ΔU bei einigen Millivolt.
5. 5. Anlegen der Messspannung aus 3., um den elektrischen Widerstand des Nanodrahts erneut zu bestimmen.
6. 6. Anlegen eines um 2 · ΔU größeren Spannungs- und somit Strompulses zur Widerstandsveränderung
7. 7. Wiederholen der Schritte 5 und 6, wobei die Spannung in Schritt 6 bei jeder Wiederholung um ΔU erhöht wird - so lange, bis genügend Messpunkte für eine Referenzkurve vorhanden sind.
8. 8. Bestimmung der Parameter m_i des funktionalen Zusammenhangs für einen spezifischen Bereich der Widerstands-Pulsstrom/Pulsspannungs-Kurve, welche sich aus den Messspannungen und Messströmen ergibt, mittels Vergleich der Daten mit angegebenen Funktionen (d. h. bspw. A, B oder C bzw. anderen Anpassungsfunktionen bzw. Fitfunktionen, wobei hierin beide Begriffe synonym verwendet werden).

A method for generating a reference curve for the change in resistance of nanowires made of aluminum oxide, comprising:

1. 1. Deploy:
   • at least one exemplary nanowire made of granular aluminum oxide with approximately the same thickness and width as the nanowires to be modified,
   • at least one voltage and power supply set up in such a way as to generate a voltage and current pulse,
   • at least one measuring device that enables simultaneous electrical contacting of both wire ends and with which a voltage can be applied across the nanowire by means of the voltage source from (b.).
2. 2. With the help of the measuring device, both ends of the exemplary nanowire are electrically contacted with the voltage and power supply.
3. 3. Applying a measuring voltage using the voltage and power supply to determine the output resistance of the nanowire. Taking into account Ohm's law U = R · I and the selected wire geometry as well as the sheet resistance, the expected resistance of the nanowire can be estimated. Based on this, the measuring voltage used should be selected so that the expected measuring current does not exceed 0.1 microampere (µA) in order to avoid an undesired change in resistance.
4. 4. Applying a voltage and thus a current pulse that is larger than the measurement voltage to change the resistance by means of the voltage and power supply. The difference ΔU between the measurement voltage and the voltage that is applied to change the resistance can be selected as small as desired. For these examples, the pulse duration was typically a few tens of milliseconds and ΔU a few millivolts.
5. 5. Apply the measurement voltage from 3. to determine the electrical resistance of the nanowire again.
6. 6. Apply a voltage and thus a current pulse that is 2 · ΔU larger to change the resistance
7. 7. Repeat steps 5 and 6, whereby the voltage in step 6 is increased by ΔU with each repetition - until there are enough measuring points for a reference curve.
8. 8. Determination of the parameters m _{i of} the functional relationship for a specific range of the resistance pulse current / pulse voltage curve, which results from the measurement voltages and measurement currents, by comparing the data with the specified functions (ie for example A, B or C or other adaptation functions or fit functions, both terms being used synonymously here).

With the specific parameters m _i , a value for the required voltage pulse and thus current pulse can be estimated for nanowires from the same class as the nanowire used for the reference curve.

The example described above and the method or exemplary embodiment described therein can be used in addition to or in support of the method described above.

An exemplary application in the field of superconducting circuits is described below:

The method can be used, for example, in the field of superconducting circuits. Superconducting circuits are usually built using thin-film technology from inductances and capacitors as well as one or more non-linear components. The non-linear component is usually a superconducting Josephson tunnel contact, but other types such as e.g. B. semiconducting contacts or wires with a wire thickness in a range from approximately 10 nm to approximately 100 nm, ie in particular nanowires, are possible. The non-linearity manifests itself in a Josephson contact z. B. by a low-loss and variable by a magnetic field inductance. In superconducting circuits, it plays a decisive role for the characteristic properties both in direct and in alternating current operation, how large the inductance of the circuit is. In addition to the geometric inductivity, the kinetic (internal) inductivity of a superconducting nanowire must also be taken into account. In some types of circuits, this is the dominant form of inductance. The kinetic inductance of a superconducting nanowire is directly proportional to its normally conducting resistance, whereby normally conducting is understood to mean the non-superconducting state. A nanowire with a normally conducting resistance in a range from approximately 1 kΩ up to approximately 10 MΩ therefore also generally has an increased kinetic inductance in the superconducting state compared to a nanowire with a smaller resistance compared to the above-mentioned nanowire with a high normal conductivity made of the same material. Since the normal conducting resistance of the nanowire determines the order of magnitude of the kinetic inductance, this can only be achieved by e.g. B. the working temperature or the working current can be influenced to a limited extent and not permanently. If the nanowire is only a few nanometers wide, non-linear effects that depend on the resistance, among other things, can lead to the nanowire having a non-linear inductance. This is based on the fact that the small cross-section of the conductor means that the current density is high and the current-carrying capacity (critical current) is limited to a few nanoamps. Such a nanowire can e.g. B. can be used in superconducting quantum circuits as a non-linear component.

Quantum circuits are a sub-class of superconducting circuits. With a special focus on the inherent quantum properties of the circuit, they enable e.g. B. so-called quantum bit (a so-called qubit) to perform arithmetic operations.

Technical challenges are now based on the fact that the manufacture of superconducting (quantum) circuits depends on very precise compliance with the manufacturing parameters of the inductances, capacitances and non-linear components. In particular, the widespread Josephson tunnel contacts are subject to great manufacturing-related fluctuations, which are often outside of acceptable operational tolerances. A readjustment z. B. the critical current of these tunnel contacts, in particular after a characterization at low temperatures, is generally not possible. This also applies to the magnetic and kinetic inductance and the capacitance of a superconductor in a circuit.

The method disclosed herein enables the controlled and permanent change in the electrical resistance of, in particular, nanowires after such a nanowire has been fabricated. The method can be used, for example, repetitively to determine the electrical resistance of the nanowire, i.e. H. especially of nanowires, systematically and specifically to reduce them to the desired resistance. Since the kinetic inductance is directly linked to the normally conducting electrical resistance, this is also reduced. In the case of a nanowire, the normally conductive electrical resistance is also linked to the critical current, which increases proportionally with reduced resistance. This effect can also be used to adapt the non-linearity of a (quantum) circuit. The inductance and non-linearity of a (quantum) circuit can thus be subsequently adjusted over a wide range. By means of the method disclosed herein, manufacturing tolerances of such nanowires can also be subsequently compensated or adapted.

One embodiment of the method disclosed herein includes, for example, the following method steps:

After lithographic production using conventional thin-film technology, the nanowire is characterized by a small measuring current (e.g. less than 10 ^-7 amps) and the initial electrical resistance is determined. By applying current / voltage pulses with a significantly larger and increasing amplitude (e.g. greater than 10 ^-6 amperes), the resistance of the nanowire is continuously reduced until the targeted end resistance is reached. The change in resistance is permanent. Using the example of granular aluminum oxide nanowires, a change in resistance of several hundred kilohms was demonstrated. It was also shown that the method can be used regardless of the working temperature, ie it can be used both at room temperature and at low temperatures.

It is known that films with a film thickness in a range from approximately 10 nm to approximately 100 nm made of granular aluminum oxide change their electrical resistance when heated to a great extent (cf. [3]).

The method disclosed herein enables a precise technical realization of desired resistance values and the post-correction of manufacturing-related deviations in the normally conducting resistance of lithographically produced nanowires. The prerequisite for the function is that it can be electrically contacted and that the nanowire is connected in such a way that it represents the dominant current path for the readjusting current pulses. We are not aware that a similar process has been used to readjust the resistance. What is special here is that the method disclosed herein makes it possible to provide systematic changes in the resistance value of the normally conducting resistance through the targeted application of currents or voltages.

E.g. In superconducting circuits, the normally conductive electrical resistance of specific components can be of decisive importance for the overall circuit. The normally conductive electrical resistance influences both the (kinetic) inductance and the critical current in the superconducting state. Here the non-linearity is closely related to the critical current connected. In a superconducting quantum circuit, the energy gap between the discrete energy levels is directly linked to the non-linearity or to the inductances and capacities of a superconducting qubit. In conventional superconducting qubits, the nonlinearity is not generated by a superconducting nanowire but by a Josephson tunnel barrier, the manufacture of which is also subject to significant manufacturing-related fluctuations. In order to compensate for this, a magnetic field can be applied to Josephson junctions, but this is generally not locally limited and can therefore also influence other parts of the quantum circuit. An essential advantage of the method presented or disclosed herein is, after characterizing the non-linearity, the critical current or the kinetic inductance, to iteratively change the normally conductive resistance until the desired properties are permanently achieved. Since this can take place independently of the operation of the circuit, there are no interactions of the type described in the previous section when adjusting by means of a temporary magnetic field.

wobei hierbei h und k_B die Planck- bzw. Boltzmann-Konstante repräsentier und R_n den normalleitenden Widerstand. T_c repräsentiert hierbei die supraleitende Phasenübergangstemperatur des Nanodrahts. Bei der Bestimmung der Charakterisierungsmessströme ist besondere Vorsicht geboten, da durch zu hohe Ströme bzw. Spannungen, die zu einer ungewollten Reduzierung des elektrischen Widerstands führen, das Messergebnis verfälscht werden kann. Es sollte daher bei möglichst kleinen Strömen gemessen werden, und gegebenenfalls sollte der Messwert über einen längeren Zeitraum integriert werden. Bei der elektrischen Charakterisierung von granularen Aluminiumoxid-Nanodrähten ist aufgefallen, dass sich der Widerstand bei zu hohen Messströmen mit einer Stromstärke in einem Bereiche von ungefähr 11 µA bis zu ungefähr 100 µA kontinuierlich verringert. Daraufhin wurde der Effekt genauer untersucht. Die Messungen wurden bei Raumtemperatur sowie bei tiefen Temperaturen (d. h. ungefähr -273 °C, (20 mK)) durchgeführt.The process has already been demonstrated in the laboratory on several nanowires made of superconducting granular aluminum oxide of various lengths. For this purpose, the normally conducting resistance was reduced in individual steps by a total of several hundred kiloohms (kΩ), which led to an increase in the critical current from around 0 nanoampere to 250 nanoampere (nA). Superconducting nanowire qubits were produced, the normally conducting resistance changed using the method and the qubit properties including life and coherence times in the superconducting state were determined. The kinetic inductance Lk of a superconducting nanowire is defined as follows using the formula (2): $${\text{L.}}_{\text{k}}=0.18\cdot \text{H}\cdot {\text{R.}}_{\text{n}}\text{/}\left(2\mathrm{\pi }\cdot {\text{k}}_{\text{B.}}\cdot {\text{T}}_{\text{c}}\right)$$

where h and k _{B represent} the Planck and Boltzmann constants and R _n the normally conducting resistance. T _c here represents the superconducting phase transition temperature of the nanowire. Particular caution is required when determining the characterization measurement currents, as excessively high currents or voltages, which lead to an undesired reduction in electrical resistance, can falsify the measurement result. Measurements should therefore be made with the lowest possible currents and, if necessary, the measured value should be integrated over a longer period of time. During the electrical characterization of granular aluminum oxide nanowires, it was noticed that the resistance decreases continuously when the measured currents are too high with a current in a range from approximately 11 µA to approximately 100 µA. The effect was then examined more closely. The measurements were carried out at room temperature as well as at low temperatures (ie approximately -273 ° C, (20 mK)).

The method disclosed herein can be used in all areas in which an adjustable electrical resistance is helpful and its operation is carried out with particularly small electrical currents. This is particularly the case for superconducting circuits. Circuits with a high kinetic inductivity (high kinetic inductance here means greater than the geometric inductance of the circuit) benefit in particular.

Further application possibilities therefore open up in the field of sensor technology for photon and particle detection with photon detectors such as “superconducting nanowire single-photon detectors” (SNSPD) or “microwave kinetic inductance detectors” (MKIT). With these two types of detectors, the normally conductive electrical resistance of the electrical conductors also plays a decisive role in terms of performance. Further specific applications are also given with so-called “parametric amplifiers”. Here z. B. the nonlinear kinetic inductance is used to amplify microwave signals. Other possible applications also exist in the areas of superconducting quantum sensing and computing as well as quantum simulation, which has been developing for around two decades.

Explanations for the manufacture of granular alumina nanowires, including:

1. 1) Durch ein Aufdampfverfahren wird in einer Vakuumkammer ein dünner Metallfilm auf ein dielektrisches Substrat aufgetragen. Das Verfahren wird an einem granularen Aluminiumoxid Film demonstriert. Details zu dem Aufdampfprozess werden weiter unten genauer ausgeführt.
2. 2) Auf den zuvor aufgebrachten Metallfilm wird durch ein Standardverfahren mittels Spincoating ein Doppellacksystem aufgebracht. In einem ersten Schritt wird eine 50-100 nm dicke Polymethylmethacrylat (PMMA) Lackschicht aufgetragen, bevor anschließend eine ungefähr 40 bis zu ungefähr 60 nm dicke Wasserstoff-Silsesquioxan (HSQ, Type XR-1541, Dow Corning) Schicht aufgebracht wird.
3. 3) Mittels Elektronenstrahllithographie werden die Lacke in den Bereichen einer am Computer generierten Struktur belichtet und chemisch entwickelt.
4. 4) Durch ein anisotropes Ätzverfahren wird die entwickelte Lackstruktur in den granularen Aluminiumoxid Metallfilm übertragen. Hierfür wird der Chip in einer Vakuumkammer bei einem Druck von etwa 10 Millibar einem Beschuss mit Argon/Chlor (1:1) Ionen bei einer Leistung von etwa 100 Watt ausgesetzt. Nach einer Bestrahlungsdauer von etwa 1 Minute ist die Lackstruktur in einen etwa 20 Nanometer dicken granularen Aluminiumoxid Film übertragen.
5. 5) Die Lackmaske wird chemisch durch N-Methyl-2-pyrrolidon entfernt (Lift-Off).
6. 6) Die derart generierten Nanodrähte aus granularem Aluminiumoxid werden elektrisch kontaktiert. Hierbei wurden zwei Verfahren erfolgreich getestet, direktes Kontaktieren mit elektrisch leitfähigen Nadeln und Ultraschallbonden mit Aluminium-Draht (Durchmesser 25,4 Mikrometer (µm)).
7. 7) Der elektrische Widerstand der Nanodrähte ist gegeben durch den Flächenwiderstand R_n, die Breite W und die Länge L eines Nanodrahts und ergibt sich zu R = R_n · L / W. Aufgrund von fabrikationsspezifischen Schwankungen in R_n, L und W durch das Verfahren mit den Schritten 1) - 6) ist R somit auch Toleranzen unterworfen, die sich je nach Widerstandswert zwischen ungefähr 0.1 Ohm und ungefähr 1 Ohm bewegen. Typische Werte für R können im Bereich von ungefähr 100 Ohm bis zu ungefähr mehreren Megaohm liegen.
8. 8) R wird durch einen (kleinen) Messstrom von ungefähr I = 10^-7 Ampere überprüft. Hierbei fließt mit Hilfe einer Stromquelle der Messstrom durch den Nanodraht, der zu einem Spannungsabfall U führt und an den Enden des Nanodrahts abgegriffen wird. Der Widerstand R ergibt sich durch den Quotienten R=U/I. Dieses Verfahren wird immer zur Überprüfung des Widerstands durchgeführt. Für den Messstrom muss aufgrund der Drahteigenschaften eine obere Grenze angegeben werden, damit die elektrischen Eigenschaften des Nanodrahts nicht beeinträchtigt werden. Der erlaubte maximale Messstrom ist sowohl abhängig von der Geometrie (L, W) des Nanodrahts, als auch vom Flächenwiderstand R_n. Ein typischer Wert für den maximalen Messstrom I_max liegt im Bereich von etwa 10^-6 Ampere.

The nanowire is produced, for example, by a lithographic technique. This includes the following procedural steps:

1. 1) A thin metal film is applied to a dielectric substrate in a vacuum chamber using a vapor deposition process. The process is demonstrated on a granular aluminum oxide film. Details on the vapor deposition process are set out in more detail below.
2. 2) A double lacquer system is applied to the previously applied metal film using a standard spin coating method. In a first step, a 50-100 nm thick polymethyl methacrylate (PMMA) lacquer layer is applied before an approximately 40 to approximately 60 nm thick hydrogen silsesquioxane (HSQ, Type XR-1541, Dow Corning) layer is applied.
3. 3) Using electron beam lithography, the lacquers are in the areas of a computer generated structure exposed and chemically developed.
4. 4) The developed lacquer structure is transferred to the granular aluminum oxide metal film by an anisotropic etching process. For this purpose, the chip is bombarded with argon / chlorine (1: 1) ions at a power of around 100 watts in a vacuum chamber at a pressure of around 10 millibars. After an irradiation time of about 1 minute, the lacquer structure is transferred into a granular aluminum oxide film about 20 nanometers thick.
5. 5) The lacquer mask is removed chemically using N-methyl-2-pyrrolidone (lift-off).
6. 6) The nanowires made of granular aluminum oxide generated in this way are electrically contacted. Two methods were successfully tested, direct contact with electrically conductive needles and ultrasonic bonding with aluminum wire (diameter 25.4 micrometers (µm)).
7. 7) The electrical resistance of the nanowires is given by the sheet resistance R _n , the width W and the length L of a nanowire and results in R = R _n · L / W. Due to manufacturing-specific fluctuations in R _n , L and W caused by the Procedure with steps 1) - 6), R is therefore also subject to tolerances that vary between approximately 0.1 ohm and approximately 1 ohm, depending on the resistance value. Typical values for R can range from about 100 ohms to about several megohms.
8. 8) R is checked by a (small) measuring current of approximately I = 10 ^-7 amps. With the help of a current source, the measurement current flows through the nanowire, which leads to a voltage drop U and is tapped at the ends of the nanowire. The resistance R results from the quotient R = U / I. This procedure is always used to check resistance. Due to the wire properties, an upper limit must be specified for the measuring current so that the electrical properties of the nanowire are not impaired. The maximum permitted measuring current depends on the geometry (L, W) of the nanowire and on the sheet resistance R _n . A typical value for the maximum measurement current I _max is in the range of approximately 10 ^-6 amperes.

Explanations of the evaporation process:

As stated above, the aim of the method disclosed herein is to produce nanowires with an electrical resistance for an application. The basic requirement for this is to provide a metal film with a suitable sheet resistance R _n . In the following, a process is described which, by adding oxygen, makes it possible to produce granular aluminum oxide films during the evaporation of aluminum, which have values for R _n reproducibly over a range from a few ohms / area square to 10 kiloohms / area square.

1. a) Vor dem eigentlichen Aufdampfverfahren von granularem Aluminiumoxid werden auf ein dielektrisches Substrat zwei elektrisch leitfähige Kontaktstreifen (z. B. aus Platin oder Silber) aufgebracht, die es erlauben, den elektrischen Flächenwiderstand des Filmes in situ, d. h. während des Aufdampfprozesses in der Vakuumkammer, zu messen. Hierfür werden die Kontaktstreifen mit einer metallischen Klemme kontaktiert und über isolierte Drähte sowie über eine elektrische Vakuumdurchführung mit einem Widerstandsmessgerät außerhalb der Vakuumkammer verbunden.
2. b) Der Probenteller mit dem kontaktierten Substrat wird in die Vakuumkammer eingebracht, die anschließend bis zu einem Druck von etwa 10^-8 mbar abgepumpt wird.
3. c) Das Substrat wird durch Beschuss mit Argon-Ionen vor dem Bedampfen gereinigt.
4. d) Der granulare Aluminiumoxid-Film wird durch physisches oder thermisches Verdampfen von Aluminium in einer verdünnten Sauerstoff-Atmosphäre (Partialdruck Sauerstoff von ungefähr 10^-5 mbar) aufgedampft. Der resultierende elektrische Flächenwiderstand des Filmes ergibt sich aus den Parametern Filmdicke FD, Aufdampfrate AR und Sauerstoffpartialdruck P_ox, wobei allerdings für Flächenwiderstände größer 100 Ohm keine präzise Funktion bekannt ist, durch die der Flächenwiderstand bei gegebenen FD, AR, und P_ox vorhergesagt werden kann. Es existieren jedoch Erfahrungswerte, die als Basis für einen Aufdampfprozess verwendet werden können und in der Literatur beschrieben sind.
5. e) Der Schlüssel zu reproduzierbaren Filmen liegt in einem genauen Monitoring des elektrischen Widerstands der granularen Aluminiumoxid-Filme während des Aufdampfprozesses.

The process comprises the following process steps:

1. a) Before the actual vapor deposition process of granular aluminum oxide, two electrically conductive contact strips (e.g. made of platinum or silver) are applied to a dielectric substrate, which allow the electrical sheet resistance of the film to be measured in situ, i.e. during the vapor deposition process in the vacuum chamber, to eat. For this purpose, the contact strips are contacted with a metal clamp and connected to an ohmmeter outside the vacuum chamber via insulated wires and an electrical vacuum feed-through.
2. b) The sample plate with the contacted substrate is placed in the vacuum chamber, which is then pumped out to a pressure of about 10 ^-8 mbar.
3. c) The substrate is cleaned by bombardment with argon ions before vapor deposition.
4. d) The granular aluminum oxide film is deposited by physical or thermal evaporation of aluminum in a dilute oxygen atmosphere (partial pressure of oxygen of approximately 10 ^-5 mbar). The resulting electrical sheet resistance of the film results from the parameters film thickness FD, evaporation rate AR and oxygen partial _pressure P _ox , although no precise function is known for sheet resistances greater than 100 Ohm by which the sheet resistance can be predicted for a given FD, AR and P _ox . However, there are empirical values that can be used as a basis for a vapor deposition process and are described in the literature.
5. e) The key to reproducible films is precise monitoring of the electrical resistance of the granular aluminum oxide films during the vapor deposition process.

In addition, the rate and the thickness of the growing film are continuously measured by means of a quartz oscillator. As soon as the growing film has formed a conductive layer between the two contact strips, Rn can be measured as a function of AR, FD, P _ox . The surface resistance to be expected is continuously extrapolated from this as a function of FD and AR or P _{ox can} be adjusted accordingly that the desired sheet resistance is achieved for a specified thickness.

When determining the resistance, it must be ensured that the lowest possible excitation (usually a measuring current of a few µA) is used to determine the sheet resistance.

f) Once the desired film thickness or the targeted sheet resistance has been reached, the process is ended and the substrate can be removed from the vacuum chamber. If no further measures are taken to protect the surface, the resistance of the granular aluminum oxide film of the removed substrate is slightly increased by the natural oxide layer that is about 3 nm thick. Such a measure can e.g. B. be the additional growth of an insulating aluminum oxide film. This can be achieved by a further aluminum oxide vapor deposition process in connection with an increase in the oxygen partial pressure to values> 10 ^-4 mbar.

Further details and features of the present invention emerge from the following description of a preferred exemplary embodiment, in particular in conjunction with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments or forms.

The exemplary embodiments and forms are shown schematically in the following figures. Here, the same reference numerals in the figures denote the same or functionally identical elements or elements that correspond to one another with regard to their functions.

• 1 eine beispielhafte Graphik zur Veranschaulichung des gemeinsamen funktionalen Zusammenhangs;
• 2 eine schematische Darstellung eines exemplarischen Aufbaus zur Durchführung eines erfindungsgemäßen Verfahrens zum Anpassen des elektrischen Widerstands von einem Nanodraht oder von zusätzlichen Nanodrähten;
• 3 eine schematische Darstellung einer ersten Ausführungsform eines erfindungsgemäßen Verfahrens zum Anpassen des elektrischen Widerstands von einem Nanodraht;
• 4 eine schematische Darstellung einer zweiten Ausführungsform eines erfindungsgemäßen Verfahrens zum Anpassen des elektrischen Widerstands des Nanodrahts sowie zusätzlicher Nanodrähte.

For the purposes of illustration and without restrictive effect, further features and advantages of the invention emerge from the description of the accompanying drawings. Show in it:

• 1 an exemplary graphic to illustrate the common functional relationship;
• 2 a schematic representation of an exemplary structure for performing a method according to the invention for adapting the electrical resistance of a nanowire or additional nanowires;
• 3 a schematic representation of a first embodiment of a method according to the invention for adjusting the electrical resistance of a nanowire;
• 4th a schematic representation of a second embodiment of a method according to the invention for adapting the electrical resistance of the nanowire and additional nanowires.

1 represents an exemplary graphic to illustrate the common functional relationship and has already been described above.

2 shows a schematic representation of an exemplary structure for carrying out a method according to the invention for adapting the electrical resistance of a nanowire or of additional nanowires.

Such an exemplary structure for carrying out the claimed method according to the invention 100 or. 200 according to claims 1 or 2 is arranged as follows:

A nanowire N with an electrical resistance R (N) is over the connection points A. and the pole Pl electrically conductive to the power supply E. connected.

The electrical energy supply E. is set up so that it is attached to the nanowire N between the connection points A. an electrical pulse eP with a predeterminable pulse height ePh and duration ePd can be applied. In addition, the electrical pulse eP is provided by means of a specifiable electrical current I. and a specifiable electrical voltage U formed, and its pulse height ePh is determined by means of the specifiable electrical current I. or the specifiable electrical voltage U regulated (eP (I, U)). The from the electrical energy supply to the nanowire during the pulse duration ePd N The electrical power output P (U, I) is derived from the electrical current flowing during the pulse duration ePd I. and the voltage drop across the nanowire U formed (eP = ePh (I, U), ePd → P (I, U)).

By means of the electrical energy supply E. an electrical measuring pulse eMP with a specifiable, first pulse height eMPh and duration eMPd, ie eMP (eMPh, eMPd), can be applied to the nanowire N between the connection points A. for determining an actual electrical resistance value IRW of the nanowire N be created.

From the electrical power supply E. to the nanowire N between the connection points A. to adjust the resistance R. of the nanowire N Applicable electrical follow-up pulse eFP (is applied if the actual resistance value IRW of the nanowire N is greater than the target resistance value SRW), the pulse height eFPh and / or duration of eFPd, ie eFP (eFPh (P +), eFPd (P +) → eFPh (P ++), eFPd (P ++)). Here, P + denotes a previously determinable, first value compared to the predeterminable, first pulse height eMPh and / or duration eMPd and P ++ a previously determinable, second value compared to the predeterminable, second pulse height eFPh and / or duration eFPd.

The measuring device M. is set up such that when the electrical pulse eP is applied, a measured value MW for the through the nanowire N flowed current I. or a reading MW for one above the nanowire N falling voltage U is detectable. From the measured value MW ( U , I. ) for one through the nanowire N flowed current I. and the measured value MW ( U , I. ) for one over the nanowire N falling voltage U an actual resistance value IRW (MW (U, I) → IRW) of the nanowire N determinable. This can be compared with a previously determined electrical target resistance value SRW (IRW = / ≠ SRW).

3 shows a schematic representation of a first embodiment of a method according to the invention 100 for adjusting the electrical resistance of a nanowire.

A structure or arrangement for carrying out the method 100 includes: a nanowire N , an electrical power supply E. and a measuring device ( M. ). The electrical energy supply E. is electrically conductive with two electrical poles Pl at the electrically conductive connection points A. with the nanowire N connected. In addition, the electrical energy supply E. set up so that it is attached to the nanowire N between the connection points A. an electrical pulse eP with a predeterminable pulse height ePh and duration ePd can be applied. In addition, the electrical pulse eP is provided by means of a specifiable electrical current I. and a specifiable electrical voltage U formed, and its pulse height ePh is determined by means of the specifiable electrical current I. or the specifiable electrical voltage U regulated. The from the electrical energy supply to the nanowire during the pulse duration ePd N The electrical power P output is derived from the electrical current flowing during the pulse duration ePd I. and the voltage drop across the nanowire U educated. The measuring device M. is set up such that when the electrical pulse eP is applied, a measured value MW for the through the nanowire N flowed current I. or a reading MW for one above the nanowire N falling voltage U is detectable. The measured value is MW for one through the nanowire N flowed current I. and the reading MW for one above the nanowire N falling voltage U an actual resistance value IRW of the nanowire N determinable.

The procedure 100 to adjust the electrical resistance R. of a nanowire N between at least two electrically conductive connection points A. , includes:

Providing at least one nanowire N , an electrical power supply E. and a measuring device M. . The electrical energy supply E. is electrically conductive with two electrical poles Pl at the electrically conductive connection points A. with the nanowire N connected. In addition, the electrical energy supply E. set up so that it is attached to the nanowire N between the connection points A. an electrical pulse eP with a predeterminable pulse height ePh and duration ePd can be applied. In addition, the electrical pulse eP is provided by means of a specifiable electrical current I. and a specifiable electrical voltage U formed, and its pulse height ePh is determined by means of the specifiable electrical current I. or the specifiable electrical voltage U regulated. The from the electrical energy supply to the nanowire during the pulse duration ePd N The electrical power P output is derived from the electrical current flowing during the pulse duration ePd I. and the voltage drop across the nanowire U educated. The measuring device M. is set up such that when the electrical pulse eP is applied, a measured value MW for the through the nanowire N flowed current I. or a reading MW for one above the nanowire N falling voltage U is detectable. The measured value is MW for one through the nanowire N flowed current I. and the reading MW for one above the nanowire N falling voltage U an actual resistance value IRW of the nanowire N determinable - 110.

Applying an electrical measuring pulse eMP by means of the electrical energy supply E. to the nanowire with a specifiable, first pulse height eMPh and duration eMPd N between the connection points A. for determining an actual electrical resistance value IRW of the nanowire N - 120 ;

Acquiring - 130 - the measured value MW for the through the nanowire N flowed current I. and the reading MW for one above the nanowire N falling voltage U by means of the measuring device M. - 130;

Determination of an actual electrical resistance value IRW of the nanowire N between the two connection points A. from the measured values MW - 140;

Compare whether the actual electrical resistance value IRW of the nanowire N SRW - 150 is greater than or equal to a predetermined electrical target resistance value;

Applying a subsequent electrical pulse eFP with a predeterminable second pulse height eFPh and / or duration eFPd to the nanowire N between the connection points A. to adjust the resistance R. of the nanowire N when the actual resistance value IRW of the nanowire N is greater than the target resistance value SRW-160, the predeterminable second pulse height eFPh and / or duration eFPd of the subsequent electrical pulse eFP by a previously determinable first value P + compared to the predeterminable first pulse height eMPh and / or duration eMPd of the measuring pulse eMP is increased or longer; and

Repeat the aforementioned process steps 110 to 160 , ie the process step of applying an electrical measuring pulse eMP - 110 up to the process step of applying a subsequent electrical pulse eFP - 160 as long as the actual electrical resistance value IRW of the nanowire N is greater than the previously determinable, electrical target resistance value SRW - 170, with the predeterminable second pulse height eFPh and / or duration eFPd of the subsequent electrical pulse eFP in each iteration by a previously determinable second value P ++ compared to the predeterminable second pulse height eFPh and / or - the duration of the eFPd is increased or longer.

4th shows a schematic representation of a second embodiment of a method according to the invention for adapting the electrical resistance of the nanowire and additional nanowires.

The procedure 200 to adjust the electrical resistance R. of the nanowire N and at least one additional nanowire or additional nanowires Nx, which has a common functional relationship gfZ between the voltage drop across the nanowire U and the current flowing through the nanowire I. comprises:

Carrying out the method steps of the aforementioned method 100 (see description for 3 ), ie the process step of providing a nanowire N , an electrical power supply E. and a measuring device M. - 110 up to the method step of repeating the aforementioned method steps, ie the method step of applying an electrical measuring pulse eMP - 110 up to the process step of applying a subsequent electrical pulse eFP - 160, - 170 of the process 100 according to claim 1 to the nanowire N , this serving as a reference nanowire RN - 210;

Acquisition of a common functional relationship gfZ between the applied electrical subsequent pulses eFP and the respective change in electrical resistance R. in the reference nanowire RN - 220,

Determine a reference curve RK , which is based on the common functional relationship gfZ, by means of method step 230; and

Applying the electrical follow-up pulse (eFP) with a predeterminable second pulse height (eFPh) and / or duration (eFPd) to the nanowire ( N ) between the connection points ( A. ) to adjust the resistance ( R. ) of the nanowire ( N ), whereby the previously determinable, second value P ++ for the predeterminable, second electrical pulse height eFPh and / or duration eFPd of the electrical subsequent pulse eFP is taken from the reference curve RK - 240.

Reading list

• [1] "Materials in Electrical Engineering", Chapter 6, Hansgeorg Hofmann, Jürgen Spindler, 2018, Carl Hanser Verlag Munich;
• [2] "ELECTRONIC MATERIALS HANDBOOK - Volume 1 Packaging", ASM INTERNATIONAL Handbook Committee .
• [3] "Aluminum oxide wires for superconducting high kinetic inductance circuits", H. Rotzinger, et al. Supercond. Sci. Technol. 30 (2017) 025002, doi: 10.1088 / 0953-2048 / 30/2/025002

List of reference symbols

100

Procedure for adjusting the electrical resistance R. of a nanowire N ;

110

Providing at least one nanowire N , a power supply and a measuring device M. according to the features under item 1.1 of claim 1;

120

Applying an electrical measuring pulse eMP according to the technical features under item 1.2 of claim 1;

130

Acquisition of the measured value MW according to the technical feature under point 1.3 of claim 1;

140

Determining an electrical actual resistance value IRW according to the technical feature under item 1.4 of claim 1;

150

Compare whether the actual electrical resistance value IRW of the nanowire N is greater than or equal to a previously determinable, electrical target resistance value SRW according to the feature under item 1.5 of claim 1;

160

Applying a subsequent electrical pulse eFP according to the technical features under point 1.6 of claim 1;

170

Repeating the method steps according to the features under items 1.2 to 1.6 of claim 1 according to the technical features under item 1.7 of claim 1;

200

Procedure 200 to adjust the electrical resistance R. of the nanowire N and the at least one additional nanowire or the additional nanowire (s) Nx with a common functional relationship, based on the method steps according to claim 1

210

Carry out the procedural steps 1.1 to 1.7 of the procedure 100 according to claim 1;

220

Detection of a common functional relationship (gfZ) according to the technical feature under point 2.2 of claim 2

230

Determining a reference curve ( RK ) according to the technical feature under item 2.3 of claim 2;

240

Applying the electrical follow-up pulse (eFP) with a predeterminable second pulse height (eFPh) and / or duration (eFPd) to the nanowire ( N ) between the connection points ( A. ) to adjust the resistance ( R. ) of the nanowire ( N ) according to claim 2;

R.

Electrical resistance;

N

Nanowire;

A.

Connection points;

E.

Power supply that comes with the nanowire N via the Pole Pl and connection points A. is electrically conductively connected;

P1

Pole / pole;

eP

electrical pulse;

ePh

electrical pulse height of the electrical pulse eP;

ePd

electrical pulse duration of the electrical pulse eP;

I.

electrical current;

U

electrical voltage;

M.

Measuring device which is set up in such a way that when the electrical pulse eP is applied, a measured value MW for the through the nanowire N flowed current I. or a reading MW for one above the nanowire N falling voltage U can be detected, from the measured value MW for a through the nanowire N flowed current I. and the measured value MW for one above the nanowire ( N ) falling voltage U an actual resistance value IRW of the nanowire N is determinable;

MW

Measured value, which from the measuring device M. is captured;

IRW

electrical actual resistance value, which can be determined from the measured values;

SRW

previously determinable electrical target resistance value;

eMP

electrical measuring pulse;

eMPh

electrical measurement pulse height of the electrical measurement pulse eMP;

eMPd

electrical measuring pulse duration of the electrical measuring pulse eMP;

eFP

electrical pulse;

eFPh

electrical follow-up pulse height of the electrical follow-up pulse eFP;

eFPd

electrical follow-up pulse duration of the electrical follow-up pulse eFP;

P +

previously determinable, first value compared to the specifiable, first pulse height eMPh and / or duration eMPd;

P ++

previously determinable, second value compared to the predeterminable, second pulse height eFPh and / or duration eFPd;

Nx

additional nanowires which have a common functional relationship between reference nanowire RN and the at least one additional nanowire or the additional nanowires Nx;

RN

Reference nanowire, which is used to determine or record a common functional relationship gfZ between reference nanowire RN and the at least one additional nanowire or additional nanowires Nx;

RK

Reference curve based on the common functional relationship gfZ between reference nanowire RN and the at least one additional nanowire or the additional nanowires Nx;

gfZ

common functional relationship between reference nanowire RN and the at least one additional nanowire or the additional nanowires Nx.

QUOTES INCLUDED IN THE DESCRIPTION

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Non-patent literature cited

• "" ELECTRONIC MATERIALS HANDBOOK - Volume 1 Packaging ", ASM INTERNATIONAL Handbook Committee [0101]
• "Aluminum oxide wires for superconducting high kinetic inductance circuits", H. Rotzinger, et al. Supercond. Sci. Technol. 30 (2017) 025002, doi: 10.1088 / 0953-2048 / 30/2/025002 [0101]

Claims (9)

Method (100) for adapting the electrical resistance (R) of a nanowire (N) between at least two electrically conductive connection points (A), comprising: 1.1. Provide at least - (110): 1.1.1. a nanowire (N); 1.1.2. an electrical energy supply (E), 1.1.2.1. wherein the electrical energy supply (E) with two electrical poles (Pl) is electrically conductively connected to the electrically conductive connection points (A) with the nanowire (N), 1.1.2.2. wherein the electrical energy supply (E) is set up in such a way that an electrical pulse (eP) with a predetermined pulse height (ePh) and duration (ePd) can be applied to the nanowire (N) between the connection points (A), 1.1.2.3. wherein the electrical pulse (eP) is formed by means of a specifiable electrical current (I) and a specifiable electrical voltage (U) and its pulse height (ePh) is regulated by means of the specifiable electrical current (I) or the specifiable electrical voltage (U), and 1.1.2.4. wherein the electrical power (P) delivered by the electrical energy supply to the nanowire (N) during the pulse duration (ePd) is formed from the electrical current (I) flowing during the pulse duration (ePd) and the electrical voltage (U) falling across the nanowire becomes; and 1.1.3. a measuring device (M), 1.1.3.1. wherein the measuring device (M) is set up in such a way that, when the electrical pulse (eP) is applied, a measured value (MW) for the current (I) flowing through the nanowire (N) or a measured value (MW) for a value above the nanowire (N ) falling voltage (U) can be detected, and 1.1.3.2. where from the measured value (MW) for a current (I) flowing through the nanowire (N) and the measured value (MW) for a voltage (U) falling across the nanowire (N) an actual resistance value (IRW) of the nanowire (N) ) is determinable; 1.2. Application of an electrical measuring pulse (eMP) by means of the electrical energy supply (E) with a predeterminable, first pulse height (eMPh) and duration (eMPd) to the nanowire (N) between the connection points (A) to determine an actual electrical resistance value (IRW ) the nanowire (N) - (120); 1.3. Detecting the measured value (MW) for the current (I) flowing through the nanowire (N) and the measured value (MW) for a voltage (U) falling across the nanowire (N) by means of the measuring device (M) - (130); 1.4. Determining an electrical actual resistance value (IRW) of the nanowire (N) between the two connection points (A) from the measured values (MW) - (140); 1.5. Comparing whether the actual electrical resistance value (IRW) of the nanowire (N) is greater than or equal to a previously determinable, desired electrical resistance value (SRW) - (150); 1.6. Applying a subsequent electrical pulse (eFP) with a predeterminable second pulse height (eFPh) and / or duration (eFPd) to the nanowire (N) between the connection points (A) to adjust the resistance (R) of the nanowire (N), if the actual resistance value (IRW) of the nanowire (N) is greater than the target resistance value (SRW) - (160), 1.6.1. where the specifiable, second pulse height (eFPh) and / or duration (eFPd) of the electrical subsequent pulse (eFP) by a previously determinable, first value (P +) compared to the specifiable, first pulse height (eMPh) and / or duration (eMPd) the measuring pulse (eMP) is increased or longer; and 1.7. Repeat method steps 1.2 to 1.6 as long as the actual electrical resistance value (IRW) of the nanowire (N) is greater than the previously determinable, nominal electrical resistance value (SRW) - (170), 1.7.1. where in each iteration the predeterminable, second pulse height (eFPh) and / or duration (eFPd) of the electrical subsequent pulse (eFP) by a previously determinable, second value (P ++) compared to the predeterminable, second pulse height (eFPh) and / or - duration (eFPd) is increased or longer. Method (200) for adapting the electrical resistance (R) of the nanowire (N) and at least one additional nanowire or additional nanowires (Nx), which / which have a common functional relationship (gfZ) between the voltage (U) and the voltage drop across the nanowire the current (I) flowing through the nanowire, comprising: 2.1. Carrying out method steps 1.1 to 1.7 of method (100) according to Claim 1 on the nanowire (N), this serving as a reference nanowire (RN) - (210); 2.2. Detection of a common functional relationship (gfZ) between the applied electrical follow-up pulses (eFP) and the respective change in the electrical resistance (R) in the reference nanowire (RN) - (220), 2.3. Determination of a reference curve (RK), which is based on the common functional relationship (gfZ), by means of method step 2.2- (240); and 2.4. Applying the electrical follow-up pulse (eFP) with a predeterminable, second pulse height (eFPh) and / or duration (eFPd) to the nanowire (N) between the connection points (A) to adapt the resistance (R) of the nanowire (N), 2.4 .1. the specifiable, second electrical pulse height (eFPh) and / or duration (eFPd) of the electrical subsequent pulse (eFP) being taken from the reference curve (RK) - (240). Method (100, 200) according to Claim 1 or 2 , wherein the nanowire (N) and / or the has / have at least one additional nanowire or the additional nanowires (Nx) at least partially aluminum oxide (Al ₂ O ₃ ) or is / are formed therefrom. Method (100, 200) according to one of the Claims 1 to 3 wherein the nanowire (N) and / or the at least one additional nanowire or the additional nanowires (Nx) has a diameter of approximately 10 nm to approximately 200 nm. Method (100, 200) according to one of the Claims 1 to 4th , wherein the nanowire (N) and / or the at least one additional nanowire or the additional nanowires (Nx) has a length in a range from approximately 10 nm to approximately 10 μm. Method (100, 200) according to one of the Claims 1 to 5 , wherein the electrical measuring pulse (eMP) is applied with a current strength in a range from approximately 10 ^-8 A to approximately 10 ^-7 A. Method (100, 200) according to one of the Claims 1 to 6th , wherein the electrical follow-up pulse (eFP) is applied with a pulse duration in a range from approximately 1 ms to approximately 300 ms. Method (100, 200) according to one of the Claims 1 to 7th , wherein the electrical sequence pulse (eFP) is applied with an amplitude of the voltage pulse in a range from approximately 10 ^-3 V to approximately 10 ⁺² V. Method (100, 200) according to one of the Claims 1 to 8th , wherein the nanowire (N) and / or the at least one additional nanowire or the additional nanowires (Nx) is / are cooled to a temperature in a range from approximately 10 mK to approximately 77 K.

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