Method for producing a superconducting workpiece or for changing the superconducting properties of a workpiece

Abstract

The present invention relates to a method for producing a superconducting workpiece (1) or for changing the superconducting properties of a workpiece (1). First, a monocrystalline or polycrystalline body is produced or provided. A further step is the introduction of point defects into a crystal structure of the body, such that stress fields are produced in the crystal structure, wherein the introduction of point defects comprises temperature treatment of the body with at least a first temperature step in which the body is kept at a temperature of 300 to 800°C for at least 10 minutes.

Description

[0001] 1 CH R-11326-24

[0002] 07.08.2025

[0003] Method for manufacturing a superconducting workpiece or for modifying the superconducting properties of a workpiece

[0004] The present invention relates to a method for producing a superconducting workpiece or for modifying the superconducting properties of a workpiece.

[0005] Superconductivity describes a physical phenomenon in which certain materials exhibit no measurable electrical resistance below a critical temperature. The practical application of superconductors is limited by the need for extremely low temperatures and their sensitivity to strong magnetic fields or high currents. These limitations are quantified by the critical temperature, the critical magnetic field, and the critical current density. Improving the superconducting properties of materials, particularly increasing the critical temperature and their resistance to magnetic fields and currents, is of great scientific and technological interest, as it could potentially enable far-reaching applications in fields such as power transmission, medical technology, and quantum computing.

[0006] Besides their vanishing electrical resistance, superconducting materials are characterized by perfect diamagnetism, known as the Meissner-Ochsenfeld effect, which occurs in so-called superconductors of the first kind. Materials that, in the superconducting state below a critical temperature, allow an external magnetic field to penetrate the material in the form of flux quanta are called superconductors of the second kind. 2 CH R-11326-24

[0007] 07.08.2025

[0008] A generally accepted explanation of the phenomenon of superconductivity describes the formation of so-called Cooper pairs, which are coupled charge carriers, especially electrons, that move collectively through the material without dissipating energy.

[0009] In conventional superconductors, this coupling of two charge carriers is ensured by a phonon, i.e., the quantized lattice vibration of a crystal lattice. The mutually repelling charge carriers exchange mechanical momentum via the surrounding crystal lattice and thus experience an effectively attractive interaction even over large distances. For example, the surrounding lattice shields the negatively charged electron more effectively than usual, so that the second electron is attracted by the shielding polarization cloud. The frequency of the averaging phonon must be low for this to occur.

[0010] The present invention is based on the understanding that electrons, in addition to the coupling described via phonons, can also couple with each other in other ways and thus form Cooper pairs. The described coupling requires the exchange of momentum between the charge carriers. Besides lattice vibrations, electrons can exchange momentum via other scattering partners. For example, deviations from the perfect lattice periodicity of a crystal can occur, such as those introduced by point defects. Point defects, which exhibit a volume misfit compared to the crystal lattice, form long-range distortion fields, whereby the displacement of individual lattice atoms, compared to their (perfect) position, decreases with the square of the distance to the point defect. Thus, the distortion field changes only slowly at a certain distance from the point defect itself.Compared to the phonon spectrum, the impulse transfers are small, which is a consequence of the slowly changing distortion field. 3 CH R-11326-24.

[0011] 07.08.2025

[0012] The process can be explained intuitively as follows: In the vicinity of the distorting point defects, the crystal lattice is compressed and thus exhibits a slightly higher density compared to the uncompressed lattice. The electrons, propagating in waveforms, therefore experience an increased refractive index and consequently a slower propagation speed. The shielding effect described above is thus potentiated by the lattice compression, and due to the slowing down, the electron behaves as if under the influence of an attractive potential.

[0013] With a sufficient number of charge carriers and a large spatial extent of the distortion field, there is a high probability that within a short time an electron will be scattered from its original path, transferring a certain amount of momentum, while another electron will absorb precisely this momentum and also be deflected from its path. This can be interpreted as the coupling described above and leads to the generation of a Cooper pair.

[0014] The lattice distortions are stable over the entire temperature range, from well below room temperature to the melting point of the material. The individual atomic displacements are large compared to their thermal motion. Furthermore, the distortion fields are inherently very long-range. Their effect on the charge carriers is therefore very little dependent on temperature and is difficult to mask due to the thermal motion of the atoms. The effect described above using an attractive potential is thus long-range, allowing even distant charge carriers to be coupled together.

[0015] By means of long-range distortion fields caused by point defects, a large number of charge carriers can be coupled to one another, with this coupling being only slightly dependent on the temperature of the material. In this way, high Cooper-pair densities can be achieved, the 4 CH R-11326-24

[0016] 07.08.2025

[0017] The interaction is relatively weakly influenced by temperature. Therefore, distortion fields at point defects can be used to establish particularly high critical temperatures for the transition to the superconducting state, high critical currents, and high critical magnetic fields.

[0018] The object of the present invention is to use these findings for the production of a superconducting workpiece or for the modification, in particular for the improvement, of the superconducting properties of a workpiece.

[0019] The problem is solved by a method with the features of independent patent claims.

[0020] According to the invention, the method for producing a superconducting workpiece or for modifying the superconducting properties of the workpiece is characterized by the following steps:

[0021] First, a monocrystalline liner or polycrystalline body is produced or provided. The crystalline structure of the body must allow the movement of charge carriers within it. Typical monocrystalline or polycrystalline bodies are made of metal or semiconductor materials, for example. Suitable manufacturing methods include conventional crystal growth techniques, such as the Czochralski method.

[0022] A further step is the introduction of point defects into the crystal structure of the body, creating stress fields within the crystal structure. The introduction of point defects includes a temperature treatment of the body with at least one initial temperature step, in which the body is held at a temperature of 300 to 800 °C for at least 10 minutes. The point defects and their stress fields enable 5 CH R-11326-24

[0023] On August 7, 2025, the momentum transfer described above, and thus the coupling of electrons to Cooper pairs, will be achieved. This will allow superconductivity to be created in the body below a critical temperature or for existing superconducting properties of the body to be improved.

[0024] A point defect within the meaning of this invention is in particular a local deviation from the ideal crystal structure (in the polycrystal from the local ideal crystal structure) which extends over an area that is typically no larger than a few atomic distances.

[0025] The first temperature step can, for example, serve the nucleation and stabilization of point defects. In particular, this can lead to the formation of defect clusters that reach a stable nucleus size, preventing their subsequent disintegration. The first temperature step preferably determines the number and distribution of the point defects. Nucleation can occur either homogeneously, i.e., randomly within the crystal lattice, or heterogeneously, i.e., at existing defects or interfaces. Growth can occur through the incorporation of further crystal defects, especially foreign atoms, particularly dopants, lattice vacancies, or interstitial lattice atoms or their agglomerates.

[0026] The duration of the first temperature step can range from 10 minutes to several hours. In particular, the duration can range from one hour to five hours, and especially from three hours. The body can be brought to the temperature of the first temperature step, for example, by means of a defined temperature ramp, in particular by means of a constant temperature increase between 2 °C and 50 °C per minute, and especially at a rate of 15 °C per minute. A duration of at least 10 minutes in this temperature range ensures that a thermodynamic quasi-equilibrium is established in the defect structure, which is important for the stability and reproducibility of the superconducting properties. 6 CH R-11326-24

[0027] 07.08.2025

[0028] The introduction of point defects into the crystalline structure of the body can also include the modification of point defects that already existed during the manufacturing of the body.

[0029] Point defects can have the additional advantage of acting as so-called pinning centers within the crystal. Through the pinning effect, the magnetic flux tubes in superconductors of the second kind are localized, and their migration is suppressed under an applied external current. This allows for higher critical currents and critical magnetic fields than would be possible without pinning centers.

[0030] For this process, it is extremely advantageous if the body is made of a semiconductor material, preferably an elemental semiconductor material, and in particular silicon. Superconductivity has previously been observed only under extreme conditions, or not at all, especially in elemental semiconductors.

[0031] In her doctoral thesis, "Supraconductivite et proprietes physiques du silicium tres fortement dope" (University of Grenoble, 2012), Audrey Grockowiak describes boron doping of silicon down to the atomic percent range. This dopant concentration is far higher than the concentrations typically used in the semiconductor industry. Furthermore, this method requires complex and industrially unproven procedures such as laser implantation. Despite this, the critical temperatures achieved were significantly below 1 K, severely limiting its practical applicability.

[0032] The inventive method enables the simpler generation of superconductivity in elemental semiconductors, thereby opening up the potential for versatile technical applications of these superconducting semiconductors. In particular, the body consists exclusively of a semiconductor material, preferably an elemental semiconductor material, and 7 CH R-11326-24

[0033] August 7, 2025, especially from silicon. The body can, for example, be formed as a wafer, especially from a crystal growth process.

[0034] It is also advantageous if the introduction of point defects involves the introduction of a foreign substance into the material. The targeted introduction of foreign substances allows for precise control over the type and concentration of the resulting defects. By selecting suitable foreign substances, substitution defects or more complex defect structures can be specifically created. The introduction of foreign substances, particularly doping in semiconductor materials, also influences the charge carrier concentration and the Fermi energy of the material, which in turn affects its superconducting properties. By selectively combining the introduction of foreign substances with thermal treatment, an optimal defect structure can be achieved that positively influences the critical temperature, the critical current density, and the critical magnetic field.

[0035] Similarly, the introduction of a foreign substance leading to n- or p-doping of the material offers advantages. Targeted n- or p-doping allows for fine-tuned manipulation of the electronic band structure and charge carrier concentration. In n-doping, additional electrons are introduced into the conduction band, while p-doping creates holes in the valence band. This modification of the charge carrier density directly influences the Fermi energy and the density of states at the Fermi edge, which are crucial parameters for superconducting properties. Furthermore, the type of doping can determine the nature of the charge carriers involved in the formation of Cooper pairs. In n-doped materials, for example, Cooper pairs may be formed predominantly from electrons, while in p-doped materials, holes may potentially assume this role. 8 CH R-11326-24

[0036] 07.08.2025

[0037] Choosing between n- and p-type doping allows for optimization of charge carrier mobility, which in turn affects the coherence length and London penetration depth. These parameters are crucial for the material's behavior in magnetic fields and for the critical current density. The option to select between n- and p-type doping expands the scope for optimizing superconducting properties and enables adaptation to specific application requirements, such as integration into existing semiconductor devices or the realization of Josephson junctions.

[0038] Furthermore, it is advantageous if the foreign substance is oxygen, boron, and / or arsenic. Oxygen, as a group V1 element, tends to form precipitates and complex defect structures in semiconductors such as silicon. These structures generate local distortion fields in the crystal lattice, which, as described above, can serve to couple charge carriers into Cooper pairs. Particularly in silicon, oxygen can be introduced into the crystal lattice during crystal growth, although this effect is normally undesirable. The present invention, however, can utilize this effect and possibly even enhance it by introducing additional oxygen.

[0039] Boron, as a group III element, leads to p-type doping and, at sufficient concentrations, can significantly distort the lattice structure. These distortions modify the phonon spectra and can enhance electron-phonon coupling, which in turn affects the critical temperature. This effect can occur in addition to charge carrier coupling via point defects. Arsenic, as a group V element, causes n-type doping and, due to its size, can also induce lattice distortions. The electrons introduced by arsenic increase the charge carrier density in the conduction band, which affects the plasma frequency and thus the penetration depth of the magnetic field. The combination of these dopants allows for manipulation of the electronic and structural properties of the material. Through targeted doping and thermal 9 CH R-11326-24

[0040] 07.08.2025

[0041] Post-treatment allows the creation of defect structures and electronic states that are advantageous for optimizing the superconducting properties, in particular the critical temperature, critical magnetic field and critical current density.

[0042] It is also highly advantageous if the foreign substance is present in a supersaturated solution within the body at room temperature. The presence of the foreign substance in a supersaturated solution at room temperature creates a metastable state within the body's crystal lattice. This supersaturation generates a thermodynamic disequilibrium, which forms the basis for controlled precipitation and defect formation processes during subsequent temperature treatments. The excess foreign substance atoms exceeding the solubility limit tend to agglomerate and form precipitates or complex defect structures. The supersaturated solution of the foreign substance can be present, in particular, before or during the body's temperature treatment.

[0043] Supersaturation also enables precise control of defect density and distribution through targeted thermal post-treatments. At elevated temperatures, excess foreign atoms can diffuse and lead to nucleation and growth processes, thus allowing control over the size and density of the defect structures. Supersaturation can also influence the electronic structure of the material, particularly by inducing local variations in charge carrier density and band structure. These inhomogeneities can lead to the formation of superconducting islands or filaments, which may be coupled by a Josephson effect and thus at least partially determine the macroscopic superconducting properties of the material.

[0044] In this context, it is advantageous if the point defects include extra-phase inclusions, especially precipitates. Extra-phase inclusions, particularly in the form of precipitates, represent a 10 CH R-11326-24

[0045] August 7, 2025: A special class of point defects exists that have a significant impact on the superconducting properties of the material. These inclusions typically form during thermal treatment from supersaturated solutions of foreign substances. In the case of silicon, these can be, for example, silicon dioxide precipitates that form from excess oxygen. The foreign-phase inclusions generate local distortion fields in the surrounding crystal lattice, which can extend over several atomic layers. These distortion fields act as effective scattering centers for electrons and can thus influence the formation of Cooper pairs. The size and distribution of the precipitates can be precisely controlled by suitable temperature profiles, thereby enabling the establishment of an optimal defect structure for superconductivity.

[0046] Precipitates can also act as the aforementioned pinning centers for magnetic flux tubes, increasing the critical current density of the superconductor. The out-of-phase inclusions also influence the local electronic structure of the material by generating band bending and potential barriers. These can lead to the formation of quantum wells or wires, in which the electron density is locally increased, which in turn can promote Cooper pair formation. The chemical nature of the precipitates can additionally modify electron-phonon coupling, affecting the critical temperature.

[0047] It is also advantageous if the temperature treatment includes a second temperature step in which the body is held at a temperature of 800 to 1100 °C for at least 10 minutes. This second temperature step can promote the further development and growth of the defect structures within the body. In this temperature range, the diffusion rate of the foreign substance atoms, particularly the dopants and point defects, increases significantly, leading to growth and maturation processes. The defect nuclei formed during the first temperature step grow into larger structures, their size and distribution being determined by the 11 CH R-11326-24

[0048] 07.08.2025

[0049] The temperature and duration of this step can be controlled. In silicon, for example, oxygen precipitates can grow to their final size in this temperature range. The elevated temperature also allows for the rearrangement and relaxation of the crystal lattice in the vicinity of the defects, which influences the stress fields and thus the scattering properties for electrons. This process can lead to the formation of coherent or semi-coherent interfaces between the precipitates and the matrix, which in turn modifies the electronic properties at these interfaces.

[0050] The duration of the second temperature step can range from 10 minutes to several hours. In particular, the duration can range from one hour to five hours, and especially three hours. The body can be brought to the temperature of the second temperature step, for example, by means of a defined temperature ramp, in particular by means of a constant temperature increase between 2 °C and 50 °C per minute, and especially 15 °C per minute. The second temperature step can, in particular, follow the first temperature step immediately. A duration of at least 10 minutes in this temperature range ensures that a thermodynamic quasi-equilibrium is established in the defect structure, which is important for the stability and reproducibility of the superconducting properties.

[0051] It is also advantageous if the heat treatment includes a third temperature step, in which the body is held at a temperature of 1100 to 1200 °C for at least 10 minutes. This third temperature step can lead to the maturation of previously formed point defects. For example, the third temperature step can result in so-called Ostwald maturation, in which larger defects grow at the expense of smaller ones. In silicon, this process can lead to the dissolution of smaller oxygen precipitates and the growth of larger precipitates. 12 CH R-11326-24

[0052] 07.08.2025

[0053] Simultaneously, stacking faults and twin grain boundaries can form at these temperatures, which, as two-dimensional defects, influence the electronic structure and thus the superconducting properties. The temperature of 1100 to 1200 °C is close to the melting point of many semiconductor materials, leading to increased solubility of impurities. This allows for a redistribution of impurities and can, in particular, lead to the formation of highly doped regions or segregations at defect boundaries.

[0054] The duration of the third temperature step can range from 10 minutes to several hours. In particular, the duration can range from one hour to five hours, and especially three hours. The body can be brought to the temperature of the third temperature step, for example, by means of a defined temperature ramp, in particular by means of a constant temperature increase between 2 °C and 50 °C per minute, and especially 15 °C per minute. The third temperature step can, in particular, follow directly after the second temperature step. The duration of at least 10 minutes in this temperature range ensures that a thermodynamic quasi-equilibrium is established in the defect structure, which is important for the stability and reproducibility of the superconducting properties.

[0055] It is particularly advantageous if the heat treatment includes a fourth temperature step in which the body is cooled in a controlled manner. This fourth temperature step can, for example, serve to relieve stress within the body and / or to stabilize the created defect structure. The temperature ramp in the fourth temperature step can, for example, be between 2 °C and 50 °C per minute.

[0056] In materials with anisotropic crystal structure, the cooling rate can influence the preferred orientation of defect structures, which can lead to anisotropy in the superconducting properties. Controlled cooling also allows for the adjustment of the interface sharpness between matrix 13 CH R-11326-24.

[0057] August 7, 2025, and precipitates, which influences the electronic structure at these interfaces. Furthermore, the cooling rate can control the density of frozen vacancies and their agglomerates, which serve as additional scattering centers for electrons. In multi-component systems, the cooling rate influences phase separation and can lead to the formation of nanocomposites that modify the superconducting properties at the nanoscale.

[0058] Placing the workpiece in a foreign substance atmosphere during heat treatment offers particular advantages. For example, the foreign substance atmosphere allows atoms or molecules of the foreign substance to penetrate the workpiece during the heat treatment. Specifically, the foreign substance atmosphere creates a defined partial pressure of the foreign substance at the workpiece surface, thereby establishing a chemical potential that drives the diffusion of the foreign substance into the workpiece. This enables, for example, in-situ doping during heat treatment, where the doping depth and concentration can be controlled by the temperature, treatment duration, and partial pressure of the dopant.

[0059] The continuous supply of foreign matter atoms can counteract depletion at the surface and thus ensure a more homogeneous distribution in the volume. At high temperatures, the foreign matter atmosphere can also lead to the generation of surface defects, which serve as nucleation centers for the formation of defect structures in the volume. The presence of the foreign matter atmosphere can also influence the thermodynamic equilibrium between dissolved foreign matter atoms and, for example, precipitates, thereby modifying the kinetics of defect formation and maturation. In multi-component systems, the foreign matter atmosphere can selectively influence the stoichiometry at the surface and lead to the formation of gradients or layered structures that spatially modulate the superconducting properties. The foreign matter atmosphere can also 14 CH R-11326-24

[0060] August 7, 2025, as a source for the formation of interstitial atoms or complex defects. By specifically selecting the composition of the foreign substance atmosphere, co-doping or counter-doping can also be achieved, contributing to the fine-tuning of the electronic structure and superconducting properties.

[0061] Doping of the body can occur during heat treatment via the presence of a dopant atmosphere. However, it is also possible that the body was doped before the heat treatment but is nevertheless placed in a dopant atmosphere during the treatment. The dopant atmosphere may be present only in certain temperature steps of the heat treatment, or different atmospheres, for example with different dopant concentrations, pressures, and / or different dopant substances, may be present in different temperature steps. The body may also be placed in a vacuum in some or all temperature steps.The body can also be placed in a noble gas atmosphere, for example an argon atmosphere, during individual or all temperature steps, in order to suppress reactions of the body with the atmosphere during the temperature treatment or individual temperature steps.

[0062] Furthermore, there are advantages to epitaxially depositing one or more layers onto the substrate. Epitaxial deposition allows for targeted modification of the material's surface properties. This process creates a crystallographically oriented layer that interacts with the substrate in a defined manner. At the interface between the substrate and the epitaxial layer, stress fields arise due to lattice mismatches, and these fields can extend into the body's volume. 15 CH R-11326-24

[0063] 07.08.2025

[0064] The epitaxial layer can, for example, act as a diffusion barrier or source for dopants, thus contributing to the generation of concentration gradients that spatially modulate the superconducting properties. With a suitable choice of layer material, two-dimensional superconducting states can arise at the interface between the substrate and the layer, differing in their properties from those of the bulk material. Multilayer epitaxial structures enable the realization of Josephson junctions or superconducting quantum interference devices (SQUIDs) directly on the substrate.

[0065] The one or more layers may contain, in particular, germanium, silicon-germanium alloys, gallium arsenide, gallium nitride, aluminium nitride, indium phosphide, silicon carbide, zinc oxide, magnesium oxide, strontium titanate, yttrium barium copper oxide, hafnium oxide, zirconium oxide, aluminium oxide and / or titanium nitride.

[0066] It is particularly advantageous if the introduction of point defects involves irradiating the body with electromagnetic radiation and / or particle radiation. In this way, point defects can be selectively introduced into the body's crystal lattice, or existing point defects can be manipulated. Furthermore, the introduction of a foreign substance, especially doping, can be carried out by irradiation.

[0067] For example, when using high-energy electromagnetic radiation, such as X-rays or gamma rays, secondary electrons can be generated through Compton scattering or photoelectric effects, which in turn induce point defects in the lattice. Particle radiation, such as electron, proton, or neutron beams, can directly remove atoms from their lattice sites through collision processes, thus creating, for example, Frenkel pairs. Heavier particles can also be directly incorporated into the crystal lattice, for example, by means of ion implantation. 16 CH R-11326-24

[0068] 07.08.2025

[0069] The type and energy of the radiation used determine the depth distribution and nature of the defects produced. High-energy particles can trigger defect cascades leading to more complex defect structures. Irradiation can also be used for the targeted activation or deactivation of dopants, which influences the local charge carrier concentration. Irradiation performed at low temperatures can generate metastable defect configurations that can be transformed into stable structures advantageous for superconductivity by subsequent thermal treatments. The defects created by irradiation can serve as nucleation centers for the formation of larger defect structures during subsequent temperature treatments.

[0070] The properties of the workpiece produced by the process can be examined using various measurement techniques. For example, defect states in the crystal lattice of the workpiece can be measured by microscopy, chemical etching, and / or diffraction and scattering methods, particularly using electrons, neutrons, and X-rays. Microscopy techniques such as transmission electron microscopy (TEM) allow the direct visualization of point defects, precipitates, and more complex defect structures at the atomic level. High-resolution TEM can also reveal local lattice distortions relevant to electron scattering and the formation of Cooper pairs. Chemical etching, especially selective etching, can be used to visualize the spatial distribution of defects on the workpiece surface. The etch pit density and morphology provide information about the type and concentration of defects.

[0071] Stress states of the workpiece can also be detected by diffraction methods, in particular using electrons, neutrons, and X-rays, especially by determining a static Debye-Waller factor and measuring diffuse scattering intensity near Bragg reflections. The determination of the static Debye-Waller factor by 17 CH R-11326-24

[0072] 07.08.2025

[0073] X-ray or neutron diffraction provides quantitative information about the mean square displacement of atoms from their ideal lattice positions. An increased static Debye-Waller factor indicates the presence of lattice distortions. Analysis of the diffuse scattering intensity near Bragg reflections allows the characterization of short-range ordering phenomena and local distortion fields.

[0074] The workpiece according to the invention is characterized in that it is produced by means of a method according to the preceding description, wherein the described method steps and their features can be implemented individually or in any combination.

[0075] The achievement or improvement of superconducting properties by the method according to the invention promises a wide range of applications for the workpiece. In energy technology, such a workpiece can, for example, be used to manufacture high-performance power cables that, due to their negligible electrical resistance, enable virtually lossless energy transmission over long distances. The increased critical current density and the improved behavior in magnetic fields make the workpiece ideal for use in superconducting magnets, such as those used in magnetic resonance imaging or particle accelerators. The ability to spatially modulate the superconducting properties through targeted defect manipulation allows, for example, the fabrication of Josephson junctions and superconducting quantum interference units directly on a silicon substrate.This may open up possibilities for integrating highly sensitive magnetic field sensors into existing semiconductor technologies, with applications in medical diagnostics and non-destructive material testing.

[0076] The workpiece could potentially be used in the field of quantum information processing to realize qubits. The compatibility of the 18 CH R-11326-24

[0077] 07.08.2025

[0078] Methods using existing silicon-based technologies enable the direct integration of superconducting circuits into conventional semiconductor chips, potentially leading to hybrid systems that combine the advantages of both technologies. In high-frequency technology, these superconducting components can be used to manufacture resonators and filters with extremely high quality factors.

[0079] The single figure shows a schematic view of a workpiece 1 produced according to the invention. The workpiece 1 is provided with eight contacts 2 for measuring the film resistance in a Van der Pauw geometry. In this geometry, a current is applied across two of the contacts 2, and the resulting voltage drop is measured across two other contacts 2. The current path and the voltage path never cross.

[0080] The original body from which workpiece 1 was produced by the inventive method is a boron-doped silicon wafer that was drawn in the [1 00] crystal direction. The initial boron concentration was 10 19 cm -3The body was heated to 800 °C in the first step of a temperature treatment, with a heating rate of 15 °C per minute. The body was held at 800 °C for three hours. This was followed by a second temperature treatment, in which the body was held at 880 °C for three hours. During the temperature treatment, the body was in an atmospheric environment.

[0081] To verify the superconducting properties of workpiece 1, layer resistance measurements were performed with various combinations of contacts 2 at a workpiece 1 temperature of 4.8 K. As a reference, a measurement was also taken of a workpiece 1 in which the process step of introducing point defects was not carried out (also at a temperature of 4.8 K). The following table shows the measurement results.

[0082] The measurement results of the sample produced according to the inventive method exhibit remarkable variability, indicating a significant directional dependence of the conductivity. Compared to the untreated sample, some measurements show a lower resistance. It is noteworthy that the lowest measured resistances of the temperature-treated samples are below the value of the untreated sample, indicating improved conductivity in certain directions. The measurement in the Van der Pauw geometry results in an averaging over different current paths, whereby the measured total resistance is derived from a combination of potentially superconducting (with negligible resistance) and normal-conducting paths.

[0083] In untreated silicon, conductivity is not direction-dependent. Accordingly, anisotropic conductivity was generated by the method according to the invention. The observed anisotropy of the conductivity could be attributed to a directed arrangement of defect structures or precipitates that formed during the temperature treatment and now act as preferred paths for superconducting currents. 20 CHR-1 1326-24

[0084] 07.08.2025

[0085] List of reference signs

[0086] 1 Workpiece 2 Contact

Claims

1. 1 CH R-11326-24 07.08.2025 Patent claims 1. Method for producing a superconducting workpiece (1) or for modifying the superconducting properties of a workpiece (1), wherein the method comprises the following steps: - Production or provision of a single-crystal or polycrystalline body, - Introducing point defects into a crystal structure of the body, such that stress fields are created in the crystal structure, wherein the introduction of point defects includes a temperature treatment of the body with at least one first temperature step in which the body is held at a temperature of 300 to 800 °C for at least 10 minutes.

2. Method according to the preceding claim, characterized in that the body is made of a semiconductor material, in particular an elemental semiconductor material and in particular silicon.

3. Method according to one of the preceding claims, characterized in that the introduction of point defects comprises the introduction of a foreign substance into the body.

4. Method according to the previous claim, characterized in that the introduction of the foreign substance leads to n- or p-doping of the body.

5. Method according to one of claims 3 or 4, characterized in that the foreign substance is oxygen, boron and / or arsenic. 2 CH R-11326-24 07.08.2025 6. Method according to one of claims 3 to 5, characterized in that the foreign substance is present in the body in a supersaturated solution at room temperature.

7. Method according to one of claims 3 to 6, characterized in that the point defects comprise extra-phase inclusions, in particular precipitates.

8. Method according to one of the preceding claims, characterized in that the temperature treatment comprises a second temperature step in which the body is held at a temperature of 800 to 1100 °C for at least 10 minutes.

9. Method according to one of the preceding claims, characterized in that the temperature treatment comprises a third temperature step in which the body is held at a temperature of 1100 to 1200 °C for at least 10 minutes.

10. Method according to one of the preceding claims, characterized in that the temperature treatment comprises a fourth temperature step in which the body is cooled in a controlled manner.

11. Method according to one of the preceding claims, characterized in that the body is arranged in an atmosphere containing foreign substances during the temperature treatment.

12. Method according to one of the preceding claims, characterized in that one or more layers are applied epitaxially to the body.

13. Method according to one of the preceding claims, characterized in that the introduction of point defects involves irradiating the 3 CH R-11326-24 07.08.2025 includes bodies with electromagnetic radiation and / or particle radiation.

14. Workpiece (1) produced according to one or more of the preceding method claims.

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