Hvordan forskere gjorde halvledere superledende

Begrænsninger for superledning

Electricity has been one of the most transformative technologies in history, allowing for the transmission of a very useful form of energy over long distances. But every “normal” electric system faces electric resistance, which results in the generation of heat when an electric current is applied.

Et alternativ findes: superledende materialer. Superledende materialer har nul elektrisk modstand, hvilket gør det muligt for ekstremt kraftige strømme at flyde uden at generere varme.

Uden superledning ville mange moderne teknologier ikke være mulige, herunder partikelacceleratorer (for eksempel CERN), MR‑scannere og maglev‑tog.

Superledning vil blive en afgørende komponent i de mest lovende megaprojekter og teknologiske innovationer, som ITER og kernefusion, masse‑drivere, kvantecomputere, osv.

Strømlinjer uden tab kunne også være afgørende for at udvikle ultra‑lange netværksforbindelser, hjælpe med at udjævne produktionen af vedvarende energi over vejrforhold og tidszoner, og løse nogle af begrænsningerne ved sol‑ og vindenergi.

Dog er superledning indtil nu kun mestret for materialer, der udviser den ved ultra‑lave temperaturer, kun få grader over det absolutte nulpunkt. Eller ved ekstremt højt tryk. Eller begge dele.

This makes it not only too complex for any but the most demanding applications (maglev, MRI, etc.) as well as very costly, making it uneconomical for many applications that could benefit from superconductive materials for any large-scale use.

Mange veje til superledning

It now seems that the material produced under high pressure might be able to retain some of its superconductivity at lower pressure gennem en eksperimentel metode kaldet pressure-quench protocol (PQP).

Recently, det snoede lag af WSe₂ (tungsten selenid) appeared to be a good material candidate for higher-temperature superconductors as well.

Another new class of potential superconductors, bilag‑nickeler, kan også være blevet tilføjet til listen i år.

Still, all of these materials are relatively new and exotic, making them rather far from mass production and deployment at scale.

This could change, thanks to the discovery that germanium-based semiconductors could be turned into superconductors. This research was done by scientists at the University of Queensland (Australia), New York University, ETH Zürich (Switzerland), and The Ohio State University, who published their findings in Nature Nanotechnology¹, under the title “Superconductivity in substitutional Ga-hyperdoped Ge epitaxial thin films”.

Fra halvledere til superledere

Germanium-halvledere

Germanium and silicon are both so-called Group IV elements, with diamond-like crystal structures. This crystalline structure makes them behave as something between a metal (conductive of electricity) and an insulator (non-conductive), making them useful for semiconductor production.

Germanium semiconductor production is already well understood and performed at scale for various electronic and optical devices. Det var faktisk et af de første materialer, der blev brugt til dioder og transistorer, og det blev kun erstattet af silicium takket være de lavere omkostninger og overlegen termisk stabilitet.

Today, germanium, which is crucial for electronics and infrared optics, including sensors on missiles and defense satellites, is mostly produced from zinc and molybdenum mines.

To create superconductivity, you need electrons to pair up, letting them move through the material without resistance.

Allerede i 2023 blev der fundet en superledende fase i germaniumfilm, a work conducted by researchers responsible for this latest discovery, doping gallium material with germanium.

Source: ResearchGate

“This works because group IV elements don’t naturally superconduct under normal conditions, but modifying their crystal structure enables the formation of electron pairings that allow superconductivity.”

Javad Shabani – Director of NYU’s Center of Quantum Information Physics.

Skaleringspotentiale

While previous attempts to create superconducting behavior in semiconductors such as germanium and silicon proved the concept, they struggled to build it at scale.

The main issues were to maintain the atomic structure with appropriate conduction properties. Normally, high levels of gallium destabilize the crystal, preventing superconductivity.

Still, this is a promising idea, as germanium semiconductor manufacturing is a very well-understood technology, with plenty of equipment ready to use.

“Germanium is already a workhorse material for advanced semiconductor technologies, so by showing it can also become superconducting under controlled growth conditions there’s now potential for scalable, foundry-ready quantum devices.”

Dr Peter Jacobson – Researcher at University of Queensland

Ny produktionsmetode

Most doping methods try to implement the ions into the material, but lead to rather irregular results. While that can be enough to improve semiconductor performance, this is too imprecise to induce superconductivity.

Instead, the researchers used a technique called molecular beam epitaxy (MBE). It directs beams of atomic or molecular sources onto a heated substrate in an ultra-high vacuum (UHV) environment.

Source: ExplainThatStuff

This gives precise control over the composition, thickness, and doping of the growing film.

“Rather than ion implantation, molecular beam epitaxy (MBE) was used to precisely incorporate gallium atoms into the germanium’s crystal lattice.

Using epitaxy – growing thin crystal layers – means we can finally achieve the structural precision needed to understand and control how superconductivity emerges in these materials.”

Dr Julian Steele – Researcher at University of Queensland

When using synchrotron-based X-ray absorption, the researchers found that gallium dopants are incorporated within the germanium lattice, introducing a tetragonal distortion to the crystal unit cell.

Source: Nature Nanotechnology

This structural order creates a narrow electronic band for the emergence of superconductivity in Ge.

Source: Nature Nanotechnology

More importantly, this method can work at the wafer-level scale, the same methods used to mass-produce electronics chips.

Source: WaferWorld

“This theoretical work confirmed that gallium atoms substitute neatly into the germanium lattice, creating the electronic conditions for superconductivity.

It’s an elegant example of how computation and experiment together can solve a problem that has challenged materials science for more than half a century.”

Dr Carla Verdi – Researcher at University of Queensland

Anvendelser

The superconductivity this method creates is not a room-temperature superconductivity, as it requires temperatures as low as 3.5°K (-269°C / -453°F), a phenomenon still eluding material science.

Still, the ease of its production, using well-established machinery used by the semiconductor industry, could radically change how superconducting chips are made.

In turn, this could radically change how materials for quantum computers are produced. Most likely, instead of expensive superconducting material, a future quantum computer could be just using a “normal” gallium-germanium semiconductor wafer, turned superconducting in specific spots of the chip.

“These materials opens a pathway for a new era of hybrid quantum devices and could underpin future quantum circuits, sensors and low-power cryogenic electronics, all of which need clean interfaces between superconducting and semiconducting regions.”

Dr Peter Jacobson – Researcher at University of Queensland

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Investering i fremstilling af halvledere

TSMC

Semiconductor production is an industry dominated by the combination of very niche and complex expertise, and the need to mass-produce at scale to reduce costs.

No company has been as successful at mastering this business model as TSMC, the Taiwanese company leading the world in the manufacturing of ultra-advanced chips.

TSMC produces, of course, mostly silicon chips, including the most powerful 3 and 2nm node chips. And as it produces mostly the most advanced and expensive chips, it controls more than half of the global revenues of the semiconductor foundry industry.

Source: Eric Flaningam

TSMC is today evolving to start producing silicon chips in the US, notably with a massive investment in its new Arizona foundries.

Still, TSMC is also an expert at advanced germanium-based transistors and other semiconductors.

So while the company is mostly driving its current profit from advanced chips and the manufacturing of AI-hardware for the likes of Nvidia (NVDA ), it could also be one of the main beneficiaries of the discovery that common semiconductor manufacturing methods can produce.

Seneste TSMC (TSM) aktienyheder og udviklinger

Studie refereret:

^{1. Steele, J.A., Strohbeen, P.J., Verdi, C. et al. Superconductivity in substitutional Ga-hyperdoped Ge epitaxial thin films. Nat. Nanotechnol. (2025). https://doi.org/10.1038/s41565-025-02042-8}