Graphene Breakthrough: Two New Methods Push Electronic Quality Beyond Traditional Semiconductors

Published on Quantum Server Networks

Graphene reaches ultimate electronic quality

Graphene, the wonder material made of a single layer of carbon atoms arranged in a honeycomb lattice, has long fascinated researchers for its strength, flexibility, and conductivity. While it holds the record for the highest electron mobility at room temperature, its performance at cryogenic conditions has lagged behind traditional semiconductors such as gallium arsenide (GaAs).

Now, in a historic advance, two independent teams—one from the National University of Singapore (NUS) and another from The University of Manchester—have developed methods that finally push graphene’s electronic quality beyond GaAs. The results, published in Nature Communications and Nature, set new records in both transport and quantum mobility, enabling the observation of quantum effects at ultra-low magnetic fields.

The Challenge: Disorder in Graphene Devices

A major obstacle in harnessing graphene’s full potential is electronic disorder. Stray electric fields from charged defects in surrounding materials create fluctuations in charge density—known as electron-hole puddles—that scatter electrons and degrade mobility. Overcoming this issue has been the key to unlocking graphene’s ultimate performance.

Breakthrough Method 1: Twisted Graphene with Electrostatic Screening

The NUS-led team, headed by Assistant Professor Alexey Berdyugin, tackled the problem by stacking two graphene layers with a large twist angle (10–30°). This ensured electronic decoupling while allowing one layer to act as a metallic screen. By doping this layer, they effectively suppressed disruptive electric fields.

The outcome was remarkable: charge inhomogeneity dropped to just a few electrons per square micrometer, transport mobility exceeded 20 million cm²/Vs, and quantum mobility surpassed the best GaAs-based devices. Crucially, Landau quantization—a hallmark of quantum behavior—was observed at magnetic fields as low as 5–6 milli-Tesla, hundreds of times weaker than usually required.

Breakthrough Method 2: Proximity Screening with Graphite

The Manchester-led study, led by Nobel Laureate Sir Andre Geim and Dr. Daniil Domaretskiy, used a different strategy. They placed graphene less than a nanometer away from a metallic graphite gate, separated by an ultrathin dielectric made of hexagonal boron nitride.

This setup created exceptionally strong Coulomb screening, reducing charge disorder to near-pristine levels—roughly one excess electron per 100 million carbon atoms. Hall mobilities reached over 60 million cm²/Vs, surpassing all previous semiconductor benchmarks. Astonishingly, quantum Hall plateaus appeared at fields below 5 milli-Tesla, and Shubnikov–de Haas oscillations emerged at just 1 milli-Tesla, comparable to Earth’s natural magnetic field.

Why This Matters

These complementary approaches address the same core problem—charged impurity disorder—from two different directions. Together, they offer a new toolkit for creating ultra-clean graphene devices that can unlock fundamental physics and power new applications.

  • Quantum Technologies – enabling exploration of correlated electron states and quantum phenomena.
  • High-Speed Electronics – pushing toward faster and more energy-efficient devices.
  • Sensing & Metrology – advancing standards based on the quantum Hall effect.
  • Next-Generation Computing – providing cleaner platforms for emerging quantum information systems.

“These results change what we thought was possible for graphene,” said first author Ian Babich of NUS. “The performance we can now achieve means there is a whole new space of physics to explore.”

➤ Read the original article on TechXplore

Footnote: This blog article was prepared with the assistance of AI technologies to enhance readability and structure.

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