The future of electronics is atomically thin. Two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides (TMDs), offer unprecedented opportunities for ultra-scaled transistors, flexible devices, and high-performance optoelectronics. However, a persistent bottleneck stands in the way: the contact interface between 2D materials and metal electrodes.
A new review led by researchers at South China Normal University and the International Quantum Academy in Shenzhen provides a comprehensive examination of this critical interface. Published on May 15, 2026, in Nano Research , the paper explores the physics and engineering of 2D material-metal contacts, highlighting both the challenges and opportunities presented by the Schottky barrier.
"The contact interface is no longer just a connection-it is a functional part of the device," said corresponding author Xu Zhou, a professor at South China Normal University. "In transistors, the Schottky barrier is a performance limiter. But in photodetectors or sensors, it becomes an essential component. Understanding this duality is key to designing better devices."
The review outlines how the atomic thinness of 2D materials makes traditional contact engineering approaches-such as heavy doping-ineffective. Instead, the team discusses innovative strategies for achieving ultralow-resistance Ohmic contacts, including van der Waals (vdW) integration, interfacial doping, edge contacts, and the use of semimetals like bismuth and antimony. These methods help overcome Fermi-level pinning (FLP), a phenomenon that often locks the interface into a Schottky behavior regardless of the metal used.
"Fermi level pining (FLP) is one of the most stubborn issues in 2D electronics," explained co-corresponding author Xiaozhi Xu. "It arises from defects, chemical bonding, or strain at the interface. This review emphasizes that by controlling these factors (through cleaner fabrication or novel contact geometries) one can depin the Fermi level and recover tunability."
The authors also explore the functional use of Schottky contacts in devices such as photodetectors and gas sensors, where the built-in electric field enables efficient charge separation and signal modulation. By tailoring the Schottky barrier height, researchers can optimize responsivity, response time, and power consumption.
Looking ahead, the review calls for a shift from empirical contact design to theory-informed engineering, supported by advanced characterization and scalable fabrication techniques. "We need standardized metrology and integration methods that are compatible with existing semiconductor manufacturing," said co-corresponding author Jing Liang. "Only then can 2D materials transition from lab curiosities to industrial realities."
With contributions from a multidisciplinary team of physicists and materials scientists, this review provides a foundational reference for researchers aiming to push the boundaries of 2D electronics and optoelectronics.
This work was supported by the National Natural Science Foundation of China (92577101, 52102044, 52372046 ， 12322406), National Key R&D Program of China (2022YFA1403503), the Guangzhou Science and Technology Program (2025A04J5461), and the Guangdong Provincial Basic and Applied Basic Research
Fund (2023A1515012743).
DOI Link:
https://doi.org/10.26599/NR.2026.94908584
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.
