For nearly two decades, two-dimensional (2D) semiconductors have been heralded as the potential successors to silicon transistors, offering the promise of smaller, faster, and more energy-efficient processors. However, new research from Duke University suggests that the methods used to evaluate these transistors may significantly overestimate their performance, posing challenges for their commercial viability.
The study, published online in ACS Nano on February 17, was conducted by a team led by Aaron Franklin, the Edmund T. Pratt, Jr. Distinguished Professor of Electrical and Computer Engineering. The findings indicate that the prevalent use of a “contact gating” architecture in testing inflates the performance metrics of 2D transistors, which could mislead future technological developments.
Understanding the Limitations of Current Testing Methods
Transistors are the fundamental building blocks of computers, responsible for switching electrical currents on and off to create the binary code that underpins all digital technology. While silicon has long been the material of choice for these components, its physical limits are being reached as technology demands ever-smaller and faster processors. This has led researchers to explore 2D materials, which can be as thin as a single atom, for their potential to revolutionize transistor technology.
To evaluate these materials, researchers often employ a “back-gated” architecture, where all components of the transistor are built on a single silicon substrate. This method simplifies fabrication and accelerates experimentation. However, it also introduces the phenomenon of “contact gating,” where the gate not only controls the semiconductor channel but also affects the metal contacts, artificially boosting performance by reducing contact resistance.
Groundbreaking Findings from Duke University
Aaron Franklin’s team, including PhD student Victoria Ravel, has developed a new device architecture to better understand the impact of contact gating. Ravel fabricated a symmetric dual-gate transistor, allowing for a direct comparison between devices with and without contact gating. This innovative approach revealed that contact gating can significantly inflate performance, particularly as devices are scaled down to dimensions relevant for future technologies.
“Most reports of high-performance 2D transistors use a device design that isn’t compatible with commercial technologies,” Franklin explained. “What we show is that this design changes how the transistor operates in a way that can significantly inflate performance.”
The research demonstrated that in larger devices, contact gating roughly doubled performance. As devices were miniaturized, the effect became even more pronounced, with performance boosts of up to six times observed at channel lengths of 50 nanometers and contact lengths of 30 nanometers.
Implications for Future Transistor Technologies
The findings have significant implications for the future of 2D materials in commercial applications. As Franklin noted, “If 2D materials are going to replace silicon channels someday, we need to be honest about how device architecture shapes what we measure. This work is about setting that foundation.”
The team plans to further explore the scaling potential of these materials, aiming to reduce contact lengths to 15 nanometers and experiment with alternative contact metals to minimize resistance. Their broader goal is to establish clearer design rules for integrating 2D semiconductors into future transistor technologies.
This research underscores the importance of developing accurate testing methodologies that reflect the true potential of emerging materials. As the semiconductor industry continues to push the boundaries of technology, understanding these nuances will be crucial for the successful commercialization of next-generation transistors.
CITATION: “Impact of Contact Gating on Scaling of Monolayer 2D Transistors Using a Symmetric Dual-Gate Structure.” Victoria M. Ravel, Sarah R. Evans, Samantha K. Holmes, James L. Doherty, Md Sazzadur Rahman, Tania Roy, and Aaron D. Franklin. ACS Nano, 2026. DOI: 10.1021/acsnano.5c19797
The research was supported by the National Science Foundation under grants 2227175, 2401367, and 2328712.
