Computer-rendered illustration of a nanoribbon transistor made from molybdenum disulfide (MoS₂), one of the two-dimensional semiconductors studied. The blue and yellow spheres represent molybdenum and sulfur atoms. Missing sulfur atoms and red oxygen atoms at the etched edges illustrate possible atomic-scale edge defects, a key concern when narrowing the transistor channel. Gray source and drain metal contacts connect to the channel on each side, while the purple layer underneath represents the gate structure used to control the transistor. The study shows that such atomically thin channels can be narrowed to about 25 nanometers while still retaining well-behaved transistor behavior.
Image Credit: Tara Peña
Scientific Frontline: Extended "At a Glance" Summary: 2D Semiconductor Nanoribbon Transistors
The Core Concept: Two-dimensional (2D) semiconductors are atomically thin materials that can be scaled down to channel widths as small as 25 nanometers without experiencing performance degradation, presenting a viable alternative to traditional silicon in advanced microchips.
Key Distinction/Mechanism: While conventional silicon transistors face fundamental physical limits at nanometer scales, 2D semiconductor transistors utilize a novel "dog-bone" structure. This design features an extremely narrow channel anchored by wider regions under the electrical contacts, allowing the material to maintain precise electrical control and well-behaved switching behavior despite the increased prominence of atomic-scale edge defects.
Major Frameworks/Components:
- Two-dimensional (2D) materials, specifically focusing on molybdenum disulfide and tungsten disulfide.
- Nanoribbon transistor architectures scaled down to 25 nanometers in width (approximately 3,000 times narrower than a human hair).
- A stabilizing "dog-bone" device design to anchor the atomically thin channels.
- Improved metal contact integration, which increased the current density in tungsten disulfide devices by more than 100 times compared to previous demonstrations.
Branch of Science: Nanotechnology, Materials Science, Solid-State Physics, and Electrical Engineering.
Future Application: The development of next-generation, high-performance microchips, enabling more powerful and highly energy-efficient computing architectures that can successfully bypass the physical scaling limitations of silicon.
Why It Matters: As the semiconductor industry struggles to continue shrinking traditional silicon components, proving that 2D materials remain effective and reliable at industry-relevant dimensions removes a critical obstacle to developing the next era of sustainable, low-power electronics.
Atomically thin semiconductors can be scaled down to dimensions relevant for future microchips without losing performance, according to a new study published in Nature Nanotechnology. The finding removes a key obstacle to the use of two-dimensional semiconductors in next-generation electronics and could pave the way for more powerful and energy-efficient computing technologies.
Modern computer chips contain billions of silicon transistors—tiny electrical switches that process, store, and move information. For decades, shrinking these transistors has been the main way to make electronics faster, more powerful, and more energy-efficient. But continuing this trend is becoming increasingly difficult, as the most critical dimensions in advanced transistors are already measured in just a few nanometers. At these dimensions, silicon, the material that dominates modern electronics, begins to face fundamental material limits.
Among the most promising alternatives are atomically thin materials known as two-dimensional, or 2D, semiconductors. These materials consist of a thin layer of atoms, which enables low-power electronics thanks to their excellent electrical control. Yet a major question has remained unanswered: Can they still perform well at the extremely small dimensions required by future chip technologies?
The new study published in Nature Nanotechnology now provides a promising answer. The research team has fabricated transistors from two-dimensional semiconductors with channel widths as small as 25 nanometers—around 3,000 times narrower than a human hair. Despite their tiny size, the devices performed as well as much wider 2D semiconductor transistors. The nanofabrication and electrical characterization were carried out at Stanford University in the United States, while subsequent analysis was completed at Chalmers University of Technology in Sweden.
“These are some of the slimmest high-performance transistors demonstrated in two-dimensional semiconductors,” says Anton Persson, assistant professor at Chalmers University of Technology, Sweden, who co-led the study. “What is particularly encouraging, and actually surprised us, is that the transistors remained well-behaved even when shrunk to dimensions relevant for future industrial technologies. That has been a major uncertainty in the field.”
New Design and Manufacturing Approach Helped Overcome a Key Obstacle
While the exceptional thinness of 2D semiconductors has made them attractive for future electronics, researchers have struggled to reduce their width without degrading their performance. As transistors become narrower, their edges play a larger role, raising concerns that defects and damage could limit their performance. The new study shows that this limitation may be less severe than previously feared.
The researchers fabricated nanoribbon transistors using three different atomically thin 2D semiconductors. Across all three materials, the narrow transistors maintained a well-behaved switching behavior and performance comparable to larger devices.
“The 2D transistors made of tungsten disulfide were especially notable, as their current density improved by more than 100 times compared to previous demonstrations, thanks to better material quality and improved metal contacts,” Persson says.
The breakthrough was enabled by a combination of innovative device design and advanced nanofabrication techniques. The team developed a so-called dog-bone structure, with an extremely narrow transistor channel and wider regions under the electrical contacts to help anchor the material in place.
“Our improved nanofabrication approach was key for achieving these results,” says Tara Peña, postdoctoral scholar in electrical engineering at Stanford and co-lead author of the study. “We hope other researchers will adopt similar methods and continue optimizing 2D devices at industry-relevant dimensions.”
Toward More Sustainable Computing
The findings strengthen the case for atomically thin 2D semiconductors as potential building blocks for future generations of electronics.
“Atomically thin 2D semiconductors have many exciting properties that give us a way to explore what may become possible beyond today’s silicon electronics,” Persson says. “In the long term, technologies based on these materials could contribute to more powerful and energy-efficient electronics.”
Significant challenges remain before this technology reaches commercial production. “Our findings don’t mean that atomically thin 2D semiconductors are ready to replace silicon tomorrow,” says Eric Pop, professor at Stanford University and corresponding author of the study. “But it shows that one of the key scaling concerns may be far less limiting than previously thought.”
More About the Research
The researchers fabricated nanoribbon transistors using three different atomically thin 2D semiconductors: molybdenum disulfide (MoS₂), tungsten disulfide (WS₂), and tungsten diselenide (WSe₂). To prevent the delicate atomically thin material from tearing or peeling during fabrication, the team developed a so-called dog-bone structure. In the new design, the transistor channel is made extremely narrow, while wider regions under the electrical contacts help anchor the material in place. The researchers also employed an advanced multi-patterning technique that etched the material in two steps from different directions, enabling channels as narrow as 25 nanometers.
Funding: This research was supported by the Knut and Alice Wallenberg Foundation, the US Defense Advanced Research Projects Agency (DARPA), the Semiconductor Research Corporation (SRC), the US National Science Foundation (NSF), Intel Corporation, Samsung Electronics, and TSMC through the SystemX Alliance.
Published in journal: Nature Nanotechnology
Title: Scaling nanoribbon transistors with monolayer transition metal dichalcogenides
Authors: Tara Peña, Anton E. O. Persson, Andrey Krayev, Áshildur Friðriksdóttir, Haotian Su, Yuan-Mau Lee, Young Suh Song, Kathryn Neilson, Zhepeng Zhang, Anh Tuan Hoang, Jerry A. Yang, Lauren Hoang, Shan X. Wang, Andrew J. Mannix, Paul C. McIntyre, and Eric Pop
Source/Credit: Chalmers University of Technology | Lovisa Håkansson and Anton Persson
Edited by: Scientific Frontline
Reference Number: nt080326_02