Nav: Home

Ultra-clean fabrication platform produces nearly ideal 2D transistors

May 17, 2019

New York, NY--May 17, 2019--Semiconductors, which are the basic building blocks of transistors, microprocessors, lasers, and LEDs, have driven advances in computing, memory, communications, and lighting technologies since the mid-20th century. Recently discovered two-dimensional materials, which feature many superlative properties, have the potential to advance these technologies, but creating 2D devices with both good electrical contacts and stable performance has proved challenging.

Researchers at Columbia Engineering report that they have demonstrated a nearly ideal transistor made from a two-dimensional (2D) material stack--with only a two-atom-thick semiconducting layer--by developing a completely clean and damage-free fabrication process. Their method shows vastly improved performance compared to 2D semiconductors fabricated with a conventional process, and could provide a scalable platform for creating ultra-clean devices in the future. The study was published today in Nature Electronics.

VIDEO on the differences between 2D and 3D materials: https://youtu.be/4m-1vxXQHtY

VIDEO on the step-by-step nanofabrication of 2D material stacks: https://youtu.be/JgfkLhMo1fA

"Making devices out of 2D materials is a messy business," says James Teherani, assistant professor of electrical engineering. "Devices vary wildly from run to run and often degrade so fast that you see performance diminish while you're still measuring them."

Having grown tired of the inconsistent results, Teherani's team set out to develop a better way to make stable devices. "So," he explains, "we decided to separate the pristine device from the dirty fabrication processes that lead to variability."

As shown in this new study, Teherani and his colleagues developed a two-step, ultra-clean nanofabrication process that separates the "messy" steps of fabrication - those that involve "dirty" metallization, chemicals, and polymers used to form electrical connections to the device--from the active semiconductor layer. Once they complete the messy fabrication, they could pick up the contacts and transfer them onto the clean active device layer, preserving the integrity of both layers.

"The thinness of these semiconductors is a blessing and a curse," says Teherani. "While the thinness allows them to be transparent and to be picked up and placed wherever you want them, the thinness also means there's nearly zero volume--the device is almost entirely surface. Because of this, any surface dirt or contamination will really degrade a device."

Currently, most devices are not encapsulated with a layer that protects the surface and contacts from contamination during fabrication. Teherani's team showed that their method can now not only protect the semiconductor layer so that they don't see performance degradation over time, but it can also yield high performance devices.

Teherani collaborated with Jim Hone, Wang Fong-Jen Professor of Mechanical Engineering, making use of the fabrication and analysis facilities of the Columbia Nano Initiative and the National Science Foundation-funded Materials Research Science and Engineering Center at Columbia. The team made the transferred contacts from metal embedded in insulating hexagonal boron nitride (h-BN) outside a glovebox and then dry-transferred the contact layer onto the 2D semiconductor, which was kept pristine inside a nitrogen glovebox. This process prevents direct-metallization-induced damage while simultaneously providing encapsulation to protect the device.

Now that the researchers have developed a stable, repeatable process, they are using the platform to make devices that can move out of the lab into real-world engineering problems.

"The development of high performance 2D devices requires advances in the semiconductor materials from which they are made," Teherani adds. "More precise tools like ours will enable us to build more complex structures with potentially greater functionality and better performance."
-end-
About the Study

The study is titled "Transferred via contacts as a platform for ideal two-dimensional transistors."

Authors are: Younghun Jung1, Min Sup Choi1;2, Ankur Nipane3, Abhinandan Borah3, Bumho Kim1, Amirali Zangiabadi4, Takashi Taniguchi5, Kenji Watanabe5, Won Jong Yoo2, James Hone1, and James T. Teherani3
    1 Department of Mechanical Engineering, Columbia Engineering

    2 SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Korea

    3 Department of Electrical Engineering, Columbia Engineering

    4 Department of Applied Physics and Applied Mathematics, Columbia Engineering

    5 National Institute for Materials Science, Japan
The study was supported by the National Science Foundation through CAREER Award (ECCS-1752401) and the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634). This work is also supported by the National Research Foundation of Korea through the Global Research Laboratory (GRL) program (2016K1A1A2912707) and Research Fellow program (2018R1A6A3A11045864).

The authors declare no competing financial interests.

LINKS:

Paper: http://dx.doi.org/10.1038/s41928-019-0245-y

DOI: 10.1038/s41928-019-0245-y

VIDEO on the differences between 2D and 3D materials: https://youtu.be/4m-1vxXQHtY

VIDEO on the step-by-step nanofabrication of 2D material stacks: https://youtu.be/JgfkLhMo1fA

https://www.nature.com/natelectron/

http://engineering.columbia.edu/

https://engineering.columbia.edu/faculty/james-teherani

http://www.ee.columbia.edu/

https://engineering.columbia.edu/faculty/james-hone

https://me.columbia.edu/

http://cni.columbia.edu/

https://datascience.columbia.edu/

Columbia Engineering

Columbia Engineering, based in New York City, is one of the top engineering schools in the U.S. and one of the oldest in the nation. Also known as The Fu Foundation School of Engineering and Applied Science, the School expands knowledge and advances technology through the pioneering research of its more than 220 faculty, while educating undergraduate and graduate students in a collaborative environment to become leaders informed by a firm foundation in engineering. The School's faculty are at the center of the University's cross-disciplinary research, contributing to the Data Science Institute, Earth Institute, Zuckerman Mind Brain Behavior Institute, Precision Medicine Initiative, and the Columbia Nano Initiative. Guided by its strategic vision, "Columbia Engineering for Humanity," the School aims to translate ideas into innovations that foster a sustainable, healthy, secure, connected, and creative humanity.

Columbia University School of Engineering and Applied Science

Related Semiconductor Articles:

Paving a way to achieve unexplored semiconductor nanostructures
A research team of Ehime University paved a way to achieve unexplored III-V semiconductor nanostructures.
Researchers repurpose failed cancer drug into printable semiconductor
Many potential pharmaceuticals end up failing during clinical trials, but thanks to new research from the University of Illinois, biological molecules once considered for cancer treatment are now being repurposed as organic semiconductors for use in chemical sensors and transistors.
Clarification of a new synthesis mechanism of semiconductor atomic sheet
Researchers at Tohoku University in Japan succeeded in clarifying a new synthesis mechanism regarding transition metal dichalcogenides (TMD), which are semiconductor atomic sheets having thickness in atomic order.
Future of portable electronics -- Novel organic semiconductor with exciting properties
Organic semiconductors have advantages over inorganic semiconductors in several areas.
A new method for quantifying crystal semiconductor efficiency
Japanese scientists have found a new way to successfully detect the efficiency of crystal semiconductors.
X-rays reveal monolayer phase in organic semiconductor
An international team of researchers has investigated how the electrical properties of dihexyl-quarterthiophene thin films depend on their structure.
Atomic 'patchwork' using heteroepitaxy for next generation semiconductor devices
Researchers from Tokyo Metropolitan University have grown atomically thin crystalline layers of transition metal dichalcogenides (TMDCs) with varying composition over space, continuously feeding in different types of TMDC to a growth chamber to tailor changes in properties.
Tuning into the LCDs of tomorrow: Exploring the novel IGZO-11 semiconductor
Indium-gallium-zinc oxide ceramics are used as the backplane for flat-panel displays, this was made possible through substantial synergistic contributions coming from the powerhouse that is Japan.
Probing semiconductor crystals with a sphere of light
Tohoku University researchers have developed a technique using a hollow sphere to measure the electronic and optical properties of large semiconducting crystals.
Organic electronics: a new semiconductor in the carbon-nitride family
Teams from Humboldt-Universität and the Helmholtz-Zentrum Berlin have explored a new material in the carbon-nitride family.
More Semiconductor News and Semiconductor Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#542 Climate Doomsday
Have you heard? Climate change. We did it. And it's bad. It's going to be worse. We are already suffering the effects of it in many ways. How should we TALK about the dangers we are facing, though? Should we get people good and scared? Or give them hope? Or both? Host Bethany Brookshire talks with David Wallace-Wells and Sheril Kirschenbaum to find out. This episode is hosted by Bethany Brookshire, science writer from Science News. Related links: Why Climate Disasters Might Not Boost Public Engagement on Climate Change on The New York Times by Andrew Revkin The other kind...
Now Playing: Radiolab

Breaking Bongo
Deep fake videos have the potential to make it impossible to sort fact from fiction. And some have argued that this blackhole of doubt will eventually send truth itself into a death spiral. But a series of recent events in the small African nation of Gabon suggest it's already happening.  Today, we follow a ragtag group of freedom fighters as they troll Gabon's president - Ali Bongo - from afar. Using tweets, videos and the uncertainty they can carry, these insurgents test the limits of using truth to create political change and, confusingly, force us to ask: Can fake news be used for good? This episode was reported and produced by Simon Adler. Support Radiolab today at Radiolab.org/donate.