Nav: Home

UNIST engineers oxide semiconductor just single atom thick

February 08, 2017

ULSAN, South Korea--A new study, affiliated with UNIST has introduced a novel method for fabrication of world's thinnest oxide semiconductor that is just one atom thick. This may open up new possibilities for thin, transparent, and flexible electronic devices, such as ultra-small sensors.

This new ultra-thin oxide semiconductors was created by a team of scientists, led by Professor Zonghoon Lee of Materials Science and Engineering at UNIST. In the study, Professor Lee has succeeded in demonstrating the formation of two-dimensional zinc oxide (ZnO) semiconductor with one atom thickness.

This material is formed by directly growing a single-atom-thick ZnO layer on graphene, using atomic layer deposition. It is also the thinnest heteroepitaxial layer of semiconducting oxide on monolayer graphene.

"Flexible, high-performance devices are indispensable for conventional wearable electronics, which have been attracting attention recently," says Professor Lee. "With this new material, we can achieve truly high-performance flexible devices."

Semiconductor technology continually moves toward smaller feature sizes and greater operational efficiency and the existing silicon semiconductors seem to also follow this trend. However, as the fabrication process becomes finer, the performance becomes much critical issue and there has been much research on next-generation semiconductors, which can replace silicon.

Graphene has superior conductivity properties, but it cannot be directly used as an alternative to silicon in semiconductor electronics because it has no band gap. A bandgap gives a material the ability to start and stop the flow of electrons that carry electricity. In graphene, however, electrons move randomly at a constant speed no matter their energy and they cannot be stopped.

To solve this, the research team decided to demonstrate atom-by-atom growth of zinc and oxygen at the preferential zigzag edge of a ZnO monolayer on graphene through in situ observation. Then, they experimentally determine that the thinnest ZnO monolayer has a wide band gap (up to 4.0 eV), due to quantum confinement and graphene-like 'hyper-honeycomb' structure, and high optical transparency.

The currently-existing oxide semiconductors have a relatively large bandgap in the range of 2.9-3.5 eV. The greater the band gap energy, the lower the leakage current and excess noise.

"This is the first time to actually observe the in situ formation of hexagonal structure of ZnO," says Hyo-Ki Hong of Materials Science and Engineering, first author of the paper. "Through this process, we could understand the process and principle of 2D ZnO semiconductor productiom."

"The heteroepitaxial stack of the thinnest 2D oxide semiconductors on graphene has potential for future optoelectronic device applications associated with high optical transparency and flexibility," says Professor Lee. "This study can lead to a new class of 2D heterostructures including semiconducting oxides formed by highly controlled epitaxial growth through a deposition route."
The study has been conducted in collaboration with Professor Jung-Woo Yoo and Professor Young Chul Jun of Materials Science and Engineering, and Professor Sang Kyu Kwak of Energy and Chemical Engineering at UNIST. The findings of this research have appeared in the recent issue of the journal Nano Letters.

Journal Reference

Hyo-Ki Hong et al., "Atomic Scale Study on Growth and Heteroepitaxy of ZnO Monolayer on Graphene," Nano Letters, (2017).

Ulsan National Institute of Science and Technology(UNIST)

Related Graphene Articles:

Graphene is 3D as well as 2D
Graphene is actually a 3D material as well as a 2D material, according to a new study from Queen Mary University of London.
Conductivity at the edges of graphene bilayers
For nanoribbons of bilayer graphene, whose edge atoms are arranged in zigzag patterns, the bands of electron energies which are allowed and forbidden are significantly different to those found in monolayer graphene.
How to purify water with graphene
Scientists from the National University of Science and Technology 'MISIS' together with their colleagues from Derzhavin Tambov State University and Saratov Chernyshevsky State University have figured out that graphene is capable of purifying water, making it drinkable, without further chlorination.
Decoupled graphene thanks to potassium bromide
The use of potassium bromide in the production of graphene on a copper surface can lead to better results.
1 + 1 does not equal 2 for graphene-like 2D materials
Physicists from the University of Sheffield have discovered that when two atomically thin graphene-like materials are placed on top of each other their properties change, and a material with novel hybrid properties emerges, paving the way for design of new materials and nano-devices.
Graphene's magic is in the defects
A team of researchers at the New York University Tandon School of Engineering and NYU Center for Neural Science has solved a longstanding puzzle of how to build ultra-sensitive, ultra-small electrochemical sensors with homogenous and predictable properties by discovering how to engineer graphene structure on an atomic level.
Graphene on the way to superconductivity
Scientists at HZB have found evidence that double layers of graphene have a property that may let them conduct current completely without resistance.
A human enzyme can biodegrade graphene
Graphene Flagship partners discovered that a natural human enzyme can biodegrade graphene.
Sculpting with graphene foam
Rice University scientists have developed a simple way to produce conductive, three-dimensional objects made of graphene foam.
The photoexcited graphene puzzle solved
A boost for graphene-based light detectors.
More Graphene News and Graphene Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.