Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Diode a Few Atoms Thick Shows Surprising Quantum Effect

22.06.2015

A quantum mechanical transport phenomenon demonstrated for the first time in synthetic, atomically-thin layered material at room temperature could lead to novel nanoelectronic circuits and devices, according to researchers at Penn State and three other U.S. and international universities.

The quantum transport effect, called negative differential resistance (NDR), was observed when a voltage was applied to structures made of one-atom-thick layers of several layered materials known as van der Waals materials. The three-part structures consist of a base of graphene followed by atomic layers of either molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2), or tungsten diselenide (WSe2).


Yuchuan Lin, Penn State

Current-voltage curves of single junction (green) van der Waals solid (no NDR) and multijunction (red, orange) van der Waals solids (NDR). Stacking and choice of materials determines the location and width of peak.

NDR is a phenomenon in which the wave nature of electrons allows them to tunnel through any material with varying resistance. The potential of NDR lies in low voltage electronic circuits that could be operated at high frequency.

“Theory suggests that stacking two-dimensional layers of different materials one atop the other can lead to new materials with new phenomena,” says Joshua Robinson, a Penn State assistant professor of materials science and engineering whose student, Yu-Chuan Lin, is first author on a paper appearing online today, June 19, in the journal Nature Communications. The paper is titled “Atomically Thin Resonant Tunnel Diodes Built from Synthetic van der Waals Heterostructures.”

Achieving NDR in a resonant tunneling diode at room temperature requires nearly perfect interfaces, which are possible using direct growth techniques, in this case oxide vaporization of molybdenum oxide in the presence of sulfur vapor to make the MoS2 layer, and metal organic chemical vapor deposition to make the WSe2 and MoSe2.

“This is the first time these vertical heterostructures have been grown like this,” Robinson says. “People typically use exfoliated materials that they stack, but it has been extremely difficult to see this phenomenon with exfoliated layers, because the interfaces are not clean. With direct growth we get pristine interfaces where we see this phenomenon every time.”

What caught Lin and Robinson’s attention was a sharp peak and valley in their electrical measurements where there would normally be a regular upward slope. Any unexpected phenomenon, if it is repeatable, is of interest, Robinson says. To explain their results, they consulted an expert in nanoscale electronic devices, Suman Datta, who told them they were seeing a 2D version of a resonant tunneling diode, a quantum mechanical device that operates at low power.

“Resonant tunnel diodes are important circuit components,” says Datta, a coauthor on the paper and Penn State professor of electrical engineering. “Resonant tunneling diodes with NDR can be used to build high frequency oscillators. What this means is we have built the world’s thinnest resonant tunneling diode, and it operates at room temperature!”

Coauthor Robert Wallace of the University of Texas at Dallas says this collaborative work represents an important achievement in the realization of useful 2D integrated circuits. “The ability to observe the resonant behavior at room temperature with synthesized 2D materials rather than exfoliated, stacked flakes is exciting as it points toward the possibilities for scalable device fabrication methods that are more compatible with industrial interests. The challenge we now must address includes improving the grown 2D materials further and obtaining better performance for future device applications,” says Wallace. The UT-Dallas coauthors provided the detailed atomic resolution materials characterization for the resonant tunneling diodes discovered at Penn State.

Datta credits a theoretical understanding of the electron transport in the 2D layered materials to his post-doc, Ram Krishna Ghosh, whose calculations show close correspondence to the experimental results. Datta cautions that the new resonant tunnel diode is just one element in a circuit and the next step will require building and integrating the other circuit elements, such as transistors, in 2D. “The take home message,” he says, “is that this gives us a nugget that we as device and circuit people can start playing around with and build useful circuits for 2D electronics.”

Other coauthors include Sarah Eichfield at Penn State, Rafik Addou, Ning Lu, Hui Zhu, Xin Peng, and Moon Kim, all at UT-Dallas, Ming-Yang Li at Institute of Atomic and Molecular Sciences, Taiwan, and Lain-Jong Li, at King Abdullah University of Science and Technology, Saudi Arabia. The work was performed in conjunction with the Center for Two-Dimensional and Layered Materials (2DLM) at Penn State and supported by the Semiconductor Research Corporation and DARPA through the Center for Low Energy Systems Technology. Work at UT-Dallas was also supported through the Southwest Academy on Nanoelectronics sponsored by the Nanoelectronics Research Initiative and NIST.

DOI 10.1038/ncomms8311

About the Center for Two Dimensional and Layered Materials at Penn State

The 2DLM Center conducts multidisciplinary research in the fast emerging field of atomically thin layered materials. Based in Penn State’s Materials Research Institute, the Center works with industry partners, national labs, and academic collaborators to discover and predict new properties that arise when novel materials are created one atomic layer at a time. Visit the website at http://www.mri.psu.edu/centers/2dlm/ 

Contact Information
Walter Mills
Associate Editor Publications
wem12@psu.edu
Phone: 814-865-0285

Walter Mills | newswise
Further information:
http://www.psu.edu

Further reports about: Atoms Diode MoS2 QUANTUM Technology diodes materials molybdenum phenomenon resistance room temperature structures temperature voltage

More articles from Materials Sciences:

nachricht An innovative high-performance material: biofibers made from green lacewing silk
20.01.2017 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

nachricht Treated carbon pulls radioactive elements from water
20.01.2017 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>