Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

IBS report electric transport across molybdenum disulfide grain boundaries

27.01.2016

Scientific team from CINAP/IBS identifies previously undiscovered differences in grain boundaries

The Center for Integrated Nanostructure Physics (CINAP) within IBS has reported results correlating the flake merging angle with grain boundary (GBs) properties, and proven that increasing the merging angle of GBs drastically improves the flow of electrons.


Observing the location and angle of the GBs and the atomic structure.

Credit: IBS

This correlates to an increase in the carrier mobility from less than 1 cm2V-1s-1 for small angles, to 16cm2 V-1s-1 for angles greater than 20°. The paper, entitled, 'Misorientation-angle-dependent electrical transport across molybdenum disulfide grain boundaries' is published in the journal Nature Communications.

According to the paper, it is essential to understand the atomic structures of GBs in order to control and improve electrical transport properties in both bulk and low-dimensional materials. Grain boundaries are the direction that atoms are arranged in a material. For the experiments undertaken by scientists at CINAP, a monolayer molybdenum disulfide (MoS2) was grown by chemical vapour deposition (CVD) and subsequently transferred to a substrate of silicon dioxide (SiO2).

The team's reasoning for using MoS2 is twofold: firstly, it is a 2D semiconductor that features high electrical conductance and, crucially, has a natural bandgap, which enables it to be tuned on and off and; secondly, the grain boundaries are well-defined.

This is paramount for successful experiments. Previous research from Northwestern University found that the GBs of MoS2 provided a unique way to modulate resistance; this was achieved by using a large electric field to spatially modulate the location of the grain boundaries.

The Northwestern results, published last year in Nature Nanotechnology, opened a pathway for future research, but the debate regarding the transport physics at the GB is still under dispute. This is due to a large device-to-device performance variation, poor single-domain carrier mobility, and, most importantly, a lack of correlation between transport properties and GB atomic structures in MoS2 research.

The CINAP team, headed by the Center's director Young Hee Lee, overcame these obstacles by directly correlating four-probe transport measurements across single GBs with both high-resolution transmission electron microscopy (TEM) imaging and first-principles calculations. TEM is a microscopy technique whereby a beam of electrons is transmitted through an ultra-thin specimen, interacting with the specimen as it passes through. An exact atomic-scale image is formed from the interaction of the electrons transmitted through the specimen.

Identifying Grain Boundaries

GBs in the MoS2 layers were identified and regions with no sign of wrinkling or multilayers were then selected to prevent misinterpretations. Four-probe transport measurements were then performed on the substrate with surprising results; when measuring flake misorientations of 8-20o, mobility increased from much less than 1 cm2V-1s-1 up to 16cm2 V-1s-1. Above 20o field effect mobility saturates at a 16cm2 V-1s-1 intra-domain cutoff. Thus, GBs between flakes having a misorientation angle of 20-60o show better transport properties.

The team has, as reported in their paper, "provided a more unified picture of the relationship between mobility, merging angle and atomistic structures of the GBs of monolayer MoS2." The results provide practical expectations regarding transport properties in large-area films, which will be restricted largely by the poor mobility across GBs. The results obtained in this work are applicable to other similar 2D systems, and contribute to the fundamental understanding of transport in semiconductors.

Media Contact

Dahee Carol Kim
clitie620@ibs.re.kr
82-428-788-133

http://www.ibs.re.kr/en/ 

Dahee Carol Kim | EurekAlert!

Further reports about: IBS MoS2 atomic structures disulfide molybdenum molybdenum disulfide monolayer

More articles from Physics and Astronomy:

nachricht Observations of nearby supernova and associated jet cocoon provide new insights on gamma-ray bursts
18.01.2019 | George Washington University

nachricht A new twist on a mesmerizing story
17.01.2019 | ETH Zurich Department of Physics

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Ten-year anniversary of the Neumayer Station III

The scientific and political community alike stress the importance of German Antarctic research

Joint Press Release from the BMBF and AWI

The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Additive manufacturing reflects fundamental metallurgical principles to create materials

18.01.2019 | Materials Sciences

How molecules teeter in a laser field

18.01.2019 | Life Sciences

The cytoskeleton of neurons has been found to be involved in Alzheimer's disease

18.01.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>