Featured Research

from universities, journals, and other organizations

New semiconductor holds promise for 2-D physics, electronics

Date:
March 20, 2014
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
A unique new semiconductor, rhenium disulfide, that behaves electronically as if it were a 2-D monolayer even as a 3-D bulk material has been discovered by researchers. This not only opens the door to 2-D electronic applications with a 3D material, it also makes it possible to study 2-D physics with easy-to-make 3-D crystals.

From super-lubricants, to solar cells, to the fledgling technology of valleytronics, there is much to be excited about with the discovery of a unique new two-dimensional semiconductor, rhenium disulfide, by researchers at Berkeley Lab's Molecular Foundry. Rhenium disulfide, unlike molybdenum disulfide and other dichalcogenides, behaves electronically as if it were a 2D monolayer even as a 3D bulk material. This not only opens the door to 2D electronic applications with a 3D material, it also makes it possible to study 2D physics with easy-to-make 3D crystals.

Related Articles


"Rhenium disulfide remains a direct-bandgap semiconductor, its photoluminescence intensity increases while its Raman spectrum remains unchanged, even with the addition of increasing numbers of layers," says Junqiao Wu, a physicist with Berkeley Lab's Materials Sciences Division who led this discovery. "This makes bulk crystals of rhenium disulfide an ideal platform for probing 2D excitonic and lattice physics, circumventing the challenge of preparing large-area, single-crystal monolayers."

Wu, who is also a professor with the University of California-Berkeley's Department of Materials Science and Engineering, headed a large international team of collaborators who used the facilities at the Molecular Foundry, a U.S Department of Energy (DOE) national nanoscience center, to prepare and characterize individual monolayers of rhenium disulfide. Through a variety of spectroscopy techniques, they studied these monolayers both as stacked multilayers and as bulk materials. Their study revealed that the uniqueness of rhenium disulfide stems from a disruption in its crystal lattice symmetry called a Peierls distortion.

"Semiconducting transition metal dichalcogenides consist of monolayers held together by weak forces," says Sefaattin Tongay, lead author of a paper describing this research in Nature Communications for which Wu was the corresponding author. The paper was titled "Monolayer behaviour in bulk ReS2 due to electronic and vibrational decoupling."

"Typically the monolayers in a semiconducting transition metal dichalcogenides, such as molybdenum disulfide, are relatively strongly coupled, but isolated monolayers show large changes in electronic structure and lattice vibration energies," Tongay says. "The result is that in bulk these materials are indirect gap semiconductors and in the monolayer they are direct gap."

What Tongay, Wu and their collaborators found in their characterization studies was that rhenium disulfide contains seven valence electrons as opposed to the six valence electrons of molybdenum disulfide and other transition metal dichalcogenides. This extra valence electron prevents strong interlayer coupling between multiple monolayers of rhenium disulfide.

"The extra electron is eventually shared between two rhenium atoms, which causes the atoms to move closer to one another other, forming quasi-one-dimensional chains within each layer and creating the Peierls distortion in the lattice," Tongay says. "Once the Peierls distortion takes place, interlayer registry is largely lost, resulting in weak interlayer coupling and monolayer behavior in the bulk."

Rhenium disulfide's weak interlayer coupling should make this material highly useful in tribology and other low-friction applications. Since rhenium disulfide also exhibits strong interactions between light and matter that are typical of monolayer semiconductors, and since the bulk rhenium disulfide behaves as if it were a monolayer, the new material should also be valuable for solar cell applications. It might also be a less expensive alternative to diamond for valleytronics.

In valleytronics, the wave quantum number of the electron in a crystalline material is used to encode information. This number is derived from the spin and momentum of an electron moving through a crystal lattice as a wave with energy peaks and valleys. Encoding information when the electrons reside in these minimum energy valleys offers a highly promising potential new route to quantum computing and ultrafast data-processing.

"Rhenium atoms have a relatively large atomic weight, which means electron spin-orbit interactions are significant," Tongay says. "This could make rhenium disulfide an ideal material for valleytronics applications."

The collaboration is now looking at ways to tune the properties of rhenium disulfide in both monolayer and bulk crystals through engineered defects in the lattice and selective doping. They are also looking to alloy rhenium disulfide with other members of the dichalcogenide family.


Story Source:

The above story is based on materials provided by DOE/Lawrence Berkeley National Laboratory. The original article was written by Lynn Yarris. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sefaattin Tongay, Hasan Sahin, Changhyun Ko, Alex Luce, Wen Fan, Kai Liu, Jian Zhou, Ying-Sheng Huang, Ching-Hwa Ho, Jinyuan Yan, D. Frank Ogletree, Shaul Aloni, Jie Ji, Shushen Li, Jingbo Li, F. M. Peeters, Junqiao Wu. Monolayer behaviour in bulk ReS2 due to electronic and vibrational decoupling. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4252

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "New semiconductor holds promise for 2-D physics, electronics." ScienceDaily. ScienceDaily, 20 March 2014. <www.sciencedaily.com/releases/2014/03/140320173418.htm>.
DOE/Lawrence Berkeley National Laboratory. (2014, March 20). New semiconductor holds promise for 2-D physics, electronics. ScienceDaily. Retrieved November 25, 2014 from www.sciencedaily.com/releases/2014/03/140320173418.htm
DOE/Lawrence Berkeley National Laboratory. "New semiconductor holds promise for 2-D physics, electronics." ScienceDaily. www.sciencedaily.com/releases/2014/03/140320173418.htm (accessed November 25, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Tuesday, November 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Who Will Failed Nuclear Talks Hurt Most?

Who Will Failed Nuclear Talks Hurt Most?

Reuters - Business Video Online (Nov. 25, 2014) With no immediate prospect of sanctions relief for Iran, and no solid progress in negotiations with the West over the country's nuclear programme, Ciara Lee asks why talks have still not produced results and what a resolution would mean for both parties. Video provided by Reuters
Powered by NewsLook.com
Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Reuters - Innovations Video Online (Nov. 25, 2014) A virtual flying enthusiast converts parts of a written-off Airbus aircraft into a working flight simulator in his northern Slovenian home. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Car Park Solution for Flexible Green Energy

Car Park Solution for Flexible Green Energy

Reuters - Innovations Video Online (Nov. 24, 2014) A British solar power start-up says that by covering millions of existing car park spaces around the UK with flexible solar panels, the country's power problems could be solved. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Newsy (Nov. 23, 2014) Microsoft has robotic security guards working at its Silicon Valley Campus. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins